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Biological responses of a variety of naturally occurring compounds in vivo were restrained by their poor oral bioavailability. Silybin, as one of the active ingredients of silymarin, has presented promising bioactivity for the treatment of chronic liver diseases and cancer. However, its exposure in body was limited. In this study, silybin was demonstrated to be substrates of both BCRP and MRP2 by utilizing monolayer Caco-2 cell model and confirmed in MDCK cells overexpressing specific efflux transporter. Of all compounds screened, tangeretin, a potent inhibitor of efflux transporters of BCRP, MRP2 and P-gp, was able to enhance exposure of silybin by inhibiting functions of the barriers mediating transcellular transport. Moreover, study carried out in sandwich-cultured rat hepatocyte (SCH) model showed that the biliary excretion index (BEI) and in vitro biliary clearance of silybin decreased as levels of tangeretin increased, indicating efflux transporters mediating biliary excretion of silybin might be involved. Pharmacokinetic behaviors of silybin in rats were altered by co-administration of tangeretin, in terms of increased AUC and Cmax of silybin by comparing with that of silybin given alone. In addition, results coming from CCl4-induced acute liver injury rat model revealed that protection effect of silybin against liver damage in the presence of tangeretin was significantly enhanced. All these data were evident that efflux transporters play a critical role in transcellular transport of silybin and account for its low bioavailability. Enhanced bioavailability of silybin with co-administration of tangeretin by significantly inhibiting the efflux transporters further boost its bioactivity which is of particular importance in clinical use.

Post-traumatic stress disorder (PTSD) is a stress-related psychiatric/mental condition. Tangeretin (TAN), a major polymethoxylated flavone of citrus plants, exhibits anti-inflammatory and neuroprotective activities. However, whether TAN leads to cognitive improvement in PTSD patients remains unclear. In the present study, we explored whether TAN improved cognitive impairment induced in rats by single prolonged stress (SPS episode mimicking PTSD induction) and determined whether TAN reversed reductions in dopamine (DA) and serotonin (5-HT) levels. Rats were intraperitoneally injected with TAN for 14 consecutive days after the SPS, which had induced cognitive deficits evident in the object recognition task and the Morris water maze test; the impairments were improved by TAN (100 mg/kg). TAN rescued the neurochemical abnormalities and the SPS-induced decreases in DA and 5-HT levels in the hippocampus and amygdala. These effects may be attributable in part to induction of hippocampal genes encoding tyrosine hydroxylase and tryptophan hydroxylase-1. Our results support the idea that rats with PTSD exhibit changes in DAergic and serotonergic transmission and in memory impairment. Thus, TAN mediated reversal of memory-related behavioral dysfunction associated with traumatic stress may be a useful therapeutic intervention in PTSD patients.

Polymethoxylated flavones (nobiletin, tangeretin, etc) have excellent bioactivity, but low water-solubility and high crystallization. We developed the cinnamaldehyde (CA)-modified whey protein (WPC)-stabilized microcapsules (WPC/CA microcapsules) to encapsulate nobiletin. Microcapsules showed spherical structure and mono-modal particle size distribution after dispersing in water regardless of CA concentration. The presence of CA increased the stability of nobiletin in emulsions and microcapsules, and inhibited the formation of nobiletin crystals. in vitro digestion results demonstrated that nobiletin in microcapsules had much higher bioaccessibility (82 %–94 %) than that in emulsions (68 %–83 %). The presence of CA maintained or increased the bioaccessiiblity of nobiletin both in emulsions as well as microcapsules. The formation of nobiletin crystals in stomach decreased in WPC/CA microcapsules. The results suggested that nobiletin-fortified yogurts could be produced by adding WPC/CA microcapsules, rather than WPC/CA emulsions. Also, microcapsules-incorporated yogurt would have better physical stability, if the amount of WPC/CA microcapsules and nobiletin was carefully designed. The optimized amount of CA-loaded microcapsules was 2 %–4 % in yogurt and the nobiletin content was 13−26 mg/100 g yogurt. This knowledge can be of great significance for the development of delivery systems of polymethoxylated flavones and their functional foods.

Although the protective effects of tangeretin on neuroinflammation have been proven in cell and animal experiments, few studies explore its underlying molecular mechanism. In this study, we used the network pharmacology method combined with the transcriptome approach to investigate its underlying anti-inflammatory mechanism in human microglial cells. Based on network pharmacology analysis, four putative target proteins and ten potential pathways were identified. Among them, vascular endothelial growth factor A (VEGFA), epidermal growth factor receptor (EGFR) and the related phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT), the mitogen-activated protein kinase (MAPK), mechanistic target of rapamycin (mTOR) signaling pathway were well-supported by transcriptome data. Meanwhile, transcriptome analysis supplemented two crucial targets: the insulin receptor (InsR) and insulin-like growth factor-I (IGF-1) receptor. Subsequently, VEGFA, EGFR, IGF-1 receptor, and InsR were further verified on the protein level. Taken together, we assumed that tangeretin could exert protective effects on neuroinflammation by decreasing the expression of VEGFA, EGFR, InsR, and IGF-1 receptor in the PI3K-AKT, MAPK, mTOR signaling pathway. More importantly, it is for the first time to show that the anti-neuroinflammatory effects of tangeretin through VEGFA, EGFR, IGF-1 receptor, InsR, and mTOR signaling pathway. These works offer new insight into the anti-neuroinflammatory functions of tangeretin and propose novel information on further anti-inflammatory mechanism studies.

