title: Cytotoxic diterpenoid pseudodimers from the Korean sponge Phorbas gukhulensis.
abstract: Four 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.
authors.affiliation: Natural Products Research Institute, College of Pharmacy, Seoul National University , San 56-1, Sillim, Gwanak, Seoul 151-742, Korea.
authors.forename: Ju-eun
authors.initials: JE
authors.lastname: Jeon
authors.forename: Lijuan
authors.initials: L
authors.lastname: Liao
authors.forename: Heegyu
authors.initials: H
authors.lastname: Kim
authors.forename: Chung J
authors.initials: CJ
authors.lastname: Sim
authors.forename: Dong-Chan
authors.initials: DC
authors.lastname: Oh
authors.forename: Ki-Bong
authors.initials: KB
authors.lastname: Oh
authors.forename: Jongheon
authors.initials: J
authors.lastname: Shin
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D004224:Diterpenes / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D020014:K562 Cells; D008386:Marine Biology; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D011161:Porifera / Q000737:chemistry*; D056910:Republic of Korea; D013654:Taurine / Q000737:chemistry; D013729:Terpenes / Q000737:chemistry / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D004224:Diterpenes; D013729:Terpenes; C549725:gukulenin A; D013654:Taurine