Browsing by Author "Danalev D."
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Item Antimicrobial activity of (KLAKLAK)–NH2 analogs against pathogenic microbial strains(2024-01-01) Jaber S.; Evstatieva Y.; Nemska V.; Nikolova D.; Naydenova E.; Georgieva N.; Danalev D.Many microorganisms pose a threat to human health due to the ever-increasing bacterial resistance to conventional drugs. Nowadays, searching for new alternatives to conventional antibiotics to fight bacterial resistance is a main task. Thus, natural molecules such as amino acids and peptides arise as possible solutions to the problem. The antimicrobial activity of targeted compounds was studied by the agar-diffusion method, using the prepared working solutions of the targeted peptides with the corresponding concentrations. The results of the antimicrobial activity against different test pathogens show specificity, as antimicrobial activity against the used test microorganisms was not found in the investigated short-chain synthetic peptides Si6, Si3 and Si13. Antimicrobial activity against Bacillus cereus, Staphylococcus aureus, Staphylococcus epidermidis, Propionibacterium acnes, Escherichia coli, Pseudomonas aeruginosa, and the yeasts Malassezia furfur and Candida albicans was established for the long-chain synthetic peptides Si1, Si5 and Si16, except Si5 which does not show activity against pathogenic fungal strain C. albicans. The compound Si16 where natural Leu in (KLAKLAK)2-NH2 is replaced by unnatural Nle is the best candidate for medical drug due to the combined antibacterial and antiproliferative effect as well as long hydrolytic stability.Item ANTIMICROBIAL ACTIVITY OF AMINO ACID DERIVATIVES OF MEMANTINE(2022-01-01) Tencheva A.; Stankova I.; Angelova T.; Nemska V.; Georgieva N.; Danalev D.Memantine is adamantane derivative used in medicinal practice. It is well-proven inhibitors of the M2 ion channel of influenza virus. In addition, it is applied for treatment of patients with Alzheimer’s disease. Herein, we report the antimicrobial activity of specifically designed memantine derivatives containing spatially compact (Gly, Ala, β-Ala) and bulky (Val and Phe) amino acids. New compounds were synthesized in a solution using 2-(1H-benzotriazole-1-yl)-1,1,3,3-tetramethylaminium tetrafluoroborate (TBTU) as a coupling agent. All derivatives were obtained with good yields. Newly synthesized molecules at concentration 100 mM were tested for their antimicrobial activity using model strains of Gram-positive (Bacillus subtilis NBIMCC 3562), Gram-negative (Escherichia coli NBIMCC K12 407) microorganisms and fungal strain Candida albicans NBIMCC 74. The active compounds against model G+ microorganism are Val-MEM followed by Ala-MEM and Gly-MEM. All compounds show good activity against model G-microorganism. Introducing of bulky amino acid Phe, containing aromatic core, and Val, containing aliphatic core, leads to good antifungal activityItem Antimicrobial activity of Bulgarian products and their extracts containing bioactive components(2015-01-01) Marinkova D.; Danalev D.; Genchev G.Phytoncides are organic compounds, produced by plants in order to protect them from different microorganisms. Over the years a number of plants and their extracts are subjected to investigation of their antibacterial properties. The increase in the number of side reactions caused by antibiotics, and other drugs used in medical practice, turned back the attention of many scientists to studies of the properties and antibacterial activity of products from national cuisine. This paper reports on the antibacterial properties of honey, garlic, onions and their extracts, produced in Bulgaria. Arthrobacter oxydans 1388 (an example for Gram+ microorganism) and Pseudomonas fluorescens 1442 (an example of a Gram- microorganism) were selected as test microorganisms. Our studies have shown that Arthrobacter oxydans are sensitive to the antimicrobial activity of honey, while the Pseudomonas fluorescens show resistance. Garlic extracts have shown good activity against both Arthrobacter oxydans and Pseudomonas fluorescens.Item ANTIMICROBIAL PROFILE OF EXTRACTS FROM THE FUNGUS SPECIES LEPISTA PERSONATA(2023-01-01) Nemska V.; Yaneva S.; Georgieva N.; Danalev D.Nowadays, mushrooms are widely studied due to the various bioactive substances they produce. They define their antibacterial, antifungal, antioxidant, antitumor, cytostatic and anti-inflammatory properties which are beneficial for human health. This study aimed to determine the antimicrobial activity of different (hot and cold ethanol/ dichloromethane/ hexane) extracts from the fungus species Lepista personata against two test microorganisms: Escherichia coli NBIMCC K12 407 and Bacillus subtilis NBIMCC 3562. The antimicrobial assays were performed applying the classical disc diffusion method. The