Synthesis, characterization and examination of bioactivities of novel analogues of a wound-healing peptide

In this thesis, it is aimed to obtain new peptide biomolecules with therapeutic potential that can affect the healing of skin wounds. Harmful microorganisms such as Gram negative and Gram positive bacteria in the wound area can form a biofilm and neutralize existing antibiotics, antibodies or phagocytes, which are the body's defense cells. Antimicrobial peptides (AMPs) with wound healing activity can be used to fight these harmful bacteria in the wound area and allow the wound to heal. It has been reported that AMPs obtained from frog skin support wound healing. Brevin peptides are AMPs derived from frog skin secretions. However, it is undesirable for these peptides to have a hemolytic activity due to their long sequences and the Rana box located at their C-terminus. For this purpose, in this thesis, six short analogues of brevinin-2Ta peptide with wound healing activity isolated from Pelophylax kl. Esculentus frog, which can be synthesized more easily and cost-effectively and have no hemolytic activity, were designed. The designed short analogues were synthesized by solid phase peptide synthesis (SPPS) using a microwave assisted peptide synthesizer and then purified by reverse phase high pressure liquid chromatography (RP-HPLC). The molecular weights of the collected fractions were analyzed by liquid chromatography/quadrupole-time of flight mass spectrometry (LC-MS/Q-TOF). The purity of the peptide-containing fractions was also analyzed by analytical RP-HPLC. The antimicrobial activities of the synthesized peptides were first tested by agar diffusion test. At the end of the agar diffusion test, it was observed that the Analog-5 peptide had antibacterial activity and the minimum inhibitory concentration (MIC) values were calculated. To test the cytotoxicity of the peptides, 3-(4,5-dimethyl-2-thiazolyl)-2,5- diphenyl-2H-tetrazolium bromide (MTT) assay was performed and the wound healing effect of the peptide was examined using fibroblast cell culture with the most non- cytotoxic Analog-5 peptide. Analog-5 was found to provide faster wound closure than brevinin-2Ta peptide and when hemolytic activities of peptides were tested, all analogs viii were less hemolytic than brevinin-2Ta peptide. As a result of these findings, a new peptide with wound healing effect was obtained and this peptide may contribute to drug research and development studies.