A simple and accurate method using high performance liquid chromatography (HPLC) with dual wavelength detection was developed to simultaneously determine the contents of one flavanone glycoside (hesperidin) and five polymethoxylated flavones (PMFs: sinensetin, 4',5,7,8-tetramethoxyflavone, nobiletin, tangeretin and 5-O-desmethyl nobiletin) in Pericarpium Citri Reticulatae (Citrus reticulata 'Chachi') ('Chachi' PCR). By modifying the mobile phase compositions and detection wavelengths, an optimal HPLC condition was obtained, under which the calibration curves of all six compounds exhibited good linearity (R2>0.99). For all the tested compounds, the relative standard deviation (RSD) was less than 4%, and the accuracy ranged from 97.58 to 103.2%. The developed method was successfully applied to monitor the changes in the contents of six flavonoids in 'Chachi' PCR during storage at 25°C, over a three year period. Color parameters and antioxidant capacity were also determined to evaluate the sample quality. The contents of hesperidin decreased while all the polymethoxylated flavones and antioxidant activities increased throughout the storage period, demonstrating that polymethoxylated flavones could be used as indices for the quality change of Chachi' PCR during storage. The results from this study suggest that the longer storage periods increased the quality of PCR.

The ethyl acetate extracts from sweet orange peel (EESP) and its bioactive compounds against human hepatoma cells, in vitro and in vivo, is investigated. EESP (50–500 µg/ml) exhibits significant cytotoxicity on HepG2 cells. This antiproliferative action is partly attributable to cell cycle arrest in the G 0 /G 1 phase and apoptosis induction. EESP induces apoptosis through an increase in the Bax/Bcl-2 ratio, the down-regulation of mitochondrial membrane potential and the up-regulation of caspase-3. Excessive ROS generated by EESP contributes to apoptosis of HepG2 cells. According to the HPLC-DAD and HPLC-MS/MS analysis, nobiletin, tangeretin and another twelve compounds were present in EESP, which may account for its antiproliferative effect. When HepG2 cells are grown as xenografts in nude mice, the oral administration of EESP induces a significant decrease in tumor growth. Collectively, these results suggest that EESP could be a potential useful source for the future application of EESP in liver cancer therapy.

Obesity is characterized by a state of chronic low-grade inflammation and insulin resistance, which are aggravated by the interaction between hypertrophic adipocytes and macrophages. In this study, we investigated the effects of tangeretin on inflammatory changes and glucose uptake in a coculture of hypertrophic adipocytes and macrophages. Tangeretin decreased nitric oxide production and the expression of interleukin (IL)-6, IL-1β, tumor necrosis factor-α, inducible nitric oxide synthase, and cyclooxygenase-2 in a coculture of 3T3-L1 adipocytes and RAW 264.7 cells. Tangeretin also increased glucose uptake in the coculture system, but did not affect the phosphorylation of insulin receptor substrate (IRS) and Akt. These results suggest that tangeretin improves insulin resistance by attenuating obesity-induced inflammation in adipose tissue.

Background: Liver cancer is otherwise known as Hepatic cancer which originated from the liver. Hepatocellular carcinoma (HCC) is the common primary Liver cancer and is one of the emerging problems worldwide. Very few treatments are available to treat HCC because the molecular mechanism and other HCC mechanisms are still unclear. Cyclooxygenase 2 (COX-2), one of the most promising targets for Hepatocellular Carcinoma, is one of the dimeric enzymes which convert Arachidonic acid into Prostaglandin H2 in the step of Prostaglandin biosynthesis. Several natural bioactive compounds are involved in the treatment of various types of cancers. Tangeretin, a natural polymethoxyflavone present in the peel of citrus fruits, acts as an anti-oxidant modulator and anticancerous. Objective: The main objective of this study is to find a suitable inhibitor for Hepatocellular Carcinoma. Methods: Computational approaches like molecular docking and molecular dynamics were performed to identify the potential inhibitor for Hepatocellular Carcinoma. Results: In this study, COX-2 was considered as a potential target for Hepatocellular Carcinoma which was examined with Tangeretin. Conclusion: Tangeretin was screened against C0X-2 which includes Molecular Docking, DFT analysis, ADMET prediction, and Molecular Dynamics simulation. Tangeretin had good docking scores, fulfilled the pharmacological properties through ADMET prediction, and the Protein-Ligand complex had good stability in Molecular Dynamics simulation.

