PHENALENONE-TYPE PHYTOALEXINS FROM MUSA-ACUMINATA SYNTHESIS OF 4-PHENYL-PHENALENONES

Two new 4-phenyl-phenalenone-type phytoalexins (2, 3) have been isolat ed from rhizomes of Musa acuminata infected with the fungus Fusarium o xysporum. The structures of the new phytoalexins were elucidated on th e basis of spectroscopic evidence, chemical correlation and synthesis from commercial phenalen-1-one. The chemical shift for all of the hydr ogen 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'' as says, the new phytoalexins have shown inhibitory activity on the growt h of the germinative tube of Fusarium oxysporum f. sp. cubense race 4.