New glycosidic constituents from fruits of Lycium chinense and their antioxidant activities

Potential biologically active new constituents labd-3β, 9β-diol-3α-d-glucopyranosyl-(2a→1b)-α-d-glucopyranosyl-(2b→1c)-α-d-glucopyranosyl-(2c→1d)-α-d-arabinofuranosyl-2d-p-hydroxybenzoate (1) and α-d-glucuronopyranosyl (2→1′)-α-d-glucuronopyranosyl (2′→1″)-α-d-glucopyranosyl-2″-n-octadec-9‴-enoate (2) along with β-sitosterol-β-d-glucoside were isolated from the fruits of Lycium chinense. Their chemical structures were elucidated using detailed spectroscopic studies. The structure assignments are based on two-dimensional (2D)-NMR techniques including COSY, HSQC, HMBC and NOESY experiments. Compounds 1 and 2 were evaluated for antioxidant activities with three assay protocols such as diphenylpicrylhydrazyl (DPPH) radical scavenging activity, reducing power and the phosphomolybdenum activity, compound 2 showed more potential as compared with 1.