Flavonol glycosides from the aerial parts of Gynostemma pentaphyllum and their antioxidant activity

Metabolomics and molecular docking-directed anti-obesity study of the ethanol extract from Gynostemma pentaphyllum (Thunb.) Makino

ETHNOPHARMACOLOGICAL RELEVANCE

Gynostemma pentaphyllum (Thunb.) Makino (G. pentaphyllum) is an oriental herb documented to treat many diseases, including obesity, hyperlipidemia, metabolic syndromes and aging. However, the anti-obesity mechanism of G. pentaphyllum remains poorly understood.

AIM OF THE STUDY

To reveal the anti-obesity mechanism of G. pentaphyllum Extract (GPE) in High-Fat Diet (HFD)-induced obese mice through untargeted metabolomics, Real-Time Quantitative PCR (RT-qPCR), and immunohistochemical experiments. Additionally, to tentatively identify the active constituents through LC-MS/MS and molecular docking approaches.

MATERIALS AND METHODS

GPE was prepared using ethanol reflux and purified by HP-20 macroporous resins. The components of GPE were identified by Liquid Chromatography- Mass Spectrometry (LC-MS) system. Forty-two C57BL/6 J mice were randomly and evenly divided into six groups, with seven mice in each group: the control group, obese model group, Beinaglutide group (positive control), and GPE low, medium, and high-dose groups (50 mg/kg, 100 mg/kg, and 200 mg/kg of 80% ethanol extract). Body weight, liver weight, blood glucose, blood lipids, and liver histopathological changes were assessed. Untargeted metabolomics was employed to characterize metabolic changes in obese mice after GPE treatment. The expression of genes related to differential metabolites was verified using Real-Time Quantitative PCR (RT-qPCR) and immunohistochemical experiments. The constituents with anti-obesity effects from GPE were tentatively identified through molecular docking approaches.

RESULTS

A total of 17 compounds were identified in GPE. GPE significantly lowered body weight, total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) in obese mice and reduced liver weight and hepatic steatosis. Serum metabolomics identified 20 potential biomarkers associated with GPE treatment in obese mice, primarily related to tryptophan metabolism. GPE treatment downregulated the expression of Slc6a19 and Tph1 and upregulated Ucp1 expression. Molecular docking illustrated that compounds such as 20(R)-ginsenoside Rg3, Araliasaponin I, Damulin B, Gypenoside L, Oleifolioside B, and Tricin7-neohesperidoside identified in GPE exhibited favorable interaction with Tph1.

CONCLUSION

The extract of G. pentaphyllum can inhibit the absorption of tryptophan and its conversion to 5-HT through the Slc6a19/Tph1 pathway, upregulating the expression of Ucp1, thereby promoting thermogenesis in brown adipose tissue, facilitating weight loss, and mitigating symptoms of fatty liver. Triterpenoids such as Araliasaponin I, identified in GPE, could be the potential inhibitor of Tph1 and responsible for the anti-obesity activities.

Integrative metabolomic and transcriptomic analyses reveals the accumulation patterns of key metabolites associated with flavonoids and terpenoids of Gynostemma pentaphyllum (Thunb.) Makino

Gynostemma pentaphyllum (Thunb.) Makino (G. pentaphyllum) is a medicinal and edible plant with multiple functions of liver protection, anti-tumor, anti-inflammation, balancing blood sugar and blood lipids. The nutritional value of the G. pentaphyllum plant is mainly due to its rich variety of biologically active substances, such as flavonoids, terpenes and polysaccharides. In this study, we performed a comprehensive analysis combining metabolomics and root, stem and leaf transcriptomic data of G. pentaphyllum. We used transcriptomics and metabolomics data to construct a dynamic regulatory network diagram of G. pentaphyllum flavonoids and terpenoids, and screened the transcription factors involved in flavonoids and terpenoids, including basic helix-loop-helix (bHLH), myb-related, WRKY, AP2/ERF. Transcriptome analysis results showed that among the DEGs related to the synthesis of flavonoids and terpenoids, dihydroflavonol 4-reductase (DFR) and geranylgeranyl diphosphate synthases (GGPPS) were core genes. This study presents a dynamic image of gene expression in different tissues of G. pentaphyllum, elucidating the key genes and metabolites of flavonoids and terpenoids. This study is beneficial to a deeper understanding of the medicinal plants of G. pentaphyllum, and also provides a scientific basis for further regulatory mechanisms of plant natural product synthesis pathways and drug development.

