SciCombinator

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Journal: International journal of molecular sciences

166

We report the preparation and characterization of spherical core-shell structured Fe3O4-Au magnetic nanoparticles, modified with two component self-assembled monolayers (SAMs) consisting of 3-mercaptophenylboronic acid (3-MBA) and 1-decanethiol (1-DT). The rapid and room temperature synthesis of magnetic nanoparticles was achieved using the hydroxylamine reduction of HAuCl4 on the surface of ethylenediaminetetraacetic acid (EDTA)-immobilized iron (magnetite Fe3O4) nanoparticles in the presence of an aqueous solution of hexadecyltrimetylammonium bromide (CTAB) as a dispersant. The reduction of gold on the surface of Fe3O4 nanoparticles exhibits a uniform, highly stable, and narrow particle size distribution of Fe3O4-Au nanoparticles with an average diameter of 9 ± 2 nm. The saturation magnetization value for the resulting nanoparticles was found to be 15 emu/g at 298 K. Subsequent surface modification with SAMs against glucoside moieties on the surface of bacteria provided effective magnetic separation. Comparison of the bacteria capturing efficiency, by means of different molecular recognition agents 3-MBA, 1-DT and the mixed monolayer of 3-MBA and 1-DT was presented. The best capturing efficiency of E. coli was achieved with the mixed monolayer of 3-MBA and 1-DT-modified nanoparticles. Molecular specificity and selectivity were also demonstrated by comparing the surface-enhanced Raman scattering (SERS) spectrum of E. coli-nanoparticle conjugates with bacterial growth media.

Concepts: Bacteria, Gut flora, Nanoparticle, Escherichia coli, Chemistry, Magnetism, Proteobacteria, Magnetite

165

The Asian cycads are mostly allopatric, distributed in small population sizes. Hybridization between allopatric species provides clues in determining the mechanism of species divergence. Horticultural introduction provides the chance of interspecific gene flow between allopatric species. Two allopatrically eastern Asian Cycas sect. Asiorientales species, C. revoluta and C. taitungensis, which are widely distributed in Ryukyus and Fujian Province and endemic to Taiwan, respectively, were planted in eastern Taiwan for horticultural reason. Higher degrees of genetic admixture in cultivated samples than wild populations in both cycad species were detected based on multilocus scans by neutral AFLP markers. Furthermore, bidirectional but asymmetric introgression by horticultural introduction of C. revoluta is evidenced by the reanalyses of species associated loci, which are assumed to be diverged after species divergence. Partial loci introgressed from native cycad to the invaders were also detected at the loci of strong species association. Consistent results tested by all neutral loci, and the species-associated loci, specify the recent introgression from the paradox of sharing of ancestral polymorphisms. Phenomenon of introgression of cultivated cycads implies niche conservation among two geographic-isolated cycads, even though the habitats of the extant wild populations of two species are distinct.

Concepts: Biology, Taiwan, Gene flow, Cycad, Cycas, Cycas revoluta

165

Size-controlled and monodispersed silver nanoparticles were synthesized from an aqueous solution containing silver nitrate as a metal precursor, polyvinyl alcohol as a capping agent, isopropyl alcohol as hydrogen and hydroxyl radical scavengers, and deionized water as a solvent with a simple radiolytic method. The average particle size decreased with an increase in dose due to the domination of nucleation over ion association in the formation of the nanoparticles by gamma reduction. The silver nanoparticles exhibit a very sharp and strong absorption spectrum with the absorption maximum λmax blue shifting with an increased dose, owing to a decrease in particle size. The absorption spectra of silver nanoparticles of various particle sizes were also calculated using a quantum physics treatment and an agreement was obtained with the experimental absorption data. The results suggest that the absorption spectrum of silver nanoparticles possibly derived from the intra-band excitations of conduction electrons from the lowest energy state (n = 5, l = 0) to higher energy states (n ≥ 6; Δl = 0, ±1; Δs = 0, ±1), allowed by the quantum numbers principle. This demonstrates that the absorption phenomenon of metal nanoparticles based on a quantum physics description could be exploited to be added into the fundamentals of metal nanoparticles and the related fields of nanoscience and nanotechnology.

