Composition of the essential oils of Ocimum urticifolium (Lamiaceae) chemotypes grown in Rwanda

NTEZURUBANZA, L., SCHEFFER, J. J. C. & SVENDSEN, A. B., 1988. Composition of the essential oils of Ocimum urticifolium (Lamiaceae) chemotypes grown in Rwanda. Leaves and flowers of 48 specimen of Ocimum urticifolium (synonym: O. suave), Lamiaceae, were collected in different parts of Rwanda. The volatile components of each specimen were isolated by hydrodistillation under standardized conditions, and the 48 essential oils analysed by thin-layer chromatography. This preliminary analysis showed six different oil compositions. Thereafter, six oil samples were fractionated by liquid—solid chromatography. The fractions thus obtained, and all other oil samples were then analyzed by capillary gas chromatography. In this way 46 compounds were identified in the various oil samples. Eight components, which amounted to more than 10% in at least one oil sample, were used to characterize the oils. Twelve oil types were distinguished, three of which were dominated by one component only: eugenol, methyleugenol and transmethylisoeugenol respectively. The other types were more complex. In some parts of Rwanda almost one oil type seemed to occur, whereas in other areas a more heterogeneous collection of types was found. Eugenol was quantitatively most important in 31 of the 48 oil samples, in 22 of which this component amounted to more than 50%.