Polyphenols content and antioxidant activity of Ghure (unripe grape) marc extract: influence of extraction time,temperature and solvent type

The objective of this study was to optimise the temperature (25–50 °C), time (1–24 h) and the solvent ratio (ethanol/water, 0–100%) for the phenolic compounds extraction of Ghure marc (unripe grape) using response surface methodology. The central composite design (CCD) generated satisfactory models for the optimisation of process variables. The results revealed that the ratio (X₃) was the most significant parameter on total phenolic content (TPC) and antioxidant activity [% 2‐diphenyl‐1‐picrylhydrazyl (DPPH)], and there was a significant correlation between TPC and antioxidant activity. The optimal conditions for temperature and time were 44.93 °C and 19.34 h, respectively, and the ratio of ethanol to water was 70.08, which verified with carrying out confirmatory experiments. Under this condition, TPC and %DPPH were 388.79 mg GAE per 100 g and 91.01, respectively. The results of this study revealed that the Ghure marc can be used as a low‐cost source of natural antioxidant in food.     

Effect of crosslinking procedure on structural,thermal, and functional performances of cellulosic nanofibers: A comparison between chemical and photochemical crosslinking

In the current study, hydroxyethyl cellulose (HEC) based nanofibers were fabricated through electrospinning and then made water insoluble by chemical and photochemical crosslinking. Structural, thermal, and functional performances of electrospun fibers before and after crosslinking were fully assessed by a numerous techniques including microscopy, porosimetry, mechanical analysis, and cell culture study. Both crosslinking procures were found to able to preserve fibrous structure in an aqueous environment for short times, however; chemical process conferred better long‐term morphological stability and cell compatibility. These findings suggest that chemically crosslinked HEC mats may perform as a promising electrospun tissue engineering scaffold. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43832.     

Antibiotic Potency against E. coli Is Enhanced by Channel‐Forming Alkyl Lariat Ethers

Several N,N′‐bis(n‐alkyl‐4,13‐diaza[18]crown‐6) lariat ethers were found to significantly enhance the potency of rifampicin and tetracycline, but not erythromycin and kanamycin, against the non‐pathogenic DH5α and K‐12 strains of Escherichia coli when administered at levels below their minimum inhibitory concentrations (MICs). The enhancements in antibiotic potency observed for the lariat ethers ranged from three‐ to 20‐fold, depending on the strain of E. coli, the antibiotic, and the lengths of the alkyl chains attached at the macroring nitrogen atoms. The dialkyl lariat ethers, previously thought to only be cation carriers, formed well‐behaved, ion‐conducting pores in soybean asolectin membranes, as judged by planar bilayer conductance measurements. The ability of lariat ethers to form stable pores, which appeared to be aggregated, depended in part on alkyl chain length and in part on the composition of the bilayer membrane in which they were studied.     

Antioxidant properties of various solvent extracts of mulberry (Morus indica L.) leaves

The antioxidant properties and total phenolic contents of methanol, acetone and water extracts of mulberry (Morus indica L.) leaves were examined. Various experimental models including iron (III) reducing capacity, total antioxidant capacity, DPPH radical scavenging activity and in vitro inhibition of ferrous sulphate-induced oxidation of lipid system were used for characterization of antioxidant activity of extracts. The three extracts showed varying degrees of efficacy in each assay in a dose-dependent manner. Methanolic extract with the highest amount of total phenolics, was the most potent antioxidant in all the assays used. In addition, the effect of temperature (50 °C and 100 °C), pH (3, 5, 7, 9 and 11) and storage (5 °C) on the antioxidant activity of methanolic extract was investigated. The antioxidant activity of the extract remained unchanged at 50 °C and was maximum at neutral pH. The extract stored at 5 °C in the dark was stable for 30 days after which the antioxidant activity decreased (p ? 0.05) gradually. On the basis of the results obtained, mulberry leaves were found to serve as a potential source of natural antioxidants due to their marked antioxidant activity.     