sensitivity of test microorganisms was determined according to the zone of inhibition which appeared around the discs after 24 h of incubation at 30°C - 37°C. All extracts were dissolved in 200 mM dimethyl sulfoxide, which was used as a control sample. Results showed that E. coli NBIMCC K12 407 is susceptible to dimethyl sulfoxide whereas B. subtilis NBIMCC 3562 showed no growth inhibition. All mushroom extracts also showed no inhibitory activity against B. subtilis NBIMCC 3562. At the same time, only the dichloromethane extract obtained after hot extraction inhibited the growth of E. coli NBIMCC K12 407.Item Application of three-stage approach to isolation and purification of Pseudozyma antarctica lipase B(2018-01-01) Borisov B.; Manova D.; Yaneva S.; Danalev D.; Yotova L.Lipases are serine hydrolases defined as triacyl glycerol acyl hydrolases (EU 3.1.1.3). The unique characteristics and biotechnological potential of lipases have led to their use in food, detergents, pharmaceuticals, etc. industry. Lipolytic enzymes can be isolated from plants, animals, bacteria, fungi and yeasts. In this work we report the synthesis, isolation and purification of an extracellular lipase from Pseudozyma antarctica NBIMCC 8340 using a three-step process. The lipase activity is analyzed by potentiometric and colorimetric method at every stage of the isolation. In order to optimize the synthesis and isolation conditions two separate experiments of fermentation process, test and real one, are realized. The isolation and separation of the lipase in our case are carried out by fractional precipitation with (NH4)2SO4, followed by purification through ultrafiltration using micro concentration tubes Sartorius VIVASPIN 6. The resulting isolate of P. antarctica lipase B is detected by SDS PAGE and analyzed for lipase activity. Preparative isolation of the enzyme in native PAGE is further conducted as a third step aiming to obtain a high purity lipase. Thus a highly purified CalB of a specific activity of 92 U/mg is obtained.Item Attenuation of 1-chloro-2, 4-dinitrobenzene-induced inflammation in atopic dermatitis-like skin lesions in rats by a pyrrole containing FELL-NH2 bioconjugate: Cannabinoid receptor type 1 involvement(2024-01-01) Papadakis K.; Bezirci K.; Borisova B.; Vladimirova S.; Danalev D.; Handjieva-Darlenska T.; Tafradjiiska-Hadjiolova R.; Nocheva H.Atopic dermatitis (AD) is a chronic inflammatory skin condition of significant health and social importance, which justifies the search for new means of treatment. Since the endogenous cannabinoid system appears to be involved in the pathogenesis of AD, the proposed article summarizes the clinical impact on skin inflammation in a rat model of 1-chloro-2, 4-dinitrobenzene-induced atopic dermatitis-like condition after exogenous systemic administration of the cannabinoid receptor type 1 (CB1r) agonist anandamide, as well as after local treatment with a newly synthesized pyrrole moiety containing bioconjugate of FELL tetrapeptide with CB1r-dependent analgesic activity. The changes in skin lesions and ear thickness were estimated along with the CB1r expression immunohistochemically determined on skin punch biopsies. The results showed attenuation of skin lesions by anandamide and lack of positive effect after introduction of CB1r antagonist, accompanied by a change in CB1r expression, suggesting the involvement of the cannabinoid system in the defensive functions of the skin. The topically applied newly synthesized bioconjugate also favorably affected skin manifestations of inflammation, but without a change in CB1r expression, suggesting the involvement of other mechanisms in the reported effects.Item BENDING ELASTICITY OF PHOSPHOLIPID BILAYERS CONTAINING AN AMPHIPATHIC PEPTIDE WITH LOW MAMMALIAN CYTOTOXICITY(2022-01-01) Vitkova V.; Stoyanova-Ivanova A.; Jaber S.; Naydenova E.; Danalev D.Peptide mimetics imitate natural peptides’ structure but they could be specifically designed to be more selective concerning their toxicity to mammalian cells. In most cases this specificity is due to their ability to form α-helix in amphipathic environment. In addition, the specific activity depends on the ability of final structure to penetrate cell membrane. Being responsible for the cell integrity and compartmentalization, biomembranes also play a major role in cellular processes, in which the membrane deformations are important. In the present study we probe peptide-membrane interactions for a shortened amino acid sequence KLAKLAK-NH2 of an antimicrobial peptide with apoptotic effect. The bending rigidity of model lipid bilayers is measured by flicker spectroscopy of quasispherical unilamellar vesicles monitored and analyzed in phase contrast light microscopy. At high peptide concentrations ∼ 30 µmol/L and peptide-to-lipid total molar ratios ∼ 0.90 bilayer