Flavonol Glycosides Research Articles

Crotalaria madurensis flavonol glycosides’ antibacterial activity against Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) infections are prevalent in hospitals and often lead to significant health complications. This study aimed to explore the chemical composition of the aerial part of Crotalaria madurensis and evaluate its antioxidant and antibacterial properties. The impact of gamma irradiation on the antibacterial properties of the plant extract and metabolite 1 against MRSA was also examined. Fourier-transform infrared (FTIR) analysis was conducted on the filtrates of untreated MRSA and MRSA treated with the plant extract and metabolite 1. Four flavonol glycosides were identified as gossypetin 8-methoxy, 3-O-β-D-xylopyranoside (metabolite 1), gossypetin 8-O-β-D-glucopyranoside (metabolite 2), kaempferol 3-O-β-D-glucpyranoside (Astragalin, metabolite 3), and herbacetin 7-methoxy-3-O-β-D-glucopyranoside (metabolite 4). All metabolites exhibited significant antioxidant properties using different assays. The antibacterial efficacy of the extract and metabolite 1, which showed substantial antioxidant properties compared to the other isolated metabolites, was evaluated. Both the plant extract and metabolite 1 significantly reduced the viability and cell count of MRSA at concentrations of 1.0 and 0.5 mg/ml. The antibacterial activity of the plant extract and metabolite 1 was assessed after gamma irradiation at 50 and 100 Gy, which did not significantly affect the antibacterial efficiency. FTIR analysis indicated that the plant extract and metabolite 1 significantly altered the band frequency values, bandwidth, and peak intensity % of the treated MRSA filtrate. Molecular docking studies suggested that metabolite 1 exhibited the highest antioxidant and anti-MRSA activity, with strong binding scores like the ligand, indicating an effective interaction and high affinity between metabolite 1 and the target molecule.

Antioxidant potential and xanthine oxidase inhibition of flavonol glycosides from Phyllanthus emblica L. leaves

Context: Hyperuricemia is the cause of gout in the inflammatory joint condition. The xanthine oxidase enzyme is a therapeutic target for gout treatment because it plays a role in the generation of uric acid. Allopurinol is used to treat gout. It prevents the xanthine oxidase enzyme from producing as much uric acid. When selecting a medication, one must consider the various adverse effects of allopurinol. Phyllanthus emblica plants are among the medicinal plants that can be used as an alternative treatment for gout. Aims: To evaluate isolated compounds from the Phyllanthus emblica as antihyperuricemia candidates. Methods: The isolated compounds were characterized using High-Performance Liquid Chromatography Analysis and Thin Layer Chromatography-Densitometry. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) and cupric ion (CUPRAC) antioxidant capacity procedures were used to develop the antioxidant activity index. The ability to inhibit xanthine oxidase was determined using a spectrophotometer. Results: Compound 1 was indicated as rutin having antioxidant capacity with an antioxidant activity index (AAI) DPPH value of 7.89 ± 0.03 and AAI CUPRAC value of 15.83 ± 0.04 stronger than compound 2 (quercitrin) with an AAI DPPH value of 3.72 ± 0.01 and AAI CUPRAC 3.24 ± 0.03. The IC50 for quercitrin's inhibition of xanthine oxidase is 23.85 ± 2.04, which was higher than rutin’s IC50 value of 32.77 ± 4.49 µg/mL. Conclusions: Flavonol glycosides present in the ethanol extract of Phyllanthus emblica leaves gave potent xanthine oxidase inhibitory activity stronger than the extract. Quercitrin gave stronger xanthine oxidase inhibitory activity, but this compound has weaker antioxidant capacity compared to rutin.

