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Quercetin and its glycosides (QG), vitally natural flavonoid, have been popular for health benefits. However, the absorption and metabolism affect their bioavailability, and the metabolic transformation alters their biological activities. This review systematically summarizes the bioavailability and pathways for the absorption and metabolism of quercetin/QG in vivo and in vitro, the biological activities and mechanism of quercetin/QG and their metabolites in treating glucolipid metabolism are discussed. After oral administration, quercetin/QG are mainly absorbed by the intestine, undergo phase II metabolism in the small intestine and liver to form conjugates and are metabolized into small phenolic acids by intestinal microbiota. Quercetin/QG and their metabolites exert beneficial effects on regulating glucolipid metabolism disorders, including improving insulin resistance, inhibiting lipogenesis, enhancing thermogenesis, modulating intestinal microbiota, relieving oxidative stress, and attenuating inflammation. This review enhances understanding of the mechanism of quercetin/QG regulate glucolipid metabolism and provides scientific support for the development of functional foods., Competing Interests: Declaration of competing interest The authors confirm that they have no conflicts of interest with respect to the work described in this manuscript., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Compared with mono- O -glycosylation, di- O -glycosylation endows the precursor with better performance. However, the mining and engineering of di- O -glycosylation patterns of glycosyltransferases are limited, hindering their synthetic applications. Here, an Arabidopsis xenobiotic-transforming glycosyltransferase, UGT72B1, was found to catalyze the glycosylation of endogenous quercetin and its monoglycosides, generating di- O- glucosides. Mutating M17/G18/Y315 into L/T/Q in UGT72B1 altered its regioselectivity toward quercetin 7- O -glucoside, enzymatically generating another 3,7-di- O -glycoside with up to a 100% conversion rate, and increased the sugar donor preference. Altering the regiospecificity of glycosyltransferases likely required coordination between the entrance and the active site, where the orientations of the sugar acceptors and donors shift to adopt a lower binding energy state. Moreover, quercetin 3,4'-di- O -β-d-glucoside and quercetin 3,7-di- O -β-d-glucoside synthesized were found to have the highest anti-inflammatory activities. Overall, this work presents an efficient strategy to engineer glycosylation patterns for the synthesis of quercetin di- O -β-d-glucosides to be used as food additives, therapeutics, and nutraceuticals.

5-Heptadecylresorcinol (AR-C17), a homologue of alkylresorcinols (ARs) and mainly observed in cereal brans, has stronger physiological functions compared with its homologues. However, not only is its content rare but also the purification low. Besides, few researches on its digestion characteristics and bioavailability limits its maximum applications. Here, we mainly relied on solid-state fermentation, embedment, in vitro models to systematically evaluate processing technologies, digestion and absorption characteristics of AR-C17. We showed that the highest content of AR-C17 was 57.6 μg/g extracted from triticale bran fermented by Saccharomyces cerevisiae relying on ultrasound-assistance. Additionally, AR-C17 was chiefly absorbed in duodenum and jejunum, and its apparent absorption increased by around 2.1 times when quercetin was added as the synergistic agent, which was higher than other phenolics in bran extract. Furthermore, AR-C17 embedded by β-cyclodextrin avoided the decomposition of in strong acidic environment, enhancing the retention rate to 96 % in in vitro digestion. According to the results above, we mixed AR-C17 with the quercetin, and embedded the mixture by β-cyclodextrin, which maximized the apparent absorption of AR-C17, reaching 19.8 % when the ratio of quercetin and AR-C17 was 1:1., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Enzymatically modified isoquercitrin (EMIQ) is a glyco-chemically modified flavonoid exhibiting notably high biological activity, such as antioxidant, anti-inflammatory and anti-allergic properties. However, the utilization of expensive substrates such as isoquercitrin and cyclodextrin in the conventional approach has hindered the industrial-scale production of EMIQ due to high cost and low yields. Hence, the development of a cost-effective and efficient method is crucial for the biological synthesis of EMIQ. In this study, a natural cascade catalytic reaction system was constructed with α-L-rhamnosidase and amylosucrase using the inexpensive substrates rutin and sucrose. Additionally, a novel approach integrating gradient temperature regulation into biological cascade reactions was implemented. Under the optimal conditions, the rutin conversion reached a remarkable 95.39% at 24 h. Meanwhile, the productivity of quercetin-3-O-tetraglucoside with the best bioavailability reached an impressive 41.69%. This study presents promising prospects for future mass production of EMIQ directly prepared from rutin and sucrose., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in the paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Glycogen phosphorylase (GP) is the rate-determining enzyme in glycogenolysis, and its druggability has been extensively studied over the years for the development of therapeutics against type 2 diabetes (T2D) and, more recently, cancer. However, the conservation of binding sites between the liver and muscle isoforms makes the inhibitor selectivity challenging. Using a combination of kinetic, crystallographic, modeling, and cellular studies, we have probed the binding of dietary flavonoids epigallocatechin gallate (EGCG) and epigallocatechin (EGC) to GP isoforms. The structures of rmGPb-EGCG and rmGPb-EGC complexes were determined by X-ray crystallography, showing binding at the quercetin binding site (QBS) in agreement with kinetic studies that revealed both compounds as noncompetitive inhibitors of GP, with EGCG also causing a significant reduction in cell viability and migration of U87-MG glioblastoma cells. Interestingly, EGCG exhibits different binding modes to GP isoforms, revealing QBS as a promising site for GP targeting, offering new opportunities for the design of liver-selective GP inhibitors.

Gut microbiota provides an important insight into clarifying the mechanism of active substances with low bioavailability, but its specific action mechanism varied case by case and remained unclear. Dihydroquercetin (DHQ) is a bioactive flavonoid with low bioavailability, which showed beneficial effects on colitis alleviation and gut microbiota modulation. Herein, we aimed to explore the microbiota-dependent anticolitis mechanism of DHQ in sight of gut microbiota metabolites and their interactions with microRNAs (miRNAs). Dietary supplementation of DHQ alleviated dextran sulfate sodium-induced colitis phenotypes and improved gut microbiota dysbiosis. Fecal microbiota transplantation further revealed that the anticolitis activity of DHQ was mediated by gut microbiota. To clarify how the modulated gut microbiota alleviated colitis in mice, the tandem analyses of the microbiome and targeted metabolome were performed, and altered profiles of metabolite short-chain fatty acids (SCFAs) and bile acids and their producers were observed in DHQ-treated mice. In addition, SCFA treatment showed anticolitis activity compared to that of bile acids, along with the specific inhibition on the phosphoinositide-3-kinase (PI3K)-protein kinase B (Akt) pathway. Subsequently, the colonic miRNA profile of mice receiving SCFA treatment was sequenced, and a differentially expressed miR-10a-5p was identified. Both prediction analysis and dual-luciferase reporter assay indicated that miR-10a-5p directly bind to the 3'-untranslated regions of gene pik 3 ca , inhibit the PI3K-Akt pathway activation, and lead to colitis alleviation. Together, we proposed that gut microbiota mediated the anticolitis activity of DHQ through the SCFAs/miR-10a-5p/PI3K-Akt axis, and it provided a novel insight into clarifying the microbiota-dependent mechanism via the interaction between metabolites and miRNAs.

In recent years, kidney cancer has become one of the most serious medical issues. Kidney cancer is treated with a variety of active compounds that trigger genes that cause cancer. We identified in our earlier research that isoquercitrin (IQ) can activate PIK3CA, IGF1R, and PTGS2. However, it has a very low bioavailability because of its lower solubility in water. So, we utilized sub-merge fermentation technology with two well-known probiotics, Lactobacillus acidophilus and Bacillus subtilis, as a microbial source and mulberry fruit extract as a substrate, which has a high IQ level to improve IQ yield. Furthermore, we compared the total phenolic, flavonoid, and antioxidant contents of fermented and non-fermented samples, and we found that the fermented samples had greater levels than non-fermented sample. In addition, the high-performance liquid chromatography (HPLC) results showed that the fermented mulberry fruit extract from B. subtilis and L. acidophilus showed higher IQ values (190.73 ± 0.004 μg/ml and 220.54 ± 0.007 μg/ml, respectively), compared to the non-fermented samples, which had IQ values (80.12 ± 0.002 μg/ml). Additionally, at 62.5 µg/ml doses of each sample, a normal kidney cell line (HEK 293) showed higher cell viability for fermented and non-fermented samples. Conversely, at the same doses, the fermented samples of L. acidophilus and B. subtilis in a kidney cancer cell line (A498) showed an inhibition of cell growth around 36% and 31%, respectively. Finally, we performed RT and qRT PCR assay, and we found a significant reduction in the expression of the PTGS2, PIK3CA, and IGF1R genes. We therefore can conclude that the fermented samples have a higher concentration of isoquercitrin, and also can inhibit the expression of the genes PTGS2, PIK3CA, and IGF1R, which in turn regulates kidney cancer and inflammation., Competing Interests: Declarations Conflict of Interest The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2024. The Author(s), under exclusive licence to Microbiological Society of Korea.)

