Aureusimine B (phevalin) is a small molecular weight monoketopiperazine formed non-ribosomally by the fusion of phenylalanine and valine. Aureusimine B was isolated from S. aureus in 2010 as one of a pair of related metabolites, controversially identified as virulence factors in the pathology of Golden Staph. Aureusimine B is also an inhibitor of the protease, calpain.
Aureusimine B is soluble in ethanol, methanol, DMF or DMSO. Poor water solubility