Semax (MEHFPGP) increases of gastric mucosal homeostasis to such ulcerogenic factors as ethanol and stress. On stress ulcer model Semax and its two metabolites — HFPGP and FPGP in the wide range of doses — 0,06—3,7 mkmol/kg show protective antiulcer properties. On ethanol ulcer model only Semax in both of used doses (0,06 and 0,37 mkmol/kg) demonstrates reliable protective antiulcer property. It was supposed that Semax’s gastroprotective activity concerning of peripheral mechanisms of ulcerogenese did not depend on its metabolites. On the contrary to this fact Semax’s gastroprotective activity connected with central mechanisms of ulcerogenesis may be caused and gastroprotective activity of HFPGP and FPGP.

Semax (MEHFPGP) was shown to increase gastric mucosal homeostasis to the action of such ulcerogenic factors as ethanol and stress. In the case of the stress model of ulcer formation, Semax and its two metabolites—HFPGP and FPGP—at the wide range of doses (0.06–3.7 µmol/kg) have demonstrated protective antiulcerogenic properties. In the case of ethanol model of ulcer formation, only Semax in two used doses (0.06 and 0.37 µmol/kg) reported reliable protective antiulcerogenic property. It was supposed that Semax’s gastroprotective activity directed to peripheral mechanisms of ulcerogenesis did not depend on its metabolites’ activities. On the contrary, Semax’s gastroprotective activity directed to the central mechanisms of ulcerogenesis might be also caused by gastroprotective activities of HFPGP and FPGP metabolites.

A synthetic scheme for preparation of (Gly-Pro) n , (Pro-Gly) n (n = 2, 3), and (Pro-Gly-Pro) n (n = 1, 2) peptides was elaborated. The effect of the synthesized peptides and the Gly-Pro and Pro-Gly dipeptides on survival of cultured cells of PC12 rat pheochromocytoma was studied under the conditions of oxidative stress induced by brief incubation of the cells with hydrogen peroxide. Peptides of the general formula (Gly-Pro) n and the Pro-Gly-Pro peptide at a concentration of 0.2–100 μM were shown to decrease the number of damaged cells. The Gly-Pro peptide was the most active and decreased the number of damaged cells by 49% on average at a concentration of 100 μM.