Abstract

A new pepstatin with a phenylacetyl group, pepstatin Pa (1), and its methyl ester (2) were isolated from Streptomyces varsoviensis DSM 40346. Their structures were determined by high-resolution mass spectrometry and nuclear magnetic resonance techniques. The absolute configuration was determined using the Marfey´s method. Both pentapeptide products are inhibitors of pepsin and cathepsin D. Interestingly, the bacterial genome contains no biosynthetic gene cluster for the new pepstatin, suggesting an extrachromosomal origin of the biosynthetic genes. 

Figure 1. Structure of pepstatins and ahpatinins. Pepstain Pa (1) and its methyl ester (2) are new pepstatins with an aromatic acyl group from this work.

Acknowledgement

This work was financially supported by the Collaborative Research Fund C6026-19G from the Research Grants Council of the HKSAR Government.