Antibacterial Potential of Micromelum falcatum Leaf Extracts Against Antibiotic-Resistant Human Pathogens

Sutarat Khonkayan, Phongkeat Nareephot, Amphon Kunlauaong, Rujirek Boongapim and Surachai Rattanasuk

Background and Objective: Micromelum falcatum, a therapeutic plant belonging to the Rutaceae family, has been predominantly utilized in Traditional Chinese Medicine for its efficacy against ailments such as colds and rheumatoid arthritis, in addition to its anti-inflammatory and antimicrobial properties. This research aims to evaluate the antibacterial activity of M. falcatum extracts against four human pathogenic bacteria. Materials and Methods: Extracts were obtained from dried M. falcatum leaves using solvents including methanol, ethanol, ethyl-acetate, dichloromethane and hexane. The antibacterial activity was assessed against three antibiotic-resistant bacterial strains, namely Acinetobacter baumannii, Stenotrophomonas maltophilia and multidrug-resistant Klebsiella pneumoniae (MDR-K), as well as the reference strain Pseudomonas aeruginosa TISTR 2370. The agar disc diffusion assay served as the primary screening method for antibacterial activity. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values were determined using a microbroth dilution and colorimetric assay. The results were analyzed using Duncan’s Multiple Range Test (DMRT), which was used to determine significant mean differences at the 95% confidence level. Results: The hexane extracts demonstrated the most substantial inhibition zone diameter, measuring 10 mm, against A. baumannii, S. maltophilia and P. aeruginose TISTR 2370. The most minimal MIC (3.125 mg/mL) and MBC (6.25 mg/mL) values were observed in the methanolic and ethanolic extracts against A. baumannii, S. maltophilia and MDR-K, respectively. Conclusion: This constitutes the inaugural documentation of the antibacterial efficacy of M. falcatum extracts against antibiotic-resistant bacteria. The findings from this study present promising prospects for the creation of innovative antibiotic medications and suggest potential therapeutic uses in the management of diseases associated with the bacteria tested.

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