Antibacterial Potentiality and Brine Shrimp Lethality Bioassay of the Methanol Extract of Trema orientalis Leaves

Abstract

Aim: The aim of this study was to evaluate the antibacterial and cytotoxic activities of methanol extract of Trema orientalis leaves. Materials and Methods: Antibacterial activity of Trema orientalis leaves was tested against two Gram-positive and seven Gram-negative bacteria by disc diffusion assay. The liquid microdilution assay was used for the determination of the minimum inhibitory concentration (MIC). The brine shrimp lethality bioassay analyzed the cytotoxic activity of methanol extract of Trema orientalis leaves. Results: The methanol extract exhibited potent antibacterial activity with the zone of inhibition ranging from 9± 0.81 to 14±0.81 mm against both the tested Gram-positive and all tested Gram-negative bacteria except Pseudomonas denitrificans and Xanthomonas campestris. Comparatively, higher antibacterial activity was found against Gram-negative bacteria in case of Shigella dysenteriae and Salmonella typhi which showed 14±0.81 mm and 13±0.81mm zones of inhibition respectively. Salmonella typhi showed resistance against reference antibiotics (Tetracycline, Erythromycin, Gentamicin and Ciprofloxacin) but methanol extract of leaves exhibited potent antibacterial activity against Salmonella typhi. The MIC values for tested Gram-positive bacteria were 10 mg/mL while for Gram-negative bacteria were ranged from 1.25 to 20 mg/mL. The methanol extract of Trema orientalis leaves showed very low cytotoxicity (LC50, 170.215 μg/mL) in comparison with the standard vincristine sulphate having LC50 value 2.477 µg/mL. Conclusion: The results suggest that the methanol extract of Trema orientalis leaves has potent antibacterial activity with minimum cytotoxicity and could lead to the development of novel broad-spectrum antibacterial agent.