Global occurrence of aflatoxin M1 in milk with particular reference to Iran

Aflatoxin M₁ (AFM₁) is an hydroxylated derivative of aflatoxin B₁ (AFB₁), which occurs in the milk of lactating animals. The aim of the present study was to determine the concentrations of AFM₁ in raw milk samples collected from 18 dairy farms in Qazvin, Iran, over a period of 1 year and compare them with those found in other countries. Samples (30 per farm) were collected in the four seasons, Spring, Summer, Autumn and Winter occurring between April 2009 and March 2010, giving a total of 2160 samples. They were centrifuged and 100 μl of the resulting skimmed milk were tested for AFM₁ contamination by competitive enzyme immunoassay (EIA). All samples (100 %) were contaminated with AFM₁ with concentrations ranging from 0.04 to 148.01 ng.l^?1 and a mean of 38.82 ng.l^?1. Summer samples with a mean of 64.69 ng.l^?1 and autumn samples with a mean of 0.14 ng.l^?1 had the highest and lowest concentrations, respectively, and differed significantly (P?<?0.05). AFM₁ content in 722 samples (33.4 %) was higher than the maximum tolerance limit of 50 ng.l^?1 accepted by the European Union (EU). As contamination of milk with AFM₁ is a potential risk for human health, raw milk should be monitored for its presence.     

Evaluation of antioxidant activity of some plant extracts and their heat,pH and storage stability

In the present study, three plant foods, namely, drumstick leaves (Moringa oleifera), mint leaves (Mentha spicata) and carrot tuber (Daucus carota) were extracted with ethanol and analyzed for their antioxidant activity. The antioxidant activity of extracts was evaluated according to the amount of malonaldehyde (MDA) formed by the FeSO₄-induced oxidation of linoleic acid and a high PUFA oil (sunflower oil) at 37 °C in Trizma-buffer (pH 7.4). At a concentration of 1.5 mg/ml of linoleic acid ,the extracts from drumstick and carrot had a higher antioxidant activity (83% and 80%) than α-tocopherol (72%). In sunflower oil, the extracts from drumstick leaves and mint leaves were found to exhibit a similar activity( 46% and 44%). The extract from drumstick exhibited the highest activity in both lipid systems. In addition, the stability of extracts to pH (4 and 9) and temperature (100 °C, 15 min) was investigated. The antioxidant activity of the extracts from mint leaves and carrot was higher at pH 9 than pH 4, while that of drumstick extract remained the same under both pH conditions. The extract from carrot was more heat-stable than other extracts. The three extracts stored in the dark at 5 and 25 °C after a 15 day period did not show any significant change (p ? 0.05) in their antioxidant activity. These data indicate that selected plant extracts are potential sources of dietary antioxidants.     

One polymer,one layer,and two opposite functions: Using a pH-switchable polymer to fabricate a hydrophilic–hydrophobic fibrous membrane

Thanks to their permissibility of vapor transmitting and resistance to water penetration, hydrophilic–hydrophobic membranes (HHMs) are a critical factor in so many applications. Current strategies focus on electrospinning hybrid layers from two different hydrophilic–hydrophobic polymers. Here, we report a new generation of HHMs by electrospinning one layer of pH-switchable polymers followed by a simple post-treatment. In doing so, a hydrophobic poly(methyl methacrylate)-co-poly(N,N-diethylaminoethylmethacrylate) (PMMA-co-PDEAEMA) membrane is fabricated using the electrospinning method. Then, hydrochloric acid (HCl) vapor is used to convert one face of the membrane to a hydrophilic state. Field emission-scanning electron microscopy, drop test, water contact angle (WCA), moisture management test (MMT), t ensile strength, water vapor permeability (WVP), air permeability (AP), and cytotoxicity test were used to characterize the obtained membrane. The results show that by HCl vapor exposure, one side of the membrane gets successfully converted into a hydrophilic state, with the other side still remaining hydrophobic. The drop test and the WCA test showed that the optimal exposure time is only 5 min. This trigger has a small effect on the morphology and, subsequently, on water and air permeability as well as on the mechanical behavior of the membrane. This new generation of membranes can have applications in protective clothing and wound dressing.     

GO nanosheets localization by morphological study on PLA-GO electrospun nanocomposite nanofibers

In this study we prepare a nanocomposite substrate from poly lactic acid (PLA) and graphene oxide (GO) using electrospinning. Determining the possible placement of graphene oxide nano-sheets in the electrospun fiber mats is the main goal of this work. The investigative methods employed include scanning electron microscopy (SEM), atomic force microscopy (AFM) micrographs, tensile modulus and attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR). It is shown that the localization of nanoparticle by different methods controls different final properties. We performed the study of the mechanical properties, surface chemical structure and topology of obtaining nanofiber mats. Studies showed that the location of GO sheets depends on the lateral size of them and based on this claim we estimated three possible locations for them: (1) small GO sheets (less than 200 nm) fully or partially inside the electrospun fibers, (2) some larger ones rolling around and on the fibers surface under the high applied voltage, and (3) parts of large sheets bridging between the fibers.