The essential oils from fresh aerial parts of four Salvia species indigenous to southern Africa were obtained by hydrodistillation and analyzed by GC and GC/MS. Quantitative rather than qualitative differences in oil composition
were observed. Forty-three compounds in each species accounting for 78% (S. africana-caerulea), 78% (S. africanalutea), 96% (S. chamelaeagnea) and 81% (S. lanceolata) of the total composition were identified. Salvia africana-caerulea
and S. lanceolata were dominated by oxygen-containing sesquiterpenes (59% and 48%, respectively). Oxygen-containing monoterpenes dominated in S. chamelaeagnea (43%), while monoterpene hydrocarbons (36%) were abundant
in S. africana-lutea. Scanning electron and light microscopy of the indumentum of the leaves revealed the presence of glandular and non-glandular trichomes. Non-glandular point-shaped trichomes composed of two or three cells are common in all four species and two types of glandular trichomes were noted: peltate trichomes, with up to 16 head cells and a capitate type varying in the number of cells comprising the head and stalk. The oils were evaluated against two Gram-positive and two Gram-negative bacterial strains using the microdilution method and the MIC values ranged from 0.8 to 32 mg/mL. The oils exhibited antiplasmodial (5 < IC50 < 9 μg/mL) and anti-inflammatory (43 < IC50 < 77 μg/mL) activity as determined by the [3H]-hypoxanthine radiometric and 5-lipoxygenase methods, respectively. Compared to other naturally derived antiplasmodial compounds (e.g. quinine) the oils are more toxic to
human kidney epithelium cells (MTT method) with the IC50 values ranging from 2-7 μg/mL. The oils exhibited poor antioxidant activity against the DPPH. radical at 100 μg/mL.