Qualitative Phytochemical Screening and Antibacterial Effect of Averrhoa bilimbi Fruit Extracts Against Selected Bacteria

Abstract

Introduction: Most diseases involving bacterial infections have caused high mortality and morbidity rates worldwide. However, the misuse of synthetic antibiotics in treatments has not only caused adverse effects on patients but also led to the emergence of antibiotic-resistant bacteria. The escalating issue of antimicrobial resistance has led to the urgent need for new antimicrobial agents originating from natural resources. Thus, this study was conducted to determine the antibacterial activity of ethyl acetate and aqueous extracts of Averrhoa bilimbi fruits against selected bacteria. Methods: The antimicrobial susceptibility testing (AST) and minimum inhibitory concentration (MIC) by disc diffusion method and microdilution broth method were respectively performed to evaluate the antibacterial activity of the A. bilimbi extract against gram-positive Staphylococcus aureus (ATCC 25923) and Bacillus cereus (ATCC 14579), as well as gram-negative bacteria (Escherichia coli (ATCC 25922) and Salmonella typhimurium (ATCC 13311)). Results: Initial screening for ethyl acetate and aqueous extracts showed inhibition against all microbes with the most significant effects on B. cereus at 16 and 11.67±1.15 mm, respectively. With MIC value of 7.81 mg/ml, the lowest concentration of ethyl acetate extract was required by S. aureus and B. cereus to inhibit their growth. For aqueous extract, the lowest MIC value of 31.25 mg/ml was observed to inhibit E. coli. Moreover, A. bilimbi fruit extracts also contain alkaloids, flavonoids, phenols, terpenoids, tannins, and reducing sugars responsible for antibacterial activities. Conclusion: Therefore, A. bilimbi fruit extract with its potential antibacterial properties can be used as an alternative therapy to combat infectious diseases initiated by the selected pathogens.