Bis(indole) alkaloids as sortase A inhibitors from the sponge Spongosorites sp.

A new bis(indole) alkaloid (9) of the hamacanthin class along with the previously reported compounds of the related structural classes, topsentin class (1-4) and hamacanthin class (5-8), was isolated from the marine sponge Spongosorites sp. and their inhibitory activities toward sortase A (SrtA) that play key roles in cell-wall protein anchoring and virulence in Staphylococcus aureus were evaluated. Our studies have identified a series of SrtA inhibitors, providing the basis for further development of potent inhibitors. The preliminary structure-activity relationship, to elucidate the essential structural requirements, has been described. The fibronectin-binding activity data highlight the potential of these compounds for the treatment of S. aureus infections via inhibition of SrtA activity.