TETRACYCLINE- FORGOTTEN ANTIBIOTICS
Presently, the name tetracycline refers to a number of antibiotics of either natural, or semi-synthetic origin, derived from a system of four linearly annelated six-membered rings (1,4,4a,5,5a,6,11,12a-octahydronaphthacene) with a characteristic arrangement of double bonds. The tetracycline molecule possesses five asymmetric centers: C-4, -4a, -5a, -6, and -12a.