Evaluation of PPARα activation by known blueberry constituents

Abstract

BACKGROUND: Anthocyanins are known to have hypolipidemic properties. It was deemed necessary to determine whether major blueberry anthocyanins and catechins are ligands for the transcription factor peroxisome proliferator activated receptor alpha isoform (PPAR alpha), and compare activation with known PPAR alpha agonistic constituents, pterostilbene and resveratrol. It was also considered important to investigate the effect of pterostilbene on PPAR alpha gene expression, and relate results with hepatic mRNA PPAR alpha expression up-regulation observed previously in hamsters fed a diet supplemented with blueberry peels extract (BBX).

RESULTS: The anthocyanins and catechins did not activate PPAR alpha. Only pterostilbene exhibited a dose-dependent activation of PPAR alpha in H4IIEC3 cells. The resveratrol responses were lower than those of pterostilbene. Pterostilbene significantly and dose-dependently (at 10, 20 and 50 mu mol L-1) increased PPAR alpha gene expression and the effect at 10 mu mol L-1 was greater than 100 and 200 mu mol L-1 of fenofibrate. Analysis of BBX showed levels of pterostilbene and resveratrol at 418 and 2381 ng g(-1), respectively.

CONCLUSION: Anthocyanins and catechins do not appear to contribute to the up-regulation of hepatic PPAR alpha expression observed in hamsters. While pterostilbene and resveratrol demonstrated PPAR alpha. activation, their levels in BBX do not seem to be at efficacious concentrations. These stilbenes may contribute to the up-regulation of PPAR alpha expression by acting synergistically with each other or with other constituents in BBX.