Serap Derman

Protective effect of chemically modified SOD on lipid peroxidation and antioxidant status in diabetic rats.

Reactive oxygen species mediated oxidative stress play an important role on the injury of tissue damage and increased attention has been focused on the role of free radicals in diabetes mellitus (DM). In the present study firstly superoxide dismutase (SOD) enzyme was chemically modified with two different polymer and physicochemical properties of these conjugates clearly analyzed. Then, the stability of carboxymethylcellulose-SOD (CMC-SOD) and poly methyl vinyl ether-co-maleic anhydride-SOD (PMVE/MA-SOD) conjugates was investigated against temperature and externally added H2O2. Moreover, we investigated the effect of chemically modified SOD enzyme on lipid peroxidation and antioxidant status in streptozotocin (STZ)-induced diabetic rats. PMVE/MA-SOD conjugate treatment significantly reduced MDA level compared with the control groups, native and CMC-SOD conjugate treated groups in brain, kidney and liver tissue. GSH and SOD enzyme activity in diabetic groups was significantly increased by treatment of CMC-SOD and PMVE/MA-SOD conjugates. The protective effects on degenerative changes in diabetic rats were also further confirmed by histopathological examination. This study provides the preventative activity of SOD-polymer conjugates against complication of oxidative stress in experimentally induced diabetic rats. These results suggest that chemically modified SOD is effective on the oxidative stress-associated disease and offer a therapeutic advantage in clinical use.

Comparative evaluation of antibacterial activity of caffeic acid phenethyl ester and PLGA nanoparticle formulation by different methods.

The aim of the present study was to evaluate the antimicrobial activity of nanoparticle and free formulations of the CAPE compound using different methods and comparing the results in the literature for the first time. In parallel with this purpose, encapsulation of CAPE with the PLGA nanoparticle system (CAPE-PLGA-NPs) and characterization of nanoparticles were carried out. Afterwards, antimicrobial activity of free CAPE and CAPE-PLGA-NPs was determined using agar well diffusion, disk diffusion, broth microdilution and reduction percentage methods. P. aeroginosa, E. coli, S. aureus and methicillin-resistant S. aureus (MRSA) were chosen as model bacteria since they have different cell wall structures. CAPE-PLGA-NPs within the range of 214.0 ± 8.80 nm particle size and with an encapsulation efficiency of 91.59 ± 4.97% were prepared using the oil-in-water (o-w) single-emulsion solvent evaporation method. The microbiological results indicated that free CAPE did not have any antimicrobial activity in any of the applied methods whereas CAPE-PLGA-NPs had significant antimicrobial activity in both broth dilution and reduction percentage methods. CAPE-PLGA-NPs showed moderate antimicrobial activity against S. aureus and MRSA strains particularly in hourly measurements at 30.63 and 61.25 μg ml(-1) concentrations (both p < 0.05), whereas they failed to show antimicrobial activity against Gram-negative bacteria (P. aeroginosa and E. coli, p > 0.05). In the reduction percentage method, in which the highest results of antimicrobial activity were obtained, it was observed that the antimicrobial effect on S. aureus was more long-standing (3 days) and higher in reduction percentage (over 90%). The appearance of antibacterial activity of CAPE-PLGA-NPs may be related to higher penetration into cells due to low solubility of free CAPE in the aqueous medium. Additionally, the biocompatible and biodegradable PLGA nanoparticles could be an alternative to solvents such as ethanol, methanol or DMSO. Consequently, obtained results show that the method of selection is extremely important and will influence the results. Thus, broth microdilution and reduction percentage methods can be recommended as reliable and useful screening methods for determination of antimicrobial activity of PLGA nanoparticle formulations used particularly in drug delivery systems compared to both agar well and disk diffusion methods.

Enhancement of Antifungal Activity of Juglone (5-Hydroxy-1,4-naphthoquinone) Using a Poly(d,l-lactic-co-glycolic acid) (PLGA) Nanoparticle System

