Bisubstrate inhibitor 78 is an inhibitor of nicotinamide N-methyltransferase (NNMT; IC50= 1.41 μM).1It binds the NNMT active site in the binding pockets for the NNMT substrates S-adenosyl-L-methionine (SAM) and nicotinamide . Bisubstrate inhibitor 78 is selective for NNMT over histone-lysine N-methytransferase NSD2 and protein arginine methyltransferase 1 (PRMT1; IC50s = >50 μM for both). It reduces levels of 1-methylnicotinamide in, and inhibits proliferation of, HSC-2 oral cancer cells when used at a concentration of 100 μM.This compound is unstable in powder form and other related salt forms are recommended.