"Protocatechuic acid (PCA) at 2 or 4% was supplied to diabetic mice for 12 wks. PCA
3 treatments increased its deposit in organs, and significantly reduced plasma HbA1c level,
4 urinary glycative albumin level, and renal production of carboxymethyllysine (CML),
5 pentosidine, sorbitol and fructose (P<0.05). However, PCA treatments only at 4%
6 significantly decreased brain content of CML, pentosidine, fructose and sorbitol (P<0.05).
7 PCA treatments at 2 and 4% significantly lowered renal activity and mRNA expression of
8 aldose reductase and sorbitol dehydrogenase (P<0.05); and only at 4% significantly enhanced
9 renal glyoxalase I mRNA expression (P<0.05). PCA treatments also dose-dependently
10 decreased renal level of type IV collagen, fibronectin and transforming growth factor-beta1
11 (P<0.05), as well as dose-dependently diminished renal protein kinase C (PKC) activity
12 (P<0.05); however, only at 4% suppressed renal mRNA expression of PKC-alpha and
13 PKC-beta (P<0.05). PCA treatments at 4% significantly restored renal mRNA expression of
14 peroxisome proliferator-activated receptor (PPAR)-alpha and PPAR-gamma, as well as
15 suppressed expression of advanced glycation endproduct receptor (P<0.05). These findings
16 suggest that the supplement of protocatechuic acid might be helpful for the prevention or
17 alleviation of glycation associated diabetic complications."