Synthetic analogues of memantine as neuroprotective and influenza viral inhibitors: in vitro and physicochemical studies.

Drug compounds including memantine moieties are an important group of biologically active agents for different pathologies, including the Alzheimer's disease. In the present study, a series of memantine derivatives incorporating amino acid residues have been synthesized and their neuroprotective in vitro evaluation in respect of the Alzheimer's disease, involving the effects on the resistance to Aß toxicity, excitotoxicity, oxidative stress, hypoxia, and neuroinflammation has been studied. The cytotoxicities of the compounds were detected by CPE assay. TC50 and IC50 were determined using Reed and Muench method. Solubility and distribution were measured using a shake-flask method. Permeability of the compounds was studied using Franz diffusion cell and Permeapad™ barrier. These compounds displayed apparent multi-neuroprotective effects against copper-triggered Aß toxicity, glutamate-induced excitotoxicity, and oxidative and hypoxic injuries. They also showed the ability to inhibit the inflammatory cytokine release from the activated microglia and potential anti-neuroinflammatory effects. Especially, two most promising compounds H-4-F-Phe-memantine and H-Tyr-memantine demonstrated the equivalent functional bioactivities in comparison with the positive control memantine hydrochloride. Higher solubility in muriatic buffer than in phosphate buffer was detected. The distribution coefficients showed the optimal lipophilicity for compounds. The presented results propose new class of memantine derivatives as potential drug compounds. Based on the experimental results, the correlations have been obtained between the biological, physicochemical parameters and structural descriptors. The correlation equations have been proposed to predict the properties of new memantine derivatives knowing only the structural formula.