stacking formation is observed. A reduction of the bending constant is reported at peptide-to-lipid total molar ratio ∼ 0.80. The membrane softening indicates peripheral peptide orientation at the lipid bilayer, which is considered a prerequisite for channel formation. Based on KLAKLAK-NH2 effect on the membrane bending elasticity we provide an evaluation of the peptide partition coefficient characterizing its affinity to POPC bilayers. The acquired results might be helpful in efforts to further tailor the pharmacokinetic properties of antimicrobial peptides in combination with strengthened stability towards enzymatic degradation.Item Calibration of GC/MS method and validation of the modified sample preparation for determination of polycyclic aromatic hydrocarbons(2018-01-01) Givechev I.; Danalev D.; Yaneva S.; Tanev D.A modified procedure of EN 16619:2015 method for determination of four polycyclic aromatic hydrocarbons (PAH's) was proposed. A change in internal standard and in sample preparation procedure was made for two low fat food matrices (wheat flour and smoked pork leg). As a result a new calibration was obtained with very good linearity (correlation coefficient R2 = 0.999). Recovery rates for spiked samples from both matrices were also calculated and were found in a good fit with the European legislation specifications. The average values of the recovery rates amounted to 99.32 % (1.83 % relative standard deviation) for wheat flour and 97.25 % (2.50 % relative standard deviation) for smoked pork leg.Item Determination of N-methyl carbamates in a liver sample using an optical biosensor(2019-01-01) Yaneva S.; Stoykova I.; Danalev D.; Yotova L.N-Methyl carbamates are insecticides that inhibit acetylcholinesterase (AChE) causing same symptomatology in acute and chronic exposures. Traces of them could be found in animal tissues, milk, honey, eggs, etc. because of some foods treatment during growth. There is an increasing interest in fast screening methods for detection of different pollutant groups in the foods. Biosensors are a promising alternative of the existing chromatographic methods such as HPLC, GC, etc. They are fast, easy to use and provide fully acceptable values for the monitoring methods like sensitivity, LOD, LOQ, etc. In order to construct an optical biosensor, AChE is immobilized as a target enzyme for N-methyl carbamates on the surface of new membranes synthesized by a sol-gel technology. The designed biosensensor is tested for determination of methomyl, aldicarb, carbofuran, propoxur in liver samples. An appropriate method for sample preparation is also developed. Further, the new method is validated in accordance with document SANTE/11945/2015 covering the required criteria for N-Methyl carbamates determination. The biosensor could detect levels lower than 10 μg/kg which is the maximum residue limit (MRL) for pesticides in foods. Km of 2,2x10-3 M is calculated for acetylcholine using a 4 month life-time of a biosensor.Item Determination of organophosphorus pesticides in liver samples using an optical biosensor(2019-01-01) Yaneva S.; Stoykova I.; Danalev D.; Yotova L.Biosensors are a promising alternative of the existing chromatographic methods as GC, HPLC, etc. They are fast, easy to use and provide fully acceptable values of monitoring like sensitivity, LOD, LOQ, etc. In order to construct an optical biosensor, AChE is immobilized as a target enzyme for organophosphorus pesticides (OPPs) onto new membranes synthesized by a sol-gel technology. The designed biosensensor is tested for determination of chlorpyrifos-methyl, parathion, pirimiphos-methyl and diazinon in liver samples. An appropriate method for sample preparation is also developed. The new method is validated in accordance with document SANTE/11945/2015 covering the required criteria for pesticides determination. The biosensor developed can detect levels lower than 30μg/ kg. The latter is the maximum residue limit (MRL) for pesticides in food. Km of 2,2x10-3M for acetylcholine and 4 months life-time of the biosensor are obtained.Item DETERMINATION OF SOME PROHIBITED SUBSTANCES IN FOOD SUPPLEMENTS USING HPLC WITH MS OR UV DETECTION - VIEW ON CURRENT DEVELOPMENT(2021-01-01) Zaharieva Z.; Foteva T.; Karadjova V.; Danalev D.Nowadays bioanalytical techniques including liquid and gas chromatography combined with different types of detectors are largely introduced in a practice. They are largely used for detection and control of substances and for monitoring of the whole production process. The type of detector depends on necessary levels of detection, but also on the matrix where aimed compounds have to be determined. Herein are summarized data from the last ten years related to determination of six main prohibited substances sildenafil, tadalafil, vardenafil, dapoxetine, yohimbine and sibutramine