ABSTRACT
BACKGROUND: Parabens are esters of p-hydroxybenzoic acid and are widely used as preservatives in cosmetics, pharmaceuticals and foodstuffs. The presences of parabens in infant formulas raise concerns due to their potential to disrupt endocrine function in infants and cause reproductive toxicities. METHODS: In this study a new method was developed for extraction and determination of methylparaben in infant formulas using HPLC method and UV detector. Methanol and trichloroacetic acid were used for extraction and isocratic mobile phase comprising equal proportions of glacial acetic acid in water (50:850 v/v) and methanol was used for separation of methylparaben. RESULTS: Recovery of the extraction procedure was good and interferences between methylparaben and other ingredients peaks in HPLC chromatograms decreased. The average recoveries for methylparaben were about 88-108 %. The limit of detection and limit of quantitation for methylparaben were 0.2 and 0.5 µg/mL, respectively. Results of the method showed good reproducibility (relative standard deviation (RSD) 0.29-1.94 % for within day analysis and 0.84-2.18 % for between day analysis). Results were linear in range of 0.5-20 µg/mL methylparaben. The results of twenty real infant formula samples showed methylparaben was found only in one sample in concentration 0.3 µg/mL. CONCLUSIONS: The new extraction and measurement method was a short-time method and could be applicable for large numbers of samples. This method was fast, sensitive and accurate and was capable of being used in legal laboratory references for determination of methylparaben content.
ABSTRACT
Biosurfactants, the microbial originated surface active agents, can modify the physicochemical properties of surfaces and reduce the bacterial adhesion via changing bacterial adhesion interactions on surfaces. They were also able to block oxidative chain reactions and might show antioxidant properties. The goal of this study was to evaluate the antioxidant and antibiofilm activities of biosurfactants which were derived from two autochthonous biosurfactant-producing strains, Bacillus amyloliquefaciens NS6 (surfactin), and Pseudomonas aeruginosa MN1 (rhamnolipids). Their antioxidant activities were determined by ferric reducing antioxidant power (FRAP) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) methods. Ferric thiocyanate (FTC) assay was used for determination of their lipid peroxidation inhibition capacity. Their effect to reduce the adhesion of Streptococcus mutans on polystyrene surfaces and disruption of its pre-formed biofilms were also investigated. Our results indicated that surfactin showed higher antioxidant activity than rhamnolipids and showed relatively similar efficiency to BHA that suggests it as a good alternative for synthetic antioxidants. In other hand, rhamnolipid conditioned surfaces showed higher antiadhesive and antibiofilm activity in comparison with surfactin treated surfaces.
ABSTRACT
Vitamin D deficiency causes osteoporosis, osteopenia, fractures, rickets, and more recently is linked with some chronic illnesses such as cancer. Because of the safety and probiotic properties of the yeast Saccharomyces cerevisiae, we hypothesized that yeast cells enriched with cholecalciferol (vitamin D3) could represent a solution for prevention or treatment of vitamin D deficiency. In this study S. cerevisiae was used as a vitamin D3 accumulator for the first time and the optimal conditions for enrichment of S. cerevisiae were determined. The Plackett-Burman screening studies were used for selection of the most important factors affecting cholecalciferol entrapment. Response surface methodology was employed for optimization of cholecalciferol accumulation in S. cerevisiae cells by using Box-Behnken design. A modified quadratic polynomial model fit the data appropriately. The optimal points of variables to maximize the response were cholecalciferol initial concentration of 358021.16 IU/mL, tryptone concentration of 1.82 g/L, sucrose concentration of 7.13 % (w/v), and shaking speed of 140.46 rpm. The maximum amount of cholecalciferol in dry cell weight of S. cerevisiae was 4428.11 IU/g. The cholecalciferol entrapment in yeast biomass increased about two-folds in optimized condition which indicates efficiency of optimization.
ABSTRACT
Recombinant plasminogen activator (reteplase) is a third generation thrombolytic agent which has been used on coronary artery thrombosis and acute myocardial infarction. Clot lysis assay is usually considered as a unique method to evaluate biological activity of reteplase. In this study biological activity of reteplase was determined by APTT (activated partial thromboplastin time) lysis method. Validity of this method was evaluated in comparison with reference method, clot lysis time assay. Results of APTT lysis test showed good reproducibility (relative standard deviation (RSD) 3-5% for within day analysis and 4-7% for between day analysis), and accuracy (101.3-102.7%). APTT lysis responses were linear in range of 0.001-0.1 mg/mL reteplase. Therefore, APTT lysis method is applicable for biological activity determination of reteplase. Although more comprehensive studies are required to approve this test as a reference method, APTT lysis method seems to be valuable to receive more attention due to advantages of technical simplicity, sensitivity, applicability, and cost efficiency.
