Abstract

In south-western part of Nigeria Psidium guajava and Mangifera indica are commonly used for herbal preparations in the treatment of toothache, gastrointestinal disorders, dynsentery, diarrhoea, sore gums and sore throats. This has, therefore, led to the investigation of the antimicrobial activities of methanolic extracts of P. guajava and M. indica.  Fifteen different bacterial isolates comprising of both Gram negative and Gram positive organisms were used.  The results show that P. guajava and M. indica extracts exhibited antimicrobial activities at a concentration of 20 mg/ml.  The zones of inhibition exhibited by P. guajava extract ranged between 12 mm and 30 mm while that of M. indica varied between 11 and 28 mm.  The minimum inhibitory concentration (MIC) exhibited byP. guajava extract against the tested organisms ranged between 0.313 and 0.625 mg/ml.  On the other hand MIC exhibited by M. indica extract varied between 1.25 and 10.0 mg/ml. Overall, P. guajava extract show more antimicrobial activity than M. indica extract against tested organisms.

Key words:  Psidium guajava, Mangifera indica, antimicrobial activity.