New dammarane-type triterpenoid saponins from Gynostemma pentaphyllum and their Sirt1 agonist activity

Saponins derived from Gynostemma pentaphyllum regulate triglyceride and cholesterol metabolism and the mechanisms: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Gynostemma pentaphyllum (Thunb.) Makino (G. pentaphyllum) can be used for both medicinal and tea and has lipid-lowering properties. Modern research has shown that its main bioactive components are flavonoids and saponins. It has many beneficial effects such as hypolipidemic, anti-cancer, cardioprotective, hepatoprotective, neuroprotective, anti-diabetic and anti-inflammatory.

AIMS OF THE REVIEW

This review aimed to summarize its anti-glycolipid metabolic models and mechanisms are reviewed to facilitate a deeper understanding of the mechanism in lowering lipids.

MATERIALS AND METHODS

Information related to lipid lowering in G. pentaphyllum was collated by reviewing the relevant literature in the PubMed database from 1985 to 2023.

RESULTS

Only 101 G. pentaphyllum compounds have been initially explored for their hypolipidemic activity. There are cell models, animal models and human subjects for lipid-lowering of it. It reduced triglyceride level via PPAR/UCP-1/PGC-1α/PRDM16 and (SREBP-1c)-ACC/FAS-CPT1 signal pathways. Cholesterol-lowering effects via (SREBP-2)-HMGCR, PCSK9-LDLR and bile acid biosynthetic pathways. Activation of adenosine 5'-monophosphate-activated protein kinase (AMPK) is a key factor in the regulation of glycolipid metabolism in G. pentaphyllum. Other pathways of action of G. pentaphyllum in regulating glucolipid metabolism are also discussed in this paper.

CONCLUSION

To date, more than 328 saponins have been isolated and identified in Gynostemma. Further studies on these components, including molecular mechanisms and in vivo metabolic regulation, need to be further confirmed. G. pentaphyllum has the potential to be developed into drugs or functional foods, but further research is needed.

Dammarane-type saponins from Gynostemma pentaphyllum and their anti-aging activities via up-regulating mitochondria related proteins

The importance of mitochondria in regulation of aging has been extensively recognized and confirmed. Gynostemma pentaphyllum (Thunb.) Makino, a homology of medicine and food, has been widely utilized as dietary supplement. In this study, the transcriptome of normal cells (wild type mouse embryo fibroblasts) regulated by the 30% aqueous EtOH extract of G. pentaphyllum was firstly evaluated by RNA sequencing and the results revealed that the G. pentaphyllum could up-regulate the genes involved in oxidative phosphorylation (OXPHOS) and sirtuin (SIRT) signaling pathways, indicating its effect in promoting cell viability might be attributed to the role of improving mitochondrial functions. To further discover the bioactive compounds, sixteen undescribed dammarane-type saponins along with twenty-eight known analogues were isolated from the active extract of G. pentaphyllum. Their structures were elucidated by means of comprehensive analysis of NMR and HRMS spectroscopic data. All isolates were evaluated for the regulatory effects on SIRT3 and translocase of the outer membrane 20 (TOM20), and thirteen of them exhibited satisfactory agonist activities on both SIRT3 and TOM20 at 5 μM. Furthermore, the preliminary structure-activity relationships analysis demonstrated the additional hydroxymethyl and carbonyl groups or less sugar residues in saponins could contribute positively to the up-regulatory effect on SIRT3 and TOM20. These findings encouraged the potential roles of G. pentaphyllum and its bioactive saponins in the development of natural drugs for the treatment of aging-related diseases.

An effective and high-throughput sample preparation method involving demalonylation followed by an ultrahigh-performance liquid chromatography-charged aerosol detector for analyzing gypenoside XLIX and gypenoside A in Gynostemma longipes

