Abstract:Protocatechuic acid（PCA）is a natural phenolic compound with wide distribution.It is also a main metabolite of complex polyphenols including anthocyanin and protocatechuic acid，which has the antioxidant and neuroprotective functions.Multispectral imaging was used to measure the interaction between PCA and ovalbumin（OVA）and its effect on the antioxidant properties of PCA against ABTS+ radical.The results showed as follows.The emission intensity of OVA was quenched by PCA，and the quenching constant（Ksv）decreased with the increasing temperature，indicating the interaction between PCA and OVA was carried out by a static quenching mechanism.One binding site existed between PCA and OVA，with binding constants of about 104.The bonding was a spontaneously generated heat absorption reaction with hydrophobicity as the dominant force.The microenvironment around the Tyr residue increased in polarity and decreased in hydrophobicity after the interaction，while the microenvironment in which the Trp residue was located did not change.The ABTS+ radical scavenging ability of PCA-OVA complex wassignificantly improved compared with that of PCA and OVA（P＜0.05）.Therefore，the interaction between PCA and OVA changes the conformation of OVA，and also has certain effect in scavenging ABTS+ radical.