New Thymol Derivatives and Cytotoxic Constituents from the Root of Eupatorium cannabinum ssp asiaticum

Two new thymol (=5-methyl-2-(1-methylethyl) phenol) derivatives, 8,10-didehydro-9-(3-methylbutanoyl) thymol 3-O-tiglate (1) and 9-O-angeloyl-8-methoxythymol 3-O-isobutyrate (2), were isolated from the root of Eupatorium cannabinum ssp. asiaticum, together with six known compounds, 3-8. The structures of 1 and 2 were determined through extensive 1D/2D-NMR and MS analyses. Among the isolates, 9-acetoxy-8,10-epoxythymol 3-O-tiglate (3) was the most cytotoxic, with IC50 values of 0.02 +/- 0.01, 1.02 +/- 0.07, and 1.36 +/- 0.12 mu g/ml, respectively, against DLD-1, CCRF-CEM, and HL-60 cell lines. In addition, 10-acetoxy-9-O-angeloyl-8-hydroxythymol (4) and eupatobenzofuran (6) exhibited cytotoxicities, with IC50 values of 1.14 +/- 0.16 and 2.63 +/- 0.22, and 7.63 +/- 0.94 and 2.31 +/- 0.14 mu g/ml, respectively, against DLD-1 and CCRF-CEM cell lines.