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Shikonin, an herbal naphthoquinone, demonstrates a broad spectrum of pharmacological properties. Owing to increasingly adverse environmental conditions, human skin is vulnerable to harmful influences from dust particles. This study explored the antioxidant capabilities of shikonin and its ability to protect human keratinocytes from oxidative stress induced by fine particulate matter (PM2.5). We found that shikonin at a concentration of 3 µM was nontoxic to human keratinocytes and effectively scavenged reactive oxygen species (ROS) while increasing the production of reduced glutathione (GSH). Furthermore, shikonin enhanced GSH level by upregulating glutamate‐cysteine ligase catalytic subunit and glutathione synthetase mediated by nuclear factor‐erythroid 2‐related factor. Shikonin reduced ROS levels induced by PM2.5, leading to recovering PM2.5‐impaired cellular biomolecules and cell viability. Shikonin restored the GSH level in PM2.5‐exposed keratinocytes via enhancing the expression of GSH‐synthesizing enzymes. Notably, buthionine sulphoximine, an inhibitor of GSH synthesis, diminished effect of shikonin against PM2.5‐induced cell damage, confirming the role of GSH in shikonin‐induced cytoprotection. Collectively, these findings indicated that shikonin could provide substantial cytoprotection against the adverse effects of PM2.5 through direct ROS scavenging and modulation of cellular antioxidant system. [ABSTRACT FROM AUTHOR]

Tumor-associated macrophages (TAMs) are pivotal in the tumor microenvironment (TME) of hepatocellular carcinoma (HCC), influencing various stages from initiation to metastasis. Understanding the role of TAMs in HCC is crucial for developing novel therapeutic strategies. Macrophages exhibit plasticity, resulting in M1 and M2 phenotypes, with M1 macrophages displaying antitumor properties and M2 macrophages promoting tumor progression. Targeting TAMs to alter their polarization could offer new avenues for HCC treatment. β,β-dimethylacrylalkannin (DMAKN), a natural naphthoquinone, has gained attention for its antitumor properties. However, its impact on TAMs modulation remains unclear. This study investigates DMAKN's modulation of TAMs and its anti-HCC activity. Using an in vitro model with THP-1 cells, we induced M1 macrophages with LPS/IFN-γ and M2 macrophages with IL-4/IL-13, confirming polarization with specific markers. Co-culturing these macrophages with HCC cells showed that M1 cells inhibited HCC growth, while M2 cells promoted it. Screening for non-toxic DMAKN concentrations revealed its ability to induce M1 polarization and enhance LPS/IFN-γ-induced M1 macrophages, both showing anti-HCC effects. Conversely, DMAKN suppressed IL-4/IL-13-induced M2 polarization, inhibiting M2 macrophages' promotion of HCC cell viability. In summary, DMAKN induces and enhances M1 polarization while inhibiting M2 polarization of macrophages, thereby inhibiting HCC cell growth. These findings suggest that DMAKN has the potential to regulate TAMs in HCC, offering promise for future therapeutic development. [ABSTRACT FROM AUTHOR]

A talented endophytic Streptomyces sp. PH9030 is derived from the medicinal plant Kadsura coccinea (Lem.) A.C. Smith. The undescribed naphthoquinone naphthgeranine G (5) and seven previously identified compounds, 6–12, were obtained from Streptomyces sp. PH9030. The structure of 5 was identified by comprehensive examination of its HRESIMS, 1D NMR, 2D NMR and ECD data. The inhibitory activities of all the compounds toward α-glucosidase and their antibacterial properties were investigated. The α-glucosidase inhibitory activities of 5, 6, 7 and 9 were reported for the first time, with IC50 values ranging from 66.4 ± 6.7 to 185.9 ± 0.2 μM, as compared with acarbose (IC50 = 671.5 ± 0.2 μM). The molecular docking and molecular dynamics analysis of 5 with α-glucosidase further indicated that it may have a good binding ability with α-glucosidase. Both 9 and 12 exhibited moderate antibacterial activity against methicillin-resistant Staphylococcus aureus, with minimum inhibitory concentration (MIC) values of 16 μg/mL. These results indicate that 5, together with the naphthoquinone scaffold, has the potential to be further developed as a possible inhibitor of α-glucosidase. [ABSTRACT FROM AUTHOR]

Objectives: Breast cancer is a prevalent disease that has a substantial impact on women's mortality rates. Shikonin, a naphthoquinone derived from Lithospermum erythrorhizon, has demonstrated substantial anticancer effects. This study aims to conduct a comprehensive review of the latest research findings regarding the therapeutic efficacy of shikonin in the context of breast cancer treatment, with a specific emphasis on elucidating the underlying molecular mechanisms. Methods: A comprehensive literature review was conducted on shikonin and breast cancer by searching PubMed, Scopus, Web of Science, and Google Scholar databases. Key findings: Shikonin significantly reduces tumor cell viability, proliferation, migration, invasion, and metastasis in both in vivo and in vitro across all breast cancer subtypes. Additionally, when combined with other pharmaceutical agents, it exhibits synergistic effects. Shikonin stimulates immunogenic cell death, resulting in apoptosis and necroptosis. The induction of immunogenic cell death by shikonin enhances the immunogenicity of breast cancer cells, leading to its involvement in the development of dendritic cell-based tumor vaccines against breast cancer. Conclusion: Shikonin exhibits potent anti-breast cancer properties and shows significant potential for the advancement of immunotherapeutic approaches against breast cancer, as well as enhancing the efficacy of conventional treatment strategies. [ABSTRACT FROM AUTHOR]

A direct C−H alkylation of naphthoquinones with acetone and 1,3‐dicarbonyl compounds was developed to construct C−C bonds of alkyl‐substituted naphthoquinone derivatives. It proceeded through an oxidative radical cross dehydrogenation coupling process under simple and mild conditions. This method provides a facile and efficient route for synthesis of functionalized naphthoquinones from readily available feedstocks. [ABSTRACT FROM AUTHOR]

The catalytic asymmetric reaction of 5‐aminopyrazoles with naphthoquinone esters has been established. A wide range of unprecedented axially chiral naphthylpyrazole derivatives (29 examples) have been synthesized in moderate to excellent yields (up to 99 % yield) with excellent enantioselectivities (up to 99 % ee) by utilizing chiral phosphoric acid as a catalyst. This protocol features mild reaction conditions, a broad substrate scope, good scalability and facile derivatization. Moreover, preliminary mechanistic investigation was conducted to elucidate the mechanism. [ABSTRACT FROM AUTHOR]

An organic–inorganic hybrid is a promising electrode material for aqueous batteries due to its larger potential in improving electrochemical performance. Herein, we designed and prepared a naphthoquinone@FeOx(OH)/iron foam (NQ@FeOx(OH)/IF) hybrid electrode as a highly-efficient anode in Ni/Fe batteries via combining electro-deposition of FeOx(OH) and in situ hydrothermal growth of naphthoquinone. The as-prepared hybrid electrode materials present a 2D nanosheet morphology of FeOx(OH) and a branch/band-like structure of NQ, with the formation of NQ–FeOx(OH) interfaces. Such an interface structure is revealed to have more electron active sites, with increased electron delocalization caused by the aromatic ring structure, thereby enhancing the transport of the electrons in the electrode materials. Thus, a superior electrochemical performance of the NQ@FeOx(OH)/IF electrode was received, with a large areal capacity of ∼2.23 mA h cm−2 and a favorable rate capability of 1.09 mA h cm−2 at 40 mA cm−2. Besides, the NQ@FeOx(OH)/IF anode was coupled with the NiCo2O4 cathode to assemble a Ni/Fe battery, as a result, an admirable energy density of 235.2 W h kg−1 and a maximum power density of 5.4 kW kg−1 were obtained. The study on high-performance NQ@FeOx(OH)/IF electrode materials paves the way to design and synthesize better iron-based materials for Ni/Fe batteries. [ABSTRACT FROM AUTHOR]