Icariin ameliorates Coxsackievirus B3-induced viral myocarditis by modulating the S100 calcium binding protein A6/β-catenin/c-Myc signaling pathway

BackgroundCoxsackievirus B3 (CVB3) is a leading cause of viral myocarditis and is currently lacking specific pharmacological treatments, highlighting the critical need for therapeutic development. Icariin (ICA), a prenylated flavonol glycoside, was previously found to exhibit several pharmacological effects, but its potential to combat CVB3 remains uninvestigated. PurposeThis study aimed to elucidate the anti-CVB3 efficacy of ICA and elucidate its molecular mechanisms. MethodsCVB3-infected HeLa cells, H9C2 cells and neonate rat ventricular cardiomyocytes (NRVCs) were selected as in vitro models, and were treated with ICA at 1 and 10 μM. Additionally, BALB/c mice that were infected with CVB3 via intraperitoneal injection were chosen as in vivo model and were treated with ICA or ribavirin over 3 days. The effect of ICA against CVB3 was determined by Cell Counting Kit-8 (CCK-8) assay, western blot, real-time fluorescence quantitative PCR (RT–qPCR), terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, hematoxylin and eosin (H&E) staining, immunohistochemistry (IHC) and flow cytometry. ResultsIn this study, it was found that ICA is capable of reducing CVB3 viral load both in vitro and in vivo. Mechanistic studies suggested that ICA prevents cardiomyocyte apoptosis by attenuating the S100 calcium binding protein A6 (S100A6)/β-catenin/c-Myc signaling pathway. Additionally, ICA inhibits the secretion of proinflammatory cytokines tumor necrosis factor alpha (TNF-α), interleukin-1beta (IL-1β) and CXC motif chemokine ligand 2 (CXCL2) in heart tissue, thereby mitigating CVB3-induced myocarditis. Moreover, ICA also regulates the immune response of CD4+ T, CD8+ T and Treg cells by changing the cells numbers in spleen tissue. Lastly, ICA can reduce the load of other enteroviruses (such as CVA6, CVA16 and EV71) in rhabdomyosarcoma (RD) cells as well. ConclusionOur findings indicate that ICA provides significant protection against CVB3 infection by modulating the S100A6/β-catenin/c-Myc signaling pathway, suggesting its potential use as a novel drug against CVB3 infection in clinical application.

High-Resolution Tandem Mass Spectrometry for Metabolic Profiling of Ocotea diospyrifolia (Meisn.) Mez Leaves.

Ocotea is an important genusof Lauraceae plant familythat comprises over 400 species, many of which pose challenges in taxonomicdifferentiation due to their complex botanical characteristics. Chemosystematics, and more recently, chemophenetics, have emerged as valuable tools to address these challenges based on their natural products (NPs) composition. O. diospyrifolia (Meisn.) Mez is a poorly studied species with known pharmacological potential. Here, we applied ultra-high performance liquid chromatography coupled with high-resolution tandem mass spectrometry (UHPLC-HRMS) allied to a curated in-house database with all previous isolated NPs from the Ocotea genus (OcoteaDB), gas phase fragmentations reactions, and biosynthesis. The strategy resulted in compounds annotated in confidence levels 2 (n=27), 3 (n=231), and 4 (n=21) according to the Metabolomics Standards Initiative (MSI). Additional annotations based on fragmentation proposals (n=16) were also included. The study revealed that O. diospyrifolia is a great alkaloid producer, even though different lignoids, which also comes from the shikimate pathway, were annotated. Additionally, the flavonoid profile predominantly consists of flavonol glycosides, complementing prior reports. This study provides the first comprehensive chemical profile of O. diospyrifolia leaves, which corroborates the chemotaxonomy of the species, and also contributes to further characterization studies, as the UHPLC-HRMS data is publicly available.

Integrated Metabolome and Transcriptome Analyses Reveal the Mechanisms Regulating Flavonoid Biosynthesis in Blueberry Leaves under Salt Stress

