ANTIBACTERIAL ACTIVITIES OF ETHANOL EXTRACTS FROM Croton macrostachyus (Hochst. Ex Delile) AND Justicia schimperiana (Hochst. Ex Nees) BARK AND LEAF AGAINST CERTAIN PATHOGENIC BACTERIA

Abstract

Our study was designed to evaluate antibacterial activities of ethanol extracts from Croton macrostachyus and Justicia schimperiana bark and leaf against certain bacterial pathogens such as E. coli O157 H:7 ATCC 25922, Salmonella Typhi ATCC 13311, Staphylococcus aureus ATCC 25923 and Streptococcus pyogenes ATCC 196151. Qualitative and quantitative methods were followed to screen the phytochemicals in the plants extracts and to estimate total phenolic content (TPC) and terpenoids. Antibacterial activity was evaluated by disc diffusion method and by determination of Minimum Inhibitory Concentration (MIC). The results of the investigation revealed that both the plants were found to contain alkaloids, saponin, steroids, tannins and terpenoids. Highest TPC (3.82±0.82 mg/g Tannic Acid Equivalent) and highest Terpenoid content (118.33±4.4 mg/g) were observed in the leaf extract of C. macrostachyus. Bark extract of C. macrostachyus displayed the strongest activity against the gram-positive bacteria S. aureus with an inhibition zone of 16.17±0.67 mm. E. coli O157 H:7 and S. Typhi were found more resistant to bark extract of J. schimperiana at the concentration of 100 mg/ml. The potent plant part extract should be subjected for further phytochemical analysis and bioactive investigations.