The present invention provides a use of Rhodiola crenulata extracts in manufacturing a composition having hypoglycemic effects, wherein the active ingredients having hypoglycemic effects were further isolated from the Rhodiola crenulata extracts, being epicatechin-(4β,8)-epicatechingallate (B2-3’-O-gallate) and 2-(4-hydroxyphenyl)ethyl 3,4,5-trihydroxybenzoate (HETB). In addition, the present invention discloses that the Rhodiola crenulata extract serves as an α-glucosidase inhibitor, which has an activity in inhibiting the α-glucosidase.本發明係一種大花紅景天萃取物用於製備具降血糖功效組成物之用途,其中該大紅花萃取物中進一步分離出具降血糖功效之有效成分為表兒茶素-(4β,8)-表兒茶素没食子酸酯(epicatechin-(4β,8)-epicatechingallate,B2-3’-O-gallate)及2-(4-羥苯基)乙基3,4,5-三羥基苯甲酸酯(2-(4-hydroxyphenyl)ethyl 3,4,5-trihydroxybenzoate,HETB)。又本發明提供大花紅景天萃取物可作為α-葡萄糖苷酶抑制劑,具有抑制α-葡萄糖苷酶之活性。
