title: Eudistomidin G, a new beta-carboline alkaloid from the Okinawan marine tunicate Eudistoma glaucus and structure revision of eudistomidin B.
abstract: A new beta-carboline alkaloid, eudistomidin G (1), has been isolated from the Okinawan marine tunicate Eudistoma glaucus, and the structure was elucidated from spectroscopic data. Furthermore, the structure of eudistomidin B (2), which has been isolated from the same tunicate, was revised from 2a to 2b by detailed analyses of spectroscopic data. Asymmetric synthesis of the revised structure (2b) of eudistomidin B (2) and its (1S,10S)-diastereomer (2c) has been accomplished with the Noyori catalytic asymmetric hydrogen-transfer reaction. The absolute configuration of eudistomidin B (2) was confirmed to be 2b possessing (1R,10S)-configuration, from comparison of the (1)H NMR data, CD spectra, [alpha](D) values, and HPLC analysis of 2b, 2c, and natural eudistomidin B.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan.
authors.forename: Yohei
authors.initials: Y
authors.lastname: Takahashi
authors.forename: Haruaki
authors.initials: H
authors.lastname: Ishiyama
authors.forename: Takaaki
authors.initials: T
authors.lastname: Kubota
authors.forename: Jun'ichi
authors.initials: J
authors.lastname: Kobayashi
mesh_terms: D000818:Animals; D002243:Carbolines / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D002384:Catalysis; D002851:Chromatography, High Pressure Liquid; D009682:Magnetic Resonance Spectroscopy; D008386:Marine Biology; D008958:Models, Molecular; D015394:Molecular Structure; D013056:Spectrophotometry, Ultraviolet; D013237:Stereoisomerism; D014561:Urochordata / Q000737:chemistry*
chemical_list: D002243:Carbolines; C553908:eudistomidin G