This study aimed to synthesize and characterize juglone-entrapped poly(d,l-lactic-co-glycolic acid) (PLGA) nanoparticles and compare the antifungal properties of free juglone with its PLGA nanoparticle formulation for the first time. The juglone-loaded nanoparticles prepared using the oil-in-water (o/w) single-emulsion solvent evaporation method were characterized by the reaction yield (RY), encapsulation efficiency (EE), polydispersity index (PDI), particle size, zeta potential (ZP), FT-IR, and in vitro release properties and evaluated for their morphological features using SEM. The nanoparticle formulation had size, RY, ZP, EE, and PDI values of 212 nm, 66.91 ± 2.4%, -16.3 ± 0.7 mV, 70.66 ± 3.1%, and 0.083 ± 0.024, respectively. In vitro release showed a triphasic pattern with initial burst followed by sustained release and dormant phase over the study period, releasing about 72.8% in total after 42 days. The antifungal studies against Aspergillus flavus, Candida albicans, and Fusarium spp. using agar dilution and top agar dilution methods indicated that the juglone-encapsulated nanoparticle was more effective than free juglone. This study showed that the top agar method, which was applied for the first time on antifungal activity, is more suitable for the nanoparticular system based on sustained release. Therefore, PLGA nanoparticle formulations may be an important tool for application in many areas for the effective and beneficial use of hydrophobic compounds such as juglone.

Caffeic acid phenethyl ester loaded PLGA nanoparticles: effect of various process parameters on reaction yield, encapsulation efficiency, and particle size

CAPE loaded PLGA nanoparticles were prepared using the oil in water (o/w) single emulsion solvent evaporation methods. Five different processing parameters including initial CAPE amount, initial PLGA amount, PVA concentration in aqueous phase, PVA volume, and solvent type were screened systematically to improve encapsulation of hydrophobic CAPE molecule, simultaneously minimize particle size, and raise the reaction yield. Obtained results showed that the encapsulation efficiency of the nanoparticles significantly increased with the increase of the initial CAPE amount (p < 0.05) and particle size (p < 0.05). Furthermore, the particle size is significantly influenced by initial polymer amount (p < 0.05) and surfactant concentration (p < 0.05). By the optimization of process parameters, the nanoparticles produced 70 ± 6% reaction yield, 89 ± 3% encapsulation efficiency, -34.4±2.5 mV zeta potential, and 163±2 nm particle size with low polydispersity index 0.119±0.002. The particle size and surface morphology of optimized nanoparticles were studied and analyses showed that the nanoparticles have uniform size distribution, smooth surface, and spherical shape. Lyophilized nanoparticles with different CAPE and PLGA concentration in formulation were examined for in vitro release at physiological pH. Interestingly, the optimized nanoparticles showed a high (83.08%) and sustained CAPE release (lasting for 16 days) compared to nonoptimized nanoparticle.

Particle size and zeta potential investigation of synthetic peptide-protein conjugates / Sentetik peptid-protein konjugatlarının parçacık boyutu ve zeta potensiyel analizi

Abstract Objective: Synthetic peptides are not sufficiently large or complex by themselves to induce immune system because of their small size. Synthetic peptides are usually conjugated to different carriers such as proteins and polyelectrolytes to enhance their immunogenic properties and antigen-specific antibody production (Abs) rate. Thus, the aim of this study is synthesis of peptide-protein covalent conjugates, and size and zeta potential analysis of these conjugates. Methods: In this study, synthetic peptide antigen of the 135-161 amino acids sequence of immunogenic VP1 capsid protein of “A” type foot-and-mouth disease virus (FMDV) was covalently conjugated to bovine serum albumin (BSA) with the carbodiimide method by using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) at different molar ratios of peptide (γ=nPeptide/nBSA). Particle size and zeta potential analysis of peptide-protein bioconjugates have been performed by using dynamic and electrophoretic light-scattering methods. Results: The size and surface charge of bioconjugates are important factors in a synthetic peptide vaccine. Nevertheless, there virtually no research has been conducted on zeta potential and the size of peptide-protein bioconjugates detailed. Conclusion: Dynamic and electrophoretic light scattering analyses clearly demonstrated that zeta potential of the FMDV 135-161 synthetic peptide-BSA conjugates shifts to less negative potentials and particle sizes increase as the amount of peptide increased in conjugates. The data about peptide-carrier protein conjugates obtained by using these methods are very important for developing peptide-based vaccines. Ozet Amac: Sentetik peptidler, kucuk boyutlarından dolayı, immun sistemin uyarılması icin gerekli buyuklukte ve kompleks yapıda değildir. Sentetik peptidler, immunojenik ozelliklerinin duzenlenmesi ve antijen-spesifik antikor uretimi oranını arttırmak icin genellikle protein ve polielektrolitler gibi farklı taşıyıcılar ile konjuge edilmektedirler. Metod: Bu calışmada, A tipi şap hastalığı virusunun (FMDV) VP1 yuzey proteininin 135-161 amino asid dizili antijenik peptidi, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) kullanılarak, sığır serum albumin proteinine kovalent olarak bağlanmıştır. Bağlama peptidin farklı mol oranlarında (γ=nPeptide/nBSA) gercekleştirilmiştir. Bulgular: Sentetik peptid aşılarında biyokonjugatların boyut ve yuzey yukleri onemli faktorlerdir. Buna karşın peptid-protein biyokonjugatlarının detaylı olarak boyut ve zeta potansiyel analizlerinin yapıldığı neredeyse hic calışma bulunmamaktadır. Sonuc: Dinamik ve elektroforetik ışık sacılması sonucları; FMDV 135-161 sentetik peptid-BSA konjugatlarının zeta potansiyel değerinin mutlak mutlak kucuk değerlere kaydığını ve parcacık boyutunun da peptidin artan oranları ile beraber arttığını gostermiştir. Bu yontemler kullanılarak peptid-taşıycı protein konjugatları hakkında elde edilen veriler peptid bazlı aşı geliştirme calışmalarında oldukca onemlidir.