Tanaman yang dapat dikembangkan sebagai agen kemoprevensi kanker yaitu kulit jeruk (Citrus reticulata) dan daun teh (Camellia sinensis). Penelitian ini bertujuan untuk mengetahui potensi senyawa tangeretin dan kaempferol yang terdapat dalam masing-masing kulit jeruk daun teh sebagai agen kemoprevensi kanker secara in silico. Uji in silico menggunakan perangkat lunak Autodock Vina dengan menambatkan senyawa tangeretin dan kaempferol terhadap protein target Bcl-xL. Pada penambatan molekuler, senyawa tangeretin mempunyai afinitas -5,8 kkal/mol, sedangkan senyawa kaempferol mempunyai afinitas -6,4 kkal/mol. Tangeretin memiliki potensi yang kuat dalam aktivitas penghambatan terhadap protein Bcl-xL dan senyawa kaempferol kurang poten dalam inhibisi protein Bcl-xL.

The clinical drug-drug interactions mediated by heterotropic activation on cytochrome P450 (CYP450) kinetics, especially CYP3A4, have received wide concern in recent years. Flavonoids, a group of important natural substances with various pharmacological activities, distribute widely among vegetables, fruits and herbs. The frequent and numerous uses of flavonoids may increase the risk of food/herb-drug interactions. However, little is known about activation effects of flavonoids on CYP3A4. The aim of this study was to investigate activation of CYP3A4 by flavonoids, explore the molecular mechanism, and assess the biological effects on dronedarone (DND) induced toxicity. The results showed that flavone, tangeretin, sinensetin and 6-hydroxyflavone increased the cell viability by decreasing DND-induced cytotoxicity. These four flavonoids could activate the metabolism of DND in hamster pharmacokinetics study. Furthermore, both molecular docking and circular dichroism analysis partially illustrated the molecular mechanism of heterotropic activation. Finally, the pharmacophore model suggested B aromatic ring, hydrophobic groups at 7-position and hydrogen bond acceptors at 4-position may play a vital role in activation of flavonoids on CYP3A4. Taken together, our findings would provide useful information for predicting the potential risks of flavonoid-containing food/herb-drug interactions in humans.

Chemotherapeutics can induce oxidative stress, inflammation, apoptosis, mitochondrial dysfunction, and abnormalities in neurotransmitter metabolism leading to toxicity. Because there have been no therapeutic strategies developed to target inflammation and oxidative stress, there is a continuing need for new and improved therapy. As a result, there has been increasing interest in complementary and alternative medicine with anticancer potential. Studies have shown that the antioxidant activities and anti-inflammatory effects of citrus fruits are promising natural phytochemicals in the development of new anticancer agents. Tangeretin is a naturally polymethoxylated flavone compound extracted from the citrus peel that has shown significant intestinal absorption and adequate bioavailability, with the added benefit of promoting longevity. In addition, tangeretin is known to exhibit considerable selective toxicity to many types of cancer cell proliferation such as ovarian, brain, blood, and skin cancer. Evidence indicates that tangeretin acts through several mechanisms including growth inhibition, induction of apoptosis, autophagy, antiangiogenesis, and estrogenic-like effects. Furthermore, tangeretin works through mitigating levels of inflammatory mediators in the immune system. Using tangeretin in combination with clinically applied anticancer drugs could be a good strategy for increasing the efficiency of these agents and protecting noncancerous cells from damage caused by chemotherapy. The purpose of this review is to highlight the protective effects of a novel natural product, tangeretin against chemotherapeutic-induced toxicity. The development of chemoprevention strategies can lead to significant health care improvement in cancer survivors. Thus, study outcomes may attract more investigators to conduct tangeretin-related research and find out potentially significant impacts on health care of cancer patients and decreased health problems associated with chemotherapeutics-induced toxicity.

Glioblastoma multiforme (GBM) is the most aggressive primary brain tumor with poor prognosis, largely due to resistance to current radiotherapy and Temozolomide chemotherapy. The constitutive activation of Signal Transducer and Activator of Transcription 3 (STAT3) is evidenced as a pivotal driver of GBM pathogenesis and therapy resistance, and hence, is a promising GBM drug target. 5-acetyloxy-6,7,8,4&prime, tetramethoxyflavone (5-AcTMF) is an acetylated derivative of Tangeretin which is known to exert anticancer effects on breast, colon, lung, and multiple myeloma, however, its effect on GBM remains elusive. Herein, we reported that 5-AcTMF suppressed the viability and clonogenicity along with inducing apoptosis in multiple human GBM cell lines. Mechanistic analyses further revealed that 5-AcTMF lowered the levels of Tyrosine 705-phosphorylated STAT3 (p-STAT3), a canonical marker of STAT3 activation, but also dampened p-STAT3 upregulation elicited by Interleukin-6. Notably, ectopic expression of dominant-active STAT3 impeded 5-AcTMF-induced suppression of viability and clonogenicity plus apoptosis induction in GBM cells, confirming the prerequisite of STAT3 blockage for the inhibitory action of 5-AcTMF on GBM cell survival and growth. Additionally, 5-AcTMF impaired the activation of STAT3 upstream kinase JAK2 but also downregulated antiapoptotic BCL-2 and BCL-xL in a STAT3-dependent manner. Moreover, the overexpression of either BCL-2 or BCL-xL abrogated 5-AcTMF-mediated viability reduction and apoptosis induction in GBM cells. Collectively, we, for the first time, revealed the anticancer effect of 5-AcTMF on GBM cells, which was executed via thwarting the JAK2-STAT3-BCL-2/BCL-xL signaling axis. Our findings further implicate the therapeutic potential of 5-AcTMF for GBM treatment.

