Screening of Plectranthus species for antibacterial activity

Abstract

Methanolic extracts from 26 species of Plectranthus L'Herit were screened for in vitro antibacterial activity using the agar disc-diffusion bioasssay. A selection of four Gram-positive and three Gram-negative bacteria were tested. S. aureus and B. subtilis showed the most inhibition, with 15 out of the 26 species displaying activity against at least two Gram-positive bacteria. None of the plant extracts exhibited any activity against the Gram-negative bacteria. Identical species collected from different localities showed no significant variation in antibacterial activity. These screening results indicate that Plectranthus possess antibacterial activity.