The flavonoids play important roles in plant salt tolerance. Blueberries (Vaccinium spp.) are extremely sensitive to soil salt increases. Therefore, improving the salt resistance of blueberries by increasing the flavonoid content is crucial for the development of the blueberry industry. To explore the underlying molecular mechanism, we performed an integrated analysis of the metabolome and transcriptome of blueberry leaves under salt stress. We identified 525 differentially accumulated metabolites (DAMs) under salt stress vs. control treatment, primarily including members of the flavonoid class. We also identified 20,920 differentially expressed genes (DEGs) based on transcriptome data; of these, 568 differentially expressed transcription factors (TFs) were annotated, and bHLH123, OsHSP20, and HSP20 TFs might be responsible for blueberry leaf salt tolerance. DEGs involved in the flavonoid biosynthesis pathway were significantly enriched at almost all stages of salt stress. Salt treatment upregulated the expression of most flavonoid biosynthetic pathway genes and promoted the accumulation of flavonols, flavonol glycosides, flavans, proanthocyanidins, and anthocyanins. Correlation analysis suggested that 4-coumarate CoA ligases (4CL5 and 4CL1) play important roles in the accumulation of flavonols (quercetin and pinoquercetin) and flavan-3-ol (epicatechin and prodelphinidin C2) under salt stress, respectively. The flavonoid 3′5′-hydroxylases (F3′5′H) regulate anthocyanin (cyanidin 3-O-beta-D-sambubioside and delphinidin-3-O-glucoside chloride) biosynthesis, and leucoanthocyanidin reductases (LAR) are crucial for the biosynthesis of epicatechin and prodelphinidin C2 during salt stress. Taken together, it is one of the future breeding goals to cultivate salt-resistant blueberry varieties by increasing the expression of flavonoid biosynthetic genes, especially 4CL, F3′5′H, and LAR genes, to promote flavonoid content in blueberry leaves.

Assesment of quality of Ginkgo biloba extract and dietary supplements in Vietnam market based on flavonol glycoside content and flavonoid ratio

Ginkgo biloba is one of the oldest medicinal herbs in the world. It is commonly used as a dietary supplement to protect against blood circulation disorders, improve memory, and prevent cognitive decline. Currently, Vietnam and other countries have regulations in place to ensure the quality of Ginkgo biloba extract in their pharmacopoeia. In this study, the quality of 11 raw materials and 120 dietary supplement products containing ginkgo extract was evaluated based on flavonol glycoside content and the ratio of component flavonoids. The results revealed a significant number of unsatisfactory samples, highlighting the need for closer monitoring of quality products to protect consumer rights.

Naringenin chalcone carbon double-bond reductases mediate dihydrochalcone biosynthesis in apple leaves.

Dihydrochalcones (DHCs) are flavonoids produced as a side branch of the phenylpropanoid pathway. DHCs are found at high concentrations in apples (Malus spp.) but not in pears (Pyrus spp.) or other members of the Rosaceae. Biosynthesis of DHCs in apple has been hypothesized to occur via reduction of p-coumaroyl CoA by a Malus × domestica hydroxycinnamoyl CoA double-bond reductase (MdHCDBR) followed by the action chalcone synthase to produce phloretin or via direct reduction of naringenin chalcone to phloretin via an unknown enzyme. In this study, we report that genetic downregulation of MdHCDBR does not reduce DHC concentrations in apple leaves. We used comparative transcriptome analysis to identify candidate naringenin chalcone reductases (NCRs), designated MdNCR1a-c, expressed in apple leaves but not fruit. These MdNCR1 genes form an expanded gene cluster found exclusively in apple. Transient expression of MdNCR1 genes in Nicotiana benthamiana leaves indicated they produced DHCs at high concentrations in planta. Recombinant MdNCR1 utilized naringenin chalcone to produce phloretin at high efficiency. Downregulation of NCR genes in transgenic apple reduced foliar DHC levels by 85-95%. Reducing DHC production redirected flux to the production of flavonol glycosides. In situ localization indicated that NCR proteins were likely found in the vacuolar membrane. Active site analysis of AlphaFold models indicated that MdNCR1a-c share identical substrate binding pockets, but the pockets differ substantially in related weakly active/inactive NCR proteins. Identifying the missing enzyme required for DHC production provides opportunities to manipulate DHC content in apple and other fruits and has other applications, e.g., in biofermentation and biopharming.

Phenolic compounds from the aerial parts of Rhodiola rosea in Japan, and their antioxidant activity and chemical adaptation to alpine environment

Twelve flavonoids (1–12) including a new flavonol glycoside, hibiscetin 3-O-glucopyranoside-8-O-glucuronopyranoside, ten known galloylglucoses (13–22) and three known phenolic acids (23–25) were isolated from the aerial parts of Rhodiola rosea growing in Japan. Their chemical structures were elucidated by UV-vis spectra, LC-MS, HR-MS, acid hydrolysis, NMR, and/or HPLC, and TLC comparisons with authentic samples. Antioxidant activity of major 14 compounds was measured by H-ORAC method, and two flavonols, herbacetin 3-O-glucoside-8-O-glucuronide, and gossypetin 3-O-glucuronide-8-O-glucoside, showed the strongest activity. Moreover, chemical adaptation to severe alpine environment of R. rosea was discussed.

