Hypolipidemic mechanism of gypenosides via inhibition of pancreatic lipase and reduction in cholesterol micellar solubility

Dammarane-type triterpenoids from Gynostemma compressum X. X. Chen & D. R. Liang (Cucurbitaceae) and their AMPK activation effect in 3T3-L1 cells

Bioassay-guided fractionation of the 80% ethanol extract of Gynostemma compressum X. X. Chen & D. R. Liang (Cucurbitaceae) resulted in the isolation and identification of eight undescribed triterpenoids, gycomol VN1, gycomol VN2, and gycomosides VN1-6 from the bioactive n-butanol fraction. The structures of these compounds were elucidated by one- and two-dimensional nuclear magnetic resonance spectroscopy, high-resolution electrospray ionisation mass spectrometry, and chemical methods. All isolated compounds were evaluated for their 5'-adenosine monophosphate-activated protein kinase (AMPK) and acetyl-coenzyme A carboxylase (ACC) activation effects on 3T3-L1 cells. Importantly, gycomol VN2, gycomoside VN1, and gycomosides VN3-5 activated the phosphorylation of AMPK and its downstream substrate ACC in 3T3-L1 cells at a dose of 10 μM. These effects imply that the activation of AMPK and ACC by active compounds from G. compressum has considerable potential for the prevention of obesity and its related disorders by activating AMPK signaling pathways.

Gypenosides Prevent and Dissolve Cholesterol Gallstones by Modulating the Homeostasis of Cholesterol and Bile Acids

Gypenosides (GPs), obtained from Gynostemma pentaphyllum (Thunb.) Makino, have been traditionally prescribed to treat metabolic disorders in Asians. This study assessed whether GPs could prevent lithogenic diet (LD)-induced cholesterol gallstone (CG) formation and enhance CG dissolution in mice. Gallstone-susceptible C57BL/6J mice were fed an LD or normal chow, with or without GPs. Bile acids (BAs) in gallbladder bile were analyzed by liquid chromatography-tandem mass spectrometry. Differentially expressed hepatic genes were identified by RNA sequencing, followed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. GPs were found to prevent LD-induced CG formation and to dissolve pre-existing LD-induced CGs. GPs reduced total cholesterol levels and increased BA levels in bile, as well as reducing the BA Hydrophobicity Index, ratio of 12α-hydroxylated (12α-OH) to non-12α-OH BAs, and Cholesterol Saturation Index in gallbladder bile. GO and KEGG pathway enrichment analyses indicated that GPs-induced genes were involved in BA biosynthesis and cholesterol metabolism. GPs increased the hepatic expression of genes encoding the cytochrome P450 (Cyp) enzymes Cyp7a1, Cyp7b1, and Cyp8b1, while decreasing the hepatic expression of genes encoding the adenosine triphosphate-binding cassette (Abc) transporters Abcg5 and Abcg8. GPs may be a promising strategy for preventing and dissolving CGs.

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.

Dammarane-type saponins with proprotein convertase subtilisin/kexin type 9 inhibitory activity from Gynostemma pentaphyllum

Seven undescribed dammarane-type saponins, gypenosides LXXXI-LXXXVII, together with four known compounds, were isolated from the whole herb of Gynostemma pentaphyllum. The chemical structures of these undescribed compounds were elucidated on the basis of physical and spectroscopic analysis and comparison with literature data. All the isolates were evaluated for their proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitory activities in HepG2 cells. Among them, gypenosides LXXXII-LXXXVII, gynosaponin II, IV and VI suppressed the expression of PCSK9 in LPDS-induced HepG2 cells at 20 μM; gypenosides LXXXII, LXXXV and LXXXVII showed inhibitory activities against PCSK9 at 10 μM; notably, gypenoside LXXXII still exhibited inhibitory activity against PCSK9 at 5 μM.

Camellia nitidissima Chi leaf as pancreatic lipase inhibitors: Inhibition potentials and mechanism

In this study, Camellia nitidissima Chi leaf extract was investigated for its compounds and pancreatic lipase inhibitory potentials. The interaction was determined using ultraviolet (UV) spectroscopy, circular dichroism (CD), fluorescence spectroscopy (FS), and molecular docking to understand the inhibiton, kinetic, and conformation of extraction-pancreatic lipase complex. C. nitidissima Chi leaf extraction inhibited the pancreatic lipase activity in a dose-dependent manner at the concentration of 1-12 mg/ml. The Lineweaver-Burk plots indicated that the inhibition on pancreatic lipase by extraction was noncompetitive. In addition, the decrease in α-helix contents, increase in β-sheet and β-turn, and decrease in fluorescence intensity after extraction treatment indicated that the conformation of pancreatic lipase was changed. This work revealed that C. nitidissima Chi leaf extraction played a significant role in inhibiting pancreatic lipase activity and brought out a solution of delay fat accumulation. PRACTICAL APPLICATIONS: This study reports the components in the extract of C. nitidissima Chi leaf and its inhibitory effect and mechanism of pancreatic lipase. C. nitidissima Chi leaf is a good source of bioactive components, including multiflorin B, kaempferol-3-O-rutinoside, vicenin-2, apigenin-6-C-pentosyl-8-C-hexosyl, vitexin, kaempferol, and other ingredients. It can inhibit pancreatic lipase and be used to control obesity and treat hyperlipidemia. This study also revealed the structure changes of C. nitidissima Chi leaf extract on pancreatic lipase, and further revealed the inhibitory mechanism of C. nitidissima Chi leaf extract on lipase, which provides a theoretical basis for C. nitidissima Chi leaf as a lipase inhibitor.

