Positions of Hydroxyl Groups in Chrysin are Critical for Inhibiting Plasminogen Activator Inhibitor-1 Release from Human Umbilical Vein Endothelial Cells.

Chrysin suppresses the TNFα-induced increase in the secretion of plasma plasminogen activator inhibitor 1 (PAl-1), a risk factor for thrombotic diseases, from human umbilical vein endothelial cells (HUVECs). The present study aimed to determine the association between the location of the hydroxyl groups in chrysin.to levels of-PAI-1. in the medium of HUVEC stimulated with TNFα. We cultured HUVEC for 3 h in medium containing chrysin or various flavonoids and then stimulated them with TNFα (10 ng/mL) for 12 h. Levels of PAI-1 antigen measured using ELISA showed that chrysin significantly inhibited the PAl- I increase with an IC50 of 15.6 μM. The flavones, galangin, baicalein, 5-hydroxyflavone, 6-hydroxyflavone, 7-hydroxyflavone and quercetin did not significantly inhibit the PAI- increase. Apigenin and luteolin were cytotoxic and thus their ability to inhibit PAI production could not be evaluated. Chrysin also inhibited PAI- mRNA expression whereas the other compounds did not. Hydroxyl groups located in the A-5 and A-7 positions were essential for the inhibitoryactivity, which along with cytotoxicity, was significantly influenced by adding a third hydroxyl group.