Suggested Reaction 1.3.99.-

Left

5,6-Dihydroxy-3-methyl-2-oxo-1,2,5,6-tetrahydroquinoline
+FAD

Right

5,6-Dihydroxy-3-methyl-2-oxo-1,2-dihydroquinoline
+FADH2

[BiSSCat | GREP ]