Antioxidant properties of different fractions of Vitex negundo Linn.

Vitex negundo Linn. (VN), belonging to family Verbenaceae, is an aromatic shrub distributed throughout India. In the ayurvedic system of medicine it is used as a drug of choice to manage pain, inflammation and other related diseases. It contains many polyphenolic compounds, terpenoids, glycosidic iridoids and alkaloids. Since polyphenolic compounds have high antioxidant potential, the antioxidant potency of V. negundo was investigated by employing various established in vitro systems, such as 2,2'-azino-bis 3-ethyl benzothiazoline-6-sulfuric acid (ABTS*(+))/Lipid Peroxides (LPO)/Superoxide/Hydroxyl radical scavenging and iron ion chelation. Total antioxidant capacity was determined by the assay based on the preformed radical monocation ABTS*(+). Lipid peroxidation was assessed in terms of thiobarbituric acid reactive substances by using egg yolk homogenates as lipid rich media. Superoxide radical scavenging assay was based on the riboflavin-light-Nitro blue tetrazolium (NBT) system. Hydroxyl radical trapping potential was determined by evaluating hydroxyl radical induced deoxyribose degradation using the thiobarbituric acid method. In order to assess the metal chelation properties, hydroxyl radical induced deoxyribose degradation was evaluated in the absence of Ethylenediamine tetra acetic acid (EDTA). All the polar fractions significantly showed trapping of free radicals, and thereby inhibition of lipid peroxidation, and also chelated the iron ion. Interestingly, the hexane fraction did not show any activity against superoxides radicals and it had minimum trapping potential for other free radical (FR) species also. Thus, it may be concluded that the polar fractions of VN possess potent antioxidant properties, which may be mediated through direct trapping of the free radicals and also through metal chelation. Therefore its reported anti-inflammatory properties, could be through the down regulation of the free radical mediated pathway of inflammation. (c) 2005 Elsevier Ltd. All rights reserved.