Flavonol Derivatives Containing a Quinazolinone Moiety: Design, Synthesis, and Antiviral Activity

A series of flavonol derivatives containing quinazolinone were designed and synthesized, and their antiviral activities against tobacco mosaic virus (TMV) were evaluated. The results of the half maximal effective concentration (EC50 ) test against TMV showed that the EC50 value of curative activity of K5 was 139.6 μg/mL, which was better than that of the commercial drug ningnanmycin (NNM) 296.0 μg/mL, and the EC50 value of protective activity of K5 was 120.6 μg/mL, which was superior to that of NNM 207.0 μg/mL. The interaction of K5 with TMV coat protein (TMV-CP) was investigated using microscale thermophoresis (MST) and molecular docking and the results showed that K5 can combine with TMV-CP more strongly to TMV-CP than that NNM can. Furthermore, the assay measuring malondialdehyde (MDA) content indicated that K5 had the ability to improve the disease resistance of tobacco. Hence, this study offers strong evidence that flavonol derivatives have potential as novel antiviral agents.

Evaluation of the Antifungal Effect of Rhus verniciflua Stokes Extract for Oral Application Potential

Background and Objectives: This study confirms the possibility of using Rhus verniciflua Stokes (RVS) extract as a natural treatment for oral candidiasis. Materials and Methods: RVS was extracted with 70% ethanol to examine the antioxidant activity through polyphenol, flavonoid content, and DPPH (1,1-diphenyl-2-picrylhydrazyl). To evaluate the antifungal effect against Candida albicans (C. albicans; KCTC 7965/ATCC 10231) and evaluate the stability of RVS, a water-soluble tetrazolium salt (WST-1) assay was performed in human keratinocytes (HaCaT). Results: The findings revealed that RVS extract has fairly high antioxidant activity. The clear zones of the RVS extract against C. albicans increased in diameter due to the inhibition of fungal growth at higher concentrations. Treatment with the 1.25 mg/mL RVS extract had a more than 99% antifungal effect against C. albicans, and the 20 mg/mL RVS extract had a 100% antifungal effect. The WST-1 assay showed that the RVS extract induced low cell viability in the HaCaT cells, which inhibited their proliferation, and the RVS extract is also toxic to normal cells. Conclusions: Although the RVS extract with high antioxidant activity showed clear antifungal activity against C. albicans, it exhibited a low survival rate. Therefore, the development of a safe natural antibiotic is necessary.

Identification of Human UDP-Glucuronosyltransferase Involved in Gypensapogenin C Glucuronidation and Species Differences

Gypensapogenin C (GPC) is one of the important aglycones of Gynostemma pentaphyllum (GP), which is structurally glucuronidated and is highly likely to bind to UGT enzymes in vivo. Due to the important role of glucuronidation in the metabolism of GPC, the UDP-glucuronosyltransferase metabolic pathway of GPC in human and other species' liver microsomes is investigated in this study. In the present study, metabolites were detected using high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). The results show that GPC could generate a metabolite through glucuronidation in the human liver microsomes (HLMs). Additionally, chemical inhibitors combined with recombinant human UGT enzymes clarified that UGT1A4 is the primary metabolic enzyme for GPC glucuronidation in HLMs according to the kinetic analysis of the enzyme. Metabolic differential analysis in seven other species indicated that rats exhibited the most similar metabolic rate to that of humans. In conclusion, UGT1A4 is a major enzyme responsible for the glucuronidation of GPC in HLMs, and rats may be an appropriate animal model to evaluate the GPC metabolism.

