Inhibition of aldose reductase and anti-cataract action of trans-anethole isolated from Foeniculum vulgare Mill. fruits

Foeniculum vulgare fruits are routinely consumed for their carminative and mouth freshening effect. The plant was evaluated for aldose reductase inhibition and anti-diabetic action. Bioguided fractionation using silica gel column chromatography, HPLC, and GC–MS analysis revealed trans-anethole as the bioactive constituent possessing potent aldose reductase inhibitory action, with an IC50 value of 3.8 μg/ml. Prolonged treatment with the pet ether fraction of the F. vulgare distillate demonstrated improvement in blood glucose, lipid profile, glycated haemoglobin and other parameters in streptozotocin-induced diabetic rats. Trans-anethole could effectively show anti-cataract activity through the increase in soluble lens protein, reduced glutathione, catalase and SOD activity on in vitro incubation of the eye lens with 55 mM glucose. Trans-anethole demonstrated noncompetitive to mixed type of inhibition of lens aldose reductase using Lineweaver Burk plot.