Summary The aim of current study was the estimation of the effect of newly synthesized Galantamine peptide ester: 6-O-N-[N-(3,4-dichlorophenyl)-D,L-Alanyl]-L-Leucyl-Glycine-Galantamine (GAL – LEU) on cell growth rate of cultured 3T3 mouse embryonic fibroblast cells. 3T3 cells were in triplicate treated separately with different concentrations: 1.875 mМ ¸ 30 mМ of GAL – LEU. The applied MTT assay is based on the capacity of mitochondrial succinyl dehydrogenase of living cells to convert the yellow tetrazolium salt (3-(4′,5′-dimethylthiazol-2′-yl)-2,5-diphenyl-tetrazolium bromide) into an purpleblue formazan, which absorbance is measured spectrophotometrically at λ = 570 nm.

Cell growth inhibition (%) and the index of cell viability (%) were calculated. GAL – LEU in concentration 30 mM inhibits 99.9 % of cell growth. From equation: y = 7.603.e^0.098.x was calculated the inhibition concentration IC₅₀: 19 mM. IC₅₀ of used standard Cicloheximide is 0.26 mM. These experimental results proved that against 3T3 cell line the examined ester exerts cytotoxic activity.