Biological activities of Ocimum gratissimum (Linn) ethanol extracts on bacteria associated with surface waters Akure, Nigeria

Abstract

Background: There has been increasing antibiotic resistance by waterborne diseases related bacteria. Despite the use of various antibiotics, there is still a threat in the treatment of water-borne diseases. This study evaluated the antibacterial potentials of Ocimum gratissimum (O. gratissimum) on faecal bacteria associated with surface water. Methods: The collection, extraction, Gas chromatography, and mass spectroscopy (GC-MS) of O. gratissimum leaves and enumeration of bacterial derivatives from surface water samples were conducted per specified protocols. Antibacterial susceptibility test, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) of O. gratissimum extracts on bacteria isolates were conducted via agar well diffusion and tube dilution respectively. Results: The GC-MS revealed the presence of eugenol with the highest percentage composition of 33.0 % in ethanol extract, while γ-Terpinene had the highest percentage composition of 11.88% in aqueous extract. Escherichia coli and Enterococcus faecalis were the faecal bacteria observed. Escherichia coli had an inhibition zone of 23.67 mm and 30.67 mm at 50 mg/ml and 100 mg/ml on O. gratissimum aqueous extract respectively, while ethanol extracts were inhibited mostly with an inhibition range of 26.67 mm - 30.32 mm. The MIC obtained varied from 25 mg/ml to 50 mg/ml, the MBC was constant at 100 mg/ml for all bacterial isolates. Conclusion: Findings revealed that the ethanol extract of O. gratissimum leaf can be employed in the management of the faecal indicator bacteria observed in this study. Eugenol could be used explored for contemporary antibacterial studies to combat water-borne bacteria.

Keywords

• surface water
• bacteria
• bioactive compounds
• susceptibility
• ocimum gratissimum