title: Melophlins P, Q, R, and S: four new tetramic acid derivatives, from two Palauan marine sponges of the genus Melophlus.
abstract: Four new tetramic acid derivatives, named melophlins P, Q, R, and S (1-4), were isolated from two marine sponges of the genus Melophlus collected at Palau, together with seven known melophlins A, D, E, G, H, I, and O. The structures of the new compounds were elucidated on the basis of their spectral data. The absolute stereochemistries at the tetramic acid moieties of the new compounds were determined as 1 : 1 mixtures (racemic) by ESI-LC/MS analysis of derivatives obtained by oxidation and hydrolysis of the respective parent compounds. Melophlins P-S (1-4) showed cytotoxicity against the murine leukemia cell line L1210 with IC(50) values of 20.0, 10.5, 0.85, and 5.13 microM, respectively.
authors.affiliation: Department of Ocean Sciences, Tokyo University of Marine Science and Technology, Konan, Tokyo 108-8477, Japan.
authors.forename: Jinzhong
authors.initials: J
authors.lastname: Xu
authors.forename: Masateru
authors.initials: M
authors.lastname: Hasegawa
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Harada
authors.forename: Hisayoshi
authors.initials: H
authors.lastname: Kobayashi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nagai
authors.forename: Michio
authors.initials: M
authors.lastname: Namikoshi
mesh_terms: D000818:Animals; D004354:Drug Screening Assays, Antitumor; D006868:Hydrolysis; D007938:Leukemia / Q000473:pathology*; D008386:Marine Biology; D008826:Microbial Sensitivity Tests; D015394:Molecular Structure; D019029:Palau; D011161:Porifera / Q000737:chemistry*; D011760:Pyrrolidinones / Q000494:pharmacology*; D014407:Tumor Cells, Cultured / Q000187:drug effects
chemical_list: D011760:Pyrrolidinones; C009435:tetramic acid