In Vitro Activation of Peroxisome Proliferator Activated Receptor α by Some Extracts from Food Materials

Peroxisome proliferator activated receptor α (PPARα) is a ligand-dependent transcription factor that regulates the expression of genes involved in lipid metabolism and transport. Activators of PPARα may be potential hypolipidemic agents, like the fibrate-type drugs. This study was therefore aimed at identifying potential hypolipidemic functional foods by screening activators of PPARα from food materials. CHO-K1 cells were stably transfected with vectors (pBKCMV) carrying cDNAs of a (UAS)4-tk-alkaline phos- phatase reporter and a chimeric receptor Gal4-PPARα LBD successively. Clones of cells responsive to Wy-14643, a known PPARα activator were selected, characterized and used for testing the PPARα activating potency of fractions extracted from food materials. Food materials were extracted with ethyl acetate and the extract (EAE) was cold-saponified and tested for the PPARα activat- ing ability using the selected stable transfected clone of cells. 10 µM Wy-14643 (WY) was used as the positive control. Among food materials tested, EAE of bitter gourd showed the highest activity that exceeded Wy-14643, although the activity significantly decreased after saponification. The non-saponifiable fraction of onion EAE had a high maximal fold of activation equivalent to Wy-14643, while that of peanut, lychee, ricinus seed and longan showed moderate activity. The saponifiable fraction of ricinus seed, sesame and peanut also showed moderate activity. Further investigation is needed to explore the health benefit of the PPARα acti- vating food extracts found in this study.