Antioxidative Activity of Hop Bitter Acids and Their Analogues

Hop bitter acids, humulones (1) and lupulones (2), were shown to have potent DPPH radical scavenging activity (RSA) and lipid peroxidation inhibitory activity (LIA). Furthermore, 5-acetyl lupulones (3) and 4-methyl lupulones (4) had more potent LIA than native lupulones but no RSA. This result indicates that the β,β’-triketone moiety of the lupulones has LIA.