Induction of Peroxisome Proliferator-Activated Receptor γ (PPARγ)-Mediated Gene Expression by Tomato (Solanum lycopersicum L.) Extracts

Since beneficial effects related to tomato consumption partially overlap with those related to peroxisome proliferator-activated receptor gamma (PPAR gamma) activation, our aim was to test extracts of tomato fruits and tomato components, including polyphenols and isoprenoids, for their capacity to activate PPAR gamma using the PPAR gamma 2 CALUX reporter cell line. Thirty tomato compounds were tested; seven carotenoids and three polyphenols induced PPAR gamma 2-mediated luciferase expression. Two extracts of tomato, one containing deglycosylated phenolic compounds and one containing isoprenoids, also induced PPAR gamma 2-mediated expression at physiologically relevant concentrations. Furthermore, enzymatically hydrolyzed extracts of seven tomato varieties all induced PPAR gamma-mediated expression, with a 1.6-fold difference between the least potent and the most potent variety. The two most potent varieties had high flavonoid content, while the two least potent varieties had low flavonoid content. These data indicate that extracts of tomato are able to induce PPAR gamma-mediated gene expression in vitro and that some tomato varieties are more potent than others.