title: Rearranged vibsane-type diterpenes from Viburnum awabuki and photochemical reaction of vibsanin B.
abstract: Nine new diterpenes, neovibsanin D (1), 7-epi-neovibsanin D (2), 15-O-methylneovibsanin F (3), 14-epi-15-O-methylneovibsanin F (4), 15-O-methyl-18-oxoneovibsanin F (5), 2-O-methylneovibsanin H (6), 2-O-methylneovibsanin I (7), neovibsanin G (8), and 14-epi-neovibsanin G (9), were isolated from a methanol extract of the leaves of Viburnum awabuki. Their structures were elucidated to be uniquely rearranged vibsane-type diterpenes by spectroscopic analyses and comparison of NMR data with those of previously reported vibsane-type diterpenes. In addition, irradiation of vibsanin B (12) in methanol with a high-pressure Hg lump led to the direct formation of neovibsanins A (14) and B (15). These results gave a clue to understanding of the biogenetic interconversion of 11-membered vibsanins into neovibsanins.
authors.affiliation: Institute of Pharmacognosy, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, Japan. fukuyama@ph.bunri-u.ac.jp
authors.forename: Yoshiyasu
authors.initials: Y
authors.lastname: Fukuyama
authors.forename: Miwa
authors.initials: M
authors.lastname: Kubo
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Minami
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Yuasa
authors.forename: Asami
authors.initials: A
authors.lastname: Matsuo
authors.forename: Takako
authors.initials: T
authors.lastname: Fujii
authors.forename: Mai
authors.initials: M
authors.lastname: Morisaki
authors.forename: Kenichi
authors.initials: K
authors.lastname: Harada
mesh_terms: D004224:Diterpenes / Q000737:chemistry* / Q000302:isolation & purification; D010777:Photochemistry; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification; D018515:Plant Leaves; D027925:Viburnum
chemical_list: D004224:Diterpenes; D010936:Plant Extracts; C465905:vibsanol B