Total syntheses of borolithochromes A, D and G, red pigments isolated from fossils of Jurassic putative red alga Solenopora jurassica, have been achieved. The benzo[gh]tetraphene skeletons of the borate ligands in these substances were constructed using Diels–Alder reactions of aryl dienes with naphthoquinone, followed by intramolecular Corey–Chaykovsky reactions. Complexation of these ligands with trimethyl borate generated homocomplexes, which upon sequential O‐demethylation produced borolithochromes A and G. In the route to borolithochrome D, a heterocomplex was prepared by stepwise complexation of the ligands with 2‐(dimethylamino)ethyl dimethyl borate. The strategy devised to accomplish the first total synthesis of borolithochromes A, D and G should be applicable to the preparation of other borolithochromes as well as spiroborates possessing two fused polycyclic aromatic ligands. [ABSTRACT FROM AUTHOR]

The identification of novel acetylcholinesterase inhibitors holds significant relevance in the treatment of Alzheimer's disease (AD), the prevailing form of dementia. The exploration of alternative inhibitors to the conventional acetylcholinesterase inhibitors is steadily gaining prominence. Quinones, categorized as plant metabolites, represent a specific class of compounds. In this study, the inhibitory effects of various naphthoquinone derivatives, along with anthraquinone and its derivatives, on the acetylcholinesterase (AChE) enzyme were investigated for this purpose. An in vitro investigation was conducted to examine the effects of these compounds in order to clarify the possible mechanism of inhibition in the interaction between the enzyme and chemicals. In addition, an in silico investigation was carried out to understand the conceivable inhibitor binding process to the enzyme's active site. The acquired outcomes corroborated the in vitro results. The AChE enzyme was found to be effectively inhibited by both naphthoquinones and anthraquinones, with inhibition constant (KI) values ranging from 0.014 to 0.123 μM (micormolar). The AChE enzyme was inhibited differently by this quinone and its derivatives. Although derivatives of naphthoquinone and anthraquinone exhibited a competitive inhibitory effect, derivatives of anthraquinone exhibited a noncompetitive inhibition effect. Furthermore, because it had the lowest KI value of any of these substances, 1,5‐dihydroxyanthraquinone (1c) was shown to be the most potent inhibitor. The findings will add to the body of knowledge on the creation of fresh, potent, and successful treatment approaches. [ABSTRACT FROM AUTHOR]

Shikonin is a naphthoquinone pigment present in the hairy roots of the plant species from the Boraginaceae family. The compound has been well investigated for its highly efficient medicinal, antioxidant, and antimicrobial properties. Various extraction methodologies have been employed to maximise yield while minimising waste production of shikonin and its derivatives. Despite substantial research on shikonin and Boraginaceae plants, a research gap persists in the food industry and extraction technologies. This review addresses crucial aspects of shikonin deserving of further exploration. It begins by elucidating the attributes of the Boraginaceae plants and their medicinal traits in folklore. It proceeds to focus on the roots of the plant and its medicinal properties, followed by extraction procedures explored in the last fifteen years, emphasising the novel technologies that have been chosen to improve the yield extract while minimising extraction times. Furthermore, this review briefly outlines studies employing cell culture techniques to enhance in vitro shikonin production. Lastly, attention is directed towards research in the food industry, particularly on shikonin-loaded biodegradable films and the antioxidant activity of shikonin. This review concludes by summarising the future potential in food science and prominent research gaps in this field. [ABSTRACT FROM AUTHOR]

A new naphthoquinone, patulumnaphthoquinone A (1) and three new glycosides, patulumside B (2), patulumside C (3) and patulumside D (4) were isolated from the 30% ethanol extract of the fresh ripe fruits of Hypericum patulum Thunb. using column chromatography techniques. The structures of these compounds including absolute configurations were elucidated on the basis of HRESIMS, NMR spectroscopic analyses, calculated electronic circular dichroism spectra and comparison with the literatures. [ABSTRACT FROM AUTHOR]

Time-resolved step-scan Fourier transform infrared difference spectroscopy has been used to study cyanobacterial photosystem I photosynthetic reaction centers from Synechocystis sp. PCC 6803 (S6803) with four high-potential, 1,4-naphthoquinones incorporated into the A1 binding site. The high-potential naphthoquinones are 2-chloro-, 2-bromo-, 2,3-dichloro- and 2,3-dibromo-1,4-naphthoquinone. "Foreign minus native" double difference spectra (DDS) were constructed by subtracting difference spectra for native photosystem I (with phylloquinone in the A1 binding site) from corresponding spectra obtained using photosystem I with the different quinones incorporated. To help assess and assign bands in the difference and double difference spectra, density functional theory based vibrational frequency calculations for the different quinones in solvent, or in the presence of a single asymmetric H- bond to either a water molecule or a peptide backbone NH group, were undertaken. Calculated and experimental spectra agree best for the peptide backbone asymmetrically H- bonded system. By comparing multiple sets of double difference spectra, several new bands for the native quinone (phylloquinone) are identified. By comparing calculated and experimental spectra we conclude that the mono-substituted halogenated NQs can occupy the binding site in either of two different orientations, with the chlorine or bromine atom being either ortho or meta to the H- bonded CO group.

This study investigates the potential of 2-(4-butylbenzyl)-3-hydroxynaphthalene-1,4-dione (11) and its 12 derivatives as anticancer and biofilm formation inhibitors for methicillin-resistant staphylococcus aureus using in silico methods. The study employed various computational methods, including molecular dynamics simulation molecular docking, density functional theory, and global chemical descriptors, to evaluate the interactions between the compounds and the target proteins. The docking results revealed that compounds 9, 11, 13, and ofloxacin exhibited binding affinities of -7.6, -7.9, -7.5, and -7.8 kcal mol[sup -1], respectively, against peptide methionine sulfoxide reductase msrA/msrB (PDB: 3E0M). Ligand (11) showed better inhibition for methicillin-resistant staphylococcus aureus msrA/msrB enzyme. The complex of the 3E0M-ligand 11 remained highly stable across all tested temperatures (300, 305, 310, and 320 K). Principal Component Analysis (PCA) was employed to evaluate the behavior of the complex at various temperatures (300, 305, 310, and 320 K), demonstrating a total variance of 85%. Convergence was confirmed by the eigenvector's cosine content value of 0.43, consistently displaying low RMSD values, with the minimum observed at 310 K. Furthermore, ligand 11 emerges as the most promising candidate among the compounds examined, showcasing notable potential when considering a combination of in vitro, in vivo, and now in silico data. While the naphthoquinone derivative (11) remains the primary candidate based on comprehensive in silico studies, further analysis using Frontier molecular orbital (FMO) suggests while the Egap value of compound 11 (2.980 eV) and compound 13 (2.975 eV) is lower than ofloxacin (4.369 eV), indicating their potential, so it can be a statement that compound 13 can also be investigated in further research. [ABSTRACT FROM AUTHOR]

