Effects of reaction environments on radical-scavenging mechanisms of ascorbic acid.
J Clin Biochem Nutr
; 68(2): 116-122, 2021 Mar.
Article
in En
| MEDLINE
| ID: mdl-33879962
ABSTRACT
The effects of reaction environments on the radical-scavenging mechanisms of ascorbic acid (AscH2) were investigated using 2,2-diphenyl-1-picrylhydrazyl radical (DPPHâ¢) as a reactivity model of reactive oxygen species. Water-insoluble DPPH⢠was solubilized by ß-cyclodextrin (ß-CD) in water. The DPPHâ¢-scavenging rate of AscH2 in methanol (MeOH) was much slower than that in phosphate buffer (0.05 M, pH 7.0). An organic soluble 5,6-isopropylidene-l-ascorbic acid (iAscH2) scavenged DPPH⢠much slower in acetonitrile (MeCN) than in MeOH. In MeOH, Mg(ClO4)2 significantly decelerated the DPPHâ¢-scavenging reaction by AscH2 and iAscH2, while no effect of Mg(ClO4)2 was observed in MeCN. On the other hand, Mg(ClO4)2 significantly accelerated the reaction between AscH2 and ß-CD-solubilized DPPH⢠(DPPHâ¢/ß-CD) in phosphate buffer (0.05 M, pH 6.5), although the addition of 0.05 M Mg(ClO4)2 to the AscH2-DPPHâ¢/ß-CD system in phosphate buffer (0.05 M, pH 7.0) resulted in the change in pH of the phosphate buffer to be 6.5. Thus, the DPPHâ¢-scavenging reaction by iAscH2 in MeCN may proceed via a one-step hydrogen-atom transfer, while an electron-transfer pathway is involved in the reaction between AscH2 and DPPHâ¢/ß-CD in phosphate buffer solution. These results demonstrate that the DPPHâ¢-scavenging mechanism of AscH2 are affected by the reaction environments.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Language:
En
Journal:
J Clin Biochem Nutr
Year:
2021
Document type:
Article
Affiliation country:
Japan