Dihydro-β-agarofuran sesquiterpene polyesters isolated from the stems of Tripterygium regelii

Twelve new dihydro-β-agarofuran polyesters, triptregelines A-J (1-3 and 5-11) and triptregelols A, B (4, 12), together with five known ones (13-17) were isolated from the stems of Tripterygium regelii. The structures were determined on the basis of extensive analysis of spectroscopic data (1D, 2D NMR, and UV etc.) and HRMS data. Cytotoxic effects of these compounds were evaluated against a pair of cancer cell lines, A549 and taxol-resistant A549T. Triptofordin B (14) showed cytotoxicity against both A549 and A549T cells with IC50 value of 21.2 and 10.8μM, respectively. In addition, triptregeline B (2), triptregeline C (3), triptregeline H (9) and 1α, 6β, 15-triacetoxy-8α-benzoyloxy-4β-hydroxy-9α-(3-nicotinoyloxy)-dihydro-β-agarofuran (17) exhibited weak cytotoxic effects on taxol-resistant A549T with IC50 values ranged from 29.4 to 54.4μM. The cytotoxic effect of triptofordin B (14) was much less than taxol with IC50 value of 0.08μM on A549 cancer cell.