Pyrimido[5,4-e][1,2,4] triazine-5,7(1H, 6H)-dione derivatives were investigated as novel small molecule amplifiers of heat shock factor 1 transcriptional activity. Lead optimization led to the discovery of compound 4A-13, which displayed potent HSF1 activity under mild heat stress (EC(50) = 2.5 mu M) and significant cytoprotection in both rotenone (EC(50) = 0.23 mu M) and oxygen-glucose deprivation cell toxicity models (80% protection at 2.5 mu M). (C) 2009 Elsevier Ltd. All rights reserved.