Gymsyloside F and Gymsyloside G, Two New Pregnane Glycosides From the Leaves of Gymnema sylvestre and Their α-Glucosidase and α-Amylase Inhibitory Activities

Two new pregnane glycosides were isolated from the leaves of Gymnema sylvestre (Retz.) R.Br. ex Sm. Their chemical structures were determined as (20 S)−12 β-tigloyloxy-5 α-hydroperoxy-3 β,8 β,14 β,17 β,20-pentahydroxypregn-6-ene 3- O-β-D-glucopyranosyl-(1→4)‐6-deoxy-3- O-methyl- β-D-allopyranosyl-(1→4)- β-D-oleandropyranosyl-(1→4)- β-D-cymaropyranosyl-(1→4)- β-D-cymaropyranoside (1) and (20 S)−12 β-benzoyloxy-5 α-hydroperoxy-3 β,8 β,14 β,17 β,20-pentahydroxypregn-6-ene 3- O-β-D-glucopyranosyl-(1→4)‐6-deoxy-3- O-methyl- β-D-allopyranosyl-(1→4)- β-D-oleandropyranosyl-(1→4)- β-D-cymaropyranosyl-(1→4)- β-D-cymaropyranoside (2) on the basis of the extensive spectroscopic methods, including 1D, 2D NMR, HRESIMS, and in comparison with the reported data. At the concentration of 200 µM, compounds 1 and 2 showed moderate anti α-glucosidase and α-amylase activities with inhibitory percentage of 31.1 ± 1.2 and 42.3 ± 1.7% (for α-glucosidase), and 27.8 ± 1.3 and 34.5 ± 1.5% (for α-amylase), respectively.

Novel hypoglycemic compounds from wild mushroom Paxillus involutus

Wild mushrooms are an important source of secondary metabolites possessing a broad range of biological activities. In this study, eight new compounds, named furanopaxin A-F (1-6), deoxybisinvolutone (7), and coumarinvol (8) along with two known compounds were isolated from fruiting bodies of the wild mushroom Paxillus involutus (Batsch) Fr. Their structures were established based on HR-ESI-MS and 1D and 2D NMR spectroscopic data. The results of hypoglycemic assays indicated that compounds 5-8 possessed significant α-glucosidase inhibitory activities, with IC₅₀ values ranging from 14.65 ± 1.68 to 47.55 ± 1.47 μM, and each compound could enhance glucose consumption in insulin-resistance HepG2 cells. Further analysis by molecular docking implied that compounds 5-8 could interact with the amino acid residues of α-glucosidase, supporting the hypoglycemic activity of the compounds.

Pubescenosides E⁻K, Seven New Triterpenoid Saponins from the Roots of Ilex pubescens and Their Anti-Inflammatory Activity

Seven new triterpenoid saponins (1–7), together with three known ones (8–10), were isolated from Ilex pubescens. Elucidation of their structures was performed based on high-resolution electrospray ionisation mass spectrometry (HR-ESI-MS), infrared spectra (IR), and nuclear magnetic resonance (NMR) spectroscopic data. The anti-inflammatory activity of the isolates toward lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages was investigated. The results demonstrated that compounds 3, 5, and 6 inhibited the expression of inducible nitric oxide synthase (iNOS) protein in comparison with LPS stimulation in RAW264.7 cells.

Triterpenoids

Covering: 2013. Previous review: Nat. Prod. Rep., 2015, 29, 1028-1065This review covers the isolation and structure determination of triterpenoids reported during 2013 including squalene derivatives, lanostanes, holostanes, cycloartanes, cucurbitanes, dammaranes, euphanes, tirucallanes, tetranortriterpenoids, quassinoids, lupanes, oleananes, friedelanes, ursanes, hopanes, serratanes, isomalabaricanes and saponins; 350 references are cited.

History of Gymnemic acid, a Molecule that does not Exist

In the literature there are hundreds of articles, the first dating back to 1866 and the last to 2014, on gymnemic acid, isolated from Gy mnema sylvestre, from its isolation to the determination of its biological activities. Gymnemic acid has a CAS number but its structure is not specified. Studies during the second half of the 1970s clearly demonstrated that what was being referred to as gymnemic acid is actually a very complex mixture of dozens of substances, belonging to different classes of natural compounds. This plant, whose infusions or complex mixtures of its metabolites are the basis for many formulas sold in pharmacies and by herbalists, has anti-diabetic and slimming effects. It is certainly misleading to talk about gymnemic acid as a specific molecule. There may be doubts about the exact composition of the products, and consequently about their origin and the claimed effects.

Triterpenoids from Gymnema sylvestre and their pharmacological activities

Because plants are estimated to produce over 200,000 metabolites, research into new natural substances that can be used in the pharmaceutical, agrochemical and agro-industrial production of drugs, biopesticides and food additives has grown in recent years. The global market for plant-derived drugs over the last decade has been estimated to be approximately 30.69 billion USD. A relevant specific example of a plant that is very interesting for its numerous pharmacological properties, which include antidiabetic, anticarcinogenic, and neuroprotective effects is Gymnema sylvestre, used as a medicinal plant in Asia for thousands of years. Its properties are attributed to triterpenoidic saponins. In light of the considerable interest generated in the chemistry and pharmacological properties of G. sylvestre triterpenes and their analogues, we have undertaken this review in an effort to summarise the available literature on these promising bioactive natural products. The review will detail studies on the isolation, chemistry and bioactivity of the triterpenoids, which are presented in the tables. In particular the triterpenoids oxidised at C-23; their isolation, distribution in different parts of the plant, and their NMR spectral data; their names and physico-chemical characterisation; and the biological properties associated with these compounds, with a focus on their potential chemotherapeutic applications.

Inhibitory Effects of Gymnema (Gymnema sylvestre) Leaves on Tumour Promotion in Two-Stage Mouse Skin Carcinogenesis

Ethanol extracts of gymnema (Gymnema sylvestre) leaves exhibited marked antitumour-promoting activity in an in vivo two-stage carcinogenesis test in mice using 7,12-dimethylbenz[a]anthracene as an initiator and 12-O-tetradecanoylphorbol-13-acetate (TPA) as a promoter. From the active fraction of the ethanol extract of the gymnema leaves, three triterpenoids were isolated and identified. These compounds were evaluated for their inhibitory effects on TPA-induced inflammation (1 µg/ear) in mice. The tested compounds showed marked anti-inflammatory effects, with a 50% inhibitory dose of 50–555 nmol/ear.

C-4 gem-dimethylated oleanes of Gymnema sylvestre and their pharmacological activities

Gymnema sylvestre R. Br., one of the most important medicinal plants of the Asclepiadaceae family, is a herb distributed throughout the World, predominantly in tropical countries. The plant, widely used for the treatment of diabetes and as a diuretic in Indian proprietary medicines, possesses beneficial digestive, anti-inflammatory, hypoglycemic and anti-helmentic effects. Furthermore, it is believed to be useful in the treatment of dyspepsia, constipation, jaundice, hemorrhoids, cardiopathy, asthma, bronchitis and leucoderma. A literature survey revealed that some other notable pharmacological activities of the plant such as anti-obesity, hypolipidemic, antimicrobial, free radical scavenging and anti-inflammatory properties have been proven too. This paper aims to summarize the chemical and pharmacological reports on a large group of C-4 gem-dimethylated pentacyclic triterpenoids from Gymnema sylvestre.