Two new compounds, (6S)-hydroxy-29-nor-3,4-seco-cycloart-4(30),24-dien-3-oi
c acid (1) and 8-[1-(3,4-dihydroxyphenyl)-3-methoxy-3-oxopropyl]epicatechin
(3), were isolated by bioassay-guided fractionation from the aerial parts
of Antirhea acutata (DC.) Urb. (Rubiaceae). Compound 1 showed moderate inhi
bitory activities in cyclooxygenase-1 and -2 assays (IC50 43.7 and 4.7 muM,
respectively), while compound 3 was active in 1,1-diphenyl-2-picrylhydrazy
l free-radical and cytochrome c reduction antioxidant assays (IC50 29.1 and
16.3 muM, respectively). Additionally, one further new compound was isolat
ed, (3S,24S)-25-trihydroxy-9,19-cycloartane-29-oic acid (2), but this was i
nactive in the bioassay systems used. Compound 1 is based on the unpreceden
ted 29-nor-3,4-seco-cycloartane skeleton. (C) 2001 Elsevier Science Ltd. Al
l rights reserved.