np400389c_si_001.pdf (1.11 MB)
Cytotoxic Diterpenoid Pseudodimers from the Korean Sponge Phorbas gukhulensis
journal contribution
posted on 2016-02-18, 19:27 authored by Ju-eun Jeon, Lijuan Liao, Heegyu Kim, Chung
J. Sim, Dong-Chan Oh, Ki-Bong Oh, Jongheon ShinFour new cytotoxic diterpenoid pseudodimers
(2–5), along with a previously reported
one, gukulenin A (1), were isolated from the marine sponge Phorbas gukhulensis collected off the coast of Gagu-do,
Korea. These novel compounds,
designated gukulenins C–F (2–5), were determined by extensive spectroscopic analyses to be pseudodimers
of the gagunins, like gukulenin A. The termini of the tropolone-containing
side chains in gukulenins C–E (2–4) were found to have diverse modifications involving acetamides
or taurine, whereas gukulenin F (5) was formed from 1 by the ring-opening of a cyclic hemiketal. The relative
and absolute configurations were assigned by Murata’s and modified
Snatzke’s methods using a HETLOC experiment and a CD measurement
of a dimolybdenum complex, respectively. All of these compounds exhibited
significant cytotoxicity against the K562 and A549 cell lines.