RESUMO
Five new sesquiterpenoids, (4S, 5S, 6S, 7S, 8 R)-5,6-dihydroxy-1-acetoxy-10(14)-en-britannilactone (1), (4S, 5 R, 6S, 7S, 8 R)-5,6-dihydroxy-1-acetoxy-10(14)-en-britannilactone (2), 6-O-propionyl-britannilactone (3), 1ß-hydroxy-3α-acetoxyeudesma-11(13)-en-12,8ß-olide (4) and 1ß,5ß-dihydroxyeudesma-11(13)-en-12,8ß-olide (5), along with twelve known ones were isolated from the flowers of Pentanema britannicum (L.) D.Gut.Larr. Among them, compounds 1 and 2 were stereoisomers which belong to 1,10-seco-eudesmane sesquiterpenoid with rare double bond between C-10 and C-14. The structures of the isolated compounds were elucidated by various spectroscopic methods, including 1D and 2D NMR experiments.
RESUMO
Seven undescribed sesquiterpene lactone dimers (SLDs) (carpeabrodilactones A-G), one known SLD, and six known sesquiterpenes were isolated from the fruit of Carpesium abrotanoides L. Carpeabrodilactone A was a dimeric carabrane featuring a rare C-13-C-13' linkage. Carpeabrodilactones B and C are the first two SLDs to be described possessing a carabranolide unit and a guaianolide unit connected by an O-ether linkage. The structures of the SLDs were assigned based on HRESIMS, NMR analysis, 13C NMR calculation, ECD calculation, and modified Mosher's method. Four SLDs showed potent cytotoxicity against K562 and/or A549 cells, with IC50 values below 10 µM, but none inhibited protein tyrosine phosphatases at 40 µM, including PTP1B, SHP1, CD45, and TCPTP.