Antioxidant activity of citrus cultivars and chemical composition of Citrus karna essential oil.

The genus Citrus has a number of species and hybrids that are well established for their pharmaceutical and economic importance. The essential oil from Citrus karna Raf (Rutaceae) was analyzed for D-limonene (92.31%), the major chemical constituent, along with other minor constituents such as alpha-pinene (1.23%) and beta-pinene (1.80%). It showed significant inhibition for the oxidation of linoleic acid in the beta-carotene-linoleic acid system. Essential oils A and B obtained from C. sinensis, with 35.08% and 76.68% d-limonene, respectively, were used to evaluate the effect of the d-limonene concentration on antioxidant potential. Studies showed that d-limonene and C. karna essential oil have a similar antioxidant potential (39.6 and 38.3%, respectively). C. sinensis oils A and B showed only 10.5% and 30% antioxidant potential, respectively, indicating the possible role of d-limonene in antioxidant activity.