SESQUITERPENE LACTONES AND THYMOL ESTERS FROM VICOA-PENTANEMA

The aerial parts of Vicoa pentanema yielded four new sesquiterpene lac tones, namely, 10 alpha-hydroxy-14H-inuviscolide (1), 4 alpha,5 alpha- epoxy-10 alpha,11 beta,13H,14H-1-epi-inuviscolide 3-beta-D-glucoside ( 2), 2 alpha-O-acetyl-3 beta-hydroxyalantolactone (3), and 2 alpha,3 al pha-dihydroxyalloalantolactone (4). The structure and stereochemical a ssignments of all sesquiterpenes were based on their IH and C-13-NMR s pectral data, including those derived from 2D-NMR COSY, HETCOR, FLOCK, and NOESY experiments, as well as extensive NOE-difference studies. I n addition, the same plant material yielded the known sesquiterpene la ctones 8 beta-hydroxyparthenolide (5), 8-epi-confertin (6), 4 alpha,5 alpha-epoxy-10 alpha,14H-1-epi-inuviscolide (7), inuviscolide (8), lip iferolide (9), and carabrone (PQ), the known thymol ester 7,8-epoxy-9- (isobutyryloxy)thymolisobutyrate (11), and its hydrolysis product 7-hy droxy-8,9-bis(isobutyryloxy)thymol (12).