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Rearranged Vibsane-Type Diterpenes from Viburnum awabuki and Photochemical Reaction of Vibsanin B

2005; Pharmaceutical Society of Japan; Volume: 53; Issue: 1 Linguagem: Inglês

10.1248/cpb.53.72

1347-5223

Yoshiyasu Fukuyama, Miwa Kubo, Hiroyuki Minami, Hiroaki Yuasa, Asami Matsuo, Takako Fujii, Mai Morisaki, Kenichi Harada,

Plant biochemistry and biosynthesis

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.