In vivo and in vitro experiments revealed the neuroprotective activity of CAPAH, a representative of the new nootropic class phosphorylated carboxylic acid hydrazides. The mechanisms of this action, which were due to the membranous stabilizing activity of the drug and its affinity for glycine strychnine-sensitive sites of MMDA receptors (Ki = 8.8.10(-5) M). Six analogues of CAPAH have been also found to have affinity for these types of receptors; based on the examination of structure-affinity relationship, putative pharmacophores (only radicals of the benzene ring of a molecule in the para position exerted effects on affinity changes) were revealed. The findings give a deep insight into the mechanism of nootropic activity and open vistas for synthesizing phosphorylated carboxylic acid hydrazides as potential neuroprotective agents interacting with glycine strychnine-sensitive sites of MMDA receptor.