INHIBITORY ACTIVITY OF FIVE TROPICAL PLANTS IN MALAYSIA AGAINST MEDICALLY-IMPORTANT MICROORGANISMS
Abstract
Development and spread of microbial resistance has necessitated a search for novel antimicrobial agents for treatment of infectious diseases. Thus, the present study was carried out to evaluate the potential antibacterial activity of five tropical plants against medically-important bacteria (Gram positive: Bacillus cereus and Staphylococcus aureus; Gram negative: Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa) using colorimetric broth microdilution method with resazurin as a growth indicator. The crude ethanolic extract and its various fractions (hexane, chloroform, ethyl acetate, butanol and water) of each plant were evaluated at concentrations ranging from 5 to 0.04 mg/mL using two-fold serial dilution. All the extracts and fractions tested were found to have percent activity of 40% except the ethyl acetate fraction of Artocarpus integer fruits (20%), chloroform fraction and aqueous fraction of Euphorbia heterophylla stem (both 0%). The lowest minimal inhibitory concentration (0.04 mg/mL, average of two replicates) was given by the ethyl acetate fraction of Manihot esculenta leaves against B. cereus and P. aeruginosa. In contrast, the highest total activity was recorded on the crude ethanolic extract of Citrus grandis leaves against P. aeruginosa (171.9 mL/g). Among the bacteria studied, E. coli and S. aureus were the least susceptible bacteria, with the bacterial susceptibility index (BSI) of 36.7%. In addition, this study also demonstrated the limitation of using resazurin in natural product research, as auto-reduction of this indicator occurred in some of the fractions of Spondias cytherea fruits. Acknowledgements: Universiti Tunku Abdul Rahman for financial supportPublished
How to Cite
Issue
Section
License
Copyright: Creative Commons Attribution CC.
This license lets others distribute, remix, tweak, and build upon your work, even commercially, as long as they credit you for the original creation. This is the most accommodating of licenses offered. Recommended for maximum dissemination and use of licensed materials. View License Deed | View Legal Code Authors can also self-archive their manuscripts immediately and enable public access from their institution's repository. This is the version that has been accepted for publication and which typically includes author-incorporated changes suggested during submission, peer review and in editor-author communications.