as well as their derivatives in food supplements using high performance liquid chromatography combined with mass spectrometric or UV detection. All these compounds are in a large interest because they are introduced often in products freely distributed in the internet market.Item Development and validation of GC/MS method for simultaneous determination of 16 polycyclic aromatic hydrocarbons (PAHs) in pork meat matrix(2021-03-01) Givechev I.; Tanev D.; Danalev D.The major processes for introducing polycyclic aromatic hydrocarbons (PAHs) in food are smoking and grilling of different products. But in addition, PAHs can permeate in the food chain due to their high lipophilicity and ability to be accumulated in specific tissue, through contaminated animal feed. Further, when some parts of these animals are marketed as food, the accumulated PAHs can go to the human organism. Some of them are classified as highly toxic, carcinogenic and mutagenic for animal and human organisms so they are under consideration of International and European legislation. This work reports development and validation of simple and fast GC/MS method for 16 PAHs determination. Comparison of two methods for sample preparation in pork meat matrix standard extraction/saponification procedure and modified QuEChERS method is also done. In addition, this paper report the calibration step of instrument and a recovery study for 16 PAHs in model pork meat, using modified QuEChERS procedure for sample pretreatment. The calibration step with accessible and suitable for use in real laboratory conditions internal standard (chrysene D12) is done in the range 10–100 ppb using toluene as solvent. The obtained results show very good linearity (R2 5 0.99 to 1.00). For the recovery study six model samples were spiked with 16 PAHs and they all are subjected to QuEChERS procedure. The recovery is calculated and the obtained data (71–120%) is in a good correlation with requirements of international legislation. Finally, LOD values for all 16 investigated compounds of modified GC/MS method and for the instrument were determined.Item Development and validation of HPLC-DAD methodology for simultaneous qualitative and quantitative determination of thirteen substances with a steroid structure(2023-01-01) Zaharieva Z.; Atanasova S.; Danalev D.; Jaber S.; Foteva T.; Nemska V.; Tanev D.; Georgieva N.Using supplements in different sports is a common practice for many athletes. Unfortunately, the growth of this market has entailed some speculations, such as the addition of excessive doses of potentially toxic ingredients. Sometimes the doses listed on the package do not correspond to the real content. Some nutritional supplements on sale may contain undeclared ingredients. Some of those supplements are prohibited substances according to different regulations. Herein, a simple HPLC/DAD procedure that is easy to apply in conventional laboratory practice was developed for the simultaneous determination of 13 substances with steroid structure in nutritional supplements for sport: testosterone, testosterone propionate, testosterone enanthate, methyltestosterone, nandrolone, nandrolone propionate, nandrolone decanoate, methandienone, androstenedione, trenbolone, trenbolone acetate, trenbolone enanthate and boldenone undecylenate. The methodology includes gradient elution with mobile phase A: MeOH:ddH2O (55:45) and mobile phase B: 100% MeOH in a standard HPLC system containing a Halo 90 Å, C18 (150 x 4.6 mm, 2.7 µm) column, flow rate 0.6 mL/min, UV wavelength of 254 nm, temperature of 40 °C and 20 μL injection volume. The developed methodology was validated according to the corresponding official documents. The key parameters used for the selection of the optimal HPLC conditions were the ability of the mobile phase and solvents to be used with both an HPLC/MS and a GC/MS chromatographic system. The obtained total run time, the reproducibility of the retention times, the separation of all peaks and peak characteristics meet all requirements.Item Development and Validation of HPLC/DAD Method for Simultaneously Determination of Six Prohibited Substances in Model Matrices(2020-12-01) Zaharieva Z.; Tanev D.; Danalev D.The authorities have identified an emerging trend where over-the-counter products, represented as dietary supplements, contain hidden active ingredients that could be harmful. Consumers may unknowingly take products laced with varying quantities of approved prescription drug ingredients, controlled substances, and untested and unstudied pharmaceutically active ingredients. Hidden ingredients are increasingly becoming a problem in products promoted for sexual enhancement, weight loss, or bodybuilding. The tests have revealed the presence of some undesired substances like sildenafil, tadalafil, vardenafil, and their analogues in tainted