Resveratrol, pterostilbene, morin hydrate, and quercetin inhibit post-glutamase proteasomal activity. Relative post-glutamase activity was quantitated by measuring luminescence after treatment of RAW 264.7 whole cells (1x104 cells/well) with 20 μM of resveratrol, pterostilbene, morin hydrate, nicotinic acid, quercetin or medium alone (control). Cell viability exceeded 95 % in all the treatments. Data are means ± SD, n = 3 per-treatment, and triplicate analyses of each sample were performed. Values in a column not sharing a common symbol are significantly different at P <0.05. CTL = Control (Medium + RAW 264.7 whole cells + 0.2 % DMSO); Resv = resveratrol; Pter = pterostilbene; Mori = morin hydrate; Nico = nicotinic acid; Quer = quercetin-HCL. Figure A = actual relative luminescence unit (RLU) values. Figure B = Percentages of actual RLU values compared to control.