The molecule is riboflavin in which the double bond between positions 4a and 5 has been reduced to a single bond. It is a tautomer of a 1,5-dihydroriboflavin.
7,8-dimethyl-10-[(2S,3S,4R)-2,3,4,5-tetrahydroxypentyl]-4a,5-dihydrobenzo[g]pteridine-2,4-dione