"Zicao" has a long medicinal history and has a variety of pharmacological activities. As the main resource of "zicao" in Tibet, Onosma glomeratum Y. L. Liu (tuan hua dian zi cao), usually used for treating pneumonia in Tibet, has not been reported deeply. In order to determine the main anti-inflammatory active ingredients of Onosma glomeratum Y. L. Liu, in this study, the extracts enriched in naphthoquinones and polysaccharides were optimized prepared form Onosma glomeratum Y. L. Liu by ultrasonic extraction, and reflux extraction, respectively, with Box-Behnken design effect surface method. And their anti-inflammatory abilities were screened on LPS induced A549 cells model, for figuring out the anti-inflammatory active ingredients from Onosma glomeratum Y. L. Liu. The extract enriched naphthoquinone was obtained under following condition: extract with 85% ethanol in a liquid to material ratio of 1:40 g/mL at 30 °C for 30 minutes using ultrasound, leading to the extraction rate of total naphthoquinone as 0.98 ± 0.017%; the extract enriched polysaccharides was prepared as follows: extract 82 minutes at 100 °C with distilled water in a liquid to material ratio of 1:50 g/mL, with extraction rate of polysaccharide as 7.07 ± 0.02%. On the LPS-induced A549 cell model, the polysaccharide extract from Onosma glomeratum Y. L. Liu showed better anti-inflammatory effects than the naphthoquinone extract, indicating the extract enriched in polysaccharides is the anti-inflammatory extract of Onosma glomeratum Y. L. Liu, which could serve as a potential anti-inflammatory extract in medical and food industries in the future. [ABSTRACT FROM AUTHOR]

β-acetoxyisovalerylalkannin (β-AIVA) is one of shikonin/alkannin derivative, which were mainly extracted from Boraginaceae family. The effects of β-AIVA on human melanoma A375 cells and U918 cells were investigated in vitro. The CCK-8 assay showed that β-AIVA inhibited proliferation of cells. Results from flow cytometry, ROS assay and JC-1 assay showed that β-AIVA increased late apoptosis rate, induced the production of ROS and promoted mitochondrial depolarization in cells. β-AIVA regulated expressions of BAX and Bcl-2 proteins, and increased the expression of cleaved caspase-9 and cleaved caspase-3. These findings suggest that β-AIVA may be a potential therapeutic drug for treating melanoma. [ABSTRACT FROM AUTHOR]

A new naphthoquinone derivative (1) together with twenty-three known compounds (2–24), were isolated from the aerial parts of Rubia cordifolia L. Their structures were elucidated on the basis of NMR and HR-ESIMS data. Compounds 1–13 were assessed for their inhibitory effects on NO production in LPS-stimulated RAW 264.7 macrophage cells. Compounds 2-6 exhibited significant inhibitory activities with IC50 values of 21.37, 13.81, 24.56, 20.32, and 30.08 μmol·L−1, respectively. [ABSTRACT FROM AUTHOR]

Simple Summary: Recent research and chemical screening work has identified the distribution of two major naphthoquinone regioisomers across a representative selection (including all genera, all sections in the large genus Drosera, and 190 of ca. 260 species recognized to date) in the diverse carnivorous plant family Droseraceae (sundews, Venus's flytrap and waterwheel plant). A consistent and reliably reproducible foundation and framework for the systematic classification and phylogenetic evaluation of mutual relationships is thus provided. This review gives an updated overview of the naphthoquinone data relevant to the chemotaxonomy of the group under investigation. The essential conclusions from these data are summarized and directions are proposed for future research. Chemotaxonomy is the link between the state of the art in analytical chemistry and the systematic classification and phylogenetic analysis of biota. Although the characteristic secondary metabolites from diverse biotic sources have been used in pharmacology and biological systematics since the dawn of mankind, only comparatively recently established reproducible methods have allowed the precise identification and distinction of structurally similar compounds. Reliable, rapid screening methods like TLC (Thin Layer Chromatography) can be used to investigate sufficiently large numbers of samples for chemotaxonomic purposes. Using distribution patterns of mutually exclusive naphthoquinones, it is demonstrated in this review how a simple set of chemical data from a representative sample of closely related species in the sundew family (Droseraceae, Nepenthales) provides taxonomically and phylogenetically informative signal within the investigated group and beyond. [ABSTRACT FROM AUTHOR]

Cancer is one of the leading causes of death worldwide, with breast cancer being the second cause of cancer-related mortality among women. Natural Products (NPs) are one of the main sources for drug discovery. During a screening campaign focused on the identification of extracts from Fundación MEDINA's library inhibiting the proliferation of cancer cell lines, a significant bioactivity was observed in extracts from cultures of the fungus Angustimassarina populi CF-097565. Bioassay-guided fractionation of this extract led to the identification and isolation of herbarin (1), 1-hydroxydehydroherbarin (4) plus other three naphthoquinone derivatives of which 3 and 5 are new natural products and 2 is herein described from a natural source for the first time. Four of these compounds (1, 3, 4 and 5) confirmed a specific cytotoxic effect against the human breast cancer cell line MCF-7. To evaluate the therapeutic potential of the compounds isolated, their efficacy was validated in 3D cultures, a cancer model of higher functionality. Additionally, an in-depth study was carried out to test the effect of the compounds in terms of cell mortality, sphere disaggregation, shrinkage, and morphology. The cell profile of the compounds was also compared to that of known cytotoxic compounds with the aim to distinguish the drug mode of action (MoA). The profiles of 1, 3 and 4 showed more biosimilarity between them, different to 5, and even more different to other known cytotoxic agents, suggesting an alternative MoA responsible for their cytotoxicity in 3D cultures. [ABSTRACT FROM AUTHOR]

The emergence and worldwide dissemination of mobile tigecycline resistance genes tet(X3)/tet(X4) posed an enormous threat to the public health. Urgently, feasible strategies must be implemented to restore the clinical efficacy of tetracyclines and prolong the lifespan of existing drugs to address the emerging global antimicrobial resistance threat. Herein, versatile structural scaffolds of quinones for antibiotic adjuvants discovery enlightened a promising and underappreciated reservoir to circumvent the antibiotic resistance. 2-methoxy-1,4-naphthoquinone (MNQ) exhibited the potent potentiation (4 to 32-fold) with tetracyclines, along with effective inhibition on biofilm formation. Mechanistic studies revealed that MNQ synergistically operates with tetracyclines by inhibiting the enzymatic activity of Tet(X3)/Tet(X4) proteins through interaction with their active residues. Furthermore, exposure to MNQ significantly dissipate the proton motive force, leading to a cascade of membrane structural damage and metabolic homeostasis imbalance. Encouragingly, the MNQ-tetracyclines combination showcased substantial therapeutic benefits in two in vivo infection models, as evidenced by the reduced bacterial burden and mitigated pathological injury. Our findings propose a potential therapeutic option and a novel tetracyclines' adjuvant against drug-resistant pathogens carrying Tet(X3)/Tet(X4). [ABSTRACT FROM AUTHOR]

Two common bio-sourced naphthoquinone derivatives, vitamin K1 (phylloquinone) and vitamin K3 (menadione), were employed in free radical photopolymerization under LED light exposure at 405 nm. In comparison with juglone, a previously reported natural naphthoquinone derivative, both vitamins exhibited enhanced properties in inducing free radical photopolymerization as sole initiators (monocomponent type II) and in combination with amines, and they can act as typical type II photoinitiators. In a three-component photoinitiating system consisting of an iodonium salt, amine and the vitamin, the polymerization process of TMPTA was significantly accelerated/improved too. These three-component systems resulted in faster reactions than the system that solely contains the iodonium salt or amine as the coinitiator, and they can additionally act as sensitizing dyes. Notably, the more polar vitamin K3 alone can initiate PEGDA polymerization with a high conversion rate, suggesting its potential utility in the development of biopolymer materials. The analysis of steady-state photolysis experiments revealed that K3 rapidly reacted with the electron-rich amine under light but was also more likely to generate by-products. In contrast, the inclusion of the iodonium salt in the three-component system significantly accelerated the photolysis of K3, demonstrating the superior chemical reactivity of the three-component system. Electron spin resonance spin trapping experiments successfully captured the radicals that initiated the photopolymerization reaction. Hence, these results facilitated the further deduction of potential reaction pathways. Finally, K1/iodonium salt and K3/amine, two systems that demonstrated strong performance in free radical polymerization experiments, were successfully applied to direct laser write experiments. [ABSTRACT FROM AUTHOR]

