PABA
Essential growth factor for micro-organisms. It forms part of the molecule of folic acid and is therefore required for the synthesis of this vitamin. Mammals cannot synthesize folic acid, and PABA has no other known function; there is no evidence that it is a human dietary requirement.
Sulphanilamides (sulpha drugs) are chemical analogues of PABA, and exert their antibacterial action by antagonizing PABA utilization.