Dihydroquercetin is a vital flavonoid compound with a wide range of physiological activities. However, factors, such as metabolic regulation, limit the heterologous synthesis of dihydroquercetin in microorganisms. In this study, flavanone 3-hydroxylase (F3H) and flavanone 3'-hydroxylase (F3'H) were screened from different plants, and their co-expression in Saccharomyces cerevisiae was optimized. Promoter engineering and redox partner engineering were used to optimize the corresponding expression of genes involved in the dihydroquercetin synthesis pathway. Dihydroquercetin production was further improved through multicopy integration pathway genes and systems metabolic engineering. By increasing NADPH and α-ketoglutarate supply, the catalytic efficiency of F3'H and F3H was improved, thereby effectively increasing dihydroquercetin production (235.1 mg/L). Finally, 873.1 mg/L dihydroquercetin titer was obtained by fed-batch fermentation in a 5-L bioreactor, which is the highest dihydroquercetin production achieved through de novo microbial synthesis. These results established a pivotal groundwork for flavonoids synthesis.

This study investigates the potential of a quercetin-based emulsion system to moderate starch digestion and manage blood glucose levels, addressing the lack of in vivo research. By enhancing quercetin bioaccessibility and targeting release in the small intestine, the emulsion system demonstrates significant inhibition of starch digestion and glucose spikes through both in vitro and in vivo experiments. The system inhibits α-amylase and α-glucosidase via competitive and mixed inhibition mechanisms, primarily involving hydrogen bonds and van der Waals forces, leading to static fluorescence quenching. Additionally, this system downregulates the protein expression and gene transcription of SGLT1 and GLUT2. These findings offer a novel approach to sustaining glucose equilibrium, providing a valuable foundation for further application of quercetin emulsion in food science., Competing Interests: Declaration of competing interest We have no conflict of interest to declare., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Background: Quercitrin is a dietary flavonoid widely found in plants with various physiological activities. However, whether quercitrin alters gut microbiota in vivo is not well understood. The aim of this study was to investigate metabolism of quercitrin in the colon and its regulation on gut microbiota in mice., Results: Herein, 22 flavonoids related to quercitrin metabolism were identified based on ultra-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS/MS). Gas chromatography and 16S rDNA gene sequencing were used to investigate short-chain fatty acid (SCFA) content and diversity of composition of gut microbiota, respectively. The results showed that quercitrin significantly alters the beta-diversity of the gut microbiota, probiotics such as Akkermansia and Lactococcus were significantly increased, and the production of propanoate, isovalerate and hexanoate of the quercitrin group were enhanced significantly. The Spearman's association analysis provided evidence that Gardnerella and Akkermansia have obvious correlations with most of quercitrin metabolites and SCFAs., Conclusion: Quercitrin and its metabolites in the colon altered the structure of the mice gut microbiota and increased the content of SCFAs. Our experiments provide valuable insights into quercitrin research and application. © 2024 Society of Chemical Industry., (© 2024 Society of Chemical Industry.)

This study aimed to investigate the mechanism of action of myrrh in breast cancer (BC) treatment and identify its effective constituents. Data on the compounds and targets of myrrh were collected from the TCMSP, PubChem, and Swiss Target Prediction databases. BC-related targets were obtained from the Genecard database. A protein-protein interaction (PPI) analysis, gene ontology (GO) enrichment, and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were conducted on the intersecting targets of the disease and drug. The key targets of myrrh in BC treatment were identified based on the PPI network. The active constituents of myrrh were determined through reverse-screening using the top 20 KEGG pathways. Macromolecular docking studies, molecular dynamic (MD) simulations, and cell assays were utilized to validate the active constituents and critical targets. Network pharmacology indicated that VEGFA, TP53, ESR1, EGFR, and AKT1 are key targets of myrrh. Pelargonidin chloride, Quercetin, and Naringenin were identified as the active constituents of myrrh. Macromolecular docking showed that Quercetin and Naringenin have strong docking capabilities with ESR1. The results of MD simulation experiments align with those of molecular docking experiments. Cell and western blot assays demonstrated that Quercetin and Naringenin could inhibit MCF-7 cells and significantly reduce the expression of ESR1 protein. The findings reveal the active constituents, key targets, and molecular mechanisms of myrrh in BC treatment, providing scientific evidence that supports the role of myrrh in BC therapy. Furthermore, the results suggest that network pharmacology predictions require experimental validation for reliability., (© 2024 John Wiley & Sons Ltd.)

Quercetin (QUE) sufferred from poor processing adaptability and absorbability, hindering its application as a dietary supplement in the food industry. In this study, fatty acids (FAs)-sodium caseinate (NaCas) ligand complexes carriers were fabricated to improve the aqueous dispersibility, storage/thermal stability, and bioaccessibility of QUE using an ultrasound method. The results indicated that all six selected common dietary FAs formed stable hydrophilic complexes with NaCas and the FAs-NaCas complexes achieved an encapsulation efficiency greater than 90 % for QUE. Furthermore, the introduction of FAs enhanced the binding affinity between NaCas and QUE, but did not change the binding mode (static bursting) and types of intermolecular forces (mainly hydrogen bonding). In addition, a distinct improvement was discovered in the storage stability (>2.37-fold), thermal processing stability (>32.54 %), and bioaccessibility (>2.37-fold) of QUE. Therefore, the FAs-NaCas ligand complexes could effectively protect QUE to minimize degradation as fat-soluble polyphenol delivery vehicles., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

In plants, salicylic acid (SA) hydroxylation regulates SA homoeostasis, playing an essential role during plant development and response to pathogens. This reaction is catalysed by SA hydroxylase enzymes, which hydroxylate SA producing 2,3-dihydroxybenzoic acid (2,3-DHBA) and/or 2,5-dihydroxybenzoic acid (2,5-DHBA). Several SA hydroxylases have recently been identified and characterised from different plant species, but no such activity has yet been reported in maize. In this work, we describe the identification and characterisation of a new SA hydroxylase in maize plants. This enzyme, with high sequence similarity to previously described SA hydroxylases from Arabidopsis and rice, converts SA into 2,5-DHBA; however, it has different kinetic properties to those of previously characterised enzymes, and it also catalysers the conversion of the flavonoid dihydroquercetin into quercetin in in vitro activity assays, suggesting that the maize enzyme may have different roles in vivo to those previously reported from other species. Despite this, ZmS5H can complement the pathogen resistance and the early senescence phenotypes of Arabidopsis s3h mutant plants. Finally, we characterised a maize mutant in the S5H gene (s5h Mu ) that has altered growth, senescence and increased resistance against Colletotrichum graminicola infection, showing not only alterations in SA and 2,5-DHBA but also in flavonol levels. Together, the results presented here provide evidence that SA hydroxylases in different plant species have evolved to show differences in catalytic properties that may be important to fine tune SA levels and other phenolic compounds such as flavonols, to regulate different aspects of plant development and pathogen defence., (© 2024 John Wiley & Sons Ltd.)

Transmembrane protease/serine (TMPRSS2), a type II transmembrane serine protease, plays a crucial role in different stages of cancer. Recent studies have reported that the triggering epidermal growth factor receptor (EGFR) activation through protease action promotes metastasis. However, there are no reports on the interaction of TMPRSS2 with EGFR, especially in triple-negative triple negative (TNBC). The current study investigates the unexplored interaction between TMPRSS2 and EGFR, which are key partners mediating metastasis. This interaction is explored for potential targeting using quercetin (QUE) and taxifolin (TAX). TMPRSS2 expression patterns in breast cancer (BC) tissues and subtypes have been predicted, with the prognostic significance assessed using the GENT2.0 database. Validation of TMPRSS2 expression was performed in normal and TNBC tissues, including drug-resistant cell lines, utilizing GEO datasets. TMPRSS2 was further validated as a predictive biomarker for FDA-approved chemotherapeutics through transcriptomic data from BC patients. The study demonstrated the association of TMPRSS2 with EGFR through in silico analysis and validates the findings in TNBC cohorts using the TIMER2.0 web server and the TCGA dataset through C-Bioportal. Molecular docking and molecular dynamic simulation studies identified QUE and TAX as best leads targeting TMPRSS2. They inhibited cell-free TMPRSS2 activity like clinical inhibitor of TMPRSS2, Camostat mesylate. In cell-based assays focused on paclitaxel-resistant TNBC (TNBC/PR), QUE and TAX demonstrated potent inhibitory activity against extracellular and membrane-bound TMPRSS2, with low IC 50 values. Furthermore, ELISA and cell-based AlphaLISA assays demonstrated that QUE and TAX inhibit the interaction of TMPRSS2 with EGFR. Additionally, QUE and TAX exhibited significant inhibition of proliferation and cell cycle accompanied by notable alterations in the morphology of TNBC/PR cells. This study provides valuable insights into potential of QUE and TAX targeting TMPRSS2 overexpressing TNBC., (© 2024 John Wiley & Sons Ltd.)

