Antioxidant and radical-scavenging carbazole alkaloids from the oleoresin of curry leaf (Murraya koenigii Spreng.)

Oleoresin of curry leaves (Murraya koenigii Spreng.), obtained using acetone, was evaluated for its antioxidant activity using a P-carotene-linoleic acid model system along with the other extracts obtained using methanol, water and volatile oil. The oleoresin showed maximum activity of 83.2% at 100 ppm among all other extractives in comparison to a synthetic antioxidant, namely, butylated hydroxy anisole which exhibited 90.2% activity at the same concentration. The methanol and water extracts showed activities of 16.7% and 11.3%, respectively, at the same concentration. The volatile oil showed negligible (< 10%) activity at 100 ppm concentration. Therefore, the oleoresin was fractionated on a silica gel column to obtain five compounds. Among the five, two compounds with maximum antioxidant activity were identified by H-1 and C-13 NMR spectra as mahanimbine and koenigine. Koenigine also showed a high degree of radicals-cavenging activity. (c) 2005 Elsevier Ltd. All rights reserved.