Amino acids with basic amino side chain accelerate ability of polyphenolic compounds

Polyphenols, such as (-)-epigallocatechin gallate (EGCG), have pro-oxidant properties that lead to activation of the cellular apoptotic pathway; however, the mechanism underlying the induction of this pro-oxidant activity is unclear. We found intensive chemiluminescence for EGCG and hydroquinone (HQ) in the presence of amino acids with basic amino side-chains, such as arginine or lysine. In addition, the chemiluminescence of EGCG and arginine or lysine was totally suppressed by the addition of superoxide dismutase; whereas the chemiluminescence of HQ and arginine or lysine was totally suppressed by the addition of catalase. Furthermore, we found that polyphenols are capable of inducing oxidative stress, including depletion of albumin thiol content, elevation of plasma oxidized low-density lipoprotein and acceleration of cell death in the presence of arginine. Taking the results together, we suggest that amino acids with basic amino side-chain accelerate the production of reactive oxygen species in the presence of polyphenols. (C) 2012 Elsevier Ltd. All rights reserved.