Tangeretin, a polymethoxylated flavonoid is abundant in citrus fruits, which has been reported to inhibit inflammation by inhibiting NF-κB activation and proinflammatory cytokines. Notch blockage inhibits Th17 cells response that are involved in the development of acute lung injury (ALI). This study investigated the protective effects of tangeretin on LPS-induced ALI in mice. Male C57BL/6 mice were treated with phosphate-buffered saline (PBS), lipopolysaccharide (LPS), LPS and tangeretin, or LPS and N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester (DAPT, a Notch signaling inhibitor), which were harvested at 48 h after challenged by LPS. CD4+ T cells were treated with tangeretin or DAPT and harvested after 72 h. Tangeretin notably attenuated pathological changes and decreased the wet to dry weight ratio of the mouse lungs. The total cell and neutrophil counts, tumor necrosis factor (TNF)-α in bronchoalveolar lavage fluid (BALF), myeloperoxidase activity of lung tissue were markedly reduced by tangeretin. The percentage of CD4+IL-17 + T cells in the lungs and the concentration of interleukin (IL)-17 and IL-22 in BALF were significantly down-regulated by tangeretin. As with the positive control (DAPT), tangeretin inhibited the activity of the Notch signaling pathway accompanied with the down-regulation of acid-related orphan receptor gamma t and IL-23 receptor expression. This study demonstrated that tangeretin protects against LPS-induced ALI by suppressing Th17 response at least partially, through a Notch-dependent mechanism.

In order to establish an efficient method for separation of polymethoxyflavones (PMFs) and explore the anti-inflammatory mechanism of PMF monomers, a citrus variety rich in PMFs, Ougan (Citrus reticulata cv. Suavissima), was selected, and three monomers, including nobiletin, tangeretin, and 5-demethylnobiletin, were purified by ultrasonic-assisted extraction, solid phase extraction, and high-speed countercurrent chromatography separation. UPLC-MS was used to identify the three monomers. UPLC determined purities of 99.87% to nobiletin, 99.76% to tangeretin, and 98.75% to 5-demethylnobiletin with the standard curve method. A lipopolysaccharide (LPS)-induced NO releasing model was performed in the mouse microglia BV-2 cell line. Results illustrated that PMF monomers inhibited the NO release and the inflammation-related cytokines, including IL-1&beta, IL-6, and TNF&alpha, elevation. QRT-PCR revealed that PMFs alleviated LPS-induced upregulation of iNOS, IL-6, JAK2, TNF&alpha, IL-1&beta, and NF-&kappa, B and LPS-induced downregulation of I&kappa, B&alpha, while they did not affect TLR1, TLR2, TLR4, and TLR6. STAT3 expression was repressed by tangeretin and 5-demethylnobiletin, but not by nobiletin. Western blot assay also showed a suppression of expression and phosphorylation of JAK2 by all three PMF monomers, while STAT3 phosphorylation was restrained by tangeretin and 5-demethylnobiletin. The mechanism was primarily verified by the JAK2 inhibitor Ruxolitinib and the STAT3 inhibitor Stattic.

Objective(s): Cisplatin is an effective antineoplastic agent; its clinical utility, however, is limited by a few salient toxic side effects like nephrotoxicity. This study aimed to determine the potential protective effects of tangeretin, a citrus-derived flavonoid, against renal tubular cell injury in cisplatin-induced renal toxicity of rats. Materials and Methods: Tangeretin was injected intraperitoneally at 2.5 and 5 mg/kg doses for 10 days, and a single dose of cisplatin (8 mg/kg) was injected on the 7th day. Tests of kidney function and tubular injury in renal tissues and urine together with oxidative stress and inflammation markers were examined. Results: Tangeretin ameliorated cisplatin-induced elevations in serum creatinine, BUN, and histopathologic changes. It also attenuated kidney oxidative stress elicited by cisplatin as demonstrated by reduced MDA and increased GSH, CAT, and SOD activities, elevated Nrf2 expression and protein levels of its downstream effectors, HO-1 and NQO-1. Tangeretin further alleviated inflammation evoked by cisplatin as indicated by reduced NF-κB p65 subunit phosphorylation with a simultaneous decrement in its downstream effectors IL-1β and TNF-α expression and protein levels. Moreover, it declined caspase-3 protein levels and TUNEL positive cells in the kidneys, the markers of apoptosis and DNA fragmentation, thus improving renal endurance. Additionally, tangeretin mitigated renal levels of KIM-1 and NGAL, as well as urinary cystatin C and β2-microglobulin concentrations, the markers of renal tubular injury. Conclusion: Collectively, these data signify the binary profit of tangeretin: enhancement of renal protective mechanisms against cisplatin and attenuation of renal tubular cell injuries induced by the agent.