A Comprehensive Review of Molecular Mechanisms, Pharmacokinetics, Toxicology and Plant Sources of Juglanin: Current Landscape and Future Perspectives.

Juglanin (kaempferol 3-O-α-L-arabinofuranoside) is a flavonol glycoside occurring in many plants, including its commercial sources Juglans regia, Polygonum aviculare and Selliguea hastata. Recent extensive studies have explored the potential of using juglanin in various pathological conditions, including cardiovascular disorders, central nervous and skeletal system disorders, metabolic syndrome, hepatic injury, and cancers. The results indicated a wide range of effects, like anti-inflammatory, anti-oxidant, anti-fibrotic, anti-thrombotic, anti-angiogenic, hepatoprotective, hypolipidemic, hypoglycemic, anti-apoptotic (normal cells), and pro-apoptotic (cancer cells). The health-promoting properties of juglanin can be attributed to its influence on many signaling pathways, associated with SIRT1, AMPK, Nrf2, STING, TLR4, MAPKs, NF-κB, AKT, JAK, and their downstream genes. This review primarily summarizes the current knowledge of molecular mechanisms, pharmacokinetics, biocompatibility, and human use safety of juglanin. In addition, the most promising new plant sources and other existing challenges and prospects have also been reviewed and discussed, aiming to provide direction and rationale for the further development and broader pharmaceutical application of juglanin.

Genome-wide identification of the phenylalanine ammonia-lyase gene from Epimedium Pubescens Maxim. (Berberidaceae): novel insight into the evolution of the PAL gene family

BackgroundPhenylalanine ammonia-lyase (PAL) serves as a key gateway enzyme, bridging primary metabolism and the phenylpropanoid pathway, and thus playing an indispensable role in flavonoid, anthocyanin and lignin biosynthesis. PAL gene families have been extensively studied across species using public genomes. However, a comprehensive exploration of PAL genes in Epimedium species, especially those involved in prenylated flavonol glycoside, anthocyanin, or lignin biosynthesis, is still lacking. Moreover, an in-depth investigation into PAL gene family evolution is warranted.ResultsSeven PAL genes (EpPAL1-EpPAL7) were identified. EpPAL2 and EpPAL3 exhibit low sequence identity to other EpPALs (ranging from 61.09 to 64.38%) and contain two unique introns, indicating distinct evolutionary origins. They evolve at a rate ~ 10 to ~ 54 times slower compared to EpPAL1 and EpPAL4-7, suggesting strong purifying selection. EpPAL1 evolved independently and is another ancestral gene. EpPAL1 formed EpPAL4 through segmental duplication, which lead to EpPAL5 and EpPAL6 through tandem duplications, and EpPAL7 through transposed duplication, shaping modern EpPALs. Correlation analysis suggests EpPAL1, EpPAL2 and EpPAL3 play important roles in prenylated flavonol glycosides biosynthesis, with EpPAL2 and EpPAL3 strongly correlated with both Epimedin C and total prenylated flavonol glycosides. EpPAL1, EpPAL2 and EpPAL3 may play a role in anthocyanin biosynthesis in leaves. EpPAL2, EpPAL3, EpPAL6, and EpPAL7 might be engaged in anthocyanin production in petals, and EpPAL2 and EpPAL3 might also contribute to anthocyanin synthesis in sepals. Further experiments are needed to confirm these hypotheses. Novel insights into the evolution of PAL gene family suggest that it might have evolved from a monophyletic group in bryophytes to large-scale sequence differentiation in gymnosperms, basal angiosperms, and Magnoliidae. Ancestral gene duplications and vertical inheritance from gymnosperms to angiosperms likely occurred during PAL evolution. Most early-diverging eudicotyledons and monocotyledons have distinct histories, while modern angiosperm PAL gene families share similar patterns and lack distant gene types.ConclusionsEpPAL2 and EpPAL3 may play crucial roles in biosynthesis of prenylated flavonol glycosides and anthocyanins in leaves and flowers. This study provides novel insights into PAL gene family evolution. The findings on PAL genes in E. pubescens will aid in synthetic biology research on prenylated flavonol glycosides production.

