Phevalin is a member of the class of pyrazinones that is pyrazin-2(1H)-one substituted by an isopropyl and benzyl groups at position 3 and 6, respectively. It is a natural product found in Staphylococcus aureus that inhibits calpain in a casein hydrolysis assay (IC50 = 1.3 muM), contributes to S. aureus infection in mice, and alters human keratinocyte gene expression. It has a role as a bacterial metabolite and a calpain inhibitor. It is a member of benzenes and a pyrazinone.