Rearranged vibsane-type diterpenes from Viburnum awabuki and photochemical reaction of vibsanin B.
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.
Fukuyama
Yoshiyasu
Y
Institute of Pharmacognosy, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, Japan. fukuyama@ph.bunri-u.ac.jp
Kubo
Miwa
M
Minami
Hiroyuki
H
Yuasa
Hiroaki
H
Matsuo
Asami
A
Fujii
Takako
T
Morisaki
Mai
M
Harada
Kenichi
K
D004224:Diterpenes / Q000737:chemistry* / Q000302:isolation & purification; D010777:Photochemistry; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification; D018515:Plant Leaves; D027925:Viburnum
D004224:Diterpenes; D010936:Plant Extracts; C465905:vibsanol B