Flavonoids from the leaves and twigs of Lindera sericea (Seibold et Zucc.) Blume var. sericea (Lauraceae) from Japan and their bioactivities

Background : The leaves and twigs of Lindera sericea (Seibold et Zucc.) Blume var. sericea (Lauraceae) are used as traditional medicines for treating indigestion, stomachache, anxiety, etc. In recent years, there has been a growing interest in these plant materials as a source of healthy drinks and functional foods. The main aim of this study was to characterize the major phenolic compounds from the leaves and twigs and to evaluate their free radical scavenging and α -glucosidase inhibitory activities. Methods : The dried leaves and twigs were extracted with 70% methanol. The dried extract was then subjected to repeated column chromatography to isolate eight flavonoids. The compounds were then evaluated for their 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity and α -glucosidase inhibitory activity. Results : The isolated compounds were identified as (-)-epicatechin ( 1 ), taxifolin 3- O -glucoside ( 2 ), quercetin ( 3 ), quercitrin ( 4 ), quercetin 3- O -neohesperidoside ( 5 ), pinocembrin ( 6 ), pinostrobin ( 7 ) and pinostrobin chalcone ( 8 ) based on their nuclear magnetic resonance (NMR), spectroscopic data and comparison with literature values. All these compounds were isolated for the first time from this plant. All flavonoids except pinocembrin ( 6 ), pinostrobin ( 7 ) and pinostrobin chalcone ( 8 ) showed potent free radical scavenging activity. In α -glucosidase inhibitory activity assay, quercetin ( 4 ), quercitrin ( 5 ) and taxifolin 3- O -glucoside ( 2 ) showed potent activity. Conclusions: Eight flavonoids were reported for the first time from the leaves and twigs of the title plant. Some of these compounds showed potent free radical scavenging and α -glucosidase inhibitory activities. Keywords: Lindera sericea var. sericea ; Lauraceae; Kekuromoji; free radical; α-glucosidase