Introduction. Citrus flavonoids are important polyphenolic compounds having huge biological potential. Therapeutic potential of various flavonoidal compounds in obesity, cancer, diabetes and Alzheimer’s has been well documented in the scientific literature. Demand of natural products and their derived products including dietary supplements has been increased in the medical field. Alzheimer’s and Parkinson's disease are most common Neurodegenerative disorders affecting huge population in the world. Prevention and treatment of neurodegenerative disorders by use of natural products is warranted. Tangeretin is important polymethoxylated flavonoids derived from the peel and other parts of Citrus fruits. Tangeretin has been proven for their antiinflammatory and neuroprotective effects in several disorders. Methods. To know the therapeutic importance of tangeretin in the medicine, various scientific databases have been searched and evaluated for their role in neurodegeneration and inflammatory responses. Medicinal importance and therapeutic effect of tangeretin in neurodegeneration and related disorders have been analyzed through different scientific database. Therapeutic importance of tangeretin in neurodegeneration and inflammatory disorders has been analyzed in the present study and correlated with other biological potential. Results. From the analysis of the scientific databases of tangeretin it was found to have chemopreventive and neuroprotective potential. Scientific data analysis revealed that tangeretin reduced expression of inflammatory mediators. Experimental databases suggest that tangeretin is an effective candidate for prevention and treatment of neuroinflammation and dementia. Other experimental study suggests that tangeretin decreased nitric oxide. Tangeretin is also effective in colitis through suppression of IL12 and TNF-α expression and nuclear factor kappa-B activation. Conclusion. From the analysis of the scientific research work it was found that tangeretin have potential medicinal value for the treatment of neurodegeneration and inflammatory medicated disorders.

The purpose of this work was to elucidate the effects of citrus oil type on polymethoxyflavone (PMF) solubility and on the physicochemical properties of PMF-loaded emulsion-based delivery systems. Citrus oils were extracted from mandarin, orange, sweet orange, and bergamot. The major constituents were determined by GC/MS: sweet orange oil (97.4% d-limonene); mandarin oil (72.4% d-limonene); orange oil (67.2% d-limonene); and bergamot oil (34.6% linalyl acetate and 25.3% d-limonene). PMF-loaded emulsions were fabricated using 10% oil phase (containing 0.1% w/v nobiletin or tangeretin) and 90% aqueous phase (containing 1% w/v Tween 80) using high-pressure homogenization. Delivery systems prepared using mandarin oil had the largest mean droplet diameters (386 or 400 nm), followed by orange oil (338 or 390 nm), bergamot oil (129 or 133 nm), and sweet orange oil (122 or 126 nm) for nobiletin- or tangeretin-loaded emulsions, respectively. The optical clarity of the emulsions increased with decreasing droplet size due to reduced light scattering. The viscosities of the emulsions (with or without PMFs) were similar (1.3 to 1.4 mPa·s), despite appreciable differences in oil phase viscosity. The loading capacity and encapsulation efficiency of the emulsions depended on carrier oil type, with bergamot oil giving the highest loading capacity. In summary, differences in the composition and physical characteristics of citrus oils led to PMF-loaded emulsions with different encapsulation and physicochemical characteristics. These results will facilitate the rational design of emulsion-based delivery systems for encapsulation of PMFs and other nutraceuticals in functional foods and beverages.

Natural products, including botanical dietary supplements and exotic drinks, represent an ever-increasing share of the health-care market. The parallel ever-increasing popularity of self-medicating with natural products increases the likelihood of co-consumption with conventional drugs, raising concerns for unwanted natural product-drug interactions. Assessing the drug interaction liability of natural products is challenging due to the complex and variable chemical composition inherent to these products, necessitating a streamlined preclinical testing approach to prioritize precipitant individual constituents for further investigation. Such an approach was evaluated in the current work to prioritize constituents in the model natural product, grapefruit juice, as inhibitors of intestinal organic anion-transporting peptide (OATP)-mediated uptake. Using OATP2B1-expressing MDCKII cells (Madin-Darby canine kidney type II) and the probe substrate estrone 3-sulfate, IC50s were determined for constituents representative of the flavanone (naringin, naringenin, hesperidin), furanocoumarin (bergamottin, 6',7'-dihydroxybergamottin) and polymethoxyflavone (nobiletin and tangeretin) classes contained in grapefruit juice. Nobiletin was the most potent (IC50 , 3.7 μm); 6',7'-dihydroxybergamottin, naringin, naringenin and tangeretin were moderately potent (IC50 , 20-50 μm); and bergamottin and hesperidin were the least potent (IC50 , >300 μm) OATP2B1 inhibitors. Intestinal absorption simulations based on physiochemical properties were used to determine the ratios of unbound concentration to IC50 for each constituent within enterocytes and to prioritize in order of pre-defined cut-off values. This streamlined approach could be applied to other natural products that contain multiple precipitants of natural product-drug interactions. Copyright © 2016 John Wiley & Sons, Ltd.

