Development of a Spectrophotometric Assay System for Evaluating Reducibility of Water-Soluble Substances

The effect of gallic acid (GA) on the redox state of hemoglobin (Hb) and the structural mechanism upon the Hb− GA interaction were investigated. Results indicated that GA exhibited antioxidant and pro-oxidant effects on Hb, which depended on its concentration and the redox state of Hb. The antioxidant capacity of GA contributed to the inhibition of free iron release from Hb. GA could bind to the central cavity of Hb and interacted with the heme moiety through direct hydrophobic contacts as indicated by docking analysis, but GA did not disrupt the heme structure. Conversely, GA increased the compactness of the Hb molecule and might narrow the crevice around the heme pocket, which contributed to the inhibition of Hb autoxidation and the free iron release. Results provided significant insights into the interaction of GA with redox-active Hb, which is beneficial to the application of GA in relative meat and blood products.

Section: Resultssupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Interactions of Gallic Acid with Porcine Hemoglobin: Effect on the Redox State and Structure of Hemoglobin

Dong

Zhou

et al. 2020

“…The data are shown in percentage of MbO 2 in total myoglobins, which was calculated on the basis of absorbance at 500 and 582 nm of each 60 μmol/L pure MbO 2 and MetMb. 18 Although most polyphenols showed weak reducing activity as reductants, sinapic acid (17) (600 μmol/L) exhibited apparent potency, followed by catechin (2), nordihydroguaiaretic acid (12), taxifolin (19), morin (10), and ferulic acid (5). Unfortunately, the activity of some flavonoid polyphenols could not be measured at this concentration because of insolubility.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Although ascorbic acid is not a polyphenol, it is a potent bioreductant and can reduce MetMb to afford MbO 2 in air. 10,11 Ashida et al 12 have reported inhibition of MbO 2 oxidation by relatively low gallic acid concetrations. Mordent et al 13 have reported MetMb reduction by high ubiquinol-1 concentrations.…”

Section: ■ Introductionmentioning

confidence: 97%

“…In a previously reported study, we used polyphenols and related phenolic compounds to prevent MbO 2 oxidation in vitro ; however, some potent antioxidant polyphenols actually promoted oxidation. Although ascorbic acid is not a polyphenol, it is a potent bioreductant and can reduce MetMb to afford MbO 2 in air. , Ashida et al . have reported inhibition of MbO 2 oxidation by relatively low gallic acid concetrations.…”

Section: Introductionmentioning

confidence: 99%

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Metmyoglobin Reduction by Polyphenols and Mechanism of the Conversion of Metmyoglobin to Oxymyoglobin by Quercetin

Inai

Miura

Honda

et al. 2014

The effect of antioxidant polyphenols and related phenolic compounds from plants on the reduction of metmyoglobin (MetMb) was investigated. Potent activity in the reduction of MetMb to oxymyoglobin (MbO2), a bright red protein in meat, was observed for three flavonols, kaempferol, myricetin, and quercetin, at 300 μmol/L against 60 μmol/L MetMb. Sinapic acid, catechin, nordihydroguaiaretic acid, taxifolin, morin, and ferulic acid promoted reduction at 600 μmol/L. A mechanism for the reduction by one of the active flavonols, quercetin, was proposed on the basis of analytical results for redox reaction products derived from quercetin. This suggested the importance of a high propensity toward reduction of the flavonol structure and rapid convertibility of the quinone form to the phenol form for the MbO2 reduction and the maintenance of the level of MbO2 produced.

Effect of Polyphenols on Oxymyoglobin Oxidation: Prooxidant Activity of Polyphenols in Vitro and Inhibition by Amino Acids

Masuda

Inai

Miura

et al. 2013

Effects of various plant phenolics, including polyphenols, on the oxidation of oxymyoglobin were investigated. Most phenolics promoted the oxidation of oxymyoglobin at both pH 5.4 and 7.4. Potent oxidation-promoting activity was observed by several efficient antioxidant polyphenols with a catechol moiety. Therefore, effects of the catechol structure were investigated using dihydrocaffeic acid analogues. The results clarified that ortho- or para-substituted diphenol structures were important for promoting the oxidation of oxymyoglobin. Inhibition of such prooxidant activity for oxymyoglobin by dihydrocaffeic acid was also investigated. Although the required concentration was relatively higher than that of dihydrocaffeic acid, several amino acids inhibited the oxidation. Among these, cysteine was the most potent. Although cysteine alone completely inhibited oxidation at a concentration above 1 mmol/L, 0.1 mmol/L cysteine showed oxidation-promoting activity. In the presence of 0.1 mmol/L dihydrocaffeic acid, in the range of 0.01 mmol/L to 1 mmol/L cysteine, 0.1 mmol/L cysteine showed the most efficient inhibition. These results suggest the possibility of the formation of some equimolar complexes of dihydrocaffeic acid and cysteine such as 5'-cysteinyl dihydrocaffeic acid, which may be produced during the prooxidation of dihydrocaffeic acid, contributing to the inhibition of the oxidation of oxymyoglobin.