Azaphilones with protein tyrosine phosphatase inhibitory activity isolated from the fungus Aspergillus deflectus.

Six undescribed azaphilones, deflectins C1-C3, deflectins D1-D2, and deflectin E, along with five known azaphilones were obtained from a solid culture of the wild fungus Aspergillus deflectus NCC0415. Their structures were determined by HRESIMS, NMR and ECD analyses, together with the GIAO 13C NMR calculation method. All compounds displayed strong or moderate inhibitory activity against protein tyrosine phosphatases SHP2 and PTP1B. Structure-activity relationship analysis of these azaphilones suggested that the length of the ketone aliphatic side chain would affect their SHP2 and PTP1B inhibitory activity. In addition, the presence of a Δ8(12) double bond on γ-lactone ring and the presence of CH3-2' in fatty chains may increase their inhibitory activity.