Assessment of the Antigenotoxic Activity of Poly(d,l-lactic-co-glycolic acid) Nanoparticles Loaded with Caffeic Acid Phenethyl Ester Using the Ames Salmonella/Microsome Assay

In the present study, the antigenotoxic activity of poly(d,l-lactic- co-glycolic acid) (PLGA) nanoparticles (NPs) loaded with caffeic acid phenethyl ester (CAPE) was investigated in comparison to free CAPE using the Ames Salmonella/microsome assay. Additionally, to elucidate the impacts of the type of solvent effect on antigenotoxic activity, the following systems were tested: CAPE in water (poor solvent), ethyl alcohol (good solvent), and PLGA NPs (unknown). The effect of the NP system on solubility was investigated for the first time by assessing the antigenotoxic potential. In this study, the CAPE/PLGA NPs were synthesized using an oil-in-water (o/w) single-emulsion solvent evaporation method with an average size of 206.2 ± 1.2 nm, ζ potential of -19.8 ± 2.5 mV, encapsulation efficiency of 87.2 ± 2.5%, and drug loading of 53.3 ± 1.8%. According to the results of the antigenotoxic activity, the highest antimutagenic activity in both applied strains was found for CAPE in ethanol, and the lowest activity was detected for CAPE in water. Our study has shown that NP systems exhibit high antigenotoxic activity, which is similar to the results of CAPE dissolved in ethanol. These results have shown that NP systems increase biological activity of hydrophobic substances by increasing their solubility and that the use of PLGA instead of organic solvents in drug production may provide an increase in their medical utility.

An In vivo study: Adjuvant activity of poly-n-vinyl-2-pyrrolidone-co-acrylic acid on immune responses against Melanoma synthetic peptide

ABSTRACT Peptides have been studied as an important class of components in medicine to control many major diseases with vaccination. Polymers as adjuvants are capable of enhancing the vaccine potential against various diseases by improving the delivery of antigens, and they reduce the booster doses of vaccines. In brief, polymers are promising candidates for peptide-based vaccine delivery platforms. The purpose of the present study was to create a possible alternative approach in the treatment of malignant melanoma and/or to prevent metastasis of melanoma. The study was designed as both an experimental and an in vivo study. We prepared a complex and covalent conjugate of MAGE-3 121–134 (L-L-K-Y-R-A-R-E-P-V-T-K-A-E) T-cell epitope as a vaccine candidate for melanoma. These conjugates were able to generate an immune response in mice after a single immunization, without the help of any external adjuvant. The peptide-polymer complexes activated the immune system in the best way and formed the highest antigen specific immune response. These results indicate the adjuvant activity of Poly(N-vinyl-2- pyrrolidone-co-acrylic acid) [P(VP-co-AA)] and the potential use of P(VP-coAA)-peptide based vaccine prototypes for future melanoma cancer vaccine formulations.

Synthesis, characterization and antibacterial activity of juglone encapsulated PLGA nanoparticles

The aim of the study was to examine the effect of different process parameters which including; initial juglone amount, initial poly(d,l‐lactide co‐glycolide) amount, polyvinyl alcohol volume and polyvinyl alcohol concentration on encapsulation of juglone to poly(d,l‐lactide co‐glycolide) nanoparticles.