Concepts: Alcohol, Photon, Energy, Quantum mechanics, Chemistry, Atom, Nanotechnology, Atomic orbital

164

Many Gram-negative plant pathogenic bacteria employ a N-acylhomoserine lactone (AHL)-based quorum sensing (QS) system to regulate their virulence traits. A sustainable biocontrol strategy has been developed using quorum quenching (QQ) bacteria to interfere with QS and protect plants from pathogens. Here, the prevalence and the diversity of QQ strains inhabiting tobacco leaf surfaces were explored. A total of 1177 leaf-associated isolates were screened for their ability to disrupt AHL-mediated QS, using the biosensor Chromobacterium violaceum CV026. One hundred and sixty-eight strains (14%) are capable of interfering with AHL activity. Among these, 106 strains (63%) of the culturable quenchers can enzymatically degrade AHL molecules, while the remaining strains might use other QS inhibitors to interrupt the chemical communication. Moreover, almost 79% of the QQ strains capable of inactivating AHLs enzymatically have lactonase activity. Further phylogenetic analysis based on 16S rDNA revealed that the leaf-associated QQ bacteria can be classified as Bacillus sp., Acinetobacter sp., Lysinibacillus sp., Serratia sp., Pseudomonas sp., and Myroides sp. The naturally occurring diversity of bacterial quenchers might provide opportunities to use them as effective biocontrol reagents for suppressing plant pathogen in situ.

Concepts: Bacteria, Microbiology, Pseudomonas aeruginosa, Pathogen, Cell wall, Biofilm, Quorum sensing, Pathogenic bacteria

163

Insulin resistance is defined as a reduced ability of insulin to stimulate glucose utilization. C57BL/6 mice fed with a high-fat diet (HFD) are a model of insulin resistance. In skeletal muscle, hydrogen peroxide (H2O2) produced by NADPH oxidase 2 (NOX2) is involved in signaling pathways triggered by insulin. We evaluated oxidative status in skeletal muscle fibers from insulin-resistant and control mice by determining H2O2 generation (HyPer probe), reduced-to-oxidized glutathione ratio and NOX2 expression. After eight weeks of HFD, insulin-dependent glucose uptake was impaired in skeletal muscle fibers when compared with control muscle fibers. Insulin-resistant mice showed increased insulin-stimulated H2O2 release and decreased reduced-to-oxidized glutathione ratio (GSH/GSSG). In addition, p47phox and gp91phox (NOX2 subunits) mRNA levels were also high (~3-fold in HFD mice compared to controls), while protein levels were 6.8- and 1.6-fold higher, respectively. Using apocynin (NOX2 inhibitor) during the HFD feeding period, the oxidative intracellular environment was diminished and skeletal muscle insulin-dependent glucose uptake restored. Our results indicate that insulin-resistant mice have increased H2O2 release upon insulin stimulation when compared with control animals, which appears to be mediated by an increase in NOX2 expression.

Concepts: Oxygen, Insulin, Glucose, Redox, Glycogen, Hydrogen peroxide, NADPH oxidase, Skeletal muscle

160

The influence of seven plum rootstocks (Adesoto, Monpol, Montizo, Puebla de Soto 67 AD, PM 105 AD, St. Julien GF 655/2 and Constantí 1) on individual and total sugars, as well as on antioxidant content in fruit flesh of “Catherine” peaches, was evaluated for three years. Agronomical and basic fruit quality parameters were also determined. At twelve years after budding, significant differences were found between rootstocks for the different agronomic and fruit quality traits evaluated. The Pollizo plum rootstocks Adesoto and PM 105 AD seem to induce higher sweetness to peach fruits, based on soluble solids content, individual (sucrose, fructose and sorbitol) and total sugars. A clear tendency was also observed with the rootstock Adesoto, inducing the highest content of phenolics, flavonoids, vitamin C and relative antioxidant capacity (RAC). Thus, the results of this study demonstrate the significant effect of rootstock on the sugar profile and phytochemical characteristics of peach fruits. In addition, this work shows the importance of the sugar profile, because specific sugars play an important role in peach flavour quality, as well as the studied phytochemical compounds when looking for high quality peaches with enhanced health properties.

Concepts: Nutrition, Glucose, Antioxidant, Fruit, Sugar, Fructose, Peach, Sucrose

156

In light of their environmental and economic interests, food byproducts have been increasingly exploited and valorized for their richness in dietary fibers and antioxidants. Phenolic compounds are antioxidant bioactive molecules highly present in grape byproducts. Herein, the accelerated solvent extraction (ASE) of phenolic compounds from wet and dried grape pomace, at 45 °C, was conducted and the highest phenolic compounds yield (PCY) for wet (16.2 g GAE/100 g DM) and dry (7.28 g GAE/100 g DM) grape pomace extracts were obtained with 70% ethanol/water solvent at 140 °C. The PCY obtained from wet pomace was up to two times better compared to the dry byproduct and up to 15 times better compared to the same food matrices treated with conventional methods. With regard to Resveratrol, the corresponding dry pomace extract had a better free radical scavenging activity (49.12%) than the wet extract (39.8%). The drying pretreatment process seems to ameliorate the antiradical activity, especially when the extraction by ASE is performed at temperatures above 100 °C. HPLC-DAD analysis showed that the diversity of the flavonoid and the non-flavonoid compounds found in the extracts was seriously affected by the extraction temperature and the pretreatment of the raw material. This diversity seems to play a key role in the scavenging activity demonstrated by the extracts. Our results emphasize on ASE usage as a promising method for the preparation of highly concentrated and bioactive phenolic extracts that could be used in several industrial applications.

