IRENOLONE AND EMENOLONE - 2 NEW TYPES OF PHYTOALEXIN FROM MUSA-PARADISIACA

Phenalenone-type phytoalexins were obtained for the first time from ba nanas and identified by COSY H-1-H-1, HMQC and HMBC techniques, and X- ray analysis, among other methods. The aminoglycoside kanamycin was st udied as a phytoalexin inducer in banana leaves and fruit and compared with the effects produced by the fungus Mycosphaerella fidjiensis. Th e phenyl side chain in banana phytoalexins is not in the same position as in other plant phenalenones and so an alternative biogenetic pathw ay has been proposed and is currently being verified. The specific res ponse evoked by kanamycin opens the way to the study of the host-plant relationship from a new angle since more phytoalexin inducers can be designed on the basis of the chemical constituents of the microorganis ms involved or on synthetic kanamycin analogues and used to improve th e plants' defense mechanisms.