The major metabolite of dipeptide piracetam analogue GVS-111 in rat brain and its similarity to endogenous neuropeptide cyclo-l-prolylglycine
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- Gudasheva, T.A., Boyko, S.S., Ostrovskaya, R.U. et al. European Journal of Drug Metabolism and Pharmacokinetics (1997) 22: 245. doi:10.1007/BF03189814
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The metabolism of a new piracetam analogue, the dipeptide cognitive enhancer N-phenylacetyl-l-prolylglycine ethyl ester (GVS-111) was studied in vivo. GVS-111 itself was not found in rat brain 1 h after 5 mg/kg i.p. administration up to limit of detection (LOD) under high performance liquid chromatography (HPLC) conditions. Three substances corresponding to the three possible GVS-111 metabolites, namely phenylacetic acid, prolylglycine and cyclo-prolylglycine, were found in experimental rat brain samples as well as in controls using HPLC, gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) methods. Only cyclo-prolylglycine concentration increased (2.5-fold) 1 h after GVS-111 administration. Cyclo-prolylglycine formation from GVS-111 in the presence of plasma and brain enzymes was shown in vitro. These data could be considered as evidence that GVS-111 is prodrug which converts in the body to cyclo-prolylglycine, and which is identical to the endogenous cyclopeptide that produces the nootropic activity.