Breast cancer is one of the most prevalent cancer types worldwide. Chemotherapy is a substantial approach in the management of breast cancer despite the occurrence of chemotherapy-associated side effects and the development of multidrug resistance in cancer cells. At this point, a variety of quinone derivatives may represent potential as possible anticancer drug candidates due to possessing structural similarity towards clinically used anticancer drugs like doxorubicin. Therefore, we investigated the cytotoxic effects of various quinone derivatives with structural diversity towards a variety of breast cancer cells. We further determined their toxicity in healthy cells to evaluate their drug capability potential. Eighteen quinone derivatives (arbutin, hydroquinone, alkannin, lapachol, lawsone, juglone, aloe-emodin, aloin, cascaroside A (8-O-β-D-glucoside of 10-C-β-D-glucosyl aloe-emodin anthrone), chrysophanol, chrysophanol-8-O-β-D-glucoside, emodin, emodin-8-O-β-D-glucoside, frangulin A (emodin-6-O-a-L-rhamnoside), physcion, rhein, sennoside A, sennoside B (sennoside A and sennoside B are stereoisomers and rhein-dianthrone diglycosides in which β-D-glucose units are bound to the OH groups of rhein anthrones at their 8th positions) were tested on MCF-7, SK-BR-3, MDA-MB-468, and MDA-MB-231 breast cancer cells and on H9c2 healthy rat cardiac myoblast cells in terms of their cytotoxicity and toxicity, respectively. The resazurin reduction assay was used to determine the cytotoxicity. Among the tested compounds, two naphthoquinone derivatives alkannin and juglone exhibited remarkable cytotoxicity on breast cancer cells and exhibited alleviated toxicity profiles on healthy cells deserving further investigation as possible drug candidates against breast cancer. Structure-activity relationships of these compounds were also evaluated and discussed. Alkannin and juglone, which are naphthoquinone derivatives isolated from natural sources, may be promising agents in the development of drug-candidate molecules with increased efficacy and safety for breast cancer. [ABSTRACT FROM AUTHOR]

Secondary metabolites derived from plants are recognized as valuable products with several successful applications in the pharmaceutical, cosmetic, and food industries. The major limitation to the broader implementation of these compounds is their low manufacturing efficiency. Current efforts to overcome unprofitability depend mainly on biotechnological methods, especially through the application of plant in vitro cultures. This concept allows unprecedented bioengineering opportunities for culture system modifications with in situ product removal. The silica-based xerogels can be used as a novel, porous biomaterial characterized by a large surface area and high affinity to lipophilic secondary metabolites produced by plant tissue. This study aimed to investigate the influence of xerogel-based biomaterials functionalized with methyl, hydroxyl, carboxylic, and amine groups on Rindera graeca transgenic root growth and the production of naphthoquinone derivatives. The application of xerogel-based scaffolds functionalized with the methyl group resulted in more than 1.5 times higher biomass proliferation than for reference untreated culture. The naphthoquinone derivatives' production was noted exclusively in culture systems supplemented with xerogel functionalized with methyl and hydroxyl groups. Applying chemically functionalized xerogels as in situ adsorbents allowed for the enhanced growth and productivity of in vitro cultured R. graeca transgenic roots, facilitating product isolation due to their selective and efficient accumulation. [ABSTRACT FROM AUTHOR]

Background and purpose: Bacterial infections are treated with antibiotics, but the development of multi-drug resistant strains, which are growing at an increasing rate, is a phenomenon that threatens human societies. Therefore, alternative strategies are needed to combat infectious diseases. Today, compounds that reduce the pathogenicity of bacteria and do not interfere with their survival or growth are introduced as the next generation of antibiotics. Pseudomonas aeruginosa is one of the important and hazardous pathogens that employs its quorum-sensing network to regulate pathogenicity and virulence factors production. Here, we investigated the effect of a natural naphthoquinone compound, Lawsone (isolated from Henna), and its synthetic derivatives on the quorum-sensing system of P. aeruginosa PAO1. Materials and methods: First, the MIC of each compound was evaluated. Then, the effect of the selected compounds on biofilm formation and survival rate of biofilm sessile cells was investigated by colorimetric method. Finally, the virulence factors secretion of P. aeruginosa, including pyocyanin, pyoverdine, and protease was studied in the presence of the selected compounds. Results: The results indicated that Lawsone and NO2-481 reduced the production of P. aeruginosa biofilm by about 79% and 92%, respectively. Moreover, Lawsone and NO2-481 (at both concentrations, 250 and 125 µg/mL) decreased the viability of biofilm cells by about 70%. Furthermore, NO2-481 reduced the production of virulence factors including pyocyanin and pyoverdine by about 55% and 81%, respectively; however, it did not affect the protease production. Conclusion: NO2-481 derivative has the ability to reduce the pathogenicity of P. aeruginosa, and if it is proven to be non-cytotoxic, it can be assessed through animal and clinical studies, to be applied as an alternative compound along with antibiotics or disinfectants

A talented endophytic Streptomyces sp. PH9030 is derived from the medicinal plant Kadsura coccinea (Lem.) A.C. Smith. The undescribed naphthoquinone naphthgeranine G (5) and seven previously identified compounds, 6–12, were obtained from Streptomyces sp. PH9030. The structure of 5 was identified by comprehensive examination of its HRESIMS, 1D NMR, 2D NMR and ECD data. The inhibitory activities of all the compounds toward α-glucosidase and their antibacterial properties were investigated. The α-glucosidase inhibitory activities of 5, 6, 7 and 9 were reported for the first time, with IC50 values ranging from 66.4 ± 6.7 to 185.9 ± 0.2 μM, as compared with acarbose (IC50 = 671.5 ± 0.2 μM). The molecular docking and molecular dynamics analysis of 5 with α-glucosidase further indicated that it may have a good binding ability with α-glucosidase. Both 9 and 12 exhibited moderate antibacterial activity against methicillin-resistant Staphylococcus aureus, with minimum inhibitory concentration (MIC) values of 16 μg/mL. These results indicate that 5, together with the naphthoquinone scaffold, has the potential to be further developed as a possible inhibitor of α-glucosidase.

Currently, skin injuries have a serious impact on people's lives and socio-economic stress. Shikonin, a naphthoquinone compound derived from the root of the traditional Chinese medicine Shikonin, has favorable biological activities such as anti-inflammatory, antibacterial, immunomodulatory, anticancer, and wound-healing-promoting pharmacological activities. It has been reported that Shikonin can be used for repairing skin diseases due to its wide range of pharmacological effects. Moreover, the antimicrobial activity of Shikonin can play a great role in food and can also reduce the number of pathogenic bacteria in food. This paper summarizes the research on the pharmacological effects of Shikonin in recent years, as well as research on the mechanism of action of Shikonin in the treatment of certain skin diseases, to provide certain theoretical references for the clinical application of Shikonin, and also to provides research ideas for the investigation of the mechanism of action of Shikonin in other skin diseases. [ABSTRACT FROM AUTHOR]

Topoisomerases II are ubiquitous enzymes with significant genotoxic effects in many critical DNA processes. Additionally, epidermal growth factor receptor (EGFR) plays pivotal role in tumour growth and angiogenesis. A novel series of naphtho[2',3':4,5]thiazolo[3,2-a]pyrimidine hybrids have been designed, synthesised and evaluated for their topo IIα/EGFR inhibitory and apoptotic inducer activities. Cytotoxicity of the synthesised hybrids was evaluated against MCF-7, A549 and HCT-116 cell lines. Of the synthesised hybrids, 6i, 6a and 6c experienced superior cytotoxic activity compared to doxorubicin and erlotinib against the tested cancer cells. The molecular mechanism of these hybrids revealed their ability to successfully inhibit topo IIα and EGFR activities in micromolar concentration and may serve as topo II catalytic inhibitor. Moreover, these hybrids significantly arrested cell cycle at G2/M phase together with increased p53, caspae-7, caspase-9 levels and Bax/Bcl-2 ratio. The synthesised hybrids showed efficient binding pattern in molecular docking study and have acceptable drug likeness characters. [ABSTRACT FROM AUTHOR]

