Isolation and Characterization of Biopesticide Terpenoids from <em>Dittrichia viscosa</em> (L.) Roots

The natural products composition of the hexane and methyl tert-butyl ether extracts of Dittrichia viscosa roots have been examined. Eight terpenoids were identified by NMR and HRMS techniques, four of which (1, 5, 6 and 8) have not been previously reported as natural compounds. Of these eight compounds, four are thymol derivatives (1-4), two are guaianolides (5 and 7) and two are himachalanes (6 and 8). Additionally, the occurrence of himachalanes in this species has been noted for the first time. Furthermore, a study of the plant protection effects of some of these natural products and the chemical derivative 6a was carried out. Promising results have been obtained for compounds 1-3 and 6a as antifeedant against Spodoptera littoralis; 1-3 and 5 against Myzus persicae; 1-3 against Rhopalosiphum padi, and 4 as nematicide against Meloidogyne javanica. Finally, phytotoxic activity of 4, 5 and 6a against the monocotyledonous Lolium perenne has been also proved.