Chemical Composition andin vitroCytotoxic Activity of Essential Oils from Two Tropical Lamiaceae:Aeollanthus pubescensBenth. andOcimum gratissimumL

Essential oils of Aeollanthus pubescens Benth. and Ocimum gratissimum L. (Lamiaceae) from Togo were investigated for their percentage composition and in vitro cytotoxicity. The GC and GC-MS analyses indicated that the major constituents of both essential oils were thymol, p-cymene and γ-terpinene. Testing of these volatile oils and their major constituents from commercial origin in vitro for possible cytotoxicity on the human epidermic cell line HaCat showed that the toxicity of the essential oil of A. pubescens (IC50: 1800µg.ml−1) was higher than that of the essential oil of O. gratissimum (IC50: 2400 µg.ml−1). Pure commercial thymol standard showed a cytotoxicity (IC50: 1800 µg.ml−1) identical to that of the A. pubescens essential oil. Conversely, p-cymene and γ-terpinene standards were found almost non-toxic (IC50 >3000 µg.ml−1). These findings support the assumption that the cytotoxic activities of the tested essential oils were basically due to their high level content in thymol.