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

Guided by ethnobotanical literature and availability from natural sources, in the framework of our research on odoriferous Tanzania plants, used as edibles or spices, and their biological activities, we report herein the analysis of six samples of essential oils from four Ocimum species (O. basilicum (A and B), O. kilimandscharicum, O. lamiifolium, O. suave (A and B). Leaves and flowering tops of these Ocimum species were collected from the wild, in Mbeya region, Tanzania. The samples 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, 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 be used potentially as antimicrobial agents, as well as accordingly, as food preservatives against food spoilage microorganisms.

Acknowledgements: This study was partially supported by a grant from the Directorate of Research and Publications, Muhimbili University of Health and Allied Sciences, as well as by a grant from National Kapodistrian University of Athens (70/4/8807), which are gratefully acknowledged.

References: [1] Vagionas, K. et al. (2007) Food Chem. 105:1711.