Pectin hydroxamic acids exhibit antioxidant activities in vitro.
Commercial pectins with different degrees of esterification (DE) were reacted with equal volumes of 2 M alkaline hydroxylamine (pH 12.0) at room temperature for 4 h to prepare pectin hydroxamic acids (PHAs; DE94T4, DE65T4, and DE25T4) according to a previously reported method (Hou et al., J. Agric. Food Chem. 2003, 51, 6362-6366) and were used to test the antioxidant and antiradical activities in comparison with those of DE94, DE65, and DE25 pectins. The half-inhibition concentrations, IC(50), of scavenging activity against DPPH were 1.51, 5.43, and 5.63 mg/mL for DE94T4, DE65T4, and DE25T4, respectively, and were much lower than those of corresponding DE pectins under the same concentrations. The scavenging activities of PHAs for DPPH radicals were positively correlated with original DE values of pectin. The optimal pH of DE94T4 for scavenging DPPH radicals was 7.9 or 8.0. Using electron spin resonance (ESR) for scavenging hydroxyl radicals, under the same concentrations of 125 microg/mL, DE94T4, DE65T4, and DE25T4, respectively, exhibited 73.53, 69.01, and 55.17% antiradical activities. PHAs also exhibited protection against hydroxyl radical-mediated DNA damage and anti-human low-density lipoprotein peroxidation tests.
Yang
Sien-Sing
SS
Liver Unit, Cathay General Hospital, Taipei 106, Taiwan.
Cheng
Kur-Ta
KT
Lin
Yin-Shiou
YS
Liu
Yen-Wenn
YW
Hou
Wen-Chi
WC
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001713:Biphenyl Compounds; D002417:Cattle; D003300:Copper / Q000494:pharmacology; D004249:DNA Damage / Q000187:drug effects; D004578:Electron Spin Resonance Spectroscopy; D016166:Free Radical Scavengers; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology*; D017665:Hydroxyl Radical / Q000494:pharmacology; D015227:Lipid Peroxidation / Q000187:drug effects; D008077:Lipoproteins, LDL / Q000737:chemistry; D010368:Pectins / Q000737:chemistry*; D010851:Picrates / Q000737:chemistry
D000975:Antioxidants; D001713:Biphenyl Compounds; D016166:Free Radical Scavengers; D006877:Hydroxamic Acids; D008077:Lipoproteins, LDL; D010851:Picrates; D017665:Hydroxyl Radical; D003300:Copper; D010368:Pectins; C004931:1,1-diphenyl-2-picrylhydrazyl