The molecule is zwitterionic form of 12-dehydrotetracycline arising from transfer of a proton from the 2-hydroxy group to the adjacent tertiary amino group. It is a tautomer of a 12-dehydrotetracycline.
(4S,4aS,6S,12aR)-2-carbamoyl-4-(dimethylazaniumyl)-6,10,12a-trihydroxy-6-methyl-3,11,12-trioxo-4a,5-dihydro-4H-tetracen-1-olate