First Investigation\nof Secondary Metabolites from <i>Aspergillus xerophilus</i> Reveals Compounds with Inhibitive\nEffects against Three Phytopathogenic Fungi of Agrarian Crops

Fungal secondary metabolites play a highly significant\nrole in\n crop protection, which is related to their antifungal activity against\nagriculturally important phytopathogens. In fact, plant diseases caused\nby fungi including species belonging to the genera of <i>Alternaria</i>, <i>Botrytis</i>, and <i>Fusarium</i> have become\nincreasingly serious affecting crop yield and quality. Hence, there\nis increasing awareness by the scientific community of the importance\nof exploiting fungal products for finding new compounds able to inhibit\nphytopathogens. In this study several drimane-type sesquiterpenes\nhave been detected for the first time as products of <i>Aspergillus\nxerophilus</i> by GC-MS analysis of the organic extracts obtained\nfrom the mycelia and culture filtrates of the fungus grown on two\ndifferent substrates. Seven pure drimane-type sesquiterpenes were\nalso isolated and identified by spectroscopic methods. The inhibitory\neffects of the pure compounds have been investigated against three\nphytopathogenic fungi of agrarian crops (i.e., <i>Botrytis cinerea</i>, <i>Alternaria alternata</i>, and <i>Fusarium oxysporum</i> f. sp. <i>pisi</i>). Among the drimane-type sesquiterpenes\nisolated in this study, 9,11-dihydroxy-6-oxodrim-7-ene is the most\nactive against the three phytopathogens. Our findings also reveal\nthe high sensitivity of <i>A. alternata</i> to the isolated\ncompounds. These results pave the way for future applications in agriculture\nof both <i>A. xerophilus</i> and its metabolites.