Gynostemma pentaphyllum for dyslipidemia: A systematic review of randomized controlled trials

Objective: To evaluate the lipid-lowering effect and safety of Gynostemma pentaphyllum (GP) used alone or as adjunctive therapy for dyslipidemia. Methods: Eight databases and three clinical trial registries were searched until January 2022. Randomized controlled trials (RCTs) assessing the effectiveness of GP for dyslipidemia were included. Trial quality was assessed using the Cochrane Risk of Bias Tool 2.0. Data were analyzed by RevMan 5.4 with effects estimated as risk ratio (RR) or mean difference (MD) with 95% confidence intervals (CI). Results: Twenty-two RCTs involving 2,407 dyslipidemia participants were included. Regarding the risk of bias, 14 RCTs had some concerns, seven RCTs were high, and one trial was low. GP was comparable to n-3 fatty acids (RR 0.89, 95% CI 0.62-1.28) and red yeast rice (RR 0.33, 95% CI 0.1-1.12) on normalization of serum lipids. GP plus n-3 fatty acid was superior in normalization of triglycerides (TG) and total cholesterol (TC) than n-3 fatty acids (RR 1.34, 95% CI 1.01-1.77). GP was similar to lipid-lowering agents (statins, fibrates, and n-3 fatty acids) in regulating TG, TC, and high-density lipoprotein cholesterol (HDL-C). GP plus lipid-lowering agents were superior to lipid-lowering agents in TG (MD -0.65 mmol/L, 95% CI -1.03 to -0.28), LDL-C (MD -0.57 mmol/L, 95% CI -1.07 to -0.08), and HDL-C (MD 0.15 mmol/L, 95% CI 0.11-0.20). GP was inferior to red yeast rice in TC (MD 0.64 mmol/L, 95% CI 0.15-1.13), TG (MD 0.43 mmol/L, 95% CI 0.15-0.71), and HDL-C (MD -0.25 mmol/L, 95% CI -0.47 to -0.04). GP had fewer adverse events than lipid-lowering drugs. Conclusion: Very low certainty evidence showed that GP's effects on TC, TG, and HDL-C were comparable to that of lipid-lowering agents. Low certainty evidence showed that red yeast rice was superior to GP in TC, TG, and HDL-C. Low to moderate certainty evidence showed that the effects of GP plus lipid-lowering agents were superior to that of lipid-lowering agents on TG, LDL-C, and HDL-C. GP use for more than 8 weeks appears safe. Systematic Review Registration: https://inplasy.com/, identifier INPLASY202210135.

Crosstalk between CYP2E1 and PPARα substrates and agonists modulate adipose browning and obesity

Although the functions of metabolic enzymes and nuclear receptors in controlling physiological homeostasis have been established, their crosstalk in modulating metabolic disease has not been explored. Genetic ablation of the xenobiotic-metabolizing cytochrome P450 enzyme CYP2E1 in mice markedly induced adipose browning and increased energy expenditure to improve obesity. CYP2E1 deficiency activated the expression of hepatic peroxisome proliferator-activated receptor alpha (PPARα) target genes, including fibroblast growth factor (FGF) 21, that upon release from the liver, enhanced adipose browning and energy expenditure to decrease obesity. Nineteen metabolites were increased in Cyp2e1-null mice as revealed by global untargeted metabolomics, among which four compounds, lysophosphatidylcholine and three polyunsaturated fatty acids were found to be directly metabolized by CYP2E1 and to serve as PPARα agonists, thus explaining how CYP2E1 deficiency causes hepatic PPARα activation through increasing cellular levels of endogenous PPARα agonists. Translationally, a CYP2E1 inhibitor was found to activate the PPARα–FGF21–beige adipose axis and decrease obesity in wild-type mice, but not in liver-specific Ppara-null mice. The present results establish a metabolic crosstalk between PPARα and CYP2E1 that supports the potential for a novel anti-obesity strategy of activating adipose tissue browning by targeting the CYP2E1 to modulate endogenous metabolites beyond its canonical role in xenobiotic-metabolism.

Prebiotic properties of jiaogulan in the context of gut microbiome

Jiaogulan (Gynostemma pentaphyllum) is a traditional Chinese medicinal herb that has been widely used in food and supplemental products. In the last 20 years, extensive research has been conducted to investigate the medicinal prospects of jiaogulan, and in this regard, more than 200 compounds have been isolated with various medicinal properties such as anticancer, anti-obesity, anti-inflammation, and antioxidation. In respect of potential benefits, jiaogulan market is likely growing, and various food items comprised of jiaogulan (beverage, sport drinks, cola, beer, tea, bread, and noodles) have been commercialized in the United States of America, China, and other Asian countries. More recently, there has been growing interest in the prebiotic potential of jiaogulan, especially at the interface of the gut microbiota. This review focuses on the prebiotic and therapeutic aspects of saponins and polysaccharides of jiaogulan tea by summarizing the literature on cancer, obesity, antioxidant activity, and immune-modulatory properties.

