Inhibition effect of pyridoxamine on lipid hydroperoxide-derived modifications to human serum albumin

Abstract

Pyridoxamine (PM) is a promising drug candidate for treating various chronic conditions/diseases in which oxidative stress and carbonyl compounds are important factors affecting pathogenicity. These abilities of PM are mainly attributed to its inhibition of advanced glycation and lipoxidation end product formation, by scavenging reactive carbonyl species. PM might therefore prevent protein damage from lipid hydroperoxide-derived aldehydes such as 4-oxo-2(E)-nonenal (ONE) and 4-hydroxy-2(E)-nonenal (HNE) by trapping them. It was previously reported that PM reacts with ONE to produce pyrrolo-1,3-oxazine (PO8) through the formation of pyrido-1,3-oxazine (PO1/PO2). In this study, we found that ONE and HNE yield an identical product containing a pyrrole ring (PO7, PH2) upon reaction with PM. The structure of PO7/PH2 was shown by LC-MS and NMR analyses to be 1-(2-hydroxy-6-hydroxymethyl-3-methylpyridin-4-ylmethyl)-2-pentylpyrrole. PO1, PO7/PH2, and PO8 were the main stable PM-ONE/HNE adducts. In the incubation of human serum albumin (HSA) with ONE or HNE, Lys residues provided the most favorable modification sites for both aldehydes, and the number of HNE-modified sites was higher than that of ONE-modified sites. When HSA was allowed to react with a linoleic acid hydroperoxide in the presence of ascorbic acid, ONE modified more residues (10 Lys, 3 His, 2 Arg) than did HNE (8 His, 2 Lys), indicating the relative reactivity of aldehydes towards amino acid residues. Upon treatment with increasing concentrations of PM, the concentrations of ONE-modified HSA peptides, but not of HNE-modified peptides, were reduced significantly and dose-dependently. Concomitantly, the formation of PM-ONE adducts increased in a dose-dependent manner. The inhibition effect of PM was also confirmed in the cell system subjected to oxidative stress. Our results demonstrate that PM can inhibit lipid hydroperoxide-derived damage to proteins by trapping ONE preferentially, and the resulting PM-ONE adducts can be used as a dosimeter for ONE production to determine the levels of lipid peroxidation.

The relevance of pathophysiological alterations in redox signaling of 4-hydroxynonenal for pharmacological therapies of major stress-associated diseases

“…PM acts also by directly trapping MDA modified serum albumin, thus under physiological conditions reducing generation of lipofuscin-like fluorescence [112]. In addition, modification of lysine residues on serum albumin by 4-oxo-nonenal can be decreased after treatment with PM [113], but it is not effective in case of albumin modification by 4-HNE, which is mostly binding to the histidine residues of the albumin.…”

Oxidative Stress and 4-hydroxy-2-nonenal (4-HNE): Implications in the Pathogenesis and Treatment of Aging-related Diseases

“…The combination of the two conjugated functional groups of 4-HNE, the carbonyl group (-C =0), and a double bond (C2/C3, -C=C-) facilitates the reaction of 4-HNE with biological molecules (including lipids, nucleic acids, and proteins) [ 39 ]. A mass spectrometry-based proteomic analysis of oxidative stress found that the electrophilic double bond and nucleophilic amino acid residues on proteins enable 4-HNE to form Michael adducts with lysine (Lys) [ 40 ], histidine (His) [ 41 ], and cysteine (Cys) [ 42 ] residues to increase the molecular masses of these amino acids by 156 Da (the molecular mass of HNE), or form Schiff-base adducts with its aldehyde group and Lys to an increase in the mass by 138 Da (Schiff-base formation with a net loss of water) [ 43 , 44 ]. Moreover, the research of proteomic analysis of in vitro histone carbonylation sites showed that Schiff-base modification is labile and reversible, while that of Michael adducts are stable and non-reversible [ 45 ].…”

Patients Stratification Strategies to Optimize the Effectiveness of Scavenging Biogenic Aldehydes: Towards a Neuroprotective Approach for Parkinson's Disease

“…Interestingly, the molecule has multiple beneficial effects that are carried out by two functional groups, the hydroxyl and the aminomethyl group [ 135 ]. Among the effects is the inhibition of AGEs and ALEs formation by scavenging reactive carbonyl species [ 134 , 136 , 137 ], the sequestration of catalytic metal ions [ 138 ], the blockage of oxidative degradation of Amadori intermediates derived from glycated proteins [ 139 ], ROS and free radicals scavenging [ 140 ].…”