Antimicrobial activities of Psidium guajava, Carica papaya and Mangifera indica against some gram positive and gram negative bacteria.

Abstract

The advent of science to the search for antibiotics principally depends on medicinal plants as raw materials. This in-vitro study corroborated the antimicrobial activity of the plants used mostly in folklore medicine. The extract of leaves and barks of Psidium guajava, of Mangifera indica’s leaves and fruits and seeds of Carica papaya were tested against Bacillus cereus, Bacillus subtilis, Escherichia coli and Salmonella typhi. All extracts (except P. guajava bark) showed activity against those isolates but were dose dependent. The extract of P. guajava leaves showed the highest activity against B. cereus, B. subtilis and E. coli while M. Indica’s leaves extract was effective against S. typhi. Both fruit and seed extracts of C. papaya were more active against gram positives than gram negatives. The antibacterial activities of the plant extracts were compared to the standard disks of Streptomycin. These plants could be a potential candidate for the development of new strategies to treat bacterial infections.