UHPLC-MS/MS chemical profiling, preliminary toxicity, in vitro antioxidant potential and antimicrobial activity of Brachyotum naudinii Triana flowers

Chemical compounds of Brachyotum naudinii Triana flowers were analyzed using UHPLC-MS/MS. Anthocyanin dry extract was obtained by accelerated solvent extraction with 70% ethanol acidified with citric acid (pH 3.18) and then spray dried. Preliminary toxicity of anthocyanin extract was evaluated using Artemia salina Leach, while its antioxidant capacity was measured by DPPH• and ABTS•+ methods, and reducing capacity was assessed using FRAP assay. Results showed the flowers comprise 39% tannins, 21% flavonol glycosides, 14% organic acids, 11% anthocyanins, 7% coumaric acid derivatives, 4% polar lipids, and 4% disaccharides. Anthocyanin extract exhibited moderate toxicity against Artemia salina (LC50 = 106.9 ± 9.9 µg mL−1) and showed inhibitory effects on DPPH• and ABTS•+ radicals, as well as reducing capacity in FRAP assay, though statistically different from Trolox (p < 0.05). The flowers have demonstrated antimicrobial activity against Staphylococcus aureus and are a source of novel anthocyanin compounds with antioxidant potential.

Study on metabolic variation reveals metabolites important for flavor development and antioxidant property of Hainan Dayezhong black tea

To illustrate the development of chemical properties and characteristic flavor of Hainan Dayezhong black tea, the tea shoots under various manufacturing process were sampled and applied to targeted/widely-targeted metabolomic, transcriptomic, chemometric, and electronic sensory determinations. Totally, 2419 metabolites were identified in this study, of which 20 metabolites were selected as the biomarkers, mainly including amino acids, lipids, and pyrimidine derivatives. The metabolomic-transcriptomic integrated analysis indicated carbon fixation, flavonoid biosynthesis and amino acid metabolism were the major metabolic pathways over manufacturing process of Hainan Dayezhong black tea. The targeted metabolomic detection indicated the accumulations of free amino acids and reduction of total catechins, flavonol glycosides collectively contributed to the development of black tea taste; additionally, the antioxidative properties were decreasing along the production process. These results suggest that the tradeoff between bioactivity components and antioxidative capacity contribute to the characteristic flavor of Hainan Dayezhong black tea.

Icariin as a Treatment Proposal in Mammalian Reproduction.

Icariin (ICA), one of the main active components of Herba Epimedii, is a natural prenylated flavonol glycoside that possesses a wide range of pharmacological effects, including antioxidant, antiosteoporotic, anti-aging, neuroprotective, immunomodulatory, antitumor, and aphrodisiac effects, and prevents numerous health disorders, such as cardiovascular diseases, osteoporosis, cancer, sexual dysfunction, menstrual disorders, neurodegenerative diseases, asthma, chronic inflammation, and diabetes. In the reproductive system, it has been observed that ICA may play a role in preserving fertility by regulating different signalling pathways, such as PI3K/AKT, which improves ovarian function, and ERα/Nrf2, which enhances testicular function and prevents ROS generation. In contrast, regulating the NF/kB signalling pathway causes anti-inflammatory effects, reducing spontaneous abortions. In this study, we review and examine the relevant literature on the therapeutic potential of ICA in reproduction, highlight the various mechanisms of action and limitations for the therapeutic applications of ICA, and summarise and highlight the existing preclinical research on its effects on male and female reproduction.

A randomized, double-blind, placebo-controlled study of Cistanche tubulosa and Ginkgo biloba extracts for the improvement of cognitive function in middle-aged and elderly people.

