Affiliation: Centre for Plant Biotechnology, Department of Plant Biology and Plant Biotechnology, St. Xavier's College (Autonomous), Palayamkottai-627 002, Tamil Nadu, India.
The present study was intended to reveal the antibacterial activity of various cold organic solvent extracts of Abrus precatorius L. (Fabaceae) and Asystasia gangetica (L.) T. Anderson (Acanthaceae) against the selected pathogens. Powders of whole plant parts of A. precatorius and A. gangetica were extracted with petroleum ether, benzene, chloroform and ethanol at ambient temperature. The dried extracts were tested for antibacterial activity by agar disc diffusion method. Among the different extracts of A. precatorius, ethanolic extracts showed maximum zone of inhibition (21 mm) against Bacillus subtilis followed by 13 mm against Staphylococcus aureus. Broadest spectrum of activity was exhibited in petroleum ether extracts of A. precatorius against different bacterial pathogens (5/7 pathogens). In A. gangetica, benzene extracts exhibited broadest spectrum of activity with the maximum level of inhibition (12 mm) against B. subtilis followed by 11 mm in ethanolic extracts against Salmonella typhi. Petroleum ether extracts of A. gangetica did not show any activity against the selected pathogens. The present study results clearly show that the extracts of A. precatorius and A. gangetica had significant and considerable antibacterial activity against various pathogens and further evaluation is necessary to find out the active principle compound responsible for bioactivity.