Cornelian cherry fruits contain a wide range of phenolic acids, flavonoids, and other secondary metabolites. Selected flavonoids may inhibit the perceiving of bitterness, however, the full mechanism with all TAS2R bitter taste receptors is not known. The aim of the study was to determine the inhibitory effect of Cornus mas phenolics against the bitterness receptors TAS2R13 and TAS2R3 through functional in vitro assays and coupling studies. The overall effect was validated by analysing the inhibition of the receptors activity in cells treated with tested cornelian cherry extracts. The strength of interaction with both TAS2R receptors varied between studied compounds with different binding affinity. Most compounds bonded with the TAS2R3 receptor through a long-distant hydrophobic interaction with Trp89A and π-π orbital overlapping-between phenolic and tryptophane aromatic rings. For TAS2R13 observed were various mechanisms of interaction with the compounds. Nonetheless, naringin and quercetin had most similar binding affinity to chloroquine and denatonium-the model agonists for the receptor., (© 2024. The Author(s).)

The Pelargonium genus encompasses around 280 species, most of which are used for medicinal purposes. While P. graveolens, P. odoratissimum, and P. zonale are known to exhibit antimicrobial activity, there is an evident absence of studies evaluating all three species to understand their chemical differences and biological effects. Through the analysis of the hydroalcoholic extracts of P. graveolens, P. odoratissimum, and P. zonale, using HPLC-DAD-MS/MS, quercetin and kaempferol derivatives were identified in these three species. Conversely, gallotannins and anthocyanins were uniquely detected in P. zonale. P. graveolens stood out due to the various types of myricetin derivatives that were not detected in P. odoratissimum and P. zonale extracts. Evaluation of their biological activities revealed that P. zonale displayed superior antibacterial and antibiofilm activities in comparison to the other two species. The antibacterial efficacy of P. zonale was observed towards the clinically relevant strains of Staphylococcus aureus ATCC 25923, Methicillin-resistant Staphylococcus aureus (MRSA) 333, Enterococcus faecalis ATCC 29212, and the Vancomycin-resistant E. faecalis INSPI 032. Fractionation analysis of P. zonale suggested that the antibacterial activity attributed to this plant is due to the presence of quercetin derivatives and kaempferol and its derivatives, alongside their synergistic interaction with gallotannins and anthocyanins. Lastly, the three Pelargonium species exhibited notable antioxidant activity, which may be attributed to their high content of total phenolic compounds., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Celi et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Quercetin is a flavonoid with notable pharmacological effects and promising therapeutic potential. Quercetin plays a significant role in neuroinflammation, which helps reduce Alzheimer's disease (AD) severity. Quercetin (Q) and quercetin 3-O-glucuronide (Q3OG) are some of the most potent antioxidants available from natural sources. However, the natural form of quercetin converted into Q3OG when reacted with intestinal microbes. The study aims to ensure the therapeutic potential of Q and Q3OG. In this study, potential molecular targets of Q and Q3OG were first identified using the Swiss Target Prediction platform and pathogenic targets of AD were identified using the DisGeNET database. Followed by compound and disease target overlapping, 77 targets were placed in that AKT1, EGFR, MMP9, TNF, PTGS2, MMP2, IGF1R, MCL1, MET and PARP1 was the top-ranked target, which was estimated by CytoHubba plug-in. The Molecular docking was performed for Q and Q3OG towards the PDB:1UNQ target. The binding score of Q and Q3OG was - 6.2 kcal/mol and - 6.58 kcal/mol respectively. Molecular dynamics simulation was conducted for Q and Q3OG towards the PDB:1UNQ target at 200 ns. This study's results help identify the multiple target sites for the bioactive compounds. Thus, synthesizing new chemical entity-based quercetin on structural modification may aid in eradicating AD complications., (© 2024. The Author(s).)

This study looked at the effects of acarbose (ACA) and quercetin (QUE) on α-amylase activity, employing QUE and ACA to measure enzyme activity. The study observed that both drugs suppressed α-amylase activity, with greater inhibition reported at higher concentrations. The use of tryptophan residues as an intrinsic fluorescence probe permitted the observation of conformational changes in α-amylase, with CD measurements utilized to explore the secondary structure in the presence of QUE and ACA. Docking studies revealed an effective interaction between α-amylase, quercetin and acarbose, with a higher binding energy. Finally, a trajectory analysis was done to establish the stability and volatility of these complexes. These findings have potential significance for the development of new α-amylase-related therapeutics., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

I-Motif (iM) DNA structures represent among the most significant noncanonical nucleic acid configurations. iM-forming DNA sequences are found in an array of vital genomic locations and are particularly frequent in the promoter islands of various oncogenes. Thus, iM DNA is a crucial candidate for anticancer medicines; therefore, binding interactions between iM DNA and small molecular ligands, such as flavonoids, are critically important. Extensive sets of spectroscopic strategies and thermodynamic analysis were utilized in the present investigation to find out the favorable interaction of quercetin (Que), a dietary flavonoid that has various health-promoting characteristics, including anticancer properties, with noncanonical iM DNA structure. Spectroscopic studies and thermal analysis revealed that Que interacts preferentially with HRAS1 iM DNA compared with VEGF, BCL2 iM, and duplex DNA. Que, therefore, emerged as a suitable natural-product-oriented antagonist for targeting HRAS1 iM DNA. The innovative spectroscopic as well as mechanical features of Que and its specific affinity for HRAS1 iM may be useful for therapeutic applications and provide crucial insights for the design of compounds with remarkable medicinal properties.

Rutin, a flavonoid rich in buckwheat, is important for human health and plant resistance to external stresses. The hydrolysis of rutin to quercetin underlies the bitter taste of Tartary buckwheat. In order to identify rutin hydrolysis genes, a 200 genotypes mini-core Tartary buckwheat germplasm resource was re-sequenced with 30-fold coverage depth. By combining the content of the intermediate metabolites of rutin metabolism with genome resequencing data, metabolite genome-wide association analyses (GWAS) eventually identified a glycosyl hydrolase gene FtGH1, which could hydrolyse rutin to quercetin. This function was validated both in Tartary buckwheat overexpression hairy roots and in vitro enzyme activity assays. Mutation of the two key active sites, which were determined by molecular docking and experimentally verified via overexpression in hairy roots and transient expression in tobacco leaves, exhibited abnormal subcellular localization, suggesting functional changes. Sequence analysis revealed that mutation of the FtGH1 promoter in accessions of two haplotypes might be necessary for enzymatic activity. Co-expression analysis and GWAS revealed that FtbHLH165 not only repressed FtGH1 expression, but also increased seed length. This work reveals a potential mechanism behind rutin metabolism, which should provide both theoretical support in the study of flavonoid metabolism and in the molecular breeding of Tartary buckwheat., (© 2023 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.)

Background: Isoquercitrin (quercetin-3-O-β-D-glucopyranoside) has exhibited promising therapeutic potentials as cardioprotective, anti-diabetic, anti-cancer, and anti-viral agents. However, its structural complexity and limited natural abundance make both bulk chemical synthesis and extraction from medical plants difficult. Microbial biotransformation through heterologous expression of glycosyltransferases offers a safe and sustainable route for its production. Despite several attempts reported in microbial hosts, the current production levels of isoquercitrin still lag behind industrial standards., Results: Herein, the heterologous expression of glycosyltransferase UGT78D2 gene in Bacillus subtilis 168 and reconstruction of UDP-glucose (UDP-Glc) synthesis pathway led to the synthesis of isoquercitrin from quercetin with titers of 0.37 g/L and 0.42 g/L, respectively. Subsequently, the quercetin catabolism blocked by disruption of a quercetin dioxygenase, three ring-cleavage dioxygenases, and seven oxidoreductases increased the isoquercitrin titer to 1.64 g/L. And the hydrolysis of isoquercitrin was eliminated by three β-glucosidase genes disruption, thereby affording 3.58 g/L isoquercitrin. Furthermore, UDP-Glc pool boosted by pgi (encoding glucose-6-phosphate isomerase) disruption increased the isoquercitrin titer to 10.6 g/L with the yield on quercetin of 72% and to 35.6 g/L with the yield on quercetin of 77.2% in a 1.3-L fermentor., Conclusion: The engineered B. subtilis strain developed here holds great potential for initiating the sustainable and large-scale industrial production of isoquercitrin. The strategies proposed in this study provides a reference to improve the production of other flavonoid glycosides by engineered B. subtilis cell factories., (© 2024. The Author(s).)

