title: 6H-dibenzo[b,d]pyran-6-one derivatives from the cultured lichen mycobionts of Graphis spp. and their biosynthetic origin.
abstract: The spore-derived mycobionts of the lichen Graphis prunicola, G. cognata and G. scripta were cultivated on a malt-yeast extract medium supplemented with 10% sucrose and their metabolites were investigated. Graphislactones A-D were isolated from the cultures of G. prunicola, while alternariol and graphislactones A and C were isolated from those of G. cognata. From the cultured mycobionts of G. scripta, a new 6H-dibenzo[b,d]pyran-6-one derivative, graphislactone E with graphislactones A and C was obtained. On the other hand, cultivation of the mycobionts of G. prunicola on a malt-yeast extract medium supplemented with 2.5% sucrose and 0.25% sodium acetate produced two new metabolites, graphislactones E and F. Their structures were determined by spectroscopic methods. The biogenetic origin of the carbon skeleton in both compounds was verified by administering sodium [1-13C]-acetate and sodium [1,2-13C(2)]-acetate.
authors.affiliation: Kobe Pharmaceutical University, 4-19-1, Motoyamakita-machi, Higashinada-ku, Kobe 658-8558, Japan. tanahash@kobepharma-u.ac.jp
authors.forename: Takao
authors.initials: T
authors.lastname: Tanahashi
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Takenaka
authors.forename: Naotaka
authors.initials: N
authors.lastname: Nagakura
authors.forename: Nobuo
authors.initials: N
authors.lastname: Hamada
mesh_terms: D007783:Lactones / Q000737:chemistry* / Q000378:metabolism*; D008011:Lichens / Q000737:chemistry* / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010616:Phenanthrenes / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D007783:Lactones; D010616:Phenanthrenes; C073118:6H-dibenzo-(b,d)-pyran-6-one