Studies On Chemical Constituents Of Gynura Divaricata (L.) DC

Gynura divaricata (L.) DC of Compositae which mainly contained flavonoids, triterpenoids, sterols, pyrrolizidine alkaloids and nucleosides, was used for treating diabetes mellitus by folk people. In order to further develop G. divaricata (L.) DC, chemical constituents were isolated, alkaloids were detected by LC-MS~n, seasonal change characteristic of total flavoid content was investigated, hypoglycemic activity of total flavonoid and friedelin was determined. The results are as follow:1. Ten compounds were isolated and purified by silica gel column chromatography from G. divaricata (L.) DC. Based on spectral data and chemical evidence, these compounds were identified as: n-Eicosane (1), Tetracosanol (2), Octacosanoic acid (3), Octacosyl alcohol (4), Palmitic acid (5), Stigmasterol-3-O-β-D-glucopyranoside (6), Stigmasterol (7),β-Sitosterol (8), Daucosterol (9) and Friedelin (10).2. Two hepatotoxic pyrrolizidine alkaloids (HPAs) were detected in G. divaricata (L.) DC, whose molecule weights were 335 and 365.3. Total flavonoid content in G. divaricata (L.) DC was lowest in April～May, and was highest in June-August. Based on total flavonoid content and meteorological factors, middle August is the suitable collecting time of plant material.4. Pharmacological test showed that GDI-TF did not significantly lower the serum glucose level to normal mice, however, remarkably lower the level of serum glucose, TC and TG, and signigicantly increase SOD activity and the serum insulin level to STZ diabetic mice; friedelin also significantly lower the serum glucose level to STZ diabetic mice. It was concluded that total flavonoids (GDI-TF) and friedelin of G．divaricata (L.) DC has significant effect on lowering the serum glucose level to STZ diabetic mice. It was deduced that the mechanism of GDI-TF and friedelin for lowering the serum glucose is to control hyperlipidemia, raise the antioxidant ability of the body, reduce injury of free radicals on the islet beta cell, repairing damaged islet beta cells or promote regeneration of islet beta cells, thereby increasing the secretion of insulin, lower the serum glucose.