In this study, the feasibility of shellac nanofibers as carrier system for colonic delivery of quercetin was evaluated. Firstly, the nanofibers without and with different amounts (2.5 %, 5.0 %, and 7.5 %) of quercetin were fabricated using pure shellac as a carrier by electrospinning. The morphology of nanofibers was bead-shape confirmed by SEM. FTIR, XRD, and DSC analysis showed that quercetin was encapsulated into shellac nanofibers, forming an amorphous complex. The molecular docking simulation indicated quercetin bound well to shellac through hydrogen bonding and van der Waals forces. These nanofibers had higher thermal stability than pure quercetin, and their surface wettability exhibited a pH-responsive behavior. The loading capacity of quercetin varied from 2.25 % to 6.84 % with the increased amount of quercetin, and it affected the stability of nanofibers in food simulants by measuring the release profiles of quercetin. The shellac nanofibers had high gastrointestinal stability, with a minimum quercetin release of 16.87 % in simulated digestive fluids, while the remaining quercetin was delivered to the colon and was released gradually. Moreover, the nanofibers exerted enhanced anticancer activity against HCT-116 cells by arresting cell cycle in G0/G1 phase and inducing cell apoptosis. Overall, shellac nanofibers are promising materials for colon-targeted delivery of active compounds., Competing Interests: Declaration of competing interest There have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Auxin regulates flower and fruit abscission, but how developmental signals mediate auxin transport in abscission remains unclear. Here, we reveal the role of the transcription factor BEL1-LIKE HOMEODOMAIN11 (SlBEL11) in regulating auxin transport during abscission in tomato (Solanum lycopersicum). SlBEL11 is highly expressed in the fruit abscission zone, and its expression increases during fruit development. Knockdown of SlBEL11 expression by RNA interference (RNAi) caused premature fruit drop at the breaker (Br) and 3 d post-breaker (Br+3) stages of fruit development. Transcriptome and metabolome analysis of SlBEL11-RNAi lines revealed impaired flavonoid biosynthesis and decreased levels of most flavonoids, especially quercetin, which functions as an auxin transport inhibitor. This suggested that SlBEL11 prevents premature fruit abscission by modulating auxin efflux from fruits, which is crucial for the formation of an auxin response gradient. Indeed, quercetin treatment suppressed premature fruit drop in SlBEL11-RNAi plants. DNA affinity purification sequencing (DAP-seq) analysis indicated that SlBEL11 induced expression of the transcription factor gene SlMYB111 by directly binding to its promoter. Chromatin immunoprecipitation-quantitative polymerase chain reaction and electrophoretic mobility shift assay showed that S. lycopersicum MYELOBLASTOSIS VIRAL ONCOGENE HOMOLOG111 (SlMYB111) induces the expression of the core flavonoid biosynthesis genes SlCHS1, SlCHI, SlF3H, and SlFLS by directly binding to their promoters. Our findings suggest that the SlBEL11-SlMYB111 module modulates flavonoid biosynthesis to fine-tune auxin efflux from fruits and thus maintain an auxin response gradient in the pedicel, thereby preventing premature fruit drop., (© 2024 The Authors. Journal of Integrative Plant Biology published by John Wiley & Sons Australia, Ltd on behalf of Institute of Botany, Chinese Academy of Sciences.)

Helicobacter pylori (HP) infection is the main cause of most cases of gastritis. Quercetin has been shown to have anti-inflammatory, anti-bacterial, and antiviral activities and has been demonstrated to be involved in HP-induced gastric mucosa injury. Moreover, the secretory protein lipocalin-2 (LCN2) was elevated in HP-infected gastric mucosa. Thus, this work aimed to study the interaction between quercetin and LCN2 in HP-triggered gastric injury during gastritis. Human gastric epithelial cell line GES-1 cells were exposed to HP for functional experiments. Cell viability, apoptosis, and inflammation were evaluated by cell counting kit-8, flow cytometry, and enzyme-linked immunosorbent assay, respectively. Levels of genes and proteins were tested using quantitative reverse transcription polymerase chain reaction and western blotting analyses. The interaction between LCN2 and specificity protein 1 (SP1) was validated using chromatin immunoprecipitation assay and dual-luciferase reporter assay. Thereafter, we found quercetin treatment suppressed HP-induced GES-1 cell apoptotic and inflammatory injury and macrophage M1 polarization. LCN2 was highly expressed in HP-infected gastritis patients and HP-infected GES-1 cells, while quercetin reduced LCN2 expression in HP-infected GES-1 cells; moreover, LCN2 knockdown reversed HP-induced GES-1 cell injury and macrophage M1 polarization, and forced expression of LCN2 abolished the protective effects of quercetin on GES-1 cells under HP infection. Mechanistically, SP1 bound to LCN2 promoter and promoted its transcription. Also, SP1 overexpression counteracted the functions of quercetin on HP-stimulated GES-1 cells. In all, quercetin ameliorated HP-induced gastric epithelial cell apoptotic and inflammatory injuries, and macrophage M1 polarization via the SP1/LCN2 axis., (© 2023 John Wiley & Sons, Ltd.)

Scope: Iron deposition is frequently observed in alcoholic liver disease (ALD), which indicates a potential role of ferroptosis in its development. This study aims to explore the effects of quercetin on ferroptosis in ALD and elucidates the underlying mechanism involving the formation of mitochondria-associated endoplasmic reticulum membranes (MAMs) mediated by protein kinase RNA-like endoplasmic reticulum kinase (PERK)., Methods and Results: C57BL/6J mice are fed either a regular or an ethanol-containing liquid diet (with 28% energy form ethanol) with or without quercetin supplementation (100 mg kg -1 BW) for 12 weeks. Ethanol feeding or treatment induced ferroptosis in mice and AML12 cells, which is associated with increased MAMs formation and PERK expression within MAMs. Quercetin attenuates these changes and protects against ethanol-induced liver injury. The antiferroptotic effect of quercetin is abolished by ferroptosis inducers, but mimicked by ferroptosis inhibitors and PERK knockdown. The study demonstrates that PERK structure, rather than its kinase activity (transfected with the K618A site mutation that inhibits kinase activity-ΔK plasmid or protein C terminal knockout-ΔC plasmid of PERK), mediates the enhanced MAMs formation and ferroptosis during the ethanol exposure., Conclusion: Quercetin ameliorates ethanol-induced liver injury by inhibiting ferroptosis via modulating PERK-dependent MAMs formation., (© 2024 Wiley‐VCH GmbH.)

Background: Airway basal cells (BC) from patients with chronic obstructive pulmonary disease (COPD) regenerate abnormal airway epithelium and this was associated with reduced expression of several genes involved in epithelial repair. Quercetin reduces airway epithelial remodeling and inflammation in COPD models, therefore we examined whether quercetin promotes normal epithelial regeneration from COPD BC by altering gene expression., Methods: COPD BC treated with DMSO or 1 µM quercetin for three days were cultured at air/liquid interface (ALI) for up to 4 weeks. BC from healthy donors cultured at ALI were used as controls. Polarization of cells was determined at 8 days of ALI. The cell types and IL-8 expression in differentiated cell cultures were quantified by flow cytometry and ELISA respectively. Microarray analysis was conducted on DMSO or 1 µM quercetin-treated COPD BC for 3 days to identify differentially regulated genes (DEG). Bronchial brushings obtained from COPD patients with similar age and disease status treated with either placebo (4 subjects) or 2000 mg/day quercetin (7 subjects) for 6 months were used to confirm the effects of quercetin on gene expression., Results: Compared to placebo-, quercetin-treated COPD BC showed significantly increased transepithelial resistance, more ciliated cells, fewer goblet cells, and lower IL-8. Quercetin upregulated genes associated with tissue and epithelial development and differentiation in COPD BC. COPD patients treated with quercetin, but not placebo showed increased expression of two developmental genes HOXB2 and ELF3, which were also increased in quercetin-treated COPD BC with FDR < 0.001. Active smokers showed increased mRNA expression of TGF-β (0.067) and IL-8 (22.0), which was reduced by 3.6 and 4.14 fold respectively after quercetin treatment., Conclusions: These results indicate that quercetin may improve airway epithelial regeneration by increasing the expression of genes involved in epithelial development/differentiation in COPD., Trial Registration: This study was registered at ClinicalTrials.gov on 6-18-2019. The study number is NCT03989271., (© 2024. The Author(s).)

