JBSNF-000088 (6-Methoxynicotinamide), an analog of nicotinamide (NA), is a potent inhibitor of Nicotinamide N-methyltransferase (NNMT) with IC50 of 1.8 µM, 2.8 µM, and 5.0 µM for human NNMT(hNNMT), monkey NNMT (mkNNMT) and mouse NNMT (mNNMT), respectively.