Biol. Pharm. Bull. 29(9) 1906—1910 (2006)

and represent an essential part of aerobic life and our metabolism. They are continuously produced by the body’s normal use of oxygen such as respiration and some cell mediated immune functions. Naturally, there is a dynamic balance between the amount of free radicals generated in the body and antioxidants to quench and/or scavenge them and protect the body against their deleterious effects. The origin of diseases of multifactorial nature is being understood now to be due to the vitiation in basic homeostatic balance phenomenon in the body. The cause of a majority of disease conditions like atherosclerosis, hypertension, ischaemic diseases, Alzhemier’s disease, parkinsonism, cancer, diabetes mellitus and inflammatory conditions are being considered to be primarily due to the imbalance between prooxidant and antioxidant homeostasis. Antioxidant principles from natural resources possess multifacetedness in their multitude and magnitude of activities and provide enormous scope in correcting the imbalance. Hence, there is no doubt that phytochemicals deserve a proper position in the therapeutic armamentarium. Berberine is an isoquinoline alkaloid present in a number of clinically important medicinal plants. Berberine containing plants are used medicinally in virtually all traditional medicinal systems, and have a history of usage in Ayurvedic and Chinese medicine dating back at least 3000 years. This alkaloid has demonstrated significant antimicrobial activity against bacteria, fungi, protozoa, viruses, helminthes and chalmydia. In addition, its action includes antagonism of the effects of cholera and Escherichia coli heat stable enterotoxin, inhibition of intestinal ion secretion, inhibition of smooth muscle contraction, inhibition of ventricular tachyarrhythmias, reduction in inflammation, elevation of platelet count in patients with primary and secondary thrombocytopenia and stimulation of bile secretion and bilirubin discharge. Evidence also suggests that intravenous berberine administration can play a role in preventing the onset of ventricular tachyarrhythmia and sudden coronary death after myocardial ischemic damage. Recently berberine has been reported to reduce the blood glucose level in diabetes. The tetracyclic skeleton of berberine, a benzyl-tetra isoquinoline alkaloid derived from a benzyl tetra hydro isoquinoline system with the incorporation of an extra carbon atom, supplied from S-adenosyl methionine via an N-Methyl group. This extra skeletal carbon is known as a “berberine bridge.” Formation of the berberine bridge is readily rationalized as an oxidative process in which the N-Methyl group is oxidized to an iminium ion, and cyclization to the aromatic ring occurs by the virtue of the phenolic group. There is no data available for its antioxidant activity, though the alkaloid possesses a therapeutic potential of several kinds. Hence, the present study aims to investigate the in vitro antioxidant potential of berberine.