Antihyperglycemic activity of Selaginella tamariscina (Beauv.) Spring.

OBJECTIVE

The present study was designed to investigate the effects of the EtOH and H(2)O extracts of Selaginella tamariscina (Beauv.) Spring on hyperglycemia in diabetic rats and HepG2 cells, and to confirm the active fractions of EtOH extract in HepG2 cells.

METHODS

HepG2 cells and type II diabetic rats induced by low-dose streptozotocin (STZ) and high-fat diet (HFD) were used to evaluate the hypoglycemic effect of EtOH and H(2)O extracts of Selaginella tamariscina. HepG2 cells were used to evaluate the promotive effect of different fractions of EtOH extract obtained from a polyamide column on glucose utilization.

RESULTS

The results in HepG2 cells indicated that the EtOH extract had a better hypoglycemic effect than the H(2)O extract. The results in diabetic rats indicated that both EtOH extract and H(2)O extract were able to ameliorate the fasting blood glucose (FBG) level and improve oral glucose tolerance (OGTT). Total cholesterol (TC), triglyceride (TG), low density lipoprotein cholesterol (LDL-c), free fatty acids (FFA), tumor necrosis factor-α (TNF-α), alanine aminotransferase (ALT), aspartate aminotransferase (AST), blood urea nitrogen (BUN) and malondialdehyde (MDA) levels in serum were lowered. High density lipoprotein (HDL-c), insulin and superoxide dismutase (SOD) levels in serum were elevated as well as the hepatic glycogen content in diabetic rats. Compared with H(2)O extract, the effects of EtOH extract were more marked. The 80% ethanol fraction exhibited a stronger hypoglycemic effect than the aqueous and 50% ethanol fractions, but the 95% ethanol fraction did not show any appreciable effects in HepG2 cells.

CONCLUSIONS

The results suggested that the EtOH extract had a better hypoglycemic effect than the H(2)O extract; the 80% ethanol fraction from polyamide column had a strong hypoglycemic activity in HepG2 cells.