Inhibitory activity of flavonoids and tannins against HIV-1 protease

Twenty-nine flavonoids and six hydrolyzable tannins were studied for their inhibitory activity against human immunodeficiency virus (HIV)-1 protease u sing fluorescence and HPLC assays, Among the flavonoids, flavones. flavanon es, flavonols, catechols and chalcones, the flavonols were the most active category while flavanones and catechols displayed low activity. Quercetin w as the most potent inhibitor of the target enzyme with an LC50 value of 58. 8 mu M, while butein and luteolin showed moderate activity. Of the hydrolyz able tannins tested, three ellagitannins which contain a hexahydroxydipheno yl (HHDP) unit linked to the O-3 and O-6 positions of the sugar, were found to strongly inhibit HIV-1 protease, The IC50 values of corilagin and repan dusinic acid on HIV-1 protease were 20.7 and 12.5 mu M, respectively.