is conjugate base of organic anion tetracycline tetracycline(1-) (1S,4aS,11S,11aS,12aS)-3-carbamoyl-1-(dimethylazaniumyl)-4a,7,11-trihydroxy-11-methyl-4,6-dioxo-1,4,4a,6,11,11a,12,12a-octahydrotetracene-2,5-diolate An organic anion that is the conjugate base of tetracycline obtained by deprotonation of the two enolic hydroxy groups and protonation of the tertiary amino group. tetracycline anion tetracycline zwitterion