In Vitro Antibacterial Activity of Alchornea cordifolia and Costus afer Against Some Bacterial Isolates

Abstract

The antibacterial activity of the fresh and concentrated extracts of Alchornea cordifolia and Costus afer against five bacterial species was demonstrated in vitro. The diameter of the zones of inhibition ranged from 6.7±1.5mm to 39.±2.5mm for the fresh juices. The concentrated leaf and stem pith extracts had an inhibition range of 6.3±0.7mm to 22.0±2.5mm. The fresh stem pith juice of Alchornea cordifolia was the most potent plant part and K. varians (39.3±2.5mm) was the most susceptible isolate with a zone of inhibition, which compared well with the gentamycin control (39.3±0.6mm). Extracts from the concentrated leaves were more potent than the juice from the fresh leaves. A combination of the fresh juices did not result in higher zones of inhibition. The extracts obtained from the concentrated leaves and stem of C. afer did not inhibit any of the bacteria tested. The pattern of response exhibited by the bacteria to the extracts was shown by ANOVA to be significantly different. However, ANOVA showed no significant difference in the activity of the concentrated extracts from the leaves of lchornea cordifolia on K. varians (P>0.05). The stem pith and leaves of A. cordifolia can be exploited for use as antibacterial drugs against the bacteria tested since susceptibility to some of them compared well as to gentamycin. The traditional use of these plants for the treatment of diseases caused by the tested isolates was scientifically verified.