title: Phosphocalyculin C as a pyrophosphate protoxin of calyculin C in the marine sponge Discodermia calyx.
abstract: Calyculin C, a minor derivative of the calyculins, has an additional methyl group on C32 of calyculin A. A recent biosynthetic study of calyculins revealed that an end product of calyculin biosynthesis is the pyrophosphate form, phosphocalyculin A. However, the pyrophosphate counterpart derived from calyculin C had not been reported. We isolated phosphocalyculin C as a minor pyrophosphate derivative, by a detailed investigation of an extract from the sponge Discodermia calyx. The treatment of phosphocalyculin C with the D. calyx cell-free extract significantly enhanced its cytotoxicity, providing molecular evidence for its role as the protoxin of calyculin C.
authors.affiliation: Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Egami
authors.affiliation: Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. Electronic address: wakimoto@mol.f.u-tokyo.ac.jp.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Wakimoto
authors.affiliation: Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. Electronic address: abei@mol.f.u-tokyo.ac.jp.
authors.forename: Ikuro
authors.initials: I
authors.lastname: Abe
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D003603:Cytotoxins / Q000302:isolation & purification / Q000494:pharmacology; D011756:Diphosphates / Q000302:isolation & purification* / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D008387:Marine Toxins; D051379:Mice; D010080:Oxazoles / Q000302:isolation & purification* / Q000633:toxicity*; D011161:Porifera
chemical_list: D003603:Cytotoxins; D011756:Diphosphates; D008387:Marine Toxins; D010080:Oxazoles; C549553:calyculin C
keywords: Calyculin C; Discodermia calyx; Phosphocalyculin C; Prodrug