Antioksidacijska, citotoksična i antibakterijska svojstva samosloživih glicinsko-histidinskih dipeptida sa srebrnim nanočesticama i bez njih u bioinspiriranom filmu

Recent years have seen much attention being given to self-assembly of dipeptide-based structures, especially to self-regulation of dipeptide structures with different amino acid sequences. In this study we investigated the effects of varying solvent environments on the selfassembly of glycine-histidine (Gly-His) dipeptide structures. First we determined the morphological properties of Gly-His films formed in different solvent environments with scanning electron microscopy and then structural properties with Fourier-transform infrared (FTIR) spectroscopy. In addition, we studied the effects of Gly-His films on silver nanoparticle (AgNP) formation and the antioxidant and cytotoxic properties of AgNPs obtained in this way. We also, assessed antibacterial activities of Gly-His films against Gram-negative Escherichia coli and Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus. Silver nanoparticle-decorated Gly-His films were not significantly cytotoxic at concentrations below 2 mg/mL but had antibacterial activity. We therefore believe that AgNP-decorated Gly-His films at concentrations below 2 mg/mL can be used safely against bacteria.Posljednjih je godina mnogo pažnje posvećeno samosloživim strukturama temeljenim na dipeptidima, a posebno samoregulaciji tih struktura s različitim nizovima aminokiselina. U ovome smo ispitivanju htjeli ustanoviti djelovanje različitih otopina na slaganje struktura dipeptida glicin-histidin (GH). Prvo smo utvrdili morfološka svojstva tih GH filmova odležanih u različitim otapalima pomoću pretražne (skenirajuće) elektronske mikroskopije, a zatim i njihova strukturna svojstva pomoću infracrvene spektroskopije s Fourierovom transformacijom (FTIR). Zatim smo utvrdili djelovanje tih struktura u filmu na raspoređivanje srebrnih nanočestica (AgNP) te antioksidacijska i citotoksična svojstva filmova obogaćenih AgNP-ovima. Osim toga, ocijenili smo antibakterijsko djelovanje filmova, s Ag česticama i bez njih na Gram negativne bakterije Escherichia coli i Pseudomonas aureginosa te Gram-pozitivni Staphylococcus aureus. GH filmovi s Ag nanočesticama nisu bili značajno citotoksični pri koncentracijama nižima od 2 mg/mL, ali su iskazale antibakterijsko djelovanje. Stoga smatramo da se takvi dipeptidni filmovi sa srebrnim nanočesticama mogu sigurno primjenjivati protiv bakterija

In vitro antimicrobial activity of three new generation disinfectants

Purpose: To determine the efficacies of three commercially available new generation disinfectants against some bacteria and yeast.Methods: Three commercially available new generation disinfectant (0.2 % chlorine dioxide, 0.3 % chlorine dioxide and 50 % hydrogen peroxide-stabilized by colloidal silver) were screened for their antimicrobial activity against Escherichia coli ATCC 25922, Klebsiella pneumonia RSKK 574, Pseudomonas aeruginosa ATCC 9027, Enterococcus faecalis ATCC 29212, Staphylococcus aureus ATCC 25923, S. aureus ATCC 43300 (methicillin resistant), S. epidermidis ATCC 12228 (non-biofilm forming), S. epidermidis ATCC 35948 (biofilm forming) and Candida albicans ATCC 10231. Quantitative suspension test was used to determine the efficacies of the disinfectants at contact times of 1, 3 and 5 min.Results: All of the new generation disinfectants were effective against test microorganisms at all test contact times.Conclusions: The findings indicate that the tested new generation disinfectants may be useful for routine disinfection purposes.Keywords: Antimicrobial activity, New generation disinfectants, Routine disinfectio

Ocjena apsorpcije, djelotvornosti protiv bakterije Escherichia coli i citotoksičnosti krutih lipidnih nanočestica s moksifloksacinom

