Ferulic acid radical scavenging

The antioxidant property of ferulic acid and related compounds from rice bran was reported by Kikuzaki et al, (2002). Their results indicated that these compounds elicit their antioxidant function through radical scavenging activity and their affinity with lipid substrates. Another recent study reported by Butterfield et al, (2002) demonstrated that ferulic acid offers antioxidant protection against hydroxyl and peroxyl radical oxidation in synaptosomal and neuronal cell culture systems in vitro. The effect of ferulic acid on blood pressure (BP) was investigated in spontaneously hypertensive rats (SHR). After oral administration of ferulic acid the systolic blood pressure (SBP) decreased in a dose-dependent manner. There was a significant correlation between plasma ferulic acid and changes in the SBP of the tail artery, suggesting... 

Ferulic acid (XIX) is found ester-linked to polysaccharides in the primary cell walls of Graminaceae, which include cereals and grasses [95]. Ferulic acid is an effective scavenger of free radicals [96] and can also protect low density lipoprotein against met-myoglobin-induced oxidative damage... 

Coffee, like tea and cocoa, contains polyhydroxyphenols with antioxidative effects in vitro and in vivo which are related to reducing and radical scavenging properties. Catechol (H.23) is one of the most effective, followed by the cinnamic derivatives, ferulic (H.87), sinapic (H.90) and caffeic (H.86) acids. The benzoic acids are less effective (Bungert and Eichner, 2000). 

Although it is generally accepted that ferulic acid dimers (XX-XXHI) are generally less effective than ferulic acid (XIX) as antioxidants, when this property is evaluated through their free radical scavenging properties [100], it should be mentioned that the n-buthyl ester of the dihydrobenzofuran dimer (XXIV) obtained by oxidative dimerization of ferulic acid showed more potent cytotoxicity against several tumor cell lines that ferulic acid itself [101],... 

Hydroxycinnamates as well as their conjugates may act as powerful antioxidants. In edible plants they have received much attention as protecting agents against oxidative deterioration of food. Antioxidant mechanism studies on ferulic acid and its coupling products with linoleate on the molecular level have been conducted recently. A radical scavenging reaction occurred at the 3 -position of the ferulate radical with four types of peroxyl radicals of ethyl linoleate. The produced peroxides subsequently underwent intramolecular rearrangement to afford stable tricyclic peroxides (Masuda et al. 2006). 

Fig. 3.8, TSs and TS s symbolically represent sets of three and four transition states respectively. The structures shown near TSs and TS s are those of the last transition states in each set. RC and PC stand for reactant complex and product complex respectively. M stands for the molecule lying near ferulic acid in Fig. 3.8. In the RC of Fig. 3.8, an OH radical is already added at the CIO site. A sequence of addition and hydrogen abstraction reactions (Fig. 3.8) lead to the formation of fera-lic acid and vanillin. Thus curcumin and its degradation products in total scavenge eight OH radicals.

Agnihotri N, Mishra PC (2011) Scavenging mechanism of curcumin toward the hydroxyl radical a theoretical study of reactions producing ferulic acid and vanillin. J Phys Chem A 115 14221-14232... 

The system was applied to monitor the radical-scavenging reaction for a number of AOXs at different pHs and reaction times. The TEAC values were found to be dependent on these parameters for almost all studied compounds (Table 31.1). Only Tr and Asc reacted rapidly (99% < 10 s) with ABTS +, and their antioxidative capacity was not affected by the end-point time. Structurally similar compounds had the same pH-dependent behavior even if they differed significantly in TEAC values, for example, the TEAC values for (-l-)-catechin and (-)-epicatechin, caffeic acid, and ferulic acid. The same was observed for quercetin and its glycoside rutin the higher activity of quercetin had been reported [74]. Independent of time and pH effects, quercetin, gallic acid, (+)-catechin, and (-)-epicatechin have shown higher activities. 

Free radical scavenging activities of different phenolic acids, caffeic acid (CA), ferulic acid (FA) and p-coumaric acid (p CA) and natural antioxidants alpha tocopherol (alpha-toco) and BHA a synthetic antioxidant were compared with sinapic acid (SA). As indicated in Figure 15.10 under the tested conditions, the radical scavenging activity of the phenolic acids in the DPPH system decreased in the following order ... 

FIGURE 15.10 Radical scavenging activity of sinapic acid as compared with ferulic acid (FEA), butylated hydroxylanisole (BHA), caffeic acid (CA) and p-coumaric acid (p CA). 

To scavenge 25 x 10 DPPH radicals, the required concentrations (mM) for BHA, alpha-toc, sinapic acid, caffeic acid and ferulic acid were 2.5, 15, 30.8, 71.6 and 70.5 mM, respectively, p CA showed no significant activity towards the DPPH radical. 

There is a growing interest in naturally occurring phenolic compounds that display biological antioxidant properties such as -hydroxycinnamic acid, ferulic zcid, caffeic acid/ and curcumin which are ubiquitous in plant food. It has been demonstrated that the interaction of the oxidizing OH adduct of DNA, poly-A and poly-G with hydrox-ycinnamic acid derivatives proceed via electron transfer. Cinnamic acid derivatives have been shown to be able to scavenge superoxide, peroxyl, and hydroxyl radicals. 

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