Bioactivity-directed fractionation of the root bark of Melia volkensii
resulted in the isolation of two new natural products, meliavolkinin
(1) and melianin C (3), together with two known compounds, 1,3-diacety
lvilasinin (2) and melianin B (4). Jones oxidation of 4 gave compounds
3, 23,24-diketomelianin B (5), and 16,23,24-triketomelianin B (6). Th
e structures of the new compounds were elucidated by spectral and chem
ical data. Compounds 1-6 all showed marginal cytotoxicities against ce
rtain human tumor cell lines, while 5 showed selective cytotoxicities
for the human prostate (PC-3) and pancreatic (PACA-2), cell lines with
potencies comparable to those of adriamycin.