Hyperglycemia-related retinopathy is a disease with a high blindness rate. Recent reports indicate that many flavonol compounds have the potential to prevent the occurrence of disease in the retina by regulating the gut-retina axis. Here, we hypothesized that quercetin could alleviate the symptoms of retinopathy. To clarify the mechanism, Sprague Dawley rats were fed a high-fat diet containing quercetin for 12 weeks and injected with streptozotocin in the ninth week. Additionally, neomycin and ampicillin were used to establish a pseudo-sterile rat model. Afterward, changes in the retina were investigated by using electroretinogram and optical coherence tomography. Blood and tissue samples were collected and biochemical components were analyzed. The extent of intestinal injury was determined via hematoxylin-eosin staining. Microbial community structure was analyzed by using 16S ribosomal RNA sequencing. Finally, the expression of genes was analyzed using real-time polymerase chain reaction. The results showed that quercetin reduced the decline in electroretinography amplitude and outer nuclear layer thickness, increased the activities of antioxidant enzymes, decreased the contents of proinflammatory factors and blood glucose, enhanced the concentration of insulin, and inhibited intestinal dysbiosis and improved gut morphology. Importantly, the underexpression of nuclear factor erythroid-2 related factor 2 in the retina was reversed by quercetin. However, trend changes were no longer significant in most of the indicators after antibiotic treatment. In summary, quercetin has therapeutic effects on retinopathy by regulating the gut-retina axis and nuclear factor erythroid-2 related factor 2 pathway, and the presence of gut microbiota helps quercetin exert its effects on the retina., Competing Interests: Declaration of Competing Interest The authors declare no conflict of interest., (Copyright © 2023 Elsevier Inc. All rights reserved.)

1. The bioflavonoid quercetin is a biologically active component, but its functional regulation of granulosa cells (GCs) during chicken follicular development is little studied. To investigate the effect of quercetin on follicular development in laying hens, an in vitro study was conducted on granulosa cells from hierarchical follicles treated with quercetin.2. The effect of quercetin on cell activity, proliferation and apoptosis of granulosa cells was detected by CCK-8, EdU and apoptosis assays. The effect on progesterone secretion from granulosa cells was investigated by enzyme-linked immunosorbent assay (ELISA). Expression of proliferating cell nuclear antigen ( PCNA ) mRNA and oestrogen receptors (ERs), as well as the expression of steroid acute regulatory protein ( StAR ), cytochrome P450 cholesterol side chain cleavage enzyme ( P450scc ) and 3β-hydroxysteroid dehydrogenase ( 3β-HSD ) mRNA during progesterone synthesis, were measured by real-time quantitative polymerase chain reaction (RT-qPCR). PCNA , StAR and CYP11A1 protein expression levels were detected using Western blotting (WB).3. The results showed that treatment with quercetin in granulosa cells significantly enhanced cell vitality and proliferation, reduced apoptosis and promoted the expression of gene and protein levels of PCNA . The levels of progesterone secretion increased significantly following quercetin treatment, as did the expression levels of StAR and CYP11A1 using the Western Blot (WB) method.4. The mRNA expression levels of ERα were significantly upregulated in the 100 ng/ml and 1000 ng/ml quercetin-treated groups, while there was no significant difference in expression levels of ERβ mRNA.

Osteoarthritis (OA) is a chronic disease characterized by the progressive loss of cartilage and failure of the diarrheal joint. Quercetin has been reported to attenuate the development of OA. Bone marrow derived mesenchymal stem cell (BMSC)-derived exosomes are involved in OA progression. However, the role of BMSC-derived exosomes in quercetin-mediated progression of OA remains unclear. Western blotting and RT-qPCR were used to assess protein and mRNA levels, respectively. CCK8 assay was performed to assess cell viability, and cell apoptosis was assessed using flow cytometry. A dual-luciferase assay was performed to assess the relationship between miR-124-3p and TRAF6 expression. Furthermore, in vivo experiments were performed to test the function of exosomes derived from Quercetin-treated BMSCs in OA patients. IL-1β significantly inhibited the viability of chondrocytes, whereas the conditioned medium of Quercetin-treated BMSCs (BMSCs QUE -CM) reversed this phenomenon through exosomes. IL-1β notably upregulated MMP13 and ADAMT5 and reduced the expression of COL2A1 in chondrocytes, which were rescued by BMSCs QUE -CM. The effects of BMSCs QUE -CM on these three proteins were reversed in the absence of exosomes. Exosomes can be transferred from BMSCs to chondrocytes, and exosomes derived from Quercetin-treated BMSCs (BMSCs Que -Exo) can reverse the apoptotic effects of IL-1β on chondrocytes. The level of miR-124-3p in BMSCs was significantly upregulated by quercetin, and miR-124-3p was enriched in BMSCs Que -Exo. TRAF6 was identified as a direct target of miR-124-3p, and BMSCs Que -Exo abolished the IL-1β-induced activation of MAPK/p38 and NF-κB signaling. Furthermore, BMSCs Que -Exo significantly attenuated OA progression in vivo . Exosomes derived from Quercetin-treated BMSCs inhibited OA progression through the upregulation of miR-124-3p.

Quercetin is a key flavonol in tea plants (Camellia sinensis (L.) O. Kuntze) with various health benefits, and it often occurs in the form of glucosides. The roles of quercetin and its glucosylated forms in plant defense are generally not well-studied, and remain unknown in the defense of tea. Here, we found higher contents of quercetin glucosides and a decline of the aglucone upon Ectropis grisescens (E. grisescens) infestation of tea. Nine UGTs were strongly induced, among which UGT89AC1 exhibited the highest activity toward quercetin in vitro and in vivo. The mass of E. grisescens larvae that fed on plants with repressed UGT89AC1 or varieties with lower levels of UGT89AC1 was significantly lower than that of larvae fed on controls. Artificial diet supplemented with quercetin glucoside also reduced the larval growth rate, whereas artificial diet supplemented with free quercetin had no significant effect on larval growth. UGT89AC1 was located in both the cytoplasm and nucleus, and its expression was modulated by JA, JA-ILE, and MeJA. These findings demonstrate that quercetin glucosylation serves a defensive role in tea against herbivory. Our results also provide novel insights into the ecological relevance of flavonoid glycosides under biotic stress in plants., (© 2023 John Wiley & Sons Ltd.)

Eis (Enhanced intracellular survival) protein is an aminoglycoside acetyltransferase enzyme classified under the family - GNAT (GCN5-related family of N-acetyltransferases) secreted by Mycobacterium tuberculosis (Mtb). The enzymatic activity of Eis results in the acetylation of kanamycin, thereby impairing the drug's action. In this study, we expressed and purified recombinant Eis (rEis) to determine the enzymatic activity of Eis and its potential inhibitor. Glide-enhanced precision docking was used to perform molecular docking with chosen ligands. Quercetin was found to interact Eis with a maximum binding affinity of -8.379 kcal/mol as compared to other ligands. Quercetin shows a specific interaction between the positively charged amino acid arginine in Eis and the aromatic ring of quercetin through π-cation interaction. Further, the effect of rEis was studied on the antibiotic activity of kanamycin A in the presence and absence of quercetin. It was observed that the activity of rEis aminoglycoside acetyltransferase decreased with increasing quercetin concentration. The results from the disk diffusion assay confirmed that increasing the concentration of quercetin inhibits the rEis protein activity. In conclusion, quercetin may act as a potential Eis inhibitor., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Tartary buckwheat (Fagopyrum tataricum) is frequently employed as a resource to develop health foods, owing to its abundant flavonoids such as rutin. However, the consumption of Tartary buckwheat (TB) is limited in food products due to the strong bitterness induced by the hydrolysis of rutin into quercetin. This transformation is facilitated by the degrading enzyme (RDE). While multiple RDE isoenzymes exist in TB, the superior coding gene of FtRDEs has not been fully explored, which hinders the breeding of TB varieties with minimal bitterness. Here, we found that FtRDE2 is the most abundant enzyme in RDE crude extracts, and its corresponding gene is specifically expressed in TB seeds. Results showed that FtRDE2 has strong rutin hydrolysis activity. Overexpression of FtRDE2 not only significantly promoted rutin hydrolysis and quercetin accumulation but also dramatically upregulated genes involved in the early phase of flavonoid synthesis (FtPAL1、FtC4H1、Ft4CL1, FtCHI1) and anthocyanin metabolism (FtDFR1). These findings elucidate the role of FtRDE2, emphasizing it as an endogenous factor contributing to the bitterness in TB and its involvement in the metabolic regulatory network. Moreover, correlation analysis revealed a positive relationship between the catalytic activity of RDE extracts and the expression level of FtRDE2 during seed germination. In summary, our results suggest that FtRDE2 can serve as a promising candidate for the molecular breeding of a TB variety with minimal bitterness., Competing Interests: Declaration of competing interest The authors declare that there are no competing interests., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