sexual enhancement products. The content of these substances is usually around the daily curative dose. A simple high-performance liquid chromatography (HPLC) method for simultaneously determination of sildenafil, vardenafil, tadalafil, dapoxetine, yohimbine, and sibutramine was developed and validated. InfinityLab Poroshell 120 EC-C18 (150 '4.6 mm '4 μm particles) was used, as well as a diode-array detector (DAD) at 230 nm, and a gradient flow with 0.030 Eœ ammonium acetate buffer and acetonitrile. The method is linear in the following range: 2.5-37.5 μg/mL for yohimbine, 2.06-30.9 μg/mL for vardenafil, 2.0-30.0 μg/mL for sildenafil, 3.1-46.5 μg/mL for tadalafil, 1.98-29.7 μg/mL for dapoxetine, and 2.2-66.0 μg/mL for sibutramine. The linearity coefficient is R2 = 1 for all substances. Model matrices were spiked, and the analytical recoveries for all substances are in the range 97.5%-99.5%. The method exhibited an upper hand compared with previously reported methods in terms of speed and simplicity. Additionally, the mobile phase (also used as extracting, column washing, and diluting solvent) was composed of only buffer and acetonitrile, which rendered the method much cheaper than others.Item Development and validation of method for determination of organophosphorus pesticides traces in liver sample by GC-MS/MS-ion trap(2021-06-01) Boneva I.; Yaneva S.; Danalev D.A method for simultaneous determination of trace of four organophosphorus pesticides residues in animal liver samples has been developed and validated. This method is based on the preliminary sample preparation using extraction of target compound with a mixture of toluene-cyclohexane by means of up-to-date accelerated solvent extraction (ASE), liquid-liquid partitioning with acetonitrile and hexane, additional clean up step using QuEChERS method. Further the obtained analytes are determined by gas chromatography with ion-trap detector. The validation of the method is performed in accordance with the recommendations in Document SANTE/11945/2015 and it meets the acceptability criteria for precision, mean recovery and limits of quantification. The samples were investigated by analysing blank liver samples and samples spiked with the target analytes chlorpyrifos-methyl, parathion and pirimiphos-methyl at levels of 25, 50, and 75 ng/g and with diazinon at levels of 15, 30, and 45 ng/g. The recovery for all compounds were in the range from 73 to 104% which perfectly fit with requirements of documents and European legislations. The repeatability and within-laboratory reproducibility also reveal acceptable in documents coefficient of variation and uncertainty less than 20 and 18%, respectively. The limits of quantification were less than 3 ng/g for all compounds and allowed determination of residues below the maximum residue levels (MRLs) set in Regulation (EC) Nº396/2005.Item Enzymatic decolorization of dyes by laccase immobilized on hybrid carriers(2018-01-01) Yaneva S.; Rangelova N.; Aleksandrov L.; Danalev D.The study focused on sol-gel synthesis of biopolymer-silica hybrids further used as materials for laccase immobilization. Silica was obtained from tetraethyl orthosilicate (TEOS), while pectin, derived from citrus fruits, was used as a biopolymer. The structure of the hybrids obtained was investigated by X-ray diffraction, Fourier transform infrared spectroscopy, Scanning electron microscopy and BET analysis. The results provided to conclude that the interaction between SiO2 network and the polysaccharide proceeding via H-bonds formation was successful. Laccase was immobilized by cross-linking, while the degradation ability was tested against several dyes - Rhodamine B, Methyl orange and Malachite green. The most effective decolorization was reached for Malachite green and Methyl orange.Item Exploring the synthetic potency of the first furanothioglycoligase through original remote activation(2011-12-21) Almendros M.; Danalev D.; Franois-Heude M.; Loyer P.; Legentil L.; Nugier-Chauvin C.; Daniellou R.; Ferrières V.Thioglycosidic bonds are of utmost importance in biomolecules as their incorporation led to more stable glycomimetics with potential drug activities. Until now only chemical methods were available for their incorporation into glycofuranosyl conjugates. Herein, we wish to describe the use of the first furanothioglycoligase for the preparation of a great variety of thioaryl derivatives with moderate to excellent yields. Of great interest, a stable 1-thioimidoyl arabinofuranose, classically used in chemical glycosylation, was able to efficiently act as a donor through an original enzymatic remote activation mechanism. Study of the chemical structure as well as the nucleophilicity of the thiol allowed us to optimize this biocatalyzed process. As a consequence, this mutated enzyme constitutes an original, mild and