Antioxidants and α-glucosidase inhibitors from “Liucha” (young leaves and shoots of Sibiraea laevigata)

The young leaves and shoots of Sibiraea laevigata , known as “Liucha”, are used as tea by Tibetans to improve digestion after meals. Long-term consumption of “Liucha” will cause weight loss. In present work, we reported on the isolation and NMR and chemical analysis-based elucidation of seven new sorbitol O -caffeic acid ester derivatives named sorbitol esters A–G ( 1 – 7 ) and eighteen known phenolic compounds from S. laevigata . All of the isolates were evaluated for their antioxidant and α -glucosidase inhibitory activities. Among them sorbitol ester A ( 1 ), sorbitol ester D ( 4 ), sorbitol ester F ( 6 ), sorbitol ester G ( 7 ), isoferulic acid ( 15 ), methyl caffeate ( 18 ), trans - p -hydroxycinnamic acid ( 19 ), and kaempferol 3- O - β - d -(6″- E - p -coumaroyl)-glucopyranoside ( 25 ) showed more potent α -glucosidase inhibitory activity than the clinical drug acarbose.