DNA damages promoted by the essential oil from leaves of Casearia sylvestris Sw. (Salicaceae)

The Casearia species (Salicaceae) occur in the tropics and subtropics and their extracts are rich in clerodane-type diterpenes, known as casearins. According to the literature, extracts from Casearia sylvestris exhibit cytotoxic and genotoxic effects in different tumor cell lines, possibly related to the casearins. On the other hand, there are few studies related to the DNA damages of the essential oils from this species. This study is aimed at evaluating DNA damages promoted by the essential oil from leaves of C. sylvestris collected in Rio de Janeiro. The essential oil was obtained from fresh leaves (1.5 kg) by hydrodistillation for 2 h in a Clevenger-type apparatus, and analyzed both by gas chromatography coupled to a mass spectrometer (GC-MS) and gas chromatography coupled to a flame ionization detector (GC-FID). These analyses revealed a very diversified (n = 21 compounds) volatile fraction composed mainly of non-oxygenated sesquiterpenes (72.1%), and the major component was identified as α-humulene (17.8%). Genotoxicity was evaluated by the comet assay, showing DNA damages, mainly of classes 3 and 4 at 4.0 µg/ml (p < 0.05) according to the damage index (DI). This is the first demonstration of DNA damages in response to the essential oil of C. sylvestris. Key words: A549, α-humulene, comet assay, sesquiterpenes.