Novel p53 inactivators with neuroprotective action: Syntheses and pharmacological evaluation of 2-imino-2,3,4,5,6,7-hexahydrobenzothiazole and 2-imino-2,3,4,5,6,7-hexahydrobenzoxazole derivatives

Tumor suppressor protein, p53, is an intracellular protein that is critical within the biochemical cascade that leads to cell death via apoptosis. Recent studies identified the tetrahydrobenzothiazole analogue, pifithrin-α (2), as a p53 inhibitor that was effective in protecting neuronal cells against a variety of lethal insults and reducing the side effects of anticancer drugs. As up-regulation of p53 has been described as a common feature of several neurodegenerative disorders, including Alzheimer's disease, 2 and novel analogues (3-16) were synthesized to (i) assess the value of tetrahydrobenzothiazole analogues as neuroprotective agents and (ii) define the structural requirements for p53 inactivation. Not only did 2 exhibit neuroprotective activity in both tissue culture and in vivo stroke models but also compounds 6, 7, 10, 13, 15, and 16 proved to be highly potent in protecting PC12 cells and compounds 3, 4, and 6 were highly potent in protecting primary hippocampal cells against death induced by the DNA-damaging agent, camptothecin.