eco-friendly method of thioligation. © The Royal Society of Chemistry 2011.Item First steps of development of a method for simultaneous determination of cholesterol and fatty acids in food matrices(2018-01-01) El Mazbouh H.; Givechev I.; Tanev D.; Yaneva S.; Danalev D.Cholesterol and fatty acids are compounds with a key role in the human organism. Their levels must be strictly controlled and maintained in the human body to ensure its proper biochemical functioning. Herein, we report first steps of development of a method for cholesterol determination in food using GC/FID. The calibration, the linearity and the choice of an appropriate internal standard are discussed. The obtained correlation coefficient is R2 = 0,9992. A very good analytical yield of cholesterol 100 % is achieved following a specific procedure of sample preparation. LOQ is 50 ppm, while LOD is 15 ppm.Item Hydrolytic stability of new amino acids analogues of memantine(2020-09-01) Tencheva A.; Chayrov R.; Mandjukov P.; Stankova I.; Danalev D.In the present work, the hydrolytic stability of new memantine analogues modified with amino acids, at different pH corresponding to the human biological liquids and organs, was evaluated. Memantine is an uncompetitive N-methyl-d-aspartate receptor antagonist with low-to moderate-affinity. In addition, it is the first representative of a novel class of Alzheimer’s disease (AD) medications acting on the glutamatergic system by blocking N-methyl-D-aspartate receptors. Generally, prodrugs are compounds aiming to improve stability of active fragment and to facilitate transportation across the cell membranes or lipid barriers. The investigated series of prodrugs include modified memantine with the following amino acids: alanine, β-alanine, glycine, phenylalanine, and valine. Hydrolytic stability was determined at two different pH values 2.0 and 7.4 at 37◦C, similar to those in the human stomach and blood plasma. Specially developed UV-VIS spectrophotometric method for quantification of the concentrations of unchanged compounds was applied in the kinetic studies. Val-MEM is the most stable in neutral medium and at 37◦C compound with t1/2 = 50.2 h. The compound Phe-MEM has also very good hydrolytic stability with t1/2 = 29.6 h. The order of other compounds is: Val-MEM ≫ Phe-MEM ≫ Ala-MEM ≈ Val-MEM > β-Ala-MEM. Ala-MEM and Gly-MEM are the most stable compounds at acid condition with almost identical values for t1/2 = 17.8 h and t1/2 = 16.3 h, respectively. The stability of tested compounds in acid conditions are relatively less than in neutral one. They are ordered as follows: Ala-MEM ≈ Gly-MEM > Val-MEM ≈ Phe-MEM ≈ β-Ala-MEM. All compounds have relatively good hydrolytic stability of more than 10 h at both neutral and acid conditions, which is quite enough in order to pass in the blood circulation and to be used as a potential antimicrobial agent.Item Interaction of KLAKLAK-NH2 and Analogs with Biomimetic Membrane Models(2024-03-01) Vitkova V.; Antonova K.; Petkov O.; Stoyanova-Ivanova A.; Jaber S.; Ivanova V.; Naydenova E.; Danalev D.Background: Specifically designed peptide mimetics offer higher selectivity regarding their toxicity to mammalian cells. In addition to the α-helix conformation, the specific activity is related to the peptide’s ability to penetrate the cell membrane. The alterations in lipid membrane properties were addressed in the presence of the peptide KLAKLAK-NH2 and analogs containing β-alanine, strengthening the antibacterial activity and/or naphtalimide with proven anticancer properties. Methods: The molecular interactions of the peptide mimetics with POPC bilayers were studied using FTIR-ATR spectroscopy. The thermal shape fluctuation analysis of quasispherical unilamellar vesicles was applied to probe the membrane bending elasticity. The impedance characteristics of bilayer lipid membranes were measured using fast Fourier-transform electrochemical impedance spectroscopy. Results: A lateral peptide association with the membrane is reported for β-alanine-containing peptides. The most pronounced membrane softening is found for the NphtG-KLβAKLβAK-NH2 analog containing both active groups that corroborate with the indications for 1,8-naphthalimide penetration in the lipid hydrophobic area obtained from the FTIR-ATR spectra analysis. The β-alanine substitution induces strong membrane-rigidifying properties even at very low concentrations of both β-alanine-containing peptides. Conclusions: The reported results are expected to advance the progress in tailoring the pharmacokinetic properties of antimicrobial peptides with strengthened stability towards enzymatic degradation. The investigation of the nonspecific interactions of peptides with model lipid membranes is featured as a useful tool to assess the antitumor and antimicrobial potential of new peptide mimetics.