Evaluation of in vitro antibacterial activity of extract of semi- aquatic plants growing in the polluted water of Sri Lanka

Abstract

This study evaluated in vitro antibacterial activity and phytochemical profile of four plants (roots of Ipomoea aquatica, Lasia spinosa, Pistia stratiotes and leaves of Monochoria vaginalis) which grows in the wastewater of Sri Lanka. These plants are used in traditional and folk medicine of Sri Lanka for treatment of various bacteria induced infectious diseases. Antibacterial activity evaluated using 0.9% normal saline extracts against two Gram- positive [Staphylococcus aureus (ATCC 25923) and Bacillus subtilis (ATCC 6633)] and two Gram-negative [Escherichia coli (ATCC 25922); Pseudomonas aeruginosa (ATCC 27853)], clinically important bacterial pathogens. The plant extracts were prepared by homogenization of plant in 0.9% sterile isotonic normal saline. The antibacterial activity of the extracts were evaluated using cylinder plate method. The extracts of the four plants showed antibacterial activity with the zone of inhibition values ranging between 12- 15mm. According to the dose-response study, Pistia stratiotes exhibited the highest antibacterial efficacy and Monochoria vaginalis the lowest antibacterial efficacy against Escherichia coli (ATCC 25922). Statistical analysis showed a significant difference (P