Paranazzamides A and B, new cyclic dipeptides containing a C7-prenylated tryptophan, produced by pathogenic reptile fungi Paranannizziopsis sp. UH-21

Abstract

Two new cyclic dipeptides, paranazzamides A (1) and B (2) containing a C7-prenylated tryptophan, were isolated from a culture broth of snake fungal disease-isolate Paranannizziopsis sp. UH-21. This is the first report on the new secondary metabolites from Paranannizziopsis sp. The planar structures of 1 and 2 were elucidated using various spectroscopic techniques including MS and 1D/2D NMR. The absolute configuration of 1 was assigned by comparison with the synthesized compound. Compounds 1 and 2 exhibited no antifungal activity, no antibacterial activity, and no cytotoxic activity even at a concentration of 128 µg ml−1, whereas 1 and 2 exhibited amphotericin B potentiating activity against Candida auris in combination treatment.