Evaluation of Phytochemical, Antimicrobial Activities and Toxicological Analysis of Scent Leaf (Ocimum gratissimum L.) Leaf Extracts

Aim: The phytochemical screening, antibacterial activities and in vivo toxicity of extracts of the leaves of scent leaf (Ocimum gratissimum L.) were investigated.

Methods: All the analyses were carried out using standard scientific procedures using Soxhlet extraction, well-diffusion agar antimicrobial testing and in vivo acute toxicity testing.

Results: The phytochemical analysis according to standard screening tests using conventional protocols revealed the presence of anthraquinone, saponins, tannins, terpenoids and alkaloids, which were detected in methanol extract analyzed. But, flavonoids, glycosides, phlobatannins and steroids were not detected in the methanol extracts analyzed. While only flavonoids were detected in chloroform extract. All other phytochemicals were absent. The extract fractions generally exhibited slight antibacterial activities on Staphylococcus aureus, Bacillus subtilis, Salmonella Typhi and Escherichia coli. But, the extracts showed no effect against Candida albicans. The minimum inhibitory concentration of O. gratissimum was determined with S. aureus and B. cereus recording MICs at the lowest concentration (12.5 mg/mL) of the methanol and chloroform extracts used. While methanol and chloroform extracts were found to have recorded moderate activity S. Typhi and E. coli at the MIC of 50mg/mL. The methanol and chloroform extract recorded MBC of 50 mg/mL on B. subtilis and S. Typhi. However, Salmonella Typhi was inhibited at the concentration of 100 mg/mL of chloroform scent leaf extract. The MICs of C. albicans were not determined in the methanol and chloroform scent leaf extracts analyzed. The in vivo toxicity of O. gratissimum extracts against albino rats revealed that the plant extracts were found to exhibit mild toxicity at higher doses, but the overall remark showed that the plant extract was safe at various concentrations.

Conclusions: The plant can be used in the treatment of various diseases caused by the test microbes, and the plant has less toxicity when administered orally.