Chemical structures of the major constituents in vetiver root crude extracts and commercial vetiver oil from Vetiveria zizanioides, determined by GC/MS analysis: (A) 3,3,8,8-tetramethyltricyclo[5.1.0.0(2,4)]oct-5-ene-5-propanoic acid; (B) 6-isopropenyl-4,8a-dimethyl-1,2,3,5,6,7,8,8a-octahydronaphthalen-2-ol; (C) ethyl hexadecanoate; (D) ethyl 9,12-octadecadienoate; (E) 2-(4a,8-dimethyl-1,2,3,4,4a,5,6,7-octahydro-naphthalen-2-yl)-prop-2-en-1-ol.