title: Identification of UV-Induced Diterpenes Including a New Diterpene Phytoalexin, Phytocassane F, from Rice Leaves by Complementary GC/MS and LC/MS Approaches.
abstract: Rice phytoalexins are regarded as one of the most important weapons against pathogenic microorganisms. We attempted to identify novel phytoalexins and their derivatives using GC/MS and LC/MS analyses. Diterpene derivatives, 9β-pimara-7,15-diene-3β,6β,19-triol, 1, stemar-13-en-2α-ol, 2, and 1α,2α-dihydroxy-ent-12,15-cassadiene-3,11-dione, 3, were isolated from UV-irradiated rice leaves by chromatographic methods. These structures were confirmed by 1D- and 2D-NMR and MS analyses. Interestingly, all three compounds were accumulated following an infection by the rice blast pathogen Magnaporthe oryzae. Compounds 1 and 2 exhibited weak antifungal activity and may be the biosynthetic intermediates of rice phytoalexins momilactones and oryzalexin S, respectively. Compound 3 exhibited relatively high inhibitory activity against the fungal mycelial growth of M. oryzae to the same extent as the known phytoalexin phytocassane A. We conclude that 3 is a member of the cassane-type phytoalexin family and propose the name phytocassane F.
authors: †United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan.
authors: Kiyotaka
authors: K
authors: Horie
authors: ‡College of Agriculture, Ibaraki University, 3-21-1 Chuo, Ami, Inashiki, Ibaraki 300-0393, Japan.
authors: Yasuno
authors: Y
authors: Inoue
authors: ‡College of Agriculture, Ibaraki University, 3-21-1 Chuo, Ami, Inashiki, Ibaraki 300-0393, Japan.
authors: Miki
authors: M
authors: Sakai
authors: ‡College of Agriculture, Ibaraki University, 3-21-1 Chuo, Ami, Inashiki, Ibaraki 300-0393, Japan.
authors: Qun
authors: Q
authors: Yao
authors: ‡College of Agriculture, Ibaraki University, 3-21-1 Chuo, Ami, Inashiki, Ibaraki 300-0393, Japan.
authors: Yosuke
authors: Y
authors: Tanimoto
authors: §Department of Biosciences, Teikyo University, 1-1 Toyosatodai, Utsunomiya, Tochigi 320-8551, Japan.
authors: Jinichiro
authors: J
authors: Koga
authors: †United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan.|‡College of Agriculture, Ibaraki University, 3-21-1 Chuo, Ami, Inashiki, Ibaraki 300-0393, Japan.
authors: Hiroaki
authors: H
authors: Toshima
authors: †United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 183-8509, Japan.|‡College of Agriculture, Ibaraki University, 3-21-1 Chuo, Ami, Inashiki, Ibaraki 300-0393, Japan.
authors: Morifumi
authors: M
authors: Hasegawa
mesh_terms: D008401:Gas Chromatography-Mass Spectrometry; D020082:Magnaporthe / Q000254:growth & development; D015394:Molecular Structure; D012275:Oryza / Q000737:chemistry / Q000276:immunology* / Q000382:microbiology / Q000528:radiation effects*; D010935:Plant Diseases / Q000276:immunology / Q000382:microbiology*; D010936:Plant Extracts / Q000737:chemistry* / Q000276:immunology; D018515:Plant Leaves / Q000737:chemistry / Q000276:immunology / Q000382:microbiology / Q000528:radiation effects; D012717:Sesquiterpenes / Q000737:chemistry* / Q000276:immunology; D014466:Ultraviolet Rays; D000094162:Phytoalexins
chemical_list: D010936:Plant Extracts; D012717:Sesquiterpenes; D000094162:Phytoalexins
keywords: Magnaporthe oryzae; mass spectrometry; phytoalexin; phytocassane; rice; ultraviolet irradiation