Triterpenoids from the genus Gynostemma: Chemistry and pharmacological activities

ETHNOPHARMACOLOGICAL RELEVANCE

G. pentaphyllum, also known as Jiao-Gu-Lan, has been used traditionally as folk remedies for many diseases, including diabetes mellitus, metabolic syndrome, aging, and neurodegenerative diseases in China and some countries in East and Southeast Asia. It is considered as an "immortality herb" in Guizhou Province, because it was consumed regularly by the elderly native inhabitants. Other species of the same genus Gynostemma such as G. longipes and G. laxum have been used as alternatives to G. pentaphyllum in ethno-medicine in Vietnam and other Asian countries.

AIM OF THE REVIEW

The review aims to summarize up-to-date study results on Gynostemma species, including traditional usage, phytochemical profile, pharmacological activities, and toxicological studies, in order to suggest future research orientation and therapeutic applications on acute and chronic diseases.

MATERIALS AND METHODS

The relevant literature on the genus Gynostemma was gathered from secondary databases (Web of Science and PubMed), books, and official websites. The latest literature cited in this review was published in February 2020.

RESULTS

The genus Gynostemma has been widely used in traditional medicine, mainly for treatment of diabetes, hypertension, obesity, and hepatosteatosis. To date, 328 dammarane-type saponins were isolated and structurally elucidated from Gynostemma species. Crude extracts, saponin-rich fractions (gypenosides), and pure compounds were reported to show a wide range of pharmacological activities in both in vitro and in vivo experiments. The most notable pharmacological effects were anti-cancer, cardioprotective, hepatoprotective, neuroprotective, anti-diabetic, anti-obesity, and anti-inflammatory activities. Toxicological studies were conducted only on G. pentaphyllum, showing that the plant extracts were relatively safe in both acute and long-term toxicity experiments at the given dosage while no toxicological studies were reported for the other species.

CONCLUSIONS

The review summarizes current studies on traditional uses, phytochemistry, biological properties, and toxicology of medicinal Gynostemma species. Till now, the majority of publications still focused only on G. pentaphyllum. However, the promising preliminary data of other Gynostemma species indicated the research potential of this genus, both in phytochemical and pharmacological aspects. Furthermore, clinical data are required to evaluate the efficacy and undesired effects of crude extracts, standard saponin fractions, and pure compounds prepared from Gynostemma medicinal plants.

Characterization of the direct interaction between apple condensed tannins and cholesterol in vitro

To provide the scientific evidences for a possible new hypocholesterolemic mechanism of apple condensed tannins (ACT), the direct interaction of ACT with cholesterol (CH) was investigated in the present study. Our results suggested that the quenching of ACT fluorescence by CH was carried out according to a static mechanism, while the interaction between ACT and CH in vitro was a spontaneous process. ACT were capable of binding with CH directly, and the CH-binding capacity (35.9-43.9%) of ACT remarkably enhanced with the increase of ACT concentration (0.5-2.0 mg proanthocyanidin B₂ equivalent/mL). Besides, spectroscopic methods and morphological analysis were used to characterize the ACT-CH coprecipitates, the findings indicated that ACT were able to precipitate CH via ionic interactions, hydrophobic interactions and intermolecular hydrogen bonds rather than covalent bonds. In conclusion, the direct interaction of ACT with CH might play a role in their CH-lowering effects in humans and animals.

Gypenosides Altered Hepatic Bile Acids Homeostasis in Mice Treated with High Fat Diet

Gypenosides extracted from Gynostemma pentaphyllum (Thunb.) Makino have significant role in reducing serum lipid level and treating fatty liver diseases, however, without clear mechanism. As gypenosides share the similar core structures with bile acids (the endogenous ligands of nuclear receptor FXR), we hypothesize that gypenosides may improve hypercholesterolemia via FXR-mediated bile acids signaling. The present study was designed to validate the role of gypenosides in reducing levels of serum total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C), as well as in regulating bile acids homeostasis and related gene expression levels. The C57BL/6 male mice were divided into four groups. Mice in groups ND and HFD were fed with normal diet and high fat diet for 38 weeks, respectively. In groups HFD+GP and HFD+ST, mice were fed with high fat diet for 38 weeks and treated with gypenosides and simvastatin (positive control) from weeks 16 to 38, respectively. Serum TC and LDL-C levels were assayed by commercially available kits. Expression levels of genes were tested by the quantitative real-time PCR. The LC-MS/MS was applied to quantify major bile acids in mice livers. Our results showed that gypenosides significantly decreased serum TC and LDL-C levels. The gene expression level of Shp was downregulated while the levels of Cyp7a1, Cyp8b1, Fxr, Lrh1, Jnk1/2, and Erk1/2 were upregulated by gypenosides. Indicated by LC-MS/MS technology, gypenosides increased the hepatic levels of several free bile acids and most taurine-conjugated bile acids while decreasing glycine-conjugated bile acids levels. In addition, gypenosides decreased the CA/CDCA ratio. Gypenosides may improve the abnormal lipid profile of HFD-fed mice via two pathways: (1) enhancing the bile acids biosynthesis from cholesterol; (2) decreasing the CA/CDCA ratio which is positively related to cholesterol absorption.

