Endocrine Abstracts

The hypoglycaemic effect of Syzygium (i) cordatum (i) leaf extract was studied in non-diabetic and streptozotocin (STZ)-induced diabetic rats. The crude was subjected to column chromatography and spectroscopic analysis. Non-diabetic and STZ-diabetic rats were orally administered glucose (1.4 g.100 kg-1 (super -1) body weight) followed by extract (6 mg.100-1g (super -1) body weight). Weekly plasma glucose and terminal hepatic glycogen concentrations were recorded in control STZ-diabetic rats and diabetic rats orally treated with the leaf extract once every third day for 4 weeks. The leaf extract decreased plasma glucose from 7.7 plus or minus 0.9 mmol.l-1(super -1) to 3.7 plus or minus 0.6 mmol.l-1(super -1) (n=6) and 21.1 plus or minus 2.2 mmol.l-1 (super -1) to 12.5 plus or minus 1.8 mmol.l-1(super -1) (n=7) in non-diabetic and STZ-diabetic rats, respectively. The extract probably promoted glucose entry into cells as previously reported for corosolic acid containing herbal extracts. Spectroscopic analysis 1H (super 1) and 13C (super 13) NMR) revealed oleanolic and ursolic acids and mixtures of methyl malsinate and methyl corosolate in the leaf extract. The extract did not affect plasma glucose concentration in STZ-diabetic rats after 4 weeks, although it significantly increased hepatic glycogen content by comparison with control diabetic rats (28 (plus or minus) mg.100-1g (super -1) body weight, n=7, vs 16 plus or minus 3 mg mg.100-1g (super -1) body weight, n=6). The discrepancy between short-term and long-term effects of the extract on blood glucose may partly attributed to experimental design. Plasma glucose measurements in short-term studies were from samples collected every 30 min over a 2 hour period; while those of long-term experiments represent 24h samples at which time the extract would have been metabolized. We conclude that S.(i) cordatum (i) leaf extract could be effective in mild diabetes mellitus or in cases of glucose tolerance impairment.