Structure--activity relationship of inhibitors of hydroxyapatite formation.

The relative abilities of some compounds to inhibit the transformation of amorphous calcium phosphate into hydroxyapatite were determined. Organic diphosphates, fructose 1,6-bisphosphate, pyrophosphate, imidodiphosphate and 3-phospholycerate all inhibited to various degrees. Strong inhibition was observed with phosphonoformate, and phosphocitrate proved to be the most powerful of the inhibitors examined. On the basis of these new findings an improved concept of the structure--activity relationship of inhibitors is proposed and mechanisms for inhibitor action are discussed.