Mild cognitive impairment poses an increasing challenge to middle-aged and elderly populations. Traditional Chinese medicinal herbs like Cistanche tubulosa and Ginkgo biloba (CG) have been proposed as potential agents to improve cognitive and memory functions. A randomized controlled trial involving 100 Chinese middle-aged and elderly participants was conducted to investigate the potential synergistic effects of CG on cognitive function in individuals at risk of neurodegenerative diseases. Over 90 days, both CG group and placebo group received two tablets daily, with each pair of CG tablets containing 72 mg echinacoside and 27 mg flavonol glycosides. Cognitive functions were assessed using multiple scales and blood biomarkers were determined at baseline, Day 45, and Day 90. The CG group exhibited significant improvements in the scores of Mini-Mental State Examination (26.5 at baseline vs. 27.1 at Day 90, p < 0.001), Montreal Cognitive Assessment (23.4 at baseline vs. 25.3 at Day 90, p < 0.001), and World Health Organization Quality of Life (81.6 at baseline vs. 84.2 at Day 90, p < 0.001), all surpassing scores in placebo group. Notably, both the Cognitrax matrix test and the Wechsler Memory Scale-Revised demonstrated enhanced memory functions, including long-term and delayed memory, after CG intervention. Moreover, cognitive-related blood biomarkers, including total tau, pT181, pS199, pT231, pS396, and thyroid-stimulating hormone, significantly decreased, whereas triiodothyronine and free triiodothyronine significantly increased. No treatment-related adverse events were reported, and routine blood and urine tests remained stable. These findings indicated that CG supplementation could potentially serve as an effective supplementary solution for enhancing cognitive and memory functions.

Metabolic and Transcriptional Analysis Reveals Flavonoid Involvement in the Drought Stress Response of Mulberry Leaves.

Abiotic stress, especially drought stress, poses a significant threat to terrestrial plant growth, development, and productivity. Although mulberry has great genetic diversity and extensive stress-tolerant traits in agroforestry systems, only a few reports offer preliminary insight into the biochemical responses of mulberry leaves under drought conditions. In this study, we performed a comparative metabolomic and transcriptomic analysis on the "drooping mulberry" (Morus alba var. pendula Dippel) under PEG-6000-simulated drought stress. Our research revealed that drought stress significantly enhanced flavonoid accumulation and upregulated the expression of phenylpropanoid biosynthetic genes. Furthermore, the activities of superoxide dismutase (SOD), catalase (CAT) and malondialdehyde (MDA) content were elevated. In vitro enzyme assays and fermentation tests indicated the involvement of flavonol synthase/flavanone 3-hydroxylase (XM_010098126.2) and anthocyanidin 3-O-glucosyltransferase 5 (XM_010101521.2) in the biosynthesis of flavonol aglycones and glycosides, respectively. The recombinant MaF3GT5 protein was found to recognize kaempferol, quercetin, and UDP-glucose as substrates but not 3-/7-O-glucosylated flavonols and UDP-rhamnose. MaF3GT5 is capable of forming 3-O- and 7-O-monoglucoside, but not di-O-glucosides, from kaempferol. This implies its role as a flavonol 3, 7-O-glucosyltransferase. The findings from this study provided insights into the biosynthesis of flavonoids and could have substantial implications for the future diversified utilization of mulberry.

LC-MS and GC–MS based metabolomics analysis revealed the impact of tea trichomes on the chemical and flavor characteristics of white tea

To explore the influence of tea trichomes on the quality of white tea, liquid chromatography quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS), and headspace solid phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC–MS) were used to identify non-volatile and volatile compounds white tea without trichomes (WTwt) and pure trichomes (PT). It was found that the bitter and astringent compounds, caffeine (CAF), epigallocatechin gallate (EGCG), epicatechin gallate (ECG) and flavonol glycosides, were mainly enriched in the WTwt, with 16.3-fold, 47.1-fold and 28.7-fold decrease in CAF and EGCG and ECG, respectively, and the content of these compounds in PT were lower than the taste thresholds. In PT, kaempferol-3-O-(p-coumaroyl)-glucoside and kaempferol-3-O-(di-p-coumaroyl)-glucoside were non-volatile marker compounds, and decanal was significant aroma contributor with rOAV = 250.86. Moreover, the compounds in trichomes mainly contributed to the fruity and floral aroma of white tea, among which benzyl alcohol, (E)-geranylacetone, decanal, dodecanal and 6-methyl-5-hepten-2-one were the crucial aroma components, which were 2.1, 1.7, 1.8, 1.4 and 2.2 times as much as the WTwt in the PT, respectively. In conclusion, trichomes can improve the quality of white tea by reducing the bitterness and astringency, increasing the umami, as well as enhancing the fruity and floral aromas.

