Preparation of extracts

The plant material was cleaned, cut into small pieces and dried under a shade. It was then pulverized into coarse powder in an electric blender, weighed (~180 g dry weight) and extracted successively using petroleum ether, ethyl acetate, methanol and water respectively by soxhlet extraction each for a period of 96 h. The solvents were allowed to evaporate in a rotary evaporator at 40–45 °C and the extracts obtained were stored in a refrigerator at 4 °C. The yields of the petroleum ether, ethyl acetate, methanol and aqueous extracts were 5.6, 4.3, 5.3, and 4.2% (w/w), respectively.