7,8,10-trimethyl isoalloxazine, C¹³H¹²O²N⁴, a product of riboflavin degradation upon exposure to light in an alkali medium. Yellow crystals; soluble in alcohol and other organic solvents. Melting point, 328°C. It readily enters into oxidation-reduction reactions with amino acids and biologically important sulfur-bearing substances (for example, lipoic acid or glutathione), upon action of visible light. In connection with its ability readily to undergo conversion into the excited state, lumiflavin acts as a sensitizer in the photooxidation of purine bases, which is the basis of photoinactivation of deoxyribonucleic acid.