The present invention provides compounds having the formula: wherein A is chosen from a nitrogen-, oxygen-, or sulfur-linked aryl, alkyl, cyclic, or heterocyclic group; both B and C are hydrogen, or either B or C is a halogen, amino, or thiol group and the other of B or C is hydrogen; and D is a primary alcohol, a hydrogen, or an oxygen, nitrogen, carbon, or sulfur linked to phosphate, a phosphoryl group, a pyrophosphoryl group, or adenosine monophosphate through a phosphodiester or carbon-, nitrogen-, or sulfur-substituted phosphodiester bridge, or to adenosine diphosphate through a phosphodiester or carbon-, nitrogen-, or sulfur-substituted pyrophosphodiester bridge. The present invention also provides pharmaceutical compositions containing the above compounds, methods of using the above compounds as pharmaceuticals, and processes for preparing the above compounds. Also provided are methods for inhibiting an ADP-ribosyl transferase, ADP-ribosyl cyclase, or ADP-ribosyl hydrolase enzyme, and methods for treating a disease or condition associated with an ADP-ribosyl transferase, ADP-ribosyl cyclase, or ADP-ribosyl hydrolase enzyme in a subject in need of treatment thereof.