As an organic pseudocapacitive active material, 2, 3‐Dichloro‐1, 4‐naphthoquinone (DNQ) was used in supercapacitors. Graphene with unique structures and high electrical conductivity acts as substrate. DNQ non‐covalently modified graphene composite material (DNQ@rGO) was synthesized through the simple solvothermal synthesis. The redox reaction between naphthol and naphthoquinone occurs on reduced graphene oxide(rGO), which forms an ideal pseudocapacitance without destroying its sp2 network. The optimal DNQ@rGO electrode material obtained the specific capacitance of 361.2 Fg−1 at 5 mV s−1 in 1 mol L−1 H2SO4 and exhibited excellent rate capability (capacitance retention of 87.5 % at 100 mV s−1) in the three‐electrode system. We also prepared holey layered oxygen‐rich graphene hydrogels (HLGH) material, whose electrochemical performance is superior to traditional three‐dimensional (3D) graphene hydrogels (GH). Finally, two asymmetric supercapacitors (ASCs) were assembled by using the DNQ@rGO (positive electrode), the HLGH and GH (negative electrode). The results show that the ASC with HLGH as negative electrode achieved the high energy and power densities due to the perfect matching of capacitance and kinetics between the positive and negative electrodes. The specific capacitance was almost no loss after 4700 cycles, showing the excellent stability. [ABSTRACT FROM AUTHOR]

Intramolecular hydrogen‐bonded naphthoquinone derivatives are investigated using both DFT (density functional theory) and MP2 (Møller–Plesset perturbation theory) method. Three different sets of naphthoquinone derivatives, each set consisting of syn and anti conformers with respect to the substitution by (–OH/–NH2) at peri and para position of the ring, are considered for investigation. In all cases, the syn conformer is found to be energetically more stable compared with the anti conformer. However, the hydrogen bond strength of the anti conformer is found to be more as obtained from NBO (natural bond orbital) analysis and QTAIM (quantum theory of atoms in molecules) theory. The O···H–O interactions are associated with covalent character while O···H–N interactions are noncovalent in nature. The NCI (noncovalent interaction) isosurface clearly indicates the formation of O···H–O and O···H–N intramolecular hydrogen bond. The energy partition analysis indicates electrostatic interaction as the dominant force in stabilizing these systems. The aromaticity calculation by HOMA (harmonic oscillator model of aromaticity) index and Bird index indicate the syn conformer with higher aromaticity compared to the anti conformer. The overall stability of the syn conformers is thus dominated by the aromatic stabilization energy instead of hydrogen bonding energy. The global reactivity descriptors further support the higher stability of the syn conformers according to maximum hardness principle (MHP) and minimum electrophilicity principle (MEP). [ABSTRACT FROM AUTHOR]

Background and purpose: Bacterial infections are treated with antibiotics, but the development of multi-drug resistant strains, which are growing at an increasing rate, is a phenomenon that threatens human societies. Therefore, alternative strategies are needed to combat infectious diseases. Today, compounds that reduce the pathogenicity of bacteria and do not interfere with their survival or growth are introduced as the next generation of antibiotics. Pseudomonas aeruginosa is one of the important and hazardous pathogens that employs its quorum-sensing network to regulate pathogenicity and virulence factors production. Here, we investigated the effect of a natural naphthoquinone compound, Lawsone (isolated from Henna), and its synthetic derivatives on the quorum-sensing system of P. aeruginosa PAO1. Materials and methods: First, the MIC of each compound was evaluated. Then, the effect of the selected compounds on biofilm formation and survival rate of biofilm sessile cells was investigated by colorimetric method. Finally, the virulence factors secretion of P. aeruginosa, including pyocyanin, pyoverdine, and protease was studied in the presence of the selected compounds. Results: The results indicated that Lawsone and NO2-481 reduced the production of P. aeruginosa biofilm by about 79% and 92%, respectively. Moreover, Lawsone and NO2-481 (at both concentrations, 250 and 125 µg/mL) decreased the viability of biofilm cells by about 70%. Furthermore, NO2-481 reduced the production of virulence factors including pyocyanin and pyoverdine by about 55% and 81%, respectively; however, it did not affect the protease production. Conclusion: NO2-481 derivative has the ability to reduce the pathogenicity of P. aeruginosa, and if it is proven to be non-cytotoxic, it can be assessed through animal and clinical studies, to be applied as an alternative compound along with antibiotics or disinfectants. [ABSTRACT FROM AUTHOR]

Breast cancer is the most frequently diagnosed cancer in women and the second leading cause of cancer‐related deaths. Because triple‐negative breast cancer (TNBC) is highly resistant to clinically employed drugs, developing new drugs and treatment approaches is imperative. Naphthoquinone compounds potentially induce cancer cell death, and their clinical derivatives have been widely used as medicines. This study presents the synthesis and structure of a newly substituted naphthoquinone compound, as determined by spectroscopic techniques, then assesses the compound's ability to induce cell death on the MDA‐MB‐231 cell line using SRB viability testing, flow cytometry, and Western Blotting. The study also examines the compound's inhibition of cell migration through a scratch assay. The study discovered that the compound demonstrated an antigrowth/cytotoxic impact at concentrations of 3.12 μM and beyond. The cytotoxicity may have been caused by elevated reactive oxygen species, which resulted in DNA damage. The mode of cell death was apoptotic, confirmed by the translocation of phosphatidylserine, the activation of caspases, and the disruption of the mitochondrial membrane potential. The compound seems promising as a new anti‐malignant agent to be used for the treatment of breast cancer and deserves further attention for proof‐of‐concept in animal studies. [ABSTRACT FROM AUTHOR]

Leukemia encompasses a group of highly heterogeneous diseases that pose a serious threat to human health. The long-term outcome of patients with leukemia still needs to be improved and new effective therapeutic strategies continue to be an unmet clinical need. Shikonin (SHK) is a naphthoquinone derivative that shows multiple biological function includes anti-tumor, anti-inflammatory, and antiallergic effects. Numerous studies have reported the anti-leukemia activity of SHK during the last 3 decades and there are studies showing that SHK is particularly effective towards various leukemia cells compared to solid tumors. In this review, we will discuss the anti-leukemia effect of SHK and summarize the underlying mechanisms. Therefore, SHK may be a promising agent to be developed as an anti-leukemia drug. [ABSTRACT FROM AUTHOR]

As contaminants are often present in aquatic environments as mixtures, they may interact with each other and affect living organisms differently than when tested individually. Emerging pollutants such as pharmaceuticals and microplastics can be influenced by various environmental factors, with UV/Vis radiation being among the most significant. This study aimed to evaluate the photodegradation of the antidepressant duloxetine in the presence of four types of microplastics. Acute toxicity was tested using the Spirotox assay, duloxetine concentration was determined using HPLC-DAD analysis, and the resulting photodegradation products were tested using HPLC-MS/MS. Following 1 and 2 h of exposure in a sunlight simulator, the concentrations of duloxetine decreased by nine and thirteen times, respectively, while its toxicity to protozoa decreased by only two and three times. The presence of microplastics in the samples did not affect either the photodegradation process or the toxicity of duloxetine. HPLC-MS/MS analysis revealed the presence of 34 duloxetine photodegradation products. In silico toxicity analysis using the T.E.S.T. program for the protozoan Tetrahymena pyriformis indicated that one-third of the photoproducts were as toxic, and two products were found to be much more toxic than duloxetine. The high toxicity of one of these compounds was confirmed using the Spirotox test. [ABSTRACT FROM AUTHOR]

