Antioxidant Profiling of Leaf Extracts of Murraya koenigii (L.) Spreng (Curry Leaf) in PC-12 Cells Exposed to Neurotoxic Shock

Curry leaves (Murraya koenigii L. Spreng; Rutaceae) is a herbal species used in traditional medicine in Eastern Asia. To study antioxidative properties of aqueous extracts of curry leaves, the levels of antioxidant enzymes such as catalase (CAT), superoxide dismutase (SOD) & glutathione-S-transferase (GST) and non enzymatic parameters such as GSH and lipid peroxidation were analysed in PC-12 cells treated with 6-hydroxydopamine and curry leaf extract. Since 6-OHDA is a neurotoxic agent, it caused a decrease in levels of antioxidant enzymes, SOD, CAT, GST & GSH. Lipid peroxidation levels were increased in PC-12 cells after treatment with 6-OHDA. But on further treatment of cells exposed to 6-OHDA with curry leaf extracts, levels of these enzymes were increased to 80% as compared to control and lipid peroxidation levels were decreased to 75% as compared to control. Amino acid cysteine has been proven to be antioxidant in nature. This amino acid is also present in curry leaf extract as it was confirmed by Rf value (0.4) which was similar to the standard cysteine. Altered activities of these antioxidant enzymes upon 6-OHDA treatment were restored to near normal level upon treatment of cells with curry leaf extract. This may be due to antioxidant property of the plant extract, which regulated the neuronal cells defence system against neurotoxic shock.