Isolation and Characterization of Flavonol glycoside as Antioxidant and Antidiabetic Compounds from Ebony (DiospyroscelebicaBakh.)Leaf Ethanol Extract

Isolation and Characterization of Flavonol glycoside as Antioxidant and Antidiabetic Compounds from Ebony (DiospyroscelebicaBakh.)Leaf Ethanol Extract

Changes and biotransformation mechanism of main functional compounds during kombucha fermentation by the pure cultured tea fungus

Kombucha was fermented by the pure cultured tea fungus, and the changes of functional compounds and their transformation were explored. After fermentation, the contents of total polyphenols, total flavonoids, quercetin, kaempferol and catechins respectively enhanced by 77.14%, 69.23%, 89.11%, 70.32% and 45.77% compared with the control, while flavonol glycosides reduced by 38.98%. The bioavailability of polyphenols and flavonoids respectively increased by 29.52% and 740.6%, and DPPH and ABTS respectively increased by 43.81% and 35.08% compared with the control. Correlation analysis showed that microorganisms and the antioxidant activity were highly positive correlation with total polyphenols, total flavonoids, EGC, EC, EGCG, ECG, quercetin and kaempferol, and negative correlation with kaempferol-3-glucoside. The constructed models confirmed that organic acids were more likely to damage the structure of tea leaves, and enzymes (polygalacturonidase and tannase) and solvents (acids, alcohols and esters) had a synergistic effect on the biotransformation of functional compounds.

Investigation of the quality of Lu'an Guapian tea during Grain Rain period by sensory evaluation, objective quantitative indexes and metabolomics

The harvest date is a crucial factor in determining tea quality. For Lu'an Guapian (LAGP) tea, Grain Rain period (GRP) represents a pivotal phase in the transformation of tea quality. The sensory evaluation, computer vision and E-tongue revealed that the liquor color score, B and G values of tea infusion were increased during GRP, while the astringency, bitterness intensities and the R value of the tea infusion were decreased. Consequently, the tea infusion exhibited a greener hue and the taste became appropriate during GRP. Non-targeted metabolomics revealed that the majority of amino acids and derivatives was reduced during GRP. Furthermore, flavonoids, in particular flavonol glycosides, exhibited considerable variation during GRP. Finally, nine metabolites were identified as markers for quality transformation during GRP by PLS and Random Forest. This study investigated the quality of LAGP teas during GRP and filled the gap in the variation of LAGP tea quality during GRP.

Green and efficient extraction of polyphenols from the leaves of Quercus dentata Thunb and in vitro antioxidant activities of polyphenol extract

The ultrasonic-coupled deep eutectic solvents method was firstly applied to extract phenolic compounds efficiently from the leaves of Quercus dentata Thunb. Five factors including type of deep eutectic solvent, water content, solid-liquid ratio, extraction time and extraction temperature were investigated based on total polyphenol content. The optimal extraction parameters were obtained through response surface methodology, that is, the deep eutectic solvent was composed of choline chloride and 1, 4-butanediol (molar ratio 1:2) with water content of 38%, the solid-liquid ratio was 1:30 g/mL, the extraction time was 31 min, the extraction temperature was 55 °C. At this condition, total polyphenol content reached the highest value of 78.56 ± 2.44 mg gallic acid/g. In addition, eleven phenolic compounds were identified by high performance liquid chromatography quadrupole/time-of flight mass spectrometry as flavonol glycosides. And then, the extraction showed good antioxidant activities in reducing transition metals (Fe3+, Cu2+, Mo6+) and scavenging free radicals (DPPH·, ABTS+·, O2−· and ·OH). Among them, the IC50 values of scavenging DPPH·, ABTS+·, O2−· and ·OH free radicals were 10.87 ± 0.25 μg mL−1, 8.04 ± 0.24 μg/mL, 149.47 ± 5.27 μg/mL and 131.73 ± 5.31 μg/mL, respectively. On the other hand, the extraction at the cellular level exerted its protective effect on PC12 cells by increasing the cell survival rate of H2O2-induced damaged cells, weakening the level of reactive oxygen species in damaged cells. Overall, this study provided a green and high-efficient strategy for extracting phenolic compounds with great antioxidant activities from Q. dentata leaves.