Mechanism of gypenosides of Gynostemma pentaphyllum inducing apoptosis of renal cell carcinoma by PI3K/AKT/mTOR pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Gynostemma pentaphyllum (Thunb.) Makino is a traditional medicine commonly used in China, East Asia and Southeast Asia. In clinic, it is mainly used for hyperlipidemia and antitumor. Its antitumor activity was first recorded in "Illustrated Catalogue of Plants". Gypenosides were the main active ingredients of G. pentaphyllum. The anticancer activity of gypenosides in vivo and in vitro had been widely reported. However, the mechanism of gypenosides in renal cell carcinoma (RCC) still unclear.

AIM OF THE STUDY

In this study, we tried to investigate the active constituents from G. pentaphyllum and potential mechanisms in RCC treatment through network pharmacology and in vitro experiments.

MATERIAL/METHODS

Active compounds and their targets were evaluated and screened through TCMSP and Swiss Target Prediction database. Notably, nine preliminary screened components obtained from database were identified by LC-MS and LC-MS/MS. The targets associated with RCC were obtained from OMIM, TTD and GeneCards database. The PPI network and active component/target/pathway networks were constructed to identify the potential drug targets using String database and Cytoscape software. The functions and pathways of targets were analyzed through DAVID database. Finally, AutoDockTools 1.5.6 was used for molecular docking to assess the binding ability between compounds and targets. To support our prediction, we then explore the antitumor effect and mechanism of gypenosides by vitro experiments. CCK8 and flow cytometry were performed to evaluate cell death treated with gypenosides. Quantitative real-time PCR and Western blot were conducted to detect the changes of PI3K/AKT/mTOR signaling pathway.

RESULTS

Nine saponins and 68 targets have been screened. The hub targets covered PIK3CA, VEGFA, STAT3, JAK2, CCND1 and MAPK3. Enrichment analysis showed that the pathways mainly contained PI3K/Akt/mTOR, HIF-1, TNF, JAK-STAT and MAPK signaling pathways. Gypenosides extracted from G. pentaphyllum showed strong activity against 786-O and Caki-1 cells, and cell apoptosis were detected through Annexin V/PI dual staining assay. RT-qPCR showed that gypenosides downregulated the levels of PIK3CA, Akt and mTOR in Caki-1 and 786-O cells. Mechanistically, gypenosides induced apoptosis of RCC cells through regulating PI3K/Akt/mTOR signaling pathway which was implemented though decreasing the phosphorylation level of Akt and mTOR.

CONCLUSIONS

Gypenosides induced apoptosis of RCC cells by modulating PI3K/Akt/mTOR signaling pathway.

Rhus verniciflua Stokes extract suppresses migration and invasion in human gastric adenocarcinoma AGS cells

BACKGROUND/OBJECTIVES

Many studies have suggested that Rhus verniciflua Stokes (RVS) and its extract are anticancer agents. However, RVS had limited use because it contains urushiol, an allergenic toxin. By improving an existing allergen-removal extraction method, we developed a new allergen-free Rhus verniciflua Stokes extract (RVSE) with higher flavonoid content. In this study, we examined whether RVSE inhibits the ability of AGS gastric cancer cells to migrate and invade.

MATERIALS/METHODS

The flavonoids content of RVSE was analyzed by HPLC. The effects of RVSE on migration and invasion in AGS cells were analyzed by each assay kit. Matrix metalloproteinase (MMP)-9, plasminogen activator inhibitor-1 (PAI-1) and urokinase-type plasminogen activator (uPA) protein expression was analyzed by protein antibody array. The Phosphorylation of signal transducer and activator of transcription (STAT) 3 were assayed by Western blot analysis.

