Discovery two potent and new inhibitors of 15-lipoxygenase: (E)-3-((3,4-dihydroxybenzylidene) amino)-7-hydroxy-2H-chromen-2-one and (E)-O-(4-(((7-hydroxy-2-oxo-2H-chromen-3-yl) imino)methine)phenyl)dimethylcarbamothioate