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Human serum paraoxonase 1 (PON1; EC 3.1.8.1) is a high-density lipoprotein associated, calcium-dependent enzyme that hydrolyses aromatic esters, organophosphates and lactones and can protect the low-density lipoprotein against oxidation. In this study, in vitro inhibition effect of some dihydroxy coumarin compounds namely 6,7-dihydroxy-3-(2-methylphenyl)-2H-chromen-2-one (A), 6,7-dihydroxy-3-(3-methylphenyl)-2H-chromen-2-one (B) and 6,7-dihydroxy-3-(4-methylphenyl)-2H-chromen-2-one (C) on purified PON1 were investigated by using paraoxon as a substrate. PON1 was purified using two-step procedures, namely ammonium sulphate precipitation and Sepharose-4B-L-tyrosine-1-naphthylamine hydrophobic interaction chromatography. The purified enzyme had a specific activity of 11.76 U/mg. The dihydroxy coumarin derivatives of A and B compounds inhibited PON1 enzyme activity in a noncompetitive inhibition manner with K(i) of 0.0080±0.256 and 0.0003±0.018 mM values, respectively. C compound exerted an uncompetitive inhibition of PON1 enzyme activity with K(i) of 0.0010±0.173 mM. Moreover, dihydroxy coumarin derivatives of A, B and C compounds were effective inhibitors on purified human serum PON1 activity with IC(50) of 0.012, 0.022 and 0.003 mM values, respectively. IC(50) value of unsubstituted 6,7 dihydroxy coumarin was found as 0.178 mM. The present study has demonstrated that PON1 activity is very highly sensitive to studied coumarin derivatives.

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This study was designed to examine the in vitro antimicrobial and antioxidant activities of the methanol, ethanol, water, n-hexane and dicholoromethane extracts of two Allium species (Allium scabriflorum and Allium tchihatschewii) which are endemic for the flora of Turkey. The antimicrobial efficiency of the plant was evaluated according to disc diffusion and microdilution broth methods. The antimicrobial test results showed that the extracts of A. scabriflorum and A. tchihatschewii showed varying degrees of antimicrobial activity on the tested microorganisms. The extracts were screened for their possible antioxidant activities by three complementary tests; DPPH free radical-scavenging, scavenging of hydrogen peroxide and metal chelating activity assays. All the extracts of A. scabriflorum and A. tchihatschewii exhibited lower DPPH free radical scavenging activity but higher metal chelating activity when compared to standards. The values of scavenging of hydrogen peroxide of the extracts were higher than the standards that of α-tocopherol, BHA, BHT and trolox, but close to that of ascorbic acid. In addition to the antioxidant activity of these plants, the total phenolic compounds and flavonoids were also measured in the extracts. The results presented here may suggest that the extracts of A. scabriflorum and A. tchihatschewii possess antimicrobial and antioxidant properties, and therefore, they can be used as a natural preservative ingredient in food and/or pharmaceutical industry.Key words: Allium scabriflorum, Allium tchihatschewii, antimicrobial activity, antioxidant activity, phenolic IntroductionThe spoilage and poisoning of foods by microorganisms are problems that have not yet been brought under adequate control despite the range of robust preservation techniques available. Raw and/or processed foods are open to contamination during the production, sale and distribution of them (Deak and Beuchat, 1996). Thus, at present, it is a necessity to use the chemical preservatives to prevent the growth of food spoiling microbes in the food industry (Sağdıç and Özcan, 2003). Consumers are increasingly avoiding foods prepared with preservatives of chemical origin, and natural alternatives are therefore needed to achieve sufficiently long shelf life of foods and a high degree of safety with respect to foodborne pathogenic microorganisms (Rauha et al., 2000).Synthetic antioxidants and antimicrobials in use have been shown to have harmful side effects (Gao et al., 1999;Williams et al., 1999;Osawa and Namiki, 1981), therefore, there is a need for more effective, less toxic and cost effective antioxidants and antimicrobials from natural sources. Recently, there are a lot of reports on the antioxidant and antimicrobial activities of plant-based extract, which has a potential application both in the food and in medicinal industries (Zeng et al., 2011).Since ancient times, several species of the genus Allium have been used as foods, spices or herbal remedies. The genus Allium L. is a member of the family Liliaceae a...

