Antioxidant profile of dihydroxy- and trihydroxyphenolic acids-A structure–activity relationship study

Abstract

Eight structurally similar dihydroxy and trihydroxyphenolic acids (protocatechuic acid, 3,4-dihydroxyphenylacetic acid, hydrocaffeic acid, caffeic acid, gallic acid, 3,4,5-trihydroxyphenylacetic acid, 3-(3,4,5-trihydroxyphenyl)propanoic acid and 3-(3,4,5-trihydroxyphenyl)propenoic acid) were examined for their total antioxidant capacity (TAC). Furthermore, their ability to scavenge peroxyl radicals, generated by AAPH in liposomes, was determined. The antioxidant/pro-oxidant activity of the compounds was screened using the 2'-deoxyguanosine assay. All compounds behave as radical scavengers, with 3,4,5-trihydroxyphenylacetic acid being the most potent. Nevertheless, in the lipid peroxidation assay an inverse ranking order was observed, 3,4-dihydroxyphenylacetic acid being the most effective compound. All the dihydroxylated compounds showed a pro-oxidant behaviour leading to an increase of 50% in 8-OH-dG induction. From the structure-antioxidant activity relationship studies performed it may be concluded that the number of phenolic groups and the type of the alkyl spacer between the carboxylic acid and the aromatic ring strongly influence the antioxidant activity.

Reactivity of phenolic compounds towards free radicals under in vitro conditions

“…The trihydroxybenzoic acid derivatives, gallic acid and propyl gallate showed very good scavenging activity. For phenolic acids, it was demonstrated that compounds presenting a pyrogallol unit (three hydroxyl groups on the phenol ring) exhibited higher antioxidant properties than those presenting a catechol unit (two hydroxyl groups on the phenolic ring) (Siquet et al 2006). Ferulic acid is more effective than p-coumaric acid due to the presence of the OCH 3 group in position ortho to the hydroxyl group.…”

Antioxidant activities of the extracts from chestnut flower, leaf, skins and fruit

“…Polyphenols are bioactive compounds believed to be involved in the defence process against deleterious oxidative damage, at least in part, due to their antioxidant properties (Fresco, Borges, Diniz, & Marques, 2006). Phenolic acids have been widely investigated as potential models for the development of new primary antioxidants, which can prevent or delay in vitro and/or in vivo oxidation processes (Siquet, Paiva Martins, Lima, Reis, & Borges, 2006). These phenolic compounds are powerful antioxidants and act in a structure-dependent manner, since they can scavenge reactive oxygen species (ROS), and chelate transition metals which play vital roles in the initiation of deleterious free radical reactions (Fresco et al, 2006).…”

GC-MS profile of antimicrobial and antioxidant fractions fromCordia rothiiroots

“…Phenylpropanoids play important role as antioxidants (Kurkin 2013), which is related to the hydroxyl moiety of aromatic ring (Park et al 2003). SAR study shows that number of -OH groups and the nature of alkyl spacer between aromatic ring and carboxylic group play important role in antioxidant behaviour of a compound (Siquet et al 2006). Sesquiterpenoid hydroquinones and sesquiterpenoid quinones are also reported as antioxidant agents with hydroquinones being stronger as compared to quinones (Belisario et al 1992).…”