HSD17B13-IN-21 (compound 17) is a ppotent inhibitor of hydroxysteroid 17?-dehydrogenase 13 (HSD17B13) , with the IC 50 of < 0.1 μM and? < 1 μM estradiol and Leukotriene B3 as substrates, respectively. HSD17B13-IN-21? plays an important role in nonalcoholic fatty liver diseases (NAFLDs) including NASH (nonalcoholic steatohepatitis).