Ethnopharmacological Relevance: Carthami flos is a dried flower of the Asteraceae plant Carthamus tinctorius (L.). Danhong injection, composed of Carthami flos and Danshen can prevent the formation of postoperative peritoneal adhesions. Quercetin (QUE), an active compound of Carthami flos, has also been proved to prevent postoperative abdominal and uterine cavity adhesions. However, whether QUE is the key component in Carthami flos and the mechanism in preventing postoperative peritoneal adhesions has not been studied., Aim of the Study: To predict whether QUE is the key molecule in Carthami flos and explore the effect and mechanism of QUE in preventing postoperative peritoneal adhesions., Materials and Methods: Drug composition and target analysis was used to predict the key component in Carthami flos. The method of cecum-sidewall abrasion was used to establish adhesion models, and the antiadhesion effect of QUE was evaluated with the adhesion scoring system. Network pharmacology was used to predict the targets and potential mechanism of QUE in preventing adhesion. The mechanism was further verified by immunofluorescence, Western blot, wound healing experiment, and molecular docking., Results: Quercetin was predicted to be the key to preventing postoperative peritoneal adhesions in Carthami flos. Animal experiments revealed that QUE effectively ameliorated adhesions and reduced the expression of mesothelial-mesenchymal transition (MMT) related markers and TGF-β1. Moreover, the TGF-β1/PI3K/AKT pathway was predicted via protein-protein interaction and Kyoto encyclopedia of Genes and Genomes enrichment analysis to play a crucial part in preventing adhesion by QUE. Furthermore, in vitro experiments and molecular docking demonstrated that QUE could block the TGF-β1/PI3K/AKT pathway through forming a stable combination with TβR-II, thereby inhibiting MMT and ameliorating peritoneal adhesion., Conclusions: QUE can not only reduce postoperative TGF-β1 but also block the TGF-β1/PI3K/AKT pathway to inhibit MMT of mesothelial cells, and finally alleviate postoperative peritoneal adhesions. These findings may provide insights towards development of a safe and effective anti-adhesive drug for prevention of postoperative peritoneal adhesions., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Peyer's patches (PPs) are part of the gut-associated lymphatic tissue (GALT) and represent the first line of the intestinal immunological defense. They consist of follicles with lymphocytes and an overlying subepithelial dome with dendritic cells and macrophages, and they are covered by the follicle-associated epithelium (FAE). A sealed paracellular pathway in the FAE is crucial for the controlled uptake of luminal antigens. Quercetin is the most abundant plant flavonoid and has a barrier-strengthening effect on tight junctions (TJs), a protein complex that regulates the paracellular pathway. In this study, we aimed to analyze the effect of quercetin on porcine PPs and the surrounding villus epithelium (VE). We incubated both tissue types for 4 h in Ussing chambers, recorded the transepithelial electrical resistance (TEER), and measured the unidirectional tracer flux of [ 3 H]-mannitol. Subsequently, we analyzed the expression, protein amount, and localization of three TJ proteins, claudin 1, claudin 2, and claudin 4. In the PPs, we could not detect an effect of quercetin after 4 h, neither on TEER nor on the [ 3 H]-mannitol flux. In the VE, quercetin led to a higher TEER value, while the [ 3 H]-mannitol flux was unchanged. The pore-forming claudin 2 was decreased while the barrier-forming claudin 4 was increased and the expression was upregulated. Claudin 1 was unchanged and all claudins could be located in the paracellular membrane by immunofluorescence microscopy. Our study shows the barrier-strengthening effect of quercetin in porcine VE by claudin 4 upregulation and a claudin 2 decrease. Moreover, it underlines the different barrier properties of PPs compared to the VE.

Quercetin is a common plant flavonoid which is involved in herbivore-plant interactions. Mulberry silkworms (domestic silkworm, Bombyx mori, and wild silkworm, Bombyx mandarina) take up quercetin from mulberry leaves and accumulate the metabolites in the cocoon, thereby improving its protective properties. Here we identified a glycoside hydrolase, named glycoside hydrolase family 1 group G 5 (GH1G5), which is expressed in the midgut and is involved in quercetin metabolism in the domestic silkworm. Our results suggest that this enzyme mediates quercetin uptake by deglycosylating the three primary quercetin glycosides present in mulberry leaf: rutin, quercetin-3-O-malonylglucoside, and quercetin-3-O-glucoside. Despite being located in an unstable genomic region that has undergone frequent structural changes in the evolution of Lepidoptera, GH1G5 has retained its hydrolytic activity, suggesting quercetin uptake has adaptive significance for mulberry silkworms. GH1G5 is also important in breeding: defective mutations which result in discoloration of the cocoon and increased silk yield are homozygously conserved in 27 of the 32 Japanese white-cocoon domestic silkworm strains and 12 of the 30 Chinese ones we investigated., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Waizumi et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Importance: Anti-biofilm is an important strategy against Staphylococcus aureus chronic infection. SarA is a positive regulator of biofilm formation in S. aureus . In this study, we identified the SarA inhibitor quercetin using computer simulation screening. Previous studies have shown that quercetin inhibits biofilm; however, the underlying mechanism remains unknown. This study revealed the inhibitory effect of quercetin on the SarA protein. We also isolated the SarA protein and confirmed its interaction with quercetin in vitro . Besides, the inhibitory effect of quercetin on the transcription and translation levels of the SarA protein was also determined. The effects of quercetin on S. aureus biofilm inhibition and biofilm components were consistent with the changes in the transcription level of biofilm-related genes regulated by SarA. In summary, our study revealed the mechanism by which quercetin affects biofilm formation by inhibiting the transcriptional regulator SarA of S. aureus ., Competing Interests: The authors declare no conflict of interest.

Chronic lung diseases such as chronic obstructive pulmonary disease and cystic fibrosis are incurable. Epithelial senescence, a state of dysfunctional cell cycle arrest, contributes to the progression of such diseases. Therefore, lung epithelial cells are a valuable target for therapeutic intervention. Here, we present a 3D airway lung organoid platform for the preclinical testing of active substances with regard to senescence, toxicity, and inflammation under standardized conditions in a 96 well format. Senescence was induced with doxorubicin and measured by activity of senescence associated galactosidase. Pharmaceutical compounds such as quercetin antagonized doxorubicin-induced senescence without compromising organoid integrity. Using single cell sequencing, we identified a subset of cells expressing senescence markers which was decreased by quercetin. Doxorubicin induced the expression of detoxification factors specifically in goblet cells independent of quercetin. In conclusion, our platform enables for the analysis of senescence-related processes and will allow the pre-selection of a wide range of compounds (e.g. natural products) in preclinical studies, thus reducing the need for animal testing., (© 2023. The Author(s).)

The fusion of mononuclear trophoblasts into multinucleate syncytiotrophoblasts is the critical event in the process of syncytialization, and its dysregulation can lead to pregnancy complications, notably hypertensive disorders of pregnancy (HDP). Oxidative stress may disrupt trophoblast syncytialization in HDP. Specifically, placentas with HDP exhibit impaired mitochondria, giving rise to the generation of reactive oxygen species (ROS) and subsequent oxidative stress. Quercetin, a bioflavonoid known for its antioxidant and anti-aging properties, has the potential to mitigate oxidative stress during trophoblast syncytialization. However, the precise mechanism underlying the action of quercetin in these processes remains to be elucidated. To explore the impact of quercetin on syncytialization, mitochondrial function, and ROS generation, cyclic AMP-stimulated BeWo cells were treated with quercetin. The expression of markers associated with cell fusion, mitochondrial function, and oxidative stress was determined using qPCR and western blotting. Additionally, morphological syncytialization and mitophagy (mitochondrial degradation) were assessed by immunofluorescence analysis. Our results revealed that quercetin increased the expression of syncytialization markers and promoted cell fusion. Furthermore, this compound also upregulated markers associated with mitophagy and mitochondrial fusion, which are corroborated by visual evidence of mitophagy through the fluorescence microscope. Cell fusion naturally stimulated ROS generation, which was attenuated by quercetin. Quercetin downregulated the expression of NRF2 and HO-1 during syncytialization, while increasing the expression of sirtuin1/3/6, which are known to play essential roles in antioxidant responses. In conclusion, quercetin effectively regulates mitochondrial function through its antioxidant properties and the suppression of ROS generation, ultimately promoting trophoblast fusion, suggesting that the flavonoid has the potential to ameliorate pregnancy-related disorder stemming from placental dysplasia., (© 2024. The Author(s).)

