Triterpenoid glycosides from Stauntonia chinensis
A new bidesmoside triterpenoid saponin, named stauntoside C1 (1), along with three known saponins (2–4) was isolated from Stauntonia chinensis DC. (Lardizabalaceae). Their structures were established by means of spectral and chemical methods as 3-O-β-d-xylopyranosyl-(1 → 2)-O-β-d-xylopyranosyl-(1 → 3)-O-α-l-rhamnopyranosyl-(1 → 2)-α-l-arabinopyranosyl oleanolic acid 28-O-α-l-rhamnopyranosyl-(1 → 4)-β-d-glucopyranosyl-(1 → 6)-β-d-glucopyranosyl ester (1), scabiosaponin E (2), sieboldianoside B (3), and kizutasaponin K12 (4).
Hypoglycemic and hypolipidemic effects of total saponins from Stauntonia chinensis in diabetic db/db mice
Stauntonia chinensis DC. has been utilised as a traditional herbal medicine for its anti‐hyperglycemic characteristic, which has been associated with triterpene saponins. The goal of the current evaluation was to examine hypoglycemic activity and affiliated mechanism of total saponins from S. chinensis. The chemical composition was analysed by HPLC‐ESI‐MS/MS. The fasting blood glucose, oral glucose tolerance test, insulin tolerance test, insulin and glycogen levels of type 2 diabetic db/db mice administered total saponins were quantified to determine the hypoglycemic effects. The serum lipid profiles were assessed to determine the hypolipidemic effects. Western blotting was used to quantify the protein levels of insulin receptor substrates (IRS)‐1/PI3K/AKT, AMPK/ACC and GLUT4. Twenty triterpene saponins were identified from the total saponins, which exhibited hypoglycemic activities and modulated hyperlipidemia that was associated with type 2 diabetes. The hypoglycemic effects were partly due to the activation of GLUT4, which is regulated by IRS‐1/PI3K/AKT. The activation of the AMPK/ACC signalling pathway may be responsible for the hypolipidemic activity. This study revealed that total saponins from S. chinensis have significant hypoglycemic and hypolipidemic activity in diabetic db/db mice, indicating that these may be utilised in the development of saponins based on S. chinensis for the treatment of type 2 diabetes.
Sterol metabolism. XLI. Cholesterol A-ring autoxidations
Abstract Chromatographic and spectral evidence is adduced for the presence of cholest-5-en-3-one, cholest-4-en-3-one, and cholest-4-ene-3,6-dione in samples of cholesterol aged naturally in air or subjected to irradiation in air by 60 Co gamma radiation. These findings establish an additional mode of air oxidation of cholesterol to A-ring 3-ketones. Moreover, the oxidation by air of cholest-5-en-3-one induced by 60 Co gamma radiation yielded cholest-4-en-3-one, cholest-4-ene-3,6-dione, and the epimeric 3-oxocholest-4-ene-6-hydroperoxides. Cholest-4-en-3-one was not altered by irradiation in air, nor was cholesterol isomerized to cholest-4-en-3β-ol upon irradiation. From these observations it is deduced that the radiation-induced A-ring dehydrogenation of cholesterol yields initially cholest-5-en-3-one which upon isomerization yields cholest-4-en-3-one not further oxidized and which by a second oxidation yields the epimeric 3-oxocholest-4-ene-6-hydroperoxides which decompose to cholest-4-ene-3,6-dione.