Phenalenone-type phytoalexins from Musa acuminata synthesis of 4-phenyl-phenalenones
摘要:
Two new 4-phenyl-phenalenone-type phytoalexins (2, 3) have been isolated from rhizomes of Musa acuminata infected with the fungus Fusarium oxysporum. The structures of the new phytoalexins were elucidated on the basis of spectroscopic evidence, chemical correlation and synthesis from commercial phenalen-1-one. The chemical shift for all of the hydrogen and carbon atoms in the substances were unambiguously established by mono- and bidimensional, homo- and heteronuclear NMR experiments (H-1 NMR, C-13 NMR COSY, HMQC and HMBC). In preliminary ''in vitro'' assays, the new phytoalexins have shown inhibitory activity on the growth of the germinative tube of Fusarium oxysporum f. sp. cubense race 4.
Six new phenylphenalenone derivatives were isolated from unripe banana, Musa acuminata, fruit that had been wounded followed by inoculation with Colletotrichum musae. Absolute configurations of optically active phenylphenalenone derivatives were elucidated by their chemical conversion to L-arabitol pentaacetate. Antifungal activities against C. musae and a biosynthetic pathway of phenylphenalenones are also discussed. (C) 2001 Elsevier Science Ltd. All rights reserved.