PEROXYNITRITE SCAVENGING AND TOXICITY POTENTIAL OF DIFFERENT FRACTIONS OF THE AERIAL PARTS OF BACOPA MONNIERA LINN.

Bacopa monniera is locally referred as Brahmi Shak, has been reputed to use in the Ayurvedic system of medicine for centuries. In our ongoing study to identify the scavenger of ONOO- from natural sources, the aerial parts of Bacopa monniera Linn. was evaluated to scavenge authentic peroxynitrites (ONOO-) and to inhibit total reactive oxygen species (ROS) generation, in kidney homogenates using 2′,7′-dichlorodihydrofluorescein diacetate (DCHF-DA). A methanol (MeOH) extract of the B. monniera showed strong ONOO- scavenging activity in the ONOO- system ( IC50 = 11.23±2.14 µg/ml), and marginal activity in the total ROS systems (IC50 = 46.52±0.91µg/ml). So the MeOH extract was fractionated with several organic solvents, such as dichloromethane (CH2Cl2), ethyl acetate (EtOAc) and n-butanol (n-BuOH). The EtOAc soluble fraction, showed strong activity in all the model systems tested. The Brine shrimp lethality bioassay method was used to determine the toxicity of the extracts where Vincristin sulphate was used as a positive control. The dichloromethane (CH2Cl2) fraction showed highest activity (LC50 = 19.02 ± 1.16 µg/ml) and other showed activity in the order of: CH2Cl2 fraction > MeOH extract > EtOAc fraction > n-BuOH fraction>H2O layer.