The purpose of this study was to investigate the effects of gentamicin (GEN) on the testis and whether quercetin (QUE) has any protective effect. Twenty-four adult male Sprague-Dawley rats were divided into equal four groups: control (0.9% saline solution), GEN (80 mg∕kg GEN), QUE (50 mg∕kg QUE) and GEN+QUE (80 mg∕kg GEN + 50 mg∕kg QUE). Histopathological (HP) evaluation of testis was performed, epididymal sperm parameters were analyzed and oxidative status was evaluated. The use of QUE improved the HP findings, such as decrease in the germinal epithelial thickness in the testicular tissue of the GEN group, decrease in the Johnsen's tubular biopsy score (JTBS), increase in the rate of immature cell shedding tubules, and the apoptotic index (AI). In the GEN group, sperm count, and abnormal morphology increased compared to the control group; the viability and motility decreased according to the sperm analysis results. In the GEN+QUE group, QUE was found to improve sperm viability and morphology. In the GEN group, tissue malondialdehyde (MDA) levels increased while superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) levels decreased. Compared with the GEN+QUE group, it was found that the tissue MDA level decreased, while the levels of SOD, CAT and GPx increased. The results demonstrate that GEN impairs testicular structure and function, and QUE treatment can prevent this adverse effect.

Quercetin is a bioactive natural compound with an antioxidative property that can potentially modify plant physiology. The current investigation aimed to gauge the effect of different concentrations of foliar spray of quercetin (0, 0.5, 1, 1.5, 2.0 mM) on several morphological and physio-biochemical performances of Abelmoschus esculentus L. (Moench.) plants under normal environmental conditions. The foliar spray on the plant leaves was applied 25 days after sowing (DAS) and continued up to 30 DAS once each day. The plants were sampled at 30 and 45 DAS to monitor several parameters. The foliar treatments of quercetin significantly upgraded all the studied parameters. The results direct that most of the traits such as growth, nutrient uptake, photosynthetic, and enzyme activities were promoted in a dose-dependent way. Quercetin application lowered the reactive oxygen species (ROS) buildup by increasing the antioxidant enzyme activities. Microscopic investigations further revealed a significant enhancement in the stomatal aperture under quercetin application. Out of several doses tested, 1 mM of quercetin proved best and can be used for further investigations., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Background: Paraquat is a highly toxic quaternary ammonium herbicide widely used in agriculture. It is an agent that induces pulmonary toxicity via the redox cyclic reaction., Objective: The present study investigated the protective effect of quercetin against paraquatinduced brain mitochondria disruption in mice., Methods: Paraquat (1.25 mg/kg, intraperitoneally) was administered to the mice, and then quercetin (50, 100, 200 mg/kg) was injected i.p. Oxidative damage biomarkers such as reactive oxygen species, protein carbonyl, lipid peroxidation, glutathione content, and mitochondrial function were assessed in the brain mitochondria., Results: The results showed that paraquat significantly ( P < 0.001) increased the reactive oxygen species, protein carbonyl, and lipid peroxidation and significantly ( P < 0.0001) decreased the glutathione content and mitochondrial function in the brain cells. Administration of the quercetin at doses of 50, 100, and 200 mg/kg significantly reduced reactive oxygen species, lipid peroxidation, and protein carbonyl and improved mitochondrial function and glutathione content in the mice brain mitochondrial compared to the paraquat group. Quercetin at 200 mg/kg dose had better effectiveness than 50 and 100 mg/kg doses., Conclusion: Our results suggest that quercetin in a dose-dependent manner has neuroprotective effects, probably by free radicals scavenging or enhancing the antioxidant mechanisms in the brain mitochondria. It seems that quercetin could modulate protein and lipid oxidation and improve oxidative damage induced by paraquat in the early stages., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Cadmium (Cd) exposure causes oxidative damage to mitochondria, which would adversely affect rat testicular tissue. Quercetin (Que) is a natural antioxidant with anti-inflammatory, antioxidant and anti-apoptotic effects. However, the mechanism by which Que inhibits Cd-induced apoptosis of testicular cells remains unclear. The purpose of this study was to investigate the role of mitochondrial apoptosis pathway (Cyt-c/Caspase-9/Caspase-3/Bax/Bcl-2 pathway) in inhibiting Cd-induced apoptosis of testicular cells by Que. We used SD rats to simulate Cd chloride exposure by treating all sides of the rats with CdCl 2 and/or Que. The levels of GSH and MDA in rat testis were detected using reagent kits. The effects of CdCl 2 and/or Que on tissue damage, apoptosis, and gene and protein expression of the Cyt-c/Caspase-9/Caspase-3/Bax/Bcl-2 pathway in rat testis were examined by HE, TUNEL, RNA extraction and reverse-transcriptase polymerase chain reaction (RT-PCR), and Western blot (Wb). The results show that Cd significantly increased the contents of GSH and MDA in rat testis (P < 0.01); conversely, Que significantly reduced the contents of GSH and MDA (P < 0.01). Cd inflicted damage to testicular tissue, and Que addition significantly reduced the damage. Cd increased the number of apoptosis of testicle cells, and Que inhibited testicle-cell apoptosis. In addition, the results of reverse transcription PCR and Wb assays confirmed that, as expected, Cd increased the expression levels of Cyt-c, Caspase-9, Caspase-3, and Bax mRNAs as well as proteins. And at the same time decreased the expression of the anti-apoptotic factor Bcl-2 in the cells. Surprisingly, these effects were reversed when Que was added. Therefore, Que can play an antioxidant and anti-apoptotic role in reducing the testicular tissue damage caused by Cd exposure. This provides a conceptual basis for the later development and utilization of Que as well as the prevention and treatment of tissue damage caused by Cd exposure., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Scope: Ulcerative colitis (UC) is a classic inflammatory bowel disease (IBD) that represents a serious threat to human health. As a natural flavonoid with multiple biological activities, quercetin (QCT) suffers from low bioavailability through limitations in chemical stability. Here, the study investigates the regulatory effects of quercetin nanoparticles (QCT NPs) on dextran sulfate sodium (DSS) induced colitis mice., Methods and Results: Chitosan is modified to obtain N-succinyl chitosan (NSC) with superior water solubility. Nanoparticles composed of sodium alginate (SA) and NSC can encapsulate QCT after cross-linking, forming QCT NPs. In vitro drug release assays demonstrate the pH sensitivity of QCT NPs. Compared with free quercetin, QCT NPs have better therapeutic efficacy in modulating gut microbiota and its metabolites short chain fatty acid (SCFAs) to relieve DSS-induced colitis in mice, thereby alleviating colon inflammatory infiltration, increasing goblet cells density and mucus protein, ameliorating TNF-α, IL-1β, IL-6, IL-10, and Myeloperoxidase (MPO) levels, and recovering intestinal barrier integrity., Conclusion: pH sensitive QCT nanoparticles can reduce inflammatory reaction, improve gut microbiota, and repair intestinal barrier by targeting colon, thus improving DSS induced colitis in mice, providing reference for the treatment of colitis., (© 2023 Wiley-VCH GmbH.)