(2, 3-DN)0.23V2O5·0.22H2O (DN = dinaphthoquinone) nanosheets with rich oxygen vacancies (abbreviated as (2, 3-DN)-VO) were synthesized by a facile one-step solvothermal method. Rietveld refinement illustrates the successful intercalation of 2, 3-DN into the layered vanadium oxide. (2, 3-DN)-VO can deliver a high specific capacity of 440 mAh g−1 at 0.1 A g−1 with a capacity retention of 92.6% over 2300 discharge/charge cycles at 10 A g −1 when used as zinc-ion battery cathode. It benefits from the dual-activity of naphthoquinone and vanadium oxide. Meanwhile, the encapsulation of naphthoquinone into the interlayer channel of vanadium oxide not only can expand the interstitial spacing for the diffusion of Zn2+, but also prevent the dissolution of the organic species into the electrolyte. [ABSTRACT FROM AUTHOR]

The naphthoquinone derivative, NQ 40, has been confirmed to be an effective algicide for controlling freshwater Microcystis blooms at the microcosm and mesocosm scales. Thus, in order to determine whether this algicide can control cyanobacterial blooms in the field, larger-scale mesocosms (50 t) and test beds (3,000 t) were tested. In the mesocosm and test-bed experiments, NQ 40 was effective and selective for algicidal activity against the target cyanobacteria (Microcystis spp.). In addition, the algicidal activity of NQ 40 gradually increased until days 8 and 30, while the algal biomass decreased by 96.7 and 100%, respectively. Ecosystem health improved due to the algicidal effect of NQ 40. In the test-bed experiment, the Shannon–Wiener diversity index of phytoplankton was significantly enhanced and the unbalanced ecological pyramid caused by cyanobacterial blooms was restored in the NQ 40 treatment. Although a few factors (pH, dissolved oxygen, and phosphate) associated with phytoplankton abundance exhibited different patterns between the control and treatments, the dynamics of abiotic factors in the treatments generally showed similar trends to the control. Therefore, NQ 40 could be a promising eco-friendly algicidal substance for restoring freshwater ecosystems damaged by cyanobacterial blooms. [ABSTRACT FROM AUTHOR]

Eleutherine bulbosa (E. bulbosa) is a traditional medicinal plant known to contain 1,4- naphthoquinone as the active compound responsible for its pharmacological effects. Ensuring consistent pharmacological effects in pharmaceutical preparations necessitates the quantitative measurement of the active compound content in the extract. This study aims to establish a method for quantifying the levels of 1,4-naphthoquinone in both ethanol and water extracts of E. bulbosa and to determine the optimal levels in both extracts. The High-Performance Liquid Chromatography (HPLC) method was employed to assess the 1,4-naphthoquinone levels. Method validation was conducted to evaluate the accuracy, precision, linearity, and selectivity of the method. The validation results indicate that this method has met the standards, with the linearity test yielding an “r” value of 0.9939, the selectivity test indicating selectivity at 3.507 minutes, the precision test resulting in a %RSD of 0.7159%, and the accuracy test showing a % recovery of 99.53%. These method validation parameters satisfy the required criteria, affirming the reliability of the method employed. The average levels of 1,4-naphthoquinone in the ethanol extract were determined to be 4.5797 ppm, while in the water extract, it measured 3.2314 ppm. These findings imply that the ethanol extract contains a higher concentration of 1,4-naphthoquinone compared to the water extract. Consequently, it can be inferred that the HPLC method for quantifying 1,4- naphthoquinone levels is valid, and the ethanol extract is recommended as a superior raw material for the development of traditional medicines due to its higher content of active compounds. [ABSTRACT FROM AUTHOR]

Time-resolved step-scan FTIR difference spectroscopy at 77 K has been used to study photosystem I (PSI) from Synechocystis sp. PCC 6803 with four high-potential, 1,4–naphthoquinones (NQs) incorporated into the A1 binding site. The incorporated quinones are 2–chloro–NQ (2ClNQ), 2–bromo–NQ (2BrNQ), 2,3–dichloro–NQ (Cl2NQ), and 2,3–dibromo–NQ (Br2NQ). For completeness 2-methyl-NQ (2MNQ) was also incorporated and studied. Previously, PSI with the same quinones incorporated were studied in the, so-called, anion spectral region between 1550 and 1400 cm−1 (Agarwala et al. in Biochim Biophys Acta 1864(1):148918, 2023). Here we focus on spectra in the previously unexplored 1400–1200 cm−1 spectral region. In this region several bands are identified and assigned to the neutral state of the incorporated quinones. This is important as identification of neutral state quinone bands in the regular 1700–1600 cm−1 region has proven difficult in the past. For neutral PhQ in PSI a broad, intense band appears at ~ 1300 cm−1. For the symmetric di-substituted NQs (Cl2NQ/Br2NQ) a single intense neutral state band is found at ~ 1280/1269 cm−1, respectively. For both mono-substituted NQs, 2ClNQ and 2BrNQ, however, two neutral state bands are observed at ~ 1280 and ~ 1250 cm−1, respectively. These observations from time-resolved spectra agree well with conclusions drawn from absorption spectra of the NQs in THF, which are also presented here. Density functional theory based vibrational frequency calculations were undertaken allowing an identification of the normal modes associated with the neutral state quinone bands. [ABSTRACT FROM AUTHOR]

This study investigates the potential of 2-(4-butylbenzyl)-3-hydroxynaphthalene-1,4-dione (11) and its 12 derivatives as anticancer and biofilm formation inhibitors for methicillin-resistant staphylococcus aureus using in silico methods. The study employed various computational methods, including molecular dynamics simulation molecular docking, density functional theory, and global chemical descriptors, to evaluate the interactions between the compounds and the target proteins. The docking results revealed that compounds 9, 11, 13, and ofloxacin exhibited binding affinities of −7.6, −7.9, −7.5, and −7.8 kcal mol−1, respectively, against peptide methionine sulfoxide reductase msrA/msrB (PDB: 3E0M). Ligand (11) showed better inhibition for methicillin-resistant staphylococcus aureus msrA/msrB enzyme. The complex of the 3E0M-ligand 11 remained highly stable across all tested temperatures (300, 305, 310, and 320 K). Principal Component Analysis (PCA) was employed to evaluate the behavior of the complex at various temperatures (300, 305, 310, and 320 K), demonstrating a total variance of 85%. Convergence was confirmed by the eigenvector’s cosine content value of 0.43, consistently displaying low RMSD values, with the minimum observed at 310 K. Furthermore, ligand 11 emerges as the most promising candidate among the compounds examined, showcasing notable potential when considering a combination of in vitro, in vivo, and now in silico data. While the naphthoquinone derivative (11) remains the primary candidate based on comprehensive in silico studies, further analysis using Frontier molecular orbital (FMO) suggests while the Egap value of compound 11 (2.980 eV) and compound 13 (2.975 eV) is lower than ofloxacin (4.369 eV), indicating their potential, so it can be a statement that compound 13 can also be investigated in further research.

In this study, novel N,S-substituted naphthaquinone analogues (2, 4, 6, and 8) were synthesized from the reactions of previously known aminonaphthaquinone derivatives (1, 3, 5, and 7) with allyl mercaptan. 2-(allylthio)-3-(4-phenylpiperazin-1-yl)naphthalene-1,4-dione (2), 2-(allylthio)-3-(4-(2-fluorophenyl)piperazin-1-yl)naphthalene-1,4-dione (4), 2-(allylthio) -3-(4-benzylpiperidin-1-yl)naphthalene-1,4-dione (6) and 2-(4-chlorophenylamino)-3-(allylthio)naphthalene-1,4-dione (8) were obtained from the reactions of 2-chloro-3-(4-phenylpiperazin-1-yl)naphthalene-1,4-dione (1), 2-chloro-3-(4-(2-fluorophenyl)piperazin-1-yl)naphthalene-1,4-dione (3), 2-(4-benzylpiperidin-1-yl)-3-chloronaphthalene-1,4-dione (5), and 2-(4-chlorophenylamino) -3-chloronaphthalene-1,4-dione (7) with allyl mercaptan according to the general synthesis procedure. Synthesized new naphthaquinone analogues (2, 4, 6, and 8) were purified by column chromatography. The chemical structures of these novel N,S-substituted naphthaquinone analogues were characterized by spectroscopic methods (FT-IR, NMR, and MS).

