posted on 2013-12-27, 00:00authored byYong Zheng, Shu-Wei Zhang, Hai-Jian Cong, Yu-Jie Huang, Li-Jiang Xuan
Fourteen new cassane diterpenoids,
caesalminaxins A–L (1–14),
and three known compounds were
isolated from the seeds of Caesalpinia minax. Among
the new diterpenoids, compounds 3 and 4 possess
a rare spiro C/D ring system. The C-16 epimeric mixture 1/2 has an unprecedented carbon skeleton, presumably
derived from 3 by cleavage of the C-13–C-14 bond.
Compound 5 is the first example of a cassane diterpenoid
with a spiro A/B ring system. The structures of the compounds were
elucidated on the basis of 1D and 2D NMR analysis, and the absolute
configurations of 3, 4, 9,
and 11 were determined by single-crystal X-ray crystallography.
Biosynthesis pathways for 1/2, 3, and 5 are postulated. Compounds 4, 8, and the known bonducellpin D exhibited moderate activity
against four tested human cancer cell lines, HepG-2, K562, HeLa, and
Du145.