Browsing by Author "Tsekova D.S."
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Item ANTIMICROBIAL ACTIVITIES OF AMPHIPHILIC DERIVATIVES OF α-AMINO ACIDS(2023-01-01) Kondova V.K.; Tsekova D.S.; Anchev B.A.; Miravet J.F.; Angulo-Pachón C.Antimicrobial products are very important to the health of the society. The increasing resistance of some bacteria to existing antimicrobials require searching of new active substances with antimicrobial activities. This review is devoted to the newly synthesised amphiphilic derivatives of proteinogenic a-amino acids and study of their antimicrobial properties. For this purpose, classification of the basis of both - head charge and type of the amino acid is presented with focus on the cationic representatives as possessing well-expressed antimicrobial activities. Data about representatives of amphiphilic alpha-amino acid derivatives with proven antimicrobial activity has been summarised, presented in tables and compared. Results obtained up to now show that arginine derivatives are the most promising, but also gemini derivatives of lysine and arginine amphiphiles have higher antimicrobial activity then monomeric ones. Even though these compounds have lower toxicity thаn conventional surfactants, they are still more toxic than accepted for drug formulations, so to be used in terms of antibiotics. Characteristics of the newly designed alpha-amino acid amphiphilic derivatives should be improved before their antimicrobial potential becomes practically applicable.Item L-valine peptidomimetic effect on neural functions(2020-01-01) Encheva-Stoykova E.N.; Tsekova D.S.; Hodzhev Y.K.; Nocheva H.H.; Tancheva L.P.Peptidomimetics are a class of chemical compounds, many of which are being developed as potential medications. Social isolation stress is known to negatively affect neurodevelopment and normal neural functions. The purpose of the study was to examine the neuropharmacological effects of M6 peptidomimetic, a derivative of the branched chain amino acid L-Valine and m-pyridinic acid, while focusing on the sexual dimorphism among its effects on memory, balance and exploratory behavior in adolescent male and female rats under social isolation stress. The aim was also to compare the effects observed with those of the peptidomimetic on control (grouped) adolescent male and female rats. The post-weaning social isolation (21st PND) of 12 Wistar male and 12 female rat pups over a period of 6 weeks was used as a method of chronic stress. Half of the animals (grouped and isolated) received M6 150 mg/kg (i. p.) daily for 3 days. Then they participated in a battery of behavioral tests: Rotarod test, Hole board test, and Step-through test. The rats were tested for memory retention 1 h after acquaintance of the animal with the Step through test, and 24 h later. ANOVA (mixed design) was used to compare and analyze the results obtained. It is shown that the rats' memory and neuro-muscular coordination during their early post-adolescent period are diversely influenced by the chronic stress and the administration of peptidomimetic depending on the animals' sex and on the isolation stress effect.Item Monolayer formed by l-Asp-based gemini surfactants self-assembled in 1D nanostructures(2019-01-01) Anchev B.A.; Tsekova D.S.; Mircheva K.M.; Grozev N.A.Herein, studies on the surface activities of newly synthesized l-Asp-based gemini surfactants, both nonionic and anionic, are presented. Conductometry, tensiometry, and the Langmuir-Blodgett (LB) film technique were applied for this purpose. π-A isotherms were obtained with a Langmuir trough and Wilhelmy balance. The structures of the monolayers assembled at the air/water interface and those deposited as LB films were studied via Brewster angle microscopy (BAM) and atomic force microscopy (AFM). The 2D films formed by the anion-active compounds show a well-known pattern of a monolayer film, whereas the nonionogenic amphiphiles have been found to be 1D structures with nano-widths and micro-lengths that align with each other during the process of compression; this is the first study where the organization of 1D fibrils in 2D films during compression is reported. The scanning electron microscopy (SEM) study reveals that 1D nanostructure formation is an intrinsic tendency of these molecules as not only nonionogenic surfactants, but also the anion active representatives have been constructed in the solid state by fibrillary structures.Item On the synthesis, surface activity and supramolecular structures of pseudo double-chained L-Asp based amphiphiles(2020-01-01) Anchev B.; Grozev N.A.; Mircheva K.M.; Tsekova D.S.Eight new final compounds derivatives of L-Asp are synthesized. They contain L-Asp linked by an amide bond both to n-hexyl chain on its C-side and an acyl chain linked to the N-side. Four different acylic residues are condensed to the N side. The newly synthesized compounds belong to two series of structures, as four of them contain L-Asp-b-benzyl ester, while the other four-a typical L-Asp-b-carboxylic group. The structures of the surfactants are categorized as pseudo-double alkyl chained amphiphiles, because one of the tails has a constant length of only six carbon atoms. Some of the newly synthesized surfactants are studied as monolayers on the air/water interface. The properties of the rest of them are determined by tensiometric and conductometric methods. Nano-and micro-sized supramolecular complexes of the compounds studied are observed in monolayers using Brewster Angle Microscopy (BAM) and Scanning Electron Microscopy (SEM) for samples after solvent evaporation.Item PEPTIDES AND PEPTIDOMIMETICS IN NEUROPHARMACOLOGY (REVIEW)(2023-01-01) Encheva-Stoykova E.N.; Tsekova D.S.; Staykov H.; Kalfin R.; Tancheva L.P.Peptides and peptidomimetics are a major field of bioorganic chemistry research. We endeavored to describe the current trends in medicinal and bioorganic chemistry regarding the design of drug molecules which are peptide mimetics. To this end, we reviewed the literature regarding peptidomimetics classification, new research data on innovative potential drug molecules, current research, and its perspectives. Potential or current neuropharmacological agents that possess a peptide bond in their molecules and can be used in the treatment of pain or Alzheimer’s disease are of particular interest to our study. The inclusion criteria required that the studies explore peptides, peptide mimetics, and peptidomimetics or mimetics of peptides that show biological activity in the central/peripheral nervous system. Electronic search strategies were developed and undertaken, and relevant articles were selected and reviewed. A considerable number of pharmacological agents showing pharmacotherapeutic relevance were identified and reviewed regarding biological activity in the nervous system. The ones more closely reviewed are prospective or proven effective neuropharmacological agents that are analogs of peptides/oligopeptides. The potential for discovery of various peptides and peptidomimetics, which can affect the pathogenesis of pain, neurodegenerative diseases (Alzheimer’s disease, Parkinson’s disease and others) offers to broaden the scientific horizon; in the end leading to the synthesis of potential alternatives to current pharmacotherapeutics. Translational research can be encouraged after careful consideration of the risk-benefit ratio.Item The influence of solvents on the molecular structure and biological activity of N, N/-bis(N-nicotinoyl-L-valyl)-diaminohexane(2013-12-17) Tsekova D.S.; Klissurov R.; Tancheva L.; Encheva E.; Genadieva M.A peptidomimetic, N, N/-bis(N-nicotinoyl-L-valyl)-diaminohexane (M6) dissolved in identical concentration in three different types of solvent - sunflower oil, water and dimethyl sulfoxide (DMSO) was used for in vivo experiments with rats. Water and oil solutions did not provoke any symptoms of intoxication, while gross renal and hepatic toxicity was found when using DMSO solution. UV studies of M6 in several solvents, including water and DMSO showed solvatochromic shifts, due to intermolecular solvent-solute non-covalent interactions.