Acute modulation of rat plasma glucose byan aqueous garlic extract

In this study, the putative antidiabetic effect of garlic was re-investigated. Aqueous crude garlic solution was prepared at high concentration (2 g/ml) and extracts were obtained by ethanol precipitation followed by chromatography on C18 Sep-Pak cartridge. Garlic or extracts were administered by single intraperitoneal injection to euglycaemic rats. Plasma glucose, insulin and nitric oxide (NO) were determined after 30 min, 1 and 2 h, respectively. Garlic induced hypoglycemia and hyperinsulinemia which is mimicked by an ethanol soluble and non polar extract. This active principle appeared different from S-allyl-cystein sulfoxide based on physico-chemical properties and mode of action. Data of thin layer chromatography experiments indicated the presence of at least four molecular species, indicating a more non polar nature, with Rf values higher than S-allyl-cystein sulfoxide. The mechanism of action seemed to involve nitric oxide as its glucose induced lowering activity is abolished by diphenyleneiodonium which is a selective constitutive nitric oxide synthase inhibitor.