Anti-glycative and anti-inflammatory effects of protocatechuic acid in brain of mice treated by d-galactose

Protocatechuic acid (PCA) at 0.5%, 1% or 2% was supplied to d-galactose (DG) treated mice for 8 week. PCA intake at 2% increased its deposit in brain. DG treatment increased brain level of reactive oxygen species, protein carbonyl, carboxymethyllysine, pentosidine, sorbitol, fructose and methylglyoxal (P < 0.05). PCA intake, at 1% and 2%, lowered brain level of these parameters (P < 0.05). DG treatments enhanced activity and protein expression of aldose reductase (AR) and sorbitol dehydrogenase, as well as declined glyoxalase I (GLI) activity and protein expression (P < 0.05). PCA intake at 1% and 2% reduced activity and protein expression of AR (P < 0.05), and at 2% restored GLI activity and expression (P < 0.05). DG injection also elevated cyclooxygenase (COX)-2 activity and expression, and increased the release of interleukin (IL)-1beta, IL-6, tumor necrosis factor-alpha and prostaglandin E2 in brain (P < 0.05). PCA intake decreased these cytokines (P < 0.05), and at 1% and 2% suppressed COX-2 activity and expression (P < 0.05). PCA intake at 1% and 2% also lowered DG-induced elevation in activity, mRNA expression and protein production of nuclear factor kappa B p65 (P < 0.05). These findings suggest that the supplement of protocatechuic acid might be helpful for the prevention or alleviation of aging.