Sulphur constituents of the essential oil of nira (Allium tuberosum Rottl.) cultivated in Brazil

The essential oil, obtained from fresh leaves of nira (Allium tuberosum Rottl.) by steam distillation, was analysed by HRGC and GC–MS. Sulphur-containing compounds identified account for 84% of the oil. Besides the sulphur compounds commonly reported in the genus Allium, three unusual volatile sulphur-containing components were found and they can be grouped as 1-(methylthio)alk(en)yl alk(en)yl disulphides. The compound identified as allyl 1-(methylthio)ethyl disulphide is described in the literature for the first time.