International Journal of Medical Laboratory Research (Vol. 8 Issue 3, Dec 2023) www.ijmlr.com/IJMLR© All rights are reserved 23 ISSN No. 2456-4400 Int J Med Lab Res 2023, 8(3):23-31 RESEARCH ARTICLE PHYTOCHEMICAL ANALYSIS AND ANTIBACTERIAL EFFICACY OF OCIMUM GRATISSIMUM EXTRACTS ON MULTI-DRUG RESISTANT BACTERIA Adebesin, IO 1 , Kolapo, KT 2 , Amoka, SO 3 , Olubunmi, OH 4 , Olomoko, CR. 5 , Balogun, AO 6 , Ganiyu, LT 7 1,4 Environquest Integrated Environmental Solution, Lagos, Nigeria. 2 International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria. 356 Department of Microbiology, Faculty of Life Sciences, University of Ilorin, Ilorin, Nigeria. 7 Ladoke Akintola University of Technology, Ogbomoso, Nigeria. . Received: 30 Oct, 2023/Revision: 03 Nov, 2023 /Accepted: 30 Nov, 2023 Abstract: The continuous indiscriminate use of antibiotics in treating animals and human diseases has led to an increase in the ability of bacteria to resist the effects of various antibiotics in use, and this has led to the study and screening of plants for their ability to treat various diseases. In this study, the bioactive components and the antibacterial efficacy of Ocimum gratissimum ethanolic and methanolic leaf extracts against Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli S. marcescens and B. cereus were determined using the Analytical Methods Committee’s standard method and agar well diffusion method respectively. The phytochemical components, antibacterial activity, MIC, and MBC of O. gratissimum were determined against these isolates. The qualitative phytochemical analysis of the extracts revealed the presence of saponins, alkaloids, phenols, tannins, steroids, flavonoids, anthraquinones, terpenoids, glycoside and phlobatannins in both or either of the extracts. The result revealed ethanolic extract to be more potent than methanolic extract by producing inhibition ranges of 15-35mm, 8-27mm, 7-26mm, 9-27mm, 5-24mmm, 13-32mm (ethanol) and 12-33mm, 11-31mm, 8-23mm, 12-25mm, 8-26mm, 6-26mm (methanol) against S. aureus, K. pneumoniae, P. aeruginosa, E. coli, S. marcescens and B. cereus at 12.5-200mg/ml respectively. The MIC and MBC ranged between 12.5 - 50mg/ml and 50-100mg/ml for both extracts respectively. This study revealed that O. gratissimum possesses antibacterial efficacy on the selected isolates even at low concentrations; thereby its use is recommended for the treatment of various diseases caused by these organisms. KEYWORDS: antibacterial efficacy, MIC, MBC, phytochemicals, resistance. RESEARCH ARTICLE Corresponding Author: Ibraheem O. Adebesin , Environquest Integrated Environmental Solution, Lagos, Nigeria.