Moxifloxacin (MOX) is an important antibiotic commonly used in the treatment of recurrent Escherichia coli (E. coli) infections. The aim of this study was to investigate its antibacterial efficiency when used with solid lipid nanoparticles (SNLs) and nanostructured lipid carriers (NLCs) as delivery vehicles. For this purpose we designed two SLNs (SLN1 and SLN2) and two NLCs (NLC1 and NLC2) of different characteristics (particle size, size distribution, zeta potential, and encapsulation efficiency) and loaded them with MOX to determine its release, antibacterial activity against E. coli, and their cytotoxicity to the RAW 264.7 monocyte/macrophage-like cell line in vitro. With bacterial uptake of 57.29 %, SLN1 turned out to be significantly more effective than MOX given as standard solution, whereas SLN2, NLC1, and NLC2 formulations with respective bacterial uptakes of 50.74 %, 39.26 %, and 32.79 %, showed similar activity to standard MOX. Cytotoxicity testing did not reveal significant toxicity of nanoparticles, whether MOX-free or MOX-loaded, against RAW 264.7 cells. Our findings may show the way for a development of effective lipid carriers that reduce side effects and increase antibacterial treatment efficacy in view of the growing antibiotic resistance.Moksifloksacin je važan antibiotik koji se često rabi za liječenje rekurentne infekcije bakterijom Escherichia coli (E. coli). Cilj je ovog istraživanja bio ocijeniti njegovu djelotvornost u formulaciji s krutim lipidnim nanočesticama (engl. solid lipid nanoparticles, krat. SNL) i nanostrukturiranim lipidnim nosačima (engl. nanostructured lipid carriers, krat. NLC) kao njegovim vehikulima. U tu smo svrhu osmislili dva SLN-a (SLN1 I SLN2) te dva NLC-a (NLC1 i NLC2) različitih svojstava (veličine čestice, raspodjele veličina, zeta potencijala i sposobnosti enkapsulacije) te ih obogatili moksifloksacinom kako bismo utvrdili njegovo otpuštanje, djelovanje protiv E. coli i citotoksičnost za makrofagnu staničnu liniju RAW 264.7 in vitro. S bakterijskom apsorpcijom od 57,29 %, SLN1 se pokazao značajno djelotvornijim vehikulom moksifloksacina od njegove standardne formulacije (otopine), a formulacije s SLN2, NLC1 odnosno NLC2 s odgovarajućim apsorpcijama od 50,74 %, 39,26 % odnosno 32,79 % iskazale su djelotvornost sličnu onoj standardnog antibiotika. Test citotoksičnosti nije pokazao značajnu toksičnost nanočestica bez obzira na to jesu li sadržavale moksifloksacin ili nisu. Naši rezultati upućuju na mogući smjer razvoja djelotvornih lipidnih nosača kojima bi se mogle smanjiti nuspojave i povećati antibakterijska djelotvornost liječenja s obzirom na sve veću bakterijsku rezistentnost

Chemical composition and antimicrobial activity of the commercial Origanum onites L. oil against nosocomial carbapenem resistant extended spectrum beta lactamase producer Escherichia coli isolates

In recent years rapidly growing antibiotic resistance has increased interest toward natural products, especially essential oils because of their various effects. The aim of this study was to identify the chemical composition of the commercial Origanum onites essential oil (EO) and to investigate the antimicrobial activity by disc diffusion and dilution methods, against ten different ATCC strains, including eight bacteria, two yeasts and seventy-nine clinical nosocomial Escherichia coli isolates that produce extended spectrum beta lactamase (ESBL). The chemical composition of EO was analyzed by GC and GC-MS. The major compounds of the EO were determined as carvacrol (51.4%) followed by linalool (11.2%), p-cymene (8.9%) and γ-terpinene (6.7%). O. onites EO had antimicrobial activity against all standard strains and inhibited microbial growth of ESBL positive E. coli isolates. According to our results, O. onites EO may be an alternative to synthetic drug, used in combination with other antibiotics for treatment of infection caused by multidrug resistant bacteria after testing toxic effects and irritation at preferred doses on human