Kinetics of Inhibition of Monoamine Oxidase Using Cymbopogon martinii (Roxb.) Wats.: A Potential Antidepressant Herbal Ingredient with Antioxidant Activity.

The study was designed to evaluate the antioxidant activity and effect of Cymbopogon martinii (Roxb.) Wats. (Poaceae) leaves on the activity of monoamine oxidase and kinetics of enzyme inhibition. Ethanol extract of C. martinii and rat brain mitochondrial monoamine oxidase preparation ware used to study the kinetics of enzyme inhibition using double reciprocal Lineweaver-Burk plot. The DPPH was used as a source of free radical to evaluate antioxidant potential. It is observed that, the ethanolic extract of C. martinii inhibits the monoamine oxidase activity with competitive mode of inhibition. The V(max) (0.01 mM/min) remained constant while, K(m) varied from 21.00 ± 1.1, 43.33 ± 1.5 and 83.33 ± 1.4 mM for 100-500 μg/ml concentration of C. martinii. The K(i) values were calculated to be 90.00 ± 0.87, 75.00 ± 0.69, 68.18 ± 0.68 μg for 100-500 μg/ml concentration of C. martini. It also shows a significant DPPH (1,1-diphenyl-2-picryl hydrazine) radical scavenging (IC(50) = 0.34 ± 0.05 mg/ml) and reducing activity (IC(50) = 0.70 ± 0.22 mg/ml). The C. martini can be considered as a possible source of MAO inhibitor used in the treatment of depression and other neurological disorders.