TY - JOUR
T1 - A spectroelectrochemical and chemical study on oxidation of 7,8-dihydroxy-4-methylcoumarin (DHMC) and some related compounds in aprotic medium
AU - Petrucci, Rita
AU - Saso, Luciano
AU - Kumar, Vineet
AU - Prasad, Ashok K.
AU - Malhotra, Sanjay V.
AU - Parmar, Virinder S.
AU - Marrosu, Giancarlo
N1 - Funding Information:
We thank the Ministero dell’Università e dellaRicerca Scientifica e Tecnologica (MURST) for financial support.
PY - 2010/9
Y1 - 2010/9
N2 - Electrochemical and chemical oxidation of 7,8-hydroxy-4-methylcoumarin (DHMC 1) and 7,8-diacetoxy-4-methylcoumarin (DAMC 4) were studied to investigate the mechanisms occurring in their antioxidant activities in acetonitrile, under electron transfer and H-atom transfer conditions. Electrolysis and chemical reactions were followed on-line by monitoring the UV spectral changes with time.The anodic oxidation of DHMC, studied by cyclic voltammetry and controlled potential electrolysis, occurs via a reversible one-step two-electrons process, yielding the corresponding stable phenoxonium cation. Moreover, the chemical oxidation with an H-atom acceptor also follows a similar path, yielding the stable neutral quinonic product. Intermediates were never evidenced in both cases. Only in the presence of a strong base, an anodic oxidation product mono-electronic was evidenced, likely the DHMC radical anion.However, the anodic oxidation of the acetoxy derivative DAMC occurs at very high potential values, ruling out the possibility that the antioxidant activity observed in vivo might occur via an electron transfer mechanism; no reactions were evidenced with an H-atom acceptor.
AB - Electrochemical and chemical oxidation of 7,8-hydroxy-4-methylcoumarin (DHMC 1) and 7,8-diacetoxy-4-methylcoumarin (DAMC 4) were studied to investigate the mechanisms occurring in their antioxidant activities in acetonitrile, under electron transfer and H-atom transfer conditions. Electrolysis and chemical reactions were followed on-line by monitoring the UV spectral changes with time.The anodic oxidation of DHMC, studied by cyclic voltammetry and controlled potential electrolysis, occurs via a reversible one-step two-electrons process, yielding the corresponding stable phenoxonium cation. Moreover, the chemical oxidation with an H-atom acceptor also follows a similar path, yielding the stable neutral quinonic product. Intermediates were never evidenced in both cases. Only in the presence of a strong base, an anodic oxidation product mono-electronic was evidenced, likely the DHMC radical anion.However, the anodic oxidation of the acetoxy derivative DAMC occurs at very high potential values, ruling out the possibility that the antioxidant activity observed in vivo might occur via an electron transfer mechanism; no reactions were evidenced with an H-atom acceptor.
KW - Antioxidants
KW - Polyphenols oxidation
KW - Radical anions
KW - Semiquinones
KW - Spectroelectrochemistry
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U2 - 10.1016/j.biochi.2010.06.008
DO - 10.1016/j.biochi.2010.06.008
M3 - Article
C2 - 20600572
AN - SCOPUS:77955843272
SN - 0300-9084
VL - 92
SP - 1123
EP - 1129
JO - Biochimie
JF - Biochimie
IS - 9
ER -