Shikonin is a naphthoquinone pigment present in the hairy roots of the plant species from the Boraginaceae family. The compound has been well investigated for its highly efficient medicinal, antioxidant, and antimicrobial properties. Various extraction methodologies have been employed to maximise yield while minimising waste production of shikonin and its derivatives. Despite substantial research on shikonin and Boraginaceae plants, a research gap persists in the food industry and extraction technologies. This review addresses crucial aspects of shikonin deserving of further exploration. It begins by elucidating the attributes of the Boraginaceae plants and their medicinal traits in folklore. It proceeds to focus on the roots of the plant and its medicinal properties, followed by extraction procedures explored in the last fifteen years, emphasising the novel technologies that have been chosen to improve the yield extract while minimising extraction times. Furthermore, this review briefly outlines studies employing cell culture techniques to enhance in vitro shikonin production. Lastly, attention is directed towards research in the food industry, particularly on shikonin-loaded biodegradable films and the antioxidant activity of shikonin. This review concludes by summarising the future potential in food science and prominent research gaps in this field.

Topoisomerases II are ubiquitous enzymes with significant genotoxic effects in many critical DNA processes. Additionally, epidermal growth factor receptor (EGFR) plays pivotal role in tumour growth and angiogenesis. A novel series of naphtho[2',3':4,5]thiazolo[3,2-a]pyrimidine hybrids have been designed, synthesised and evaluated for their topo IIα/EGFR inhibitory and apoptotic inducer activities. Cytotoxicity of the synthesised hybrids was evaluated against MCF-7, A549 and HCT-116 cell lines. Of the synthesised hybrids, 6i, 6a and 6c experienced superior cytotoxic activity compared to doxorubicin and erlotinib against the tested cancer cells. The molecular mechanism of these hybrids revealed their ability to successfully inhibit topo IIα and EGFR activities in micromolar concentration and may serve as topo II catalytic inhibitor. Moreover, these hybrids significantly arrested cell cycle at G2/M phase together with increased p53, caspae-7, caspase-9 levels and Bax/Bcl-2 ratio. The synthesised hybrids showed efficient binding pattern in molecular docking study and have acceptable drug likeness characters.

Four new Cu/PPh3/naphtoquinone complexes were synthesized, characterized (IR, UV/visible, 1D/2D NMR, mass spectrometry, elemental analysis, and X-ray diffraction), and evaluated as anticancer agents. We also investigated the reactive oxygen species (ROS) generation capacity of complex 4, considering the well-established photochemical property of naphthoquinones. Therefore, employing the electron paramagnetic resonance (EPR) "spin trap", 5,5-dimethyl-1-pyrroline N-oxide (DMPO) technique, we identified the formation of the characteristic •OOH species (hydroperoxyl radical) adduct even before irradiating the solution containing complex 4. As the irradiation progressed, this radical species gradually diminished, primarily giving rise to a novel species known as •DMPO-OH (DMPO + •OH radical). These findings strongly suggest that Cu(I)/PPh3/naphthoquinone complexes can generate ROS, even in the absence of irradiation, potentially intensifying their cytotoxic effect on tumor cells. Interpretation of the in vitro cytotoxicity data of the Cu(I) complexes considered their stability in cell culture medium. All of the complexes were cytotoxic to the lung (A549) and breast tumor cell lines (MDA-MB-231 and MCF-7). However, the higher toxicity for the lung (MRC5) and breast (MCF-10A) non-tumoral cells resulted in a low selectivity index. The morphological analysis of MDA-MB-231 cells treated with the complexes showed that they could cause decreased cell density, loss of cell morphology, and loss of cell adhesion, mainly with concentrations higher than the inhibitory concentration of 50% of cell viability (IC50) values. Similarly, the clonogenic survivance of these cells was affected only with concentrations higher than the IC50 values. An antimigratory effect was observed for complexes 1 and 4, showing around 20–40% of inhibition of wound closure in the wound healing experiments. [ABSTRACT FROM AUTHOR]

Low-molecular-weight protein tyrosine phosphatases (LMW-PTPs) are involved in promoting the intracellular survival of Mycobacterium tuberculosis (Mtb), the causative organism of tuberculosis. These PTPs directly alter host signalling pathways to evade the hostile environment of macrophages and avoid host clearance. Among these, protein tyrosine phosphatase A (Mt-PTPa) is implicated in phagosome acidification failure, thereby inhibiting phagosome maturation to promote Mycobacterium tuberculosis (Mtb) survival. In this study, we explored Mt-PTPa as a potential drug target for treating Mtb. We started by screening a library of 502 pure natural compounds against the activities of Mt-PTPa in vitro, with a threshold of 50% inhibition of activity via a <500 µM concentration of the candidate drugs. The initial screen identified epigallocatechin, myricetin, rosmarinic acid, and shikonin as hits. Among these, the naphthoquinone, shikonin (5, 8-dihydroxy-2-[(1R)-1-hydroxy-4-methyl-3-pentenyl]-1,4-naphthoquinone), showed the strongest inhibition (IC50 33 µM). Further tests showed that juglone (5-hydroxy-1,4-naphthalenedione), another naphthoquinone, displayed similar potent inhibition of Mt-PTPa to shikonin. Kinetic analysis of the inhibition patterns suggests a non-competitive inhibition mechanism for both compounds, with inhibitor constants (Ki) of 8.5 µM and 12.5 µM for shikonin and juglone, respectively. Our findings are consistent with earlier studies suggesting that Mt-PTPa is susceptible to specific allosteric modulation via a non-competitive or mixed inhibition mechanism. [ABSTRACT FROM AUTHOR]

A straightforward and effective method for synthesizing coumarin-linked pyrrole derivatives fused with naphthoquinone has been reported by the one-pot reaction of aryl glyoxal, 4-hydroxycoumarin and 2-amino-1,4-naphthoquinone in hexafluoroisopropanol (HFIP) under reflux conditions. The main features of this methodology are simple reaction conditions, no use of metal or additional catalyst, less reaction time, use of recrystallization technique for purification, avoid of column chromatography, good yields of the products, creation of three new bonds (2 C-C and 1 C-N) in one-pot and occurrence of three biologically import moieties namely pyrrole, naphthoquinone and coumarin in the product. Spectroscopic techniques such as FTIR, 1H NMR, 13C NMR, and HRMS were used to characterize all of our synthesized products. To further confirm the structure of the product, single crystal XRD of one compound was recorded. A convenient and step-economical methodology has been described for the synthesis of coumarin-linked pyrrole derivatives fused with naphthoquinone from readily available starting materials such as aryl glyoxal, 4-hydroxycoumarin and 2-amino1,4-naphthoquinone by HFIP mediated multicomponent reaction. [ABSTRACT FROM AUTHOR]

