Molecular design of antibrowning agents

Tyrosinase inhibitory and antioxidant activity of gallic acid and its serie s of alkyl chain esters were investigated. All inhibited the oxidation of L -3,4-dihydroxyphenylalanine (L-DOPA) catalyzed by mushroom tyrosinase. Howe ver, gallic acid and its short alkyl chain esters were oxidized as substrat es yielding the colored oxidation products. In contrast, the long alkyl cha in esters inhibited the enzyme activity without being oxidized. This indica tes that the carbon chain length is associated with their tyrosinase inhibi tory activity, presumably by interacting with the hydrophobic protein pocke t in the enzyme. On the other hand, the esters, regardless their carbon cha in length, showed potent scavenging activity on the autoxidation of linolei c acid and 1,1-diphenyl-2-p-picryhydrazyl (DPPH) radical, suggesting that t he alkyl chain length is not related to the activity. The effects of side-c hain length of gallates in relation to their antibrowning activity-are stud ied.