Evaluation of antimicrobial activity of crude extracts of Lepidagathis keralensis against pathogenic organisms

Abstract

Lepidagathis keralensis (Acanthaceae) is a plant endemic to Kerala. The leaves and stem of the plant were extracted continuously using acetone, methanol and water. Antimicrobial efficiency of the different extracts was tested using agar well diffusion method against selected human pathogens (Pseudomonas aeroginosa, Klebsiella pneumonia, Streptococcus mutans, Staphylococcus aureus and Candida albicans). Total alkaloids and saponins of the plant were also quantitatively determined. The total alkaloid content was found to be higher in the leaves while the stem showed higher amount of saponins. Acetone extract of stem was found effective against Klebsiella pneumonia while the methanol extract of leaf inhibited effectively the growth of Pseudomonas aeroginosa and Streptococcus mutans. Staphylococcus aureus was inhibited efficiently by the aqueous extract of stem. The methanol extracts of the leaf and stem showed a maximum zone of inhibition against the fungal strain Candida albicans. The results highlight the importance of the plant as potent natural antimicrobials.