RESULTS

RVSE treatment with 0-100 μg/mL dose-dependently reduced the ability of AGS cells to migrate and invade. Notably, treatment with RVSE strongly inhibited the expression of MMP-9 and uPA and the phosphorylation of STAT3. In contrast, RVSE treatment dramatically increased the expression of PAI-1. These results indicate that the inhibition of MMP-9 and uPA expression and STAT3 phosphorylation and the stimulation of PAI-1 expression contributed to the decreased migration and invasion of AGS cells treated with RVSE.

CONCLUSIONS

These results suggest that RVSE may be used as a natural herbal agent to reduce gastric cancer metastasis.

Gynostemma Pentaphyllum Extract Ameliorates High-Fat Diet-Induced Obesity in C57BL/6N Mice by Upregulating SIRT1

Gynostemma pentaphyllum is widely used in Asia as a herbal medicine to treat type 2 diabetes, dyslipidemia, and inflammation. Here, we investigated the anti-obesity effect and underlying mechanism of G. pentaphyllum extract (GPE) enriched in gypenoside L, gypenoside LI, and ginsenoside Rg3 and obtained using a novel extraction method. Five-week-old male C57BL/6N mice were fed a control diet (CD), high-fat diet (HFD), HFD + 100 mg/kg body weight (BW)/day GPE (GPE 100), HFD + 300 mg/kg BW/day GPE (GPE 300), or HFD + 30 mg/kg BW/day Orlistat (Orlistat 30) for 8 weeks. The HFD-fed mice showed significant increases in body weight, fat mass, white adipose tissue, and adipocyte hypertrophy compared to the CD group; but GPE inhibited those increases. GPE reduced serum levels of triglyceride, total cholesterol, and LDL-cholesterol, without affecting HDL-cholesterol. GPE significantly increased AMPK activation and suppressed adipogenesis by decreasing the mRNA expression of CCAAT/enhancer binding protein-α (C/EBPα), peroxisome proliferator-activated receptor-γ (PPARγ), sterol regulatory element-binding protein-1c (SREBP1c), PPARγ coactivator-1α, fatty acid synthase (FAS), adipocyte protein 2 (AP2), and sirtuin 1 (SIRT1) and by increasing that of carnitine palmitoyltransferase (CPT1) and hormone- sensitive lipase (HSL). This study demonstrated the ameliorative effect of GPE on obesity and elucidated the underlying molecular mechanism.

New Dammarane-type Saponins from Gynostemma pentaphyllum

Six new dammarane-type saponins, gypenosides CP1-6 (16), along with 19 known compounds 7⁻25, were isolated and characterized from the aerial parts of Gynostemma pentaphyllum. Among these compounds, eight dammarane-type saponins, 2, 5, 6, 7, 11, 12, 13, and 15, exhibited the greatest antiproliferative effects against two human tumor cell lines (A549 and HepG2).

Preventive Effect of Flavonol Derivatives Abundant Sanglan Tea on Long-Term High-Fat-Diet-Induced Obesity Complications in C57BL/6 Mice

Sanglan Tea (SLT) is a Chinese medicine-based formulation that is consumed as a health drink for the effective management of obesity-associated complications. However, its chemical components and mechanism of action in the prevention of hepatic steatosis and obesity-related impairments have been uncertain. In this study, we aimed to unveil the chemical profile of SLT and to explore its preventive mechanism in high-fat-diet-induced non-alcoholic fatty liver disease (NAFLD) and obesity-related consequences in C57BL/6 mice. Ultrahigh-performance liquid chromatography (UHPLC) coupled to a quadrupole-orbitrap high-resolution mass spectrometry (MS) analysis of SLT indicated that analogs of quercetin and kaempferol are major compounds of flavonoids in SLT. A dietary supplement of SLT efficiently managed the blood glucose elevation, retained the serum total cholesterol (TC), LDL-cholesterol (LDL-C), and triglyceride (TG) levels, as well as aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activity, and reduced the fat storage in the liver induced by a high-fat diet. The underlying mechanism of this preventive effect is hypothesized to be related to the inhibition of over-expression of lipogenesis and adipogenesis-related genes. Overall, this study suggests that SLT, being rich in quercetin and kaempferol analogs, could be a potential food supplement for the prevention of high-fat-diet-induced NAFLD and obesity-related complications.