Objective To study the chemical constituents from Pericarpium Citri Reticulatae (Citrus reticulata). Methods The chemical constituents were isolated and purified by silica gel column, Sephadex LH-20, and ODS column chromatography. The structures were identified by spectral data. Results Nineteen compounds were isolated and identified as 4′,5,6,7-tetramethoxyflavone ( 1 ), 3,3′,4′,5,6,7,8-heptmethoxyflavone ( 2 ), sinensetin ( 3 ), 5- O -demethylnobiletin ( 4 ), tangeretin ( 5 ), nobiletin ( 6 ), apigenin ( 7 ), 5- O -desmethyltangeretin ( 8 ), 5,7-dihydroxy-3,3′,4′,6-tetramethoxyflavone ( 9 ), pachypodol ( 10 ), 4′,5,6,7-tetramethoxyflavanone ( 11 ), 3′,4′,5,7,8-pentamethoxyflavanone ( 12 ), agestricin C ( 13 ), scoparone ( 14 ), isoscopoletin ( 15 ), hesperidin ( 16 ), didymin ( 17 ), methylhesperidine ( 18 ), and naringin ( 19 ). Conclusion Compounds 9-15 are obtained from this plant for the first time.

China is the most important origin center of the genus Citrus L., especially the wild mandarin (Citrus reticulata Blanco). The aim of this work was to systematically qualitative and quantitative analysis of polymethoxylated flavonoids (PMFs) in seven Chinese wild mandarin citrus using ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS/MS) and UPLC-photodiode array (UPLC-PDA) analyses. This method was validated including the linearity, limit of detection (LOD), limit of quantification (LOQ), precision, repeatability, stability, and recovery. The results demonstrated that UPLC-Q-TOF-MS/MS was a powerful tool to analyze the PMFs in wild citrus peel, and this method was trustable, rapid and sample. Besides, ten PMFs were identified or tentatively characterized as 5,6,7,3′,4′-pentamethoxyflavanone (1), isosinensetin (2), sinensetin (3), 5,7,3′,4′-tetramethoxyflavone (4), 3,5,7,4′-tetramethoxyflavone (5), nobiletin (6), 3,5,6,7,8,3′,4′-heptamethoxyflavone (7), 5,7,4′-trimethoxyflavone (8), 5-Hydroxy-6,7,8,3′,4′-pentamethoxyflavone (9), and tangeretin (10). Among these compounds, 4 was the first time to be identified in citrus. Then the contents of eight PMFs (2, 3, 4, 6, 7, 8, 9, and 10) in these samples were quantified. Compounds 3, 6, and 10 were found to be the prominent PMFs. Cupigoushigan had the highest contents of 3 (2.617 mg/g DW) and 6 (11.111 mg/g DW), and Dakengyeju had the highest content of 10 (5.560 mg/g DW). Our results indicated that wild mandarins are potentially rich source of Citrus PMFs for foods or other utilization.

Tangeretin and nobiletin are polymethoxylated flavonoids in citrus peel. Both tangeretin and nobiletin are bitter; however, their bitterness has not been evaluated using human bitter taste receptors (hTAS2Rs). We screened 25 kinds of hTAS2Rs and found that hTAS2R14 and hTAS2R46 received both compounds.

Food allergy has become a worldwide problem. To find an effective way to reduce the allergic effect of allergen is an interesting topic. In this work, the interaction between ovalbumin(OVA) and tangeretin was studied by means of spectroscopy, molecular docking calculation and animal experiment. As the results show, static quenching of fluorescence intensity happened due to the interaction between OVA and tangeretin. Binding constants, binding sites, and thermometric parameters were obtained. The conformation changing of OVA occurred due to the interaction between it and tangeretin. The molecular docking calculation results show that the epitopes Arginine 84(ARG84), Leucine 87(LEU87), Asparagine 88(ASN88), Serine 103(SER103), Arginine 104(ARG104), Leucine 124(LEU124), Arginine 126(ARG126), Glycine 127(GLY127), Glycine 128(GLY128) and Tryptohan 148(TRP148) of OVA were occupied by tangeretin after the docking, which means tangeretin may have some inhibition effects. As the results of animal experiments, the amount of IgE and lung tissue sections of female BALB/c mice in different groups show that tangeretin with different concentrations has better effects than dexamethasone. In conclusion, the tangeretin may have the effects to reduce the allergic effects of OVA via occupying the IgE-binding epitopes of OVA.

