Two new amplisins with antibacterial activities from Akanthomyces attenuatus.

Akanthomyces attenuatus, a lesser-studied species within the Cordycipitaceae family, has remained largely unexplored despite significant research attention on related Cordyceps species. To address this knowledge gap, we employed the OSMAC (One Strain Many Compounds) strategy to systematically investigate its secondary metabolite profile. Our approach yielded eight distinct compounds, including two novel amplisins, whose structures were elucidated through comprehensive high-resolution electrospray ionisation mass spectrometry (HR-ESI-MS) and multidimensional nuclear magnetic resonance (NMR) analyses. Notably, bioactivity evaluation demonstrated that both amplisins possess significant antibacterial properties, positioning them as promising lead compounds. These findings not only enhance our understanding of A. attenuatus as an underexplored reservoir of bioactive metabolites but also establish a framework for future antimicrobial discovery. This work highlights the untapped potential of understudied fungal species in the search for novel therapeutic agents.