Inhibition by carboxylic acids of an o‐diphenol oxidase from Prunus avium fruits

Abstract

Aromatic carboxylic acids strongly inhibited 4-methylcatechol oxidation by an o-diphenol oxidase extracted from sweet cherry fruits (Prunus uvium). Esterification of the acids decreased their inhibitory strength. Inhibitors containing the benzene nucleus showed a greater effectiveness than the corresponding aliphatic and heterocyclic compounds (except 2-naphthalenecarboxylic acid). Similar inhibitory effects were observed by replacing the benzene ring with a highly unsaturated open chain. The inhibitory properties of benzoic acid, cinnamic acid, p-coumaric acid and 3,4-dihydroxybenzoic acid were investigated. It is proposed that the catalytic and inhibitory sites are close together in the enzyme molecule.

Dual effects of aliphatic carboxylic acids on cresolase and catecholase reactions of mushroom tyrosinase

“…Results for the Ki values have been summarized in Table 1. It is proposed that the catalytic and inhibitory sites of the enzyme seem to be close together [10]. The uncompetitive type of inhibition for propanoic acid indicates that it should be bind at a site distinct from the active site and bind just with the enzyme-substrate (ES) complex and not with the free enzyme (E).…”

“…In the case of acid derivatives, the mechanism of inhibition involves the formation of copper-carboxylic acid complex at binuclear copper site of the enzyme [10,39]. P-coumaric acid and its corresponding dihydroxy derivative, caffeic acid bind to the free copper through their carboxylic terminal that is attached to a sp 2 carbon.…”

“…Caffeic and ferulic acids activate the oxidation of catechol; protocatechuic and syringic acids activate the hydroxylation of tyramine [9]. Aromatic carboxylic acid inhibition on o-diphenol oxidase from sweet cherry fruits was reduced by esterification or by replacing the benzene ring with an aliphatic or heterocyclic group, but not by replacing it with a highly unsaturated open chain [10]. Study of phenylalkyl acids and alcohols, polyphenols, nitrophenols, esters, aldehydes, and ketones on catecholase activity showed carboxylic acids are stronger inhibitors than corresponding alcohols and aldehydes [7].…”

Inhibitory effect of pineapple shell extract and its ultrafiltered fractions on polyphenol oxidase activity and browning in fresh-cut banana slices Efecto inhibidor de extracto de cáscara de piña y sus fracciones ultrafiltradas en la actividad polifenoloxidasa y pardeamiento de rodajas de plátano recién cortadas

“…Therefore, the hydroxyl groups on aromatic ring (ring B) of myricetin might play an important role in high banana PPO inhibitory activity. Some researchers also indicated that p-coumaric acid was effective in enzymatic browning inhibition in potato (Macrae & Duggleby, 1968) and apple (Pifferi, Baldassari, & Cultrera, 1974;Walker & Wilson, 1975). Moreover, inhibitory effects of p-coumaric acid on grape PPO (Gunata, Sapis, & Moutounet, 1987) and mushroom tyrosinase (MellayHamon & Criton, 2009) were also higher than t-cinnamic acid.…”

Effect of some phenolic carboxylic acids on cherimoya (Annona cherimolia) polyphenoloxidase activity

“…Some authors have evaluated the influence of the structure of the phenolic compounds on the capacity to modify PPO activity (Kuttner and Wagreich 1953;Soler-Martinez e f a1 1965;Pifferi et al 1974;Mayer and Harel 1979;Sato 1979). Kuttner and Wagreich (1953) investigating the effects of different benzoic acids and related compounds on mushroom PPO, reported their finding that benzoic acid was the best inhibitor and that the inhibitory strength decreased with esterification or ionisation of the benzoic carboxylic group.…”