Citrus peel is rich in functional ingredients such as essential oils (0.6–1%), fibers (6.30–42.13 g/100 g db), phenols (0.67–19.62 g/100 g db), and vitamin C (0.109–1.150 g/100 g db). Flavanones (hesperidin: 0.002–80.90 mg/g db, neohesperidin: 0.05–11.70 mg/g db, narirutin: 0.03–26.90 mg/g db; naringin: 0.08–14.40 mg/g db), and polymethoxylated flavones (sinensetin: 0.08–0.29 mg/g db, nobiletin: 0.20–14.05 mg/g db, tangeretin: 0.16–7.99 mg/g db) are the main phenolic compounds (PCs) of citrus peel. Due to their antioxidant activity, PCs are used in various applications such as formulation of healthy food, cosmetic, and pharmaceutical products. PCs present sensitivity to process operating conditions (during juice processing and further thermal and nonthermal processing). This review summarizes the main publications dealing with the proximate chemical composition, the functional properties, and the potential applications of the main citrus peel compounds. The effects of conventional and nonconventio...

Polymethoxyflavones possess many biological properties, as lipid-lowering, hypoglycaemic, anti-inflammatory, antioxidant, and anticancer activities, therefore, they may be employed as nutraceuticals or therapeutic agents. The scarcity of pure polymethoxyflavones on the market as well as their low water solubility limited in vivo studies and the use of polymethoxyflavones as food or pharmaceutical supplements. Since mandarin peels are a rich source of polymethoxyflavones, tangeretin, nobiletin, sinensetin, tetra-O-methyl scutellarein, and heptamethoxyflavone were purified from a nonvolatile residue of a cold-pressed mandarin essential oil using a multidimensional preparative liquid chromatographic system coupled with a photodiode array detector and a single quadrupole mass spectrometer. A new prototype, consisting of a nano-liquid chromatography system coupled with an electron ionization mass spectrometer, was used for the characterization of the pure isolated molecules. Finally, due to the collection of highly pure nobiletin and tangeretin, the ability of 2-hydroxypropyl-β-cyclodextrin to enhance the water solubility of both polymethoxyflavones was evaluated by phase solubility studies and Job's plot method.

Introduction Citri Reticulatae Pericarpium (CRP) is a commonly-used traditional Chinese medicine with flavonoids as the major bioactive components. Nevertheless, the contents of the flavonoids in CRP of different sources may significantly vary affecting their therapeutic effects. Thus, the setting up of a reliable and comprehensive quality assessment method for flavonoids in CRP is necessary. Objective To set up a rapid and sensitive ultra-fast liquid chromatography coupled with tandem mass spectrometry (UFLC-MS/MS) method for simultaneous quantification of seven bioactive flavonoids in CRP. Methods A UFLC-MS/MS method coupled to ultrasound-assisted extraction was developed for simultaneous separation and quantification of seven flavonoids including hesperidin, neohesperidin, naringin, narirutin, tangeretin, nobiletin and sinensetin in 16 batches of CRP samples from different sources in China. Results The established method showed good linearity for all analytes with correlation coefficient (R) over 0.9980, together with satisfactory accuracy, precision and reproducibility. Furthermore, the recoveries at the three spiked levels were higher than 89.71% with relative standard deviations (RSDs) lower than 5.19%. The results indicated that the contents of seven bioactive flavonoids in CRP varied significantly among different sources. Among the samples under study, hesperidin showed the highest contents in 16 samples ranged from 27.50 to 86.30 mg/g, the contents of hesperidin in CRP-15 and CRP-9 were 27.50 and 86.30 mg/g, respectively, while, the amount of narirutin was too low to be measured in some samples. Conclusion This study revealed that the developed UFLC-MS/MS method was simple, sensitive and reliable for simultaneous quantification of multi-components in CRP with potential perspective for quality control of complex matrices. Copyright © 2016 John Wiley & Sons, Ltd.

The number of patients with central nervous system disorders is increasing. Despite diligent laboratory and clinical research over the past 30 years, most pharmacologic options for the prevention and long-term treatment of central nervous system disorders and neurodegenerative disorders have been unsuccessful. Therefore, the development of drugs and/or functional foods to prevent the onset of neurodegenerative disorders is highly expected. Several reports have shown that polymethoxylated flavones (PMFs) derived from citrus fruit, such as nobiletin, tangeretin, and 3,3′,4′,5,6,7,8-heptamethoxyflavone, are promising molecules for the prevention of neurodegenerative and neurological disorders. In various animal models, PMFs have been shown to have a neuroprotective effect and improve cognitive dysfunction with regard to neurological disorders by exerting favorable effects against their pathological features, including oxidative stress, neuroinflammation, neurodegeneration, and synaptic dysfunction as well as its related mechanisms. In this review, we describe the profitable and ameliorating effects of citrus-derived PMFs on cognitive impairment and neural dysfunction in various rat and murine models or in several models of central nervous system disorders and identify their mechanisms of action.