Concepts: Antioxidant, Thermodynamics, Vitamin C, Drying, Resveratrol, Phenolic compounds in wine, By-product, Grape seed oil

154

Cranberry consumption has shown prophylactic effects against urinary tract infections (UTI), although the mechanisms involved are not completely understood. In this paper, cranberry phenolic compounds and their potential microbial-derived metabolites (such as simple phenols and benzoic, phenylacetic and phenylpropionic acids) were tested for their capacity to inhibit the adherence of uropathogenic Escherichia coli (UPEC) ATCC®53503™ to T24 epithelial bladder cells. Catechol, benzoic acid, vanillic acid, phenylacetic acid and 3,4-dihydroxyphenylacetic acid showed anti-adhesive activity against UPEC in a concentration-dependent manner from 100-500 µM, whereas procyanidin A2, widely reported as an inhibitor of UPEC adherence on uroepithelium, was only statistically significant (p < 0.05) at 500 µM (51.3% inhibition). The results proved for the first time the anti-adhesive activity of some cranberry-derived phenolic metabolites against UPEC in vitro, suggesting that their presence in the urine could reduce bacterial colonization and progression of UTI.

Concepts: Kidney, Urinary tract infection, Urine, Escherichia coli, Urinary bladder, Urinary system, Catechin, Vanillin

148

Moringa oleifera seeds are a promising resource for food and non-food applications, due to their content of monounsaturated fatty acids with a high monounsaturated/saturated fatty acids (MUFA/SFA) ratio, sterols and tocopherols, as well as proteins rich in sulfated amino acids. The rapid growth of Moringa trees in subtropical and tropical areas, even under conditions of prolonged drought, makes this plant a reliable resource to enhance the nutritional status of local populations and, if rationalized cultivation practices are exploited, their economy, given that a biodiesel fuel could be produced from a source not in competition with human food crops. Despite the relatively diffuse use of Moringa seeds and their oil in traditional medicine, no pharmacological activity study has been conducted on humans. Some encouraging evidence, however, justifies new efforts to obtain clear and definitive information on the benefits to human health arising from seed consumption. A critical review of literature data concerning the composition of Moringa oil has set in motion a plan for future investigations. Such investigations, using the seeds and oil, will focus on cultivation conditions to improve plant production, and will study the health effects on human consumers of Moringa seeds and their oil.

Concepts: Health, Human, Agriculture, Amino acid, Nutrition, Oleic acid, Moringa oleifera, Moringa

147

Glutathione in its reduced form (GSH) is an antioxidant and also is involved in pheomelanin formation. Thus, it has been long believed that GSH has a skin whitening effect. However, its actual or direct effect is unproven. We evaluated the anti-melanogenic effects of GSH and its derivatives in vitro. We examined change of melanogenesis and its related proteins by GSH itself and its derivatives, including GSH monoethyl ester (GSH-MEE), GSH diethyl ester (GSH-DEE) and GSH monoisopropyl ester (GSH-MIPE) in Melan-A cells, Mel-Ab cells, and B16F10 cells. GSH and GSH-MEE did not display cytotoxic activity, but GSH-MIPE and GSH-DEE did. Intriguingly, GSH itself had no inhibitory effect on melanin production or intracellular tyrosinase activity. Rather, it was GSH-MEE and GSH-MIPE that profoundly reduced the amount of melanin and intracellular tyrosinase activity. Thus, GSH-MEE was selected as a suitable candidate skin-whitening agent and it did not alter melanogenesis-associated proteins such as microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase-related protein (TRP)-1, and TRP-2, but it did increase the amount of suggested pheomelanin and suggested pheomelanin/eumelanin ratio. GSH-MEE was effective for anti-melanogenesis, whereas GSH itself was not. GSH-MEE could be developed as a safe and efficient agent for the treatment of hyperpigmentation skin disorders.

Concepts: DNA, Protein, Amino acid, Melanin, Melanocyte, Tyrosinase, Acetylcysteine, Skin whitening