Chemical composition and biological activities of Santiria trimera (Burseraceae) essential oils from Gabon.

Water-distilled essential oils from leaves and bark of Santiria trimera (Oliv.) Aubrév. (Burseraceae) collected in Gabon were analyzed using capillary GC-FID and GC-MS. The leaf essential oil, which is described for the first time, was dominated by sesquiterpenes (76.5%), among which alpha-humulene (34.6%) and beta-caryophyllene (14.9%) were the major components. The bark essential oil was almost exclusively monoterpenic, with alpha-pinene (51.5%) and alpha-terpineol (16.8%) as main constituents. The antimicrobial activities of both essential oils were tested against eight Gram-positive and three Gram-negative bacteria by using agar disc diffusion and broth microdilution methods; anticandidal effect was also tested on different strains of Candida albica. The Gram-negative bacteria were the less sensitive to the leaf essential oil, which was effective against Bacillus cereus and Enterococcus faecalis. The bark essential oil was more active and, in particular, exhibited significant antimicrobial activity against Proteus mirabilis, which was resistant to the leaf oil. A weak anticandidal effect of both essential oils was observed.

Chemical composition and antimicrobial activity of the essential oils of leaves, roots and bark of Glossocalyx staudtii.

The chemical composition of the essential oils obtained by hydrodistillation from air dried leaves, bark and roots of Glossocalyx staudtii Engl. grown in Gabon was analyzed by GC and GC-MS. The essential oil content was 0.84% (w/w), 0.28% (w/w), and 0.74% (w/w), respectively. The leaf oil was characterized by a high content of monoterpene hydrocarbons (64.8%), with beta-pinene (30.6%) and alpha-pinene (22.6%) as the major constituents. The oil obtained from the bark contained 30.5% of oxygenated monoterpenes with cryptone as the main constituent (11.5%) and 28.9% of aliphatic compounds, with 9.3% of 2-tridecanone; in the roots oil, the main component was 2-tridecanone (55.2%). The antimicrobial activity of the oils was studied by means of the agar disc diffusion and broth microdilution methods. The Gram positive bacteria were the most sensitive to the essential oils. A significant anticandidal effect of the bark essential oil was observed.