In order to discover the active anti-tumor ingredients during the flavonoids separation process of Ougan (Citrus reticulata cv. Suavissima), gastric cancer cell lines including AGS, BGC-823, and SGC-7901 were employed to evaluate the proliferation inhibition abilities of Ougan extracts, flavanone components, polymethoxyflavone components, neohesperidin, nobiletin, tangeretin, and 5-demethylnobiletin. Quantitative real-time PCR was used to detect the expression of three retinoic acid receptor genes, including RARA, RARB, and RARG. Western blot and immunohistochemistry were used to detect protein expressions. The results showed that the polymethoxyflavone components and the PMFs monomers inhibited the proliferation of three gastric cancer cell lines and induced apoptosis. The mechanism exploration found that PMFs up-regulated the expression of the RARB gene selectively and activated the Caspase3, 9, and PARP1 proteins. In addition to 5-demethylnobiletin, other PMFs also upregulated the expression of cleaved Caspase8. The mechanism was preliminarily verified by a RARβ inhibitor AGN 193109. Moreover, a nude mice tumor xenograft model confirmed the tangeretin could exhibit in vivo anti-tumor effect through inducing apoptosis and upregulating RARβ protein. All result suggested that tangeretin may be a potentially novel, safe and effective drugs with less toxicity and lesser side effects for gastric cancer therapeutics.

The positive outcome of tamoxifen is reduced because of the emergence of intrinsic and acquired resistance that triggers relapse and metastasis; as such, a combination therapy containing tamoxifen should be developed to improve its effectiveness in breast cancer therapy. This study was performed via an integrative bioinformatic approach to explore tangeretin, a citrus flavonoid and potential molecular target in overcoming the resistance of breast cancer to tamoxifen (TT). Six tangeretin targets, namely, AKR1C1, TNKS2, BACE1, GSK3B, EGFR, and IGF1R, were obtained, and they showed potential for application in overcoming the resistance of breast cancer to tamoxifen. The Kaplan–Meier curve revealed that the prognosis of patients with a low mRNA expression of IGF1R was significantly worse than that of the opposite group. The validation of the gene expression with GEPIA indicated that the mRNA expression levels of AKR1C1 and EGFR were significantly higher in patients with breast cancer than in the opposite group. The mRNA levels of GSK3B and EGFR were higher in recurrent breast cancer cells treated with tamoxifen than in nonrecurrent breast cancer cells. The mRNA level of TNKS2 in recurrent breast cancer cells treated with tamoxifen was lower than that in nonrecurrent breast cancer cells. This study highlighted AKR1C1, TNKS2, BACE1, GSK3B, EGFR, and IGF1R as the six potential tangeretin targets in overcoming the resistance of breast cancer to tamoxifen. However, our results should be further validated with in vitro and in vivo studies.

Podocyte injury inevitably results in leakage of proteins from the glomerular filter and is vital in the pathogenesis of diabetic nephropathy (DN). The underlying mechanisms of podocyte injury facilitate finding of new therapeutic targets for DN treatment and prevention. Tangeretin is an O-polymethoxylated flavone present in citrus peels with anti-inflammatory and antioxidant properties. This study investigated the renoprotective effects of tangeretin on epithelial-to-mesenchymal transition-mediated podocyte injury and fibrosis through oxidative stress and hypoxia caused by hyperglycemia. Mouse podocytes were incubated in media containing 33 mM glucose in the absence and presence of 1&ndash, 20 &mu, M tangeretin for up to 6 days. The in vivo animal model employed db/db mice orally administrated with 10 mg/kg tangeretin for 8 weeks. Non-toxic tangeretin inhibited glucose-induced expression of the mesenchymal markers of N-cadherin and &alpha, smooth muscle actin in podocytes. However, the reduced induction of the epithelial markers of E-cadherin and P-cadherin was restored by tangeretin in diabetic podocytes. Further, tangeretin enhanced the expression of the podocyte slit diaphragm proteins of nephrin and podocin down-regulated by glucose stimulation. The transmission electron microscopic images revealed that foot process effacement and loss of podocytes occurred in diabetic mouse glomeruli. However, oral administration of 10 mg/kg tangeretin reduced urine albumin excretion and improved foot process effacement of diabetic podocytes through inhibiting loss of slit junction and adherenes junction proteins. Glucose enhanced ROS production and HIF-1&alpha, induction in podocytes, leading to induction of oxidative stress and hypoxia. Similarly, in diabetic glomeruli reactive oxygen species (ROS) production and HIF-1&alpha, induction were observed. Furthermore, hypoxia-evoking cobalt chloride induced epithelial-to-mesenchymal transition (EMT) process and loss of slit diaphragm proteins and junction proteins in podocytes, which was inhibited by treating submicromolar tangeretin. Collectively, these results demonstrate that tangeretin inhibited podocyte injury and fibrosis through blocking podocyte EMT caused by glucose-induced oxidative stress and hypoxia.