MUSANOLONES - 4 9-PHENYLPHENALENONES FROM RHIZOMES OF MUSA-ACUMINATA

Four new phenalenone-type phytoalexins, named musanolones C-F, have be en isolated from infected rhizomes of banana plants (Musa acuminata; A AA cultivar:Grand Nain). These phytoalexins were biosynthesized de nov o by the plants upon infection by Fusarium oxysporum f. sp. cubense ra ce 4, Panama's disease causal agent. The structures of the new phytoal exins were elucidated using spectroscopic data and chemical correlatio ns. Hydroxyanigorufone has been previously described as a constitutive natural product, from Anigozanthos rufus, but it was never described as a phytoalexin. The chemical shift for all of the hydrogen and carbo n atoms in the musanolones C-F were unambiguously established by mono- and bi-dimensional, homo- and hetero-nuclear NMR experiments ((1)HNMR , (13)CNMR, COSY, HMQC and HMBC). Preliminary in vitro assays of all t he musanolones tested until now show a strong inhibitory activity on t he growth of the germination tube of F. oxysporum f. sp. cubense race 4.