Schistosomiasis, a potentially fatal chronic disease whose etiological agents are blood trematode worms of the genus Schistosoma spp., is one of the most prevalent and debilitating neglected diseases. The treatment of schistosomiasis depends exclusively on praziquantel (PZQ), a drug that has been used since the 1970s and that already has reports of reduced therapeutic efficacy, related with the development of Schistosoma-resistant or -tolerant strains. Therefore, the search for new therapeutic alternatives is an urgent need. Plumbagin (PLUM), a naphthoquinone isolated from the roots of plants of the genus Plumbago, has aroused interest in research due to its antiparasitic properties against protozoa and helminths. Here, we evaluated the in vivo schistosomicidal potential of PLUM against Schistosoma mansoni and the in silico pharmacokinetic parameters. ADMET parameters and oral bioavailability were evaluated using the PkCSM and SwissADME platforms, respectively. The study was carried out with five groups of infected mice and divided as follows: an untreated control group, a control group treated with PZQ, and three groups treated orally with 8, 16, or 32 mg/kg of PLUM. After treatment, the Kato–Katz technique was performed to evaluate a quantity of eggs in the feces (EPG). The animals were euthanized for worm recovery, intestine samples were collected to evaluate the oviposition pattern, the load of eggs was determined on the hepatic and intestinal tissues and for the histopathological and histomorphometric evaluation of tissue and hepatic granulomas. PLUM reduced EPG by 65.27, 70.52, and 82.49%, reduced the total worm load by 46.7, 55.25, and 72.4%, and the female worm load by 44.01, 52.76, and 71.16%, for doses of 8, 16, and 32 mg/kg, respectively. PLUM also significantly reduced the number of immature eggs and increased the number of dead eggs in the oogram. A reduction of 36.11, 46.46, and 64.14% in eggs in the hepatic tissue, and 57.22, 65.18, and 80.5% in the intestinal tissue were also observed at doses of 8, 16, and 32 mg/kg, respectively. At all doses, PLUM demonstrated an effect on the histopathological and histomorphometric parameters of the hepatic granuloma, with a reduction of 41.11, 48.47, and 70.55% in the numerical density of the granulomas and 49.56, 57.63, and 71.21% in the volume, respectively. PLUM presented itself as a promising in vivo antiparasitic candidate against S. mansoni, acting not only on parasitological parameters but also on hepatic granuloma. Furthermore, in silico, PLUM showed good predictive pharmacokinetic profiles by ADMET. [ABSTRACT FROM AUTHOR]

Alkannin, shikonin and their derivatives (A/S) are secondary metabolites produced in the roots of certain plants of the Boraginaceae family such as Lithospermum erythrorhizon Siebold & Zucc. and Alkanna tinctoria (L.) Tausch. These naphthoquinones express anti-cancer, wound healing, and antimicrobial activities. To study the interactions between endophytic bacteria isolated from A. tinctoria and the antimicrobials A/S, endophytic bacteria known to be resistant to the compounds were screened for their effect on A/S in liquid medium. Thereafter, the strain Pseudomonas sp. R-72008, was selected and tested for its ability to modify A/S in nutrient medium and minimal medium with A/S as sole carbon source. Bacterial growth was recorded, and high performance liquid chromatography-diode array and ultra-high performance liquid chromatography-electrospray ionization-mass spectrometry analyses were performed to detect and quantify metabolites. In nutrient medium inoculated with R-72008, a decrease in the amount of A/S monomers initially present was observed and correlated with an increase of A/S oligomers. Moreover, a significant decrease of initial A/S monomers in minimal medium was correlated with bacterial growth, showing for the first time that a bacterial strain, Pseudomonas sp. R-72008, was able to use the naphthoquinones A/S as sole carbon source. This study opens new perspectives on the interactions between bacteria and plant antimicrobials. [ABSTRACT FROM AUTHOR]

Napabucasin (also known as BBI608) is a natural naphthoquinone originally identified as a cancer cell stemness inhibitor. Accumulated in vitro and in vivo evidence demonstrated that napabucasin showed significant anticancer effects in various types of cancers. Napabucasin inhibits cancer cell proliferation, induces apoptosis and cell cycle arrest, and suppresses metastasis and relapse. Such anticancer activities of napabucasin mainly rely on the inhibition of cancer stemness by targeting signal transducer and activator of transcription 3 (STAT3) and its related gene inhibition. However, several novel molecular targets for napabucasin, such as NAD(P)H:quinone oxidoreductase 1 (NQO1) and thioredoxin reductase 1 (TrxR1), have been reported. Napabucasin represents a promising anticancer lead for multiple cancers. In this mini review, the anticancer potential and the molecular mechanism of napabucasin will be briefly highlighted. [ABSTRACT FROM AUTHOR]

Under physiological conditions, natural enediynes antibiotics generate free radicals through a cycloaromatization reaction. The resulting highly reactive radicals can abstract hydrogen atoms on the phosphate backbone of DNA, leading to high cytotoxicity. On the other hand, anthraquinone‐fused compounds such as daunomycin and adriamycin can insert into DNA through planar aromatic ring structures, resulting in strong DNA damage. To this end, a series of naphthoquinone‐based enediynes were designed and synthesized by adjusting the type of terminal alkyne to modulate their water solubility and radical generation property. Theoretical calculations suggest that the naphthoquinone‐based enediyne generates radicals through a rearrangement (1,3‐proton transfer) followed by Myers‐Saito cyclization processes, with a much lower activation free energy barrier than Bergman cyclization (24.2 kcal/mol vs 39.8 kcal/mol). Differential scanning calorimetry and electron paramagnetic resonance results showed that naphthoquinone‐based enediynes undergo cycloaromatization at relatively low temperatures, resulting in the generation of highly reactive radical species. The enediynes with optimal water solubility displayed strong DNA cleavage ability at micromolar level and high cytotoxicity towards Hela cells, providing a half‐inhibitory concentration of 8.19 μM. [ABSTRACT FROM AUTHOR]

Naphthoquinones are natural plants products or synthesized compounds. They have α, β-cyclic aromatic dienones structure with a naphthalene skeleton. Little is known about naphthoquinone and nothing about naphtho [2,3-b] thiophen-4,9-quinone effects on bladder cancer. In this study, a naphthoquinone containing a hetero sulfur atom was synthesized using classical synthetic method. The molecular structure was elucidated by NMR techniques and the antitumor effects were evaluated on bladder tumor cell lines with different TP53 status using tripan blue and MTT cytotoxic method, quantification of reactive oxygen species (ROS), wound healing, cell morphology and cell cycle progression assays. The results showed selective cytotoxicity, colonies reduction, morphological change, inhibition of the cell migration process, induction of ROS production and cell cycle arrest. Naphtho [2,3-b] thiophen-4,9-quinone presents antiproliferative activity regardless TP53 status and may be a promising agent in the treatment of bladder cancer, as they have an oxidizing effect and interfere with cell cycle. [ABSTRACT FROM AUTHOR]

Wood is a lignocellulosic material that, because of its organic nature, is a source of nutrients for bacteria, fungi, and insects. Incisitermes marginipennis (Latreille) is an interesting dry wood-boring termite. Because it is an extremely destructive pest, difficult to control due to its cryptic lifestyle, and for its role in the biogeochemical cycle of carbon and other elements; it is a fundamental organism. The use of less toxic and eco-friendly substances is important for protecting domestic, cultural, and historical heritage made of wood or lignocellulosic materials. The aim of this study was to evaluate the biological activity of various naphthoquinones extracted from the heartwood of T. grandis on I. marginipennis. First, heartwood flour was used for Soxhlet-type extractions to isolate and characterize the heartwood compounds by thin-layer chromatography. To identify the heartwood compounds, nuclear magnetic resonance and gas chromatography coupled to a mass spectrometer were used. The information obtained was supported using the Interactive Spectroscopy software. The identified heartwood compounds were lapachol, tectoquinone, deoxylapachol, dehydro-α-lapachone, tectol and tecomaquinone-I. Using nymphal termites of I. marginipennis as a biological model, the isolated and identified molecules were under three different tests (repellent, insecticide and protective) and their biological activity was individually evaluated. The results showed that the molecules obtained have a repellent-protective effect against I. marginipennis, although not in all cases, these molecules have high percentages of mortality and decreased the weight loss of the treated material exposed to I. marginipennis. [ABSTRACT FROM AUTHOR]