Gypenosides (Gps) are the major bioactive components in Gynostemma species. They include neutral Gps and acidic malonylgypenosides (MGps). MGps are abundant in Gynostemma species and can be transformed into corresponding Gps via extraction, concentration, and drying. If only the Gps were quantified and MGps were ignored, the quality of Gynostemma species would be underestimated. This study aimed to develop a sample preparation method involving demalonylation and ultrahigh-performance liquid chromatography-charged aerosol detector (UHPLC-CAD) analysis to determine the contents of gypenoside XLIX (Gp XLIX) and gypenoside A (Gp A). First, the optimized ultrasonic extraction method was established to extract G. longipes powder ultrasonically. Then, the extracted solution was put into a closed container (centrifuge tube) and heated in a water bath at 95 °C. Then, MGps were converted into corresponding Gps. The proposed preparation method was compared with the other three methods, including water bath reflux heating, alkali hydrolysis, and extraction of heated powder, and was shown to exhibit higher conversion and better convenience. Subsequently, an UHPLC-CAD method was established and validated. Gp XLIX and Gp A showed excellent linear correlations between 15.55 and 248.8 μg/mL and 24.10-385.5 μg/mL, respectively (R² > 0.999). The limit of detection was 1.40 ng (Gp XLIX) and 2.41 ng (Gp A), and the limit of quantification was 7.77 ng and 14.46 ng, respectively. The relative standard deviation for precision, stability, and repeatability was 0.63-3.15%. The average recovery of Gp XLIX and Gp A was 98.97% and 98.23%, respectively. The established method was applied for determining Gp XLIX and Gp A contents in wild or cultivated G. longipes samples collected from the Qinba Mountains area. The contents of Gp XLIX and Gp A were 5.16-23.02 mg/g and 15.78-54.55 mg/g, respectively. Conclusively, the proposed sample preparation and analysis method could be used for the quality control and evaluation of G. longipes.

Systematical characterization of gypenosides in Gynostemma pentaphyllum and the chemical composition variation of different origins

Gynostemma pentaphyllum (Thunb.) Makino is an herbaceous plant of Cucurbitaceae family, which has been widely used as an herbal tea and traditional Chinese medicine. Since its saponins are similar to ginsenosides and have a wide range of activities, it has attracted wide interest. However, there are still a large number of unknown saponins that have not been isolated, especially some trace gypenosides. In the present study, a HILIC × RP offline two-dimensional liquid separation combined with a multimode data acquisition was developed for the systematical characterization of gypenosides. On top of the negative mode information, considering that saponins are prone to in-source fragmentations in positive ion mode, a precursor ion list data acquisition method was used for the targeted acquisition of multistage positive data. Reference herbal drug was taken as a golden sample to probe the chemical composition of G. pentaphyllum. The mixed sample of commercially available samples were also analyzed in parallel. Furthermore, the chemical compositions of commercially available samples from different sources were compared. In total, 1108 saponins were characterized, among which 588 were accurately characterized, with 574 identified in the reference herbal drug and 700 in the mixed commercially available samples. The commercially available samples showed great composition variation. These findings clarified the material basis and provided clues for quality control of G. pentaphyllum.

Chemical Characterization and Atherosclerosis Alleviation Effects of Gypenosides from Gynostemma pentaphyllum through Ameliorating Endothelial Dysfunction via the PCSK9/LOX-1 Pathway

Dietary saponins have the potential to ameliorate atherosclerosis (AS). Gypenosides of Gynostemma pentaphyllum (GPs) have been used as functional foods to exhibit antiatherosclerotic activity. The present study aimed to explore the protective effect, underlying mechanism and active substances of GPs on AS in vivo and in vitro. Results demonstrated GPs administration reduced the serum concentrations of TC and LDL-C, upregulated the plasma HDL-C content, inhibited the secretion of ICAM-1, VCAM-1, and MCP-1, and alleviated vascular lesions in VitD₃ plus high cholesterol diet-induced AS rats as well as reduced adhesion factors levels in ox-LDL-stimulated HUVECs, which was potentially associated with suppressing PCSK9/LOX-1 pathway. Further activity-guided phytochemical investigation of GPs led to the identification of five new dammarane-type glycosides (1-5) and ten known analogs (6-15). Bioassay evaluation showed compounds 1, 6, 7, 12, 13, and 14 observably reduced the expressions of PCSK9 and LOX-1, as well as the secretion of adhesion factors in injured HUVECs. Molecular docking experiments suggested that the active saponins of GPs might bind to the allosteric pocket of PCSK9 located at the catalytic and C-terminal domains, and 2α-OH-protopanaxadiol-type gypenosides might exert a higher affinity for an allosteric binding site on PCSK9 by hydrogen-bond interaction with ARG-458. These findings provide new insights into the potential nutraceutical application of GPs and their bioactive compounds in the prevention and discovery of novel therapeutic strategies for AS.