Hypoglycemic effect in diabetic rats and antimicrobial activity of Malvastrum Coromandelianum Garcke Aqueous extract

Abstract

Hypoglycemic effect of Malvastrum coromandelianum Garcke extract (ME), in normal and streptozotocin (STZ)-induced diabetic male Wistar rats was demonstrated. For glucose tolerance test in normal rats, ME fed at doses 5, 10, and 20 mg/kg body weight significantly decreased blood glucose concentration at 30 min after feeding 1 g/kg body weight glucose. Feeding ME in non-fasted, diabetic rats at single doses of 10, 50 or 100 mg/kg body weight showed that ME at doses 50 and 100 mg/kg body weight significantly decreased blood glucose concentration at 1 hr and lasted through 6 hr to a level comparable to that of insulin injection, i.p., 5 IU/ kg body weight or of normal rats. Repeated-doses of ME were given orally to STZ-induced diabetic rats at 50, 100 and 500 mg/kg body weight/day or insulin injection at 5 IU/kg body weight/day or control diabetic group fed distilled water, for 30 days. ME fed daily in diabetic rats significantly decreased fasting blood glucose concentration observed on day 15 and 30 compared with diabetic rats treated with water in control group. In diabetic rat treated with insulin 5 IU/kg body weight/d., i.p., 50 mg ME/kg body weight and 500 mg ME/kg body weight/day, p.o., showed significantly decreased fasting plasma triglyceride level after treatment for 30 days. Fasting plasma cholesterol also decreased after daily treatment for 30 days of 50, 100 and 500 mg ME/kg. Histopathological examination did not show any abnormalities of the collected organs that could be attributed to toxicity of the extract either in normal rats or diabetic rats for such repeated doses. In vitro study indicated that ME showed no inhibitory effect on glucose absorption by using everted rat’s intestinal sac model. In acute toxicity test, feeding single doses of 100 mg, 10 and 20 g of ME/Kg body weight in normal rats showed similar profile in biochemical and hematological analysis of blood in treated and control groups on day 5. In subacute toxicity test, daily feeding of 100 mg, 10 g and 20 g of ME/kg body weight for 30 day in normal rats showed similar profile in biochemical and hematological analysis. ME was tested against Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, Enterococcus. faecalis ATCC 29212 and Pseudomonas aeruginosa ATCC 27853, the result showed inhibition zone against only S. aureus ATCC 25923 by using agar diffusion method. ME gave inhibition zone against 6 out of 15 tests strains of each group of MSSA and MRSA. The broth macrodilution test showed that MICs and MBCs of ME against MSSA were 20 – 40 and 40-80 mg/ml, respectively. MICs and MBCs of ME against MRSA were 20 – 40 and 40 – 80 mg/ml respectively.