title: Phorbasides A-E, cytotoxic chlorocyclopropane macrolide glycosides from the marine sponge Phorbas sp. CD determination of C-methyl sugar configurations.
abstract: Five new cytotoxic macrolide glycosides phorbasides A-E (3-7), each possessing a macrolide ring appended to a rare ene-yne-trans-2-chlorocyclopropane, were isolated from the same Western Australian sponge (Phorbas sp.) that provided phorboxazoles A and B. The structures of 3-7 were solved by analysis of spectroscopic data including NMR, MS, and CD. A synthesis of methyl 2-O-methyl-alpha-L-evalose from L-rhamnose was completed and used for configurational assignment of the sugar residue in 3. Acid-catalyzed methanolysis of 3 followed by two-step derivatization of the liberated O-methyl glycoside gave a vicinal 4-O-naphthoyl/tertiary 3-N-(2-aminonaphthyl)carbamate derivative that exhibited exciton coupled CD identical with that of the derivative prepared from synthetic 1,2- O-dimethyl-alpha-L-evalose.
authors.affiliation: Department of Chemistry and Biochemistry and Skaggs School of Pharmacy and Pharmaceutical Sciences, La Jolla, CA 92093-0358, USA.
authors.forename: John B
authors.initials: JB
authors.lastname: MacMillan
authors.forename: Guang
authors.initials: G
authors.lastname: Xiong-Zhou
authors.forename: Colin K
authors.initials: CK
authors.lastname: Skepper
authors.forename: Tadeusz F
authors.initials: TF
authors.lastname: Molinski
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002942:Circular Dichroism / Q000379:methods; D003521:Cyclopropanes / Q000737:chemistry*; D004354:Drug Screening Assays, Antitumor; D006027:Glycosides / Q000737:chemistry*; D006801:Humans; D018942:Macrolides / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D008968:Molecular Conformation; D011161:Porifera / Q000737:chemistry*
chemical_list: D003521:Cyclopropanes; D006027:Glycosides; D018942:Macrolides; C410329:callipeltoside A; C520582:phorbaside A; C520583:phorbaside B; C530606:phorbaside C; C530607:phorbaside D; C530608:phorbaside E