Extract isolated from Angelica hirsutiflora with insulin secretagogue activity

Ethnopharmacological relevance: Angelica genus (Umbelliferae) has traditionally been used as the medicine and health food considered alleviating several disorders including diabetes mellitus. Angelica hirsutiflora Liu Chao & Chuang is an endemic species and a folk medicine in Taiwan. Aim of the study: The scientific evidence of anti-diabetic effect for Angelica hirsutiflora remains unknown. The methanolic extracts isolated from Angelica hirsutiflora were studied for its insulin secretagogue and hypoglycemic activities. Materials and methods: The in vitro effects and possible mechanisms of Angelica hirsutiflora extract on the insulin secretion in isolated mouse and human islets and pancreatic β-cell line HIT-T15 were determined; and tested the regulation of blood glucose in fasted mice and high-fat diet-induced diabetic mice. Results: Angelica hirsutiflora extract potently stimulated the release of insulin from cultured HIT-T15 cells and isolated mouse and human islets. The intracellular calcium levels were also increased in HIT-T15 cells and isolated human islets treated with Angelica hirsutiflora extract. Angelica hirsutiflora extract was capable of enhancing the phosphorylation of extracellular signal-regulated protein kinases (ERK)1/2 protein in HIT-T15 cells. Specific ERK inhibitor PD98059 inhibited the increase of insulin secretion by Angelica hirsutiflora extract in HIT-T15 cells and isolated mouse islets. When Angelica hirsutiflora extract was administered to the fasted mice, it decreased the rise in blood glucose level after starch loading. The plasma insulin level was also increased by Angelica hirsutiflora extract treatment. In high-fat diet-induced diabetic mice, Angelica hirsutiflora extract markedly improved the oral glucose intolerance as compared with the vehicle control. Conclusions: These findings support that Angelica hirsutiflora extract may be useful in the control of hyperglycemia in non-insulin-dependent diabetes mellitus by acting as an insulin secretagogue.