Sesquiterpenes and diterpenes from Ambrosia arborescens

Four sesquiterpenes and two diterpenes were isolated from the leaves of Ambrosia arborescens. The structures were elucidated by NMR spectroscopy and ESI mass spectrometry. Compounds were evaluated for antiproliferative activity. Six compounds, eudesm-11(13)-en-4β,9β-diol, 15 R,16-dihydroxy-3-oxo isopimar-9(11)-ene, 15 S,16-dihydroxy-3-oxo isopimar-9(11)-ene, 1α-hydroxy-7-oxo- iso-anhydrooplopanone, 10α-hydroxy-11,13-dihydro-5- epi-psilostachyin, and 4β-hydroxypseudoguaian-12,6-olide 4- O-β- d-glucopyranoside, together with 12 known sesquiterpenes, were isolated from the leaves of Ambrosia arborescens. Structures were elucidated by 1D and 2D NMR spectroscopy including 1D-TOCSY, DQF-COSY, 2D-ROESY, HSQC, and HMBC experiments, as well as by ESI mass spectrometry. The absolute configuration of the 15,16-diol moiety in 15 R,16-dihydroxy-3-oxoisopimar-9(11)-ene and 15 S,16-dihydroxy-3-oxoisopimar-9(11)-ene was determined using Snatzke’s method. All compounds were evaluated for antiproliferative activity.