Ocimum americanum L. (Lamiaceae) is among herbal flora of Burkina Faso used traditionally in the treatment of infectious diseases, fever and pain. Bioactive compounds were screened from this plant. Antibacterial properties of several fractions of this plant were determined. In addition, the antioxidant potential of the extracts was evaluated using three separate assays. Among five separate fractions, it appeared that ethyl acetate fraction (EAF) and dichloromethane fraction (DCMF) had the highest content of total phenolics. Levels of total phenolic compounds and flavonoids in EAF were 63.81±0.12 mg GAE and 10.72±0.06 mg QE, respectively. In correlation to levels of phenolic compounds, EAF presented the best antioxidant activity. The antibacterial activity of the tested fractions was correlated with their phenolic constituents. The EAF fraction had higher antibacterial
activity than gentamicin. The fractions exhibited higher antibacterialactivity against Gram positive bacteria such as B. cereus than Gram negative one such as E. coli. The EAF fraction displayed the best antimicrobial activities and presented synergistic or additive effect with gentamicin. Specific extraction and fractionation of O. americanum leaves yielded useful drug against gastro-enteritis pathologies caused by Gram-negative bacteria.

Polyphenols, Antioxidant, antibacterial, Gentamicin