6‐Hydroxycarvotanacetone and other constituents of the essential oil of <i>Laggera alata</i> (D. Don) Sch. Bip. ex Oliv.

Abstract

Abstract The essential oil from the herb of Laggera alata (D. Don) Sch. Bip. ex Oliv. was analysed by means of GLC, LSC, GC–MS and 1 H‐NMR spectrometry. Most of its components were identified, amongst which were phenolic ethers (about 45%), monoterpenes (22%) and sesquiterpenes (12%). The main components of the oil were 2,5‐dimethoxy‐ p ‐cymene ( = thymoquinol dimethyl ether; 44%), and sabinene (16%). Another component (3%) was found to be 2‐methyl‐5‐(1‐methylethyl)‐6‐hydroxycyclohex‐2‐en‐1‐one ( = 6‐hydroxycarvotanacetone); it has until now not been reported to occur in nature. Another rare compound detected was 4‐hydroxycarvotanacetone‐7‐ O ‐angelate (2%). An olfactographic analysis of the oil was also carried out. Chromatographic analyses of the essential oil of L. alata have not been reported previously.