HYPOGLYCEMIC EFFECT OF PARKIA-SPECIOSA SEEDS DUE TO THE SYNERGISTIC ACTION OF BETA-SITOSTEROL AND STIGMASTEROL

Oral administration of the chloroform extracts of Parkia speciosa seeds (petai papan) to alloxan-induced diabetic rats produced a significant depression in blood glucose levels. Extraction, isolation and structure elucidation of the hypoglycaemic fraction (S-9.4) gave a mixture of beta-sitosterol (66%) and stigmasterol (34%). Fraction S-9.4 produced 83% hypoglycaemic activity at 100 mg/kg body weight (BW) compared with 111% activity of glibenclamide at 5 mg/kg BW dosages. The minimum effective dose which produced statistically significant hypoglycaemic effect was 25 mg seeds/kg BW. When tested individually beta-sitosterol and stigmasterol showed no hypoglycaemic effects, indicating that synergism between beta-sitosterol and stigmasterol was necessary to effect the hypoglycaemic activity. The hypoglycaemic effect was not observed in healthy rats. The synergism of beta-sitosterol and stigmasterol to produce hypoglycaemic activity and their occurrence in Parkia speciosa Hassk has never been reported.