Kinetics of Antibacterial Activity and Physicochemical Damage Caused by the Extracts of Senna alata Flowers

Abstract

A partially purified extract of Senna alata flower exhibited appreciable antibacterial activity against Staphylococcus aureus, Bacillus subtilis, Micrococcus luteus, and Pseudomonas putida. The rate at which Gram positive bacteria were killed by the plant extract was high for the first 30 min, but decreased substantially thereafter. The effect of the extract was roughly proportional to the concentration. The mechanism of antibacterial activity of the Senna alata plant extract involved potassium ion and protein leakage. While maximum potassium leakage occurred within 30 min, protein efflux was at a peak after 75 min. Microscopic examination suggested that Bacillus subtilis cells were mummified while Staphylococcus aureus cells were lysed.