Bioactive Sesquiterpenes from the Essential Oil of Thuja orientalis

Abstract

A phytochemical investigation on the essential oil of Thuja orientalis resulted in the isolation and identification of three new sesquiterpenes, 3-methoxy-4-epoxythujopsane (1), (3,15)-4-epoxythujopsene (2), and (3,4)-thujopsen-2,15-diol (3), together with eight known sesquiterpenoids (4-11). The structures of these new compounds were elucidated based on spectroscopic data analyses including extensive 2D-NMR data and HR-ESIMS. The full assignments of H-1 and C-13 NMR chemical shifts for thujopsadiene (4) were obtained by 2D-NMR for the first time. All compounds (1-11) showed antiproliferative activities against the SK-OV-3 and SK-MEL-2 cell lines with IC50 values of 5.85-28.64 mu M. In addition, compounds 1, 3, 4, 7, 8, and 9 significantly inhibited nitric oxide production in lipopolysaccharide-activated BV-2 cells with IC50 values of 3.93-17.85 mu M without cell toxicity.