Gypenosides as natural emulsifiers for oil-in-water nanoemulsions loaded with astaxanthin: Insights of formulation, stability and release properties

The formulation, physicochemical stability and bioaccessibility of astaxanthin (AST) loaded oil-in-water nanoemulsions fabricated using gypenosides (GPs) as natural emulsifiers was investigated and compared with a synthetic emulsifier (Tween 20) that is commonly applied in food industry. GPs were capable of producing nanoemulsions with a small volume mean diameter (d_4,3 = 125 ± 2 nm), which was similar to those prepared using Tween 20 (d_4,3 = 145 ± 6 nm) under the same high-pressure homogenization conditions. GPs-stabilized nanoemulsions were stable against droplet growth over a range of pH (6-8) and thermal treatments (60-120 °C). Conversely, instability occurred under acidic (pH 3-5) and high ionic strength (25-100 mM CaCl₂) conditions. In comparison with Tween 20, GPs were more effective at inhibiting AST from degradation during 30 days of storage at both 5 and 25 °C. However, GPs led to lower lipid digestion and AST bioaccessibility from nanoemulsions than did Tween 20.

Effects of Saponins on Lipid Metabolism: A Review of Potential Health Benefits in the Treatment of Obesity

Obesity is one of the greatest public health problems. This complex condition has reached epidemic proportions in many parts of the world, and it constitutes a risk factor for several chronic disorders, such as hypertension, cardiovascular diseases and type 2 diabetes. In the last few decades, several studies dealt with the potential effects of natural products as new safe and effective tools for body weight control. Saponins are naturally-occurring surface-active glycosides, mainly produced by plants, whose structure consists of a sugar moiety linked to a hydrophobic aglycone (a steroid or a triterpene). Many pharmacological properties have been reported for these compounds, such as anti-inflammatory, immunostimulant, hypocholesterolemic, hypoglycemic, antifungal and cytotoxic activities. The aim of this review is to provide an overview of recent studies about the anti-obesity therapeutic potential of saponins isolated from medicinal plants. Results on the in vitro and in vivo activity of this class of phytochemicals are here presented and discussed. The most interesting findings about their possible mechanism of action and their potential health benefits in the treatment of obesity are reported, as well.

Potato wound-healing tissues: A rich source of natural antioxidant molecules with potential for food preservation

The need for safe, effective preservatives is a prominent issue in the food and drug industries, reflecting demand for natural alternatives to synthetic chemicals viewed as harmful to consumers and the environment. Thus, this study determined the identities and scavenging capacities of antioxidant metabolites produced as a response to potato tuber wounding, using activity-guided fractionation of polar extracts from a Yukon Gold cultivar that had previously exhibited exceptionally high radical-scavenging activity. Activity-guided fractionation using the ABTS(+) radical scavenging assay and LC-MS with TOF-MS for compositional analysis of the most potent antioxidant fractions yielded identification of nine constituents: coumaroylputrescine; feruloylquinic acid; isoferuloylputrescine; ferulic acid; 22,25-dimethoxy-3-[[2,3,4-tri-O-methyl-6-O-(2,3,4,6-tetra-O-methyl-β-d-glucopyranosyl)-β-d-glucopyranosyl]oxy]-(3β)-lanost-9(11)-en-24-one; 4-(2Z)-2-decen-1-yl-5-[1-(4-hydroxyphenyl)decyl]-1,2-benzenediol; 8-[(2E)-3,7-dimethyl-2,6-octadien-1-yl]-5-hydroxy-2,8-dimethyl-6-(3-methyl-2-buten-1-yl)-2H-1-benzopyran-4,7(3H,8H)-dione; 3-[(2-O-β-d-glucopyranosyl-β-d-glucopyranosyl)oxy]-20-[(6-O-β-d-xylopyranosyl-β-d-glucopyranosyl)oxy]-dammar-24-en-19-al; (3β)-28-oxo-28-(phenylmethoxy)oleanan-3-yl 2-O-β-d-galactopyranosyl-3-O-(phenylmethyl)-, butyl ester β-d-glucopyranosiduronic acid. A positive correlation was observed between the scavenging activities and the polarities of the active fractions. The antioxidant capacities of the fractions were also characterised by monitoring the activity throughout a 45-minute assay period.