Mechanism of resveratrol and pterostilbene inhibition of MAO enzymes. Kynuramine (2-450μM) and MAO-A or MAO-B (0.01mg/ml) were incubated for 15 minutes in the absence or presence of resveratrol (1μM) (a) or pterostilbene (0.45μM) (b). The Michaelis-Menten equation was fit to the data by nonlinear regression to compare any changes in Km or Vmax. (c) MAO-A was preincubated with tranylcypromine (1μM), resveratrol (1.6μM), or DMSO (control) for 0-60 minutes before the addition of kynuramine (20μM). (d) MAO-A was preincubated with tranylcypromine (0.5μM), pterostilbene (0.7μM), or DMSO (control) for 0-60 minutes before the addition of kynuramine (20μM). All samples were incubated at 37°C for 30 minutes. One-phase decay or straight line equations were fit to the data.