The antipsychotic drugs currently used to treat schizophrenia can be divided into two distinct classes, typical and atypical antipsychotics. Many drug molecules are enzyme inhibitors that bind reversibly or irreversibly to their target through intermolecular interactions. That's why enzyme inhibition studies are an important issue for drug design and biochemical applications. In this study, in vitro inhibition effect of some antipsychotic drugs on the purified carbonic anhydrase (CA) I and II isoenzymes were investigated by using CO2 as a substrate. CA I and II were purified from human erythrocytes by a simple one step procedure using Sepharose 4B-L-tyrosine-sulfonamide affinity column. The results showed that all the drugs inhibited the cytosolic carbonic anhydrases enzyme activity in a concentration-dependent fashion. Among the studied drugs, aripiprazole and pramipexole were found to be the most active one for hCA I (IC50: 3.64 and 5.37 μM) and hCA II (IC50: 4.16 and 4.81 μM) activity, respectively.

As a low-cost natural adsorbent, diatomite (DA) (2 μm) has several advantages including high surface area, chemical reactivity, hydrophilicity and lack of toxicity. In this study, the protein adsorption performance of supermacroporous composite cryogels embedded with Ni(2+)-attached DA particles (Ni(2+)-ADAPs) was investigated. Supermacroporous poly(2-hydroxyethyl methacrylate) (PHEMA)-based monolithic composite cryogel column embedded with Ni(2+)-ADAPs was prepared by radical cryo-copolymerization of 2-hydroxyethyl methacrylate (HEMA) with N,N'-methylene-bis-acrylamide (MBAAm) as cross-linker directly in a plastic syringe for affinity purification of human serum albumin (HSA) both from aqueous solutions and human serum. The chemical composition and surface area of DA was determined by XRF and BET method, respectively. The characterization of composite cryogel was investigated by SEM. The effect of pH, and embedded Ni(2+)-ADAPs amount, initial HSA concentration, temperature and flow rate on adsorption were studied. The maximum amount of HSA adsorption from aqueous solution at pH 8.0 phosphate buffer was very high (485.15 mg/g DA). It was observed that HSA could be repeatedly adsorbed and desorbed to the embedded Ni(2+)-ADAPs in poly(2-hydroxyethyl methacrylate) composite cryogel without significant loss of adsorption capacity. The efficiency of albumin adsorption from human serum before and after albumin adsorption was also investigated with SDS-PAGE analyses.

A novel 1-naphthylamine (NA) coupled poly(2-hydroxyethyl methacrylate-co-N-methacryloyl-(L)-histidine methyl ester) [NA-PHEMAH] supermacroporous monolithic hydrophobic cryogel was prepared via covalent coupling of NA to PHEMAH for adsorption of lysozyme from aqueous solution. Firstly, PHEMAH monolithic cryogel was prepared by radical cryocopolymerization of HEMA with MAH as a functional comonomer and N,N'-methylene-bisacrylamide (MBAAm) as a crosslinker directly in a plastic syringe, and then NA molecules were covalently attached to the imidazole rings of MAH groups of the polymeric structure. The prepared, NA-PHEMAH, supermacroporous monolithic hydrophobic cryogel was characterized by scanning electron microscopy (SEM). The effects of initial lysozyme concentration, pH, salt type, temperature and flow rate on the adsorption efficiency of monolithic hydrophobic cryogel were studied in a column system. The maximum amount of lysozyme adsorption from aqueous solution in phosphate buffer was 86.1 mg/g polymer at pH 8.0 with a flow rate of 1 mL/min. It was observed that lysozyme could be repeatedly adsorbed and desorbed with the NA-PHEMAH monolithic hydrophobic cryogel without significant loss of the adsorption capacity.