Flavonols are structurally and functionally diverse biomolecules involved in plant biotic and abiotic stress tolerance, pollen development, and inhibition of auxin transport. However, their effects on global gene expression and signaling pathways are unclear. To explore the roles of flavonol metabolites in signaling, we performed comparative transcriptome and targeted metabolite profiling of seedlings from the flavonol-deficient Arabidopsis loss-of-function mutant flavonol synthase1 (fls1) with and without exogenous supplementation of flavonol derivatives (kaempferol, quercetin, and rutin). RNA-seq results indicated that flavonols modulate various biological and metabolic pathways, with significant alterations in camalexin and aliphatic glucosinolate synthesis. Flavonols negatively regulated camalexin biosynthesis but appeared to promote the accumulation of aliphatic glucosinolates via transcription factor-mediated up-regulation of biosynthesis genes. Interestingly, upstream amino acid biosynthesis genes involved in methionine and tryptophan synthesis were altered under flavonol deficiency and exogenous supplementation. Quercetin treatment significantly up-regulated aliphatic glucosinolate biosynthesis genes compared with kaempferol and rutin. In addition, expression and metabolite analysis of the transparent testa7 mutant, which lacks hydroxylated flavonol derivatives, clarified the role of quercetin in the glucosinolate biosynthesis pathway. This study elucidates the molecular mechanisms by which flavonols interfere with signaling pathways, their molecular targets, and the multiple biological activities of flavonols in plants., (© The Author(s) 2023. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Introduction: Quercetin and apigenin are two common dietary flavonoids widely found in foods and fruits. Quercetin and apigenin can act as the inhibitors of CYP450 enzymes, which may affect the pharmacokinetics of clinical drugs. Vortioxetine (VOR), approved for marketing by the Food and Drug Administration (FDA) in 2013, is a novel clinical drug for treating major depressive disorder (MDD)., Objective: This study aimed to evaluate the effects of quercetin and apigenin on the metabolism of VOR in in vivo and in vitro experiments., Methods: Firstly, 18 Sprague-Dawley rats were randomly divided into three groups: control group (VOR), group A (VOR + 30 mg/kg quercetin) and group B (VOR + 20 mg/kg apigenin). We collected the blood samples at different time points before and after the final oral administration of 2 mg/kg VOR. Subsequently, we further used rat liver microsomes (RLMs) to investigate the half-maximal inhibitory concentration (IC 50 ) of the metabolism of vortioxetine. Finally, we evaluated the inhibitory mechanism of two dietary flavonoids on VOR metabolism in RLMs., Results: In animal experiments, we found AUC (0-∞) (area under the curve from 0 to infinity) and CLz/F (clearance) to be obviously changed. Compared to controls, AUC (0-∞) of VOR in group A and group B was 2.22 and 3.54 times higher, respectively, while CLz/F of VOR in group A and group B was significantly decreased down to nearly two-fifth and one-third. In in vitro studies, the IC 50 value of quercetin and apigenin in the metabolic rate of vortioxetine was 5.323 μM and 3.319 μM, respectively. Ki value of quercetin and apigenin was found to be 0.040 and 3.286, respectively, and the αKi value of quercetin and apigenin was 0.170 and 2.876 μM, respectively., Conclusion: Quercetin and apigenin exhibited inhibitory effects on the metabolism of vortioxetine in vivo and in vitro . Moreover, quercetin and apigenin had a mixed mechanism on the metabolism of VOR in RLMs. Thus, we should pay more attention to the combination between these dietary flavonoids and VOR in the future clinical use., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Flavonols (3-hydroxy flavones) have been studied for their beneficial bioactivities for human health. Recently, we reported that a flavonoid phosphate synthetase (BsFPS) from Bacillus subtilis BCRC 80517 can transform several flavonoids into their phosphate conjugates, which become more water-soluble and thus increase the oral bioavailability. However, the in vivo metabolism of different flavonols has yet to be determined. Here, we investigated biotransformation of three flavonols (quercetin, kaempferol and fisetin) by B. subtilis BCRC 80517. C-ring cleavage products of quercetin and kaempferol, i.e., 2-protocatechuoyl-phloroglucinol carboxylic acid (2-PCPGCA), were produced, whereas two phosphate derivatives of fisetin (fisetin 4'-O-phosphate and fisetin 3'-O-phosphate) were generated by cultivation with B. subtilis BCRC 80517. Our results indicated that there are structure-specific metabolic pathways in B. subtilis toward different flavonols, where the 5-hydroxy group determines metabolic priority. Our findings provide new insights for developing bioproduction platform to produce flavonol phosphate derivatives for nutraceutical applications., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Quercetin is a flavonol belonging to the flavonoid group of polyphenols. Quercetin is reported to have a variety of biological functions, including antioxidant, pigment, auxin transport inhibitor and root nodulation factor. Additionally, quercetin is known to be involved in bacterial pathogen resistance in Arabidopsis through the transcriptional increase of pathogenesis-related ( PR ) genes. However, the molecular mechanisms underlying how quercetin promotes pathogen resistance remain elusive. In this study, we showed that the transcriptional increases of PR genes were achieved by the monomerization and nuclear translocation of nonexpressor of pathogenesis-related proteins 1 (NPR1). Interestingly, salicylic acid (SA) was approximately 2-fold accumulated by the treatment with quercetin. Furthermore, we showed that the increase of SA biosynthesis by quercetin was induced by the transcriptional increases of typical SA biosynthesis-related genes. In conclusion, this study strongly suggests that quercetin induces bacterial pathogen resistance through the increase of SA biosynthesis in Arabidopsis .

Background: Metabolites play critical roles in regulating nutritional qualities of plants, thereby influencing their consumption and human health. However, the genetic basis underlying the metabolite-based nutrient quality and domestication of root and tuber crops remain largely unknown., Results: We report a comprehensive study combining metabolic and phenotypic genome-wide association studies to dissect the genetic basis of metabolites in the storage root (SR) of cassava. We quantify 2,980 metabolic features in 299 cultivated cassava accessions. We detect 18,218 significant marker-metabolite associations via metabolic genome-wide association mapping and identify 12 candidate genes responsible for the levels of metabolites that are of potential nutritional importance. Me3GT, MeMYB4, and UGT85K4/UGT85K5, which are involved in flavone, anthocyanin, and cyanogenic glucoside metabolism, respectively, are functionally validated through in vitro enzyme assays and in vivo gene silencing analyses. We identify a cluster of cyanogenic glucoside biosynthesis genes, among which CYP79D1, CYP71E7b, and UGT85K5 are highly co-expressed and their allelic combination contributes to low linamarin content. We find MeMYB4 is responsible for variations in cyanidin 3-O-glucoside and delphinidin 3-O-rutinoside contents, thus controlling SR endothelium color. We find human selection affects quercetin 3-O-glucoside content and SR weight per plant. The candidate gene MeFLS1 is subject to selection during cassava domestication, leading to decreased quercetin 3-O-glucoside content and thus increased SR weight per plant., Conclusions: These findings reveal the genetic basis of cassava SR metabolome variation, establish a linkage between metabolites and agronomic traits, and offer useful resources for genetically improving the nutrition of cassava and other root crops., (© 2023. The Author(s).)

Ethnopharmacological Relevance: Allium cepa L. (A. cepa) is one of the oldest cultivated plants in the world. A. cepa has been used in traditional folk medicine to treat inflammatory disease in several regions, such as Palestine and Serbia. A. cepa peel has a higher content of flavonoids, such as quercetin, than the edible parts. These flavonoids alleviate inflammatory diseases. However, the anti-inflammatory effects of A. cepa peel extract-obtained using various extraction methods-and their underlying mechanisms require further investigation., Aim of the Study: Although research to find safe anti-inflammatory substances in various natural products has been actively conducted for many years, it is important to continue identifying potential anti-inflammatory effects in natural materials. The purpose of this study was to investigate the ethnopharmacological properties of the A. cepa peel extract, whose efficacy when obtained through different extraction methods and underlying action mechanisms is not well known. The present study specifically aimed to observe the anti-inflammatory effects of the A. cepa peel extracts obtained using various extraction methods and the related detailed mechanisms of A. cepa peel extracts in lipopolysaccharide (LPS)-induced RAW264.7 cells., Materials and Methods: The total flavonoid content of the A. cepa peel extracts was determined the diethylene glycol colorimetric method and measured using a calibration curve prepared using quercetin as a standard solution. The antioxidant activity was evaluated using the ABTS assay, and cytotoxicity was measured using the MTT assay. NO production was measured using Griess reagent. Protein levels were measured by western blotting, and mRNA expression was measured by RT-qPCR. Secreted cytokines were analyzed using ELISA or cytokine arrays. In the GSE160086 dataset, we calculated Z-scores for individual genes of interest and displayed using a heat map., Results: Of the three A. cepa peel extracts obtained using different extraction methods, the A. cepa peel 50% EtOH extract (AP50E) was the most effective at inhibiting LPS-induced nitric oxide (NO) and inducible nitric oxide synthase (iNOS). Furthermore, AP50E significantly reduced the levels of pro-inflammation cytokines interleukin (IL)-1α, IL-1β, IL-6, and IL-27. Additionally, AP50E directly inhibited the Janus kinase-signaling transducer and activator of transcription (JAK-STAT) pathway., Conclusions: These results showed that AP50E exhibited an anti-inflammatory effect in LPS-induced RAW264.7 mouse macrophages by directly inhibiting JAK-STAT signaling. Based on these findings, we propose AP50E as a potential candidate for the development of preventive or therapeutic agents against inflammatory diseases., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Based on the adhesion and surface properties of Lactobacillus acidophilus NCFM, five common polyphenols in fruits and vegetables, including resveratrol, epicatechin, quercetin, hesperidin, and caffeic acid, were screened, and the reasons for resveratrol promoting adhesion were systematically explained. The results showed that resveratrol could significantly enhance NCFM adhesion to mucin (1.73 fold), followed by epicatechin (1.47 fold), caffeic acid (1.30 fold), and hesperidin (0.99 fold), while quercetin had a certain degree of inhibition (0.84 fold). The effects of these polyphenols on surface hydrophobicity and auto-aggregation of NCFM were consistent with adhesion results. Then, how resveratrol promotes NCFM adhesion was further explored. The results of the proteomic analysis showed that resveratrol changed the surface layer proteins of NCFM, involving 4 up-regulated proteins and 12 down-regulated proteins. In addition, resveratrol promoted the expression of mucin genes and the glycosylation of mucins on the HT-29 cell surface. Our results indicate that resveratrol changes the surface layer proteins of NCFM to modify surface properties and adhere to mucins. Meanwhile, resveratrol promotes expression and glycosylation of mucins in HT-29 cells. Our findings provide theoretical support for an in-depth explanation of the interaction among resveratrol, NCFM, and the HT-29 cells., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)