Chemical composition and antimicrobial activity of the essential oils of four Ocimum species growing in Tanzania

As part of ongoing research on Tanzanian plants used as edibles or spices, six samples of essential oils from four Ocimum species (O. basilicum, O. kilimandscharicum, O. lamiifolium, O. suave) were analyzed by GC and GC–MS. Eighty-one compounds, corresponding to 81.1–98.2% of the chemical components of the oils, were identified. Major compounds were either phenyl propane derivatives or terpenoids, including methyl eugenol, 1,8-cineole, camphor, bornyl acetate, germacrene-D, E-myroxide, germacrene-B, caryophylene oxide and p-cymene. The oils were also evaluated for antimicrobial activity against eight bacterial strains and three fungi. The oil of O. suave (B) showed the strongest antibacterial activity; O. suave (A), O. kilimandscharicum and, O. lamiifolium were moderately active, while O. basilicum oil was weakly active. However, none of the oils was active against the fungi species. The study has shown that, Ocimum oils could potentially be used as anti-infective agents.