Time-resolved EPR investigation of oxygen and temperature effects on synthetic eumelanin

Synthetic eumelanin produced using 5,6-dihydroxyindole-2-carboxylic acid as precursor and H2O2/horseradish peroxidase as oxidative reagent, in form of dry powder, has been investigated under photoexcitation by TR-EPR spectroscopy. The formation of spin polarized radical pairs from triplet excited states of melanin has been observed both in absence and in presence of oxygen and has been followed as a function of the temperature in the range 140–290 K. The triplet mechanism explains the observed polarization pattern in net emission. In the presence of oxygen new radical pairs are formed by interaction of melanin with molecular oxygen

Resveratrol-based benzoselenophenes with an enhanced antioxidant and chain breaking capacity

The structural modification of the resveratrol scaffold is currently an active issue in the quest for more potent and versatile antioxidant derivatives for biomedical applications. Disclosed herein is an expedient and efficient entry to a novel class of resveratrol derivatives featuring an unprecedented 2-phenylbenzoselenophene skeleton. The new compounds were obtained in good yields by direct selenenylation of resveratrol with Se(0) and SO2Cl2 in dry THF. Varying the [Se:SO2Cl2:resveratrol] ratio resulted in the formation of the parent benzoselenophene (1) and/or mono (2) and/or dichloro (3) benzoselenophene derivatives. All the benzoselenophene derivatives proved to be more efficient than resveratrol in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing/antioxidant power (FRAP) assays, with 1 showing an activity nearly comparable to that of Trolox. 1-3 also proved to be more efficient inhibitors than the parent resveratrol in kinetic experiments of styrene autoxidation. DFT calculations of the O-H bond dissociation enthalpy (BDE) revealed that the introduction of the Se-atom causes a significant decrease of the BDE of 3-OH and 5-OH, with just a small increase of the 4′-OH BDE. Compounds 1-3 showed no cytotoxicity at 5 μM concentrations on human keratinocyte (HaCaT) and intestinal (CaCo-2) cell line

improving the health quality of fried falafel middle eastern food by using transglutaminase and or pectin coating

The most disadvantage of the fried falafel balls are the highest level of acrylamide formed during Maillard reaction. Falafel balls are one of the largest deep fat frying fast food in the Middle East made basically of chickpeas. The main aim of this study was to investigate the effect of adding transglutaminase (TG, E.C. 2.3.2.13) to the falafel dough followed or not by dipping into pectin (PEC 1%) coating solution. Acrylamide, oil and water content of the fried falafel balls treated or not by TG (5 or 20U/g of chickpea proteins) and coated or not with PEC-containing film forming solutions were evaluated. In addition, the texture profile analyses were carried out. We observed, by TOF LC/MS, that the acrylamide content was reduced, compared to control sample, by 10.8% and 34.4% in the samples set up by adding 5 and 20 U TG/g respectively. In PEC-coated samples, acrylamide reduction was about by 59%, 65.3% and 84.5%, in falafel balls prepared either without of TG or containing 5U or 20 U of the enzyme, respectively, suggesting that TG-mediated crosslinks increase the water content inside the falafel balls, thus, reducing the rate of Maillard reaction. However, TG treatment does not affect oil content, while the PEC coating reduces the oil uptake about 23.5%. Finally, no difference was observed between the control sample and the one dipped in PEC regarding their texture properties hardness, chewiness and gumminess, while these properties were influenced in samples set up in the presence of the enzyme

Deposition of Antioxidant and Cytocompatible Caffeic Acid-Based Thin Films onto Ti6Al4V Alloys through Hexamethylenediamine-Mediated Crosslinking

A promising approach for advanced bone implants is thedepositionon titanium surfaces of organic thin films with improved therapeuticperformances. Herein, we reported the efficient dip-coating depositionof caffeic acid (CA)-based films on both polished and chemically pre-treatedTi6Al4V alloys by exploiting hexamethylenediamine (HMDA) crosslinkingability. The formation of benzacridine systems, resulting from theinteraction of CA with the amino groups of HMDA, as reported in previousstudies, was suggested by the yellow/green color of the coatings.The coated surfaces were characterized by means of the Folin-Ciocalteumethod, fluorescence microscopy, water contact angle measurements,X-ray photoelectron spectroscopy (XPS), zeta-potential measurements,and Fourier transform infrared spectroscopy, confirming the presenceof a uniform coating on the titanium surfaces. The optimal mechanicaladhesion of the coating, especially on the chemically pre-treatedsubstrate, was also demonstrated by the tape adhesion test. Interestingly,both films exhibited marked antioxidant properties (2,2-diphenyl-1-picrylhydrazyland ferric reducing antioxidant power assays) that persisted overtime and were not lost even after prolonged storage of the material.The feature of the coatings in terms of the exposed groups (XPS andzeta potential titration evidence) was apparently dependent on thesurface pre-treatment of the titanium substrate. Cytocompatibility,scavenger antioxidant activity, and antibacterial properties of thedeveloped coatings were evaluated. The most promising results wereobtained in the case of the chemically pre-treated CA/HMDA-based coatedsurface that showed good cytocompatibility and high reactive oxygenspecies' scavenging ability, preventing their intracellularaccumulation under pro-inflammatory conditions; moreover, an anti-foulingeffect preventing the formation of 3D biofilm-like bacterial aggregateswas observed by scanning electron microscopy. These results open newperspectives for the development of innovative titanium surfaces withthin coatings from naturally occurring phenols for bone contact implants

Pectin-Based Formulations for Controlled Release of an Ellagic Acid Salt with High Solubility Profile in Physiological Media

Among bioactive phytochemicals, ellagic acid (EA) is one of the most controversial because its high antioxidant and cancer-preventing effects are strongly inhibited by low gastrointestinal absorption and rapid excretion. Strategies toward an increase of solubility in water and bioavailability, while preserving its structural integrity and warranting its controlled release at the physiological targets, are therefore largely pursued. In this work, EA lysine salt at 1:4 molar ratio (EALYS), exhibiting a more than 400 times increase of water solubility with respect to literature reports, was incorporated at 10% in low methoxylated (LM) and high methoxylated (HM) pectin films. The release of EA in PBS at pH 7.4 from both film preparations was comparable and reached 15% of the loaded compound over 2 h. Under simulated gastric conditions, release of EA from HM and LM pectin films was minimal at gastric pH, whereas higher concentrations-up to 300 μM, corresponding to ca. 50% of the overall content-were obtained in the case of the HM pectin film after 2 h incubation at the slightly alkaline pH of small intestine environment, with the enzyme and bile salt components enhancing the release. EALYS pectin films showed a good prebiotic activity as evaluated by determination of short chain fatty acids (SCFAs) levels following microbial fermentation, with a low but significant increase of the effects produced by the pectins themselves. Overall, these results highlight pectin films loaded with EALYS salt as a promising formulation to improve administration and controlled release of the compound.This research was funded by the European Union’s Horizon 2020 research and innovation program through the Stance4Health project (Grant No. 816303).Ye

A SUPERIOR ALL-NATURAL ANTIOXIDANT MATERIAL FROM SPENT COFFEE GROUNDS FOR APPLICATION IN ACTIVE PACKAGING AND FOOD SUPPLEMENTATION

Spent coffee grounds (SCG) represent the main by-products of the coffee industry as they are obtained both during instant coffee production and as a result of coffee beverage consumption in restaurants and coffee shops. We report herein the up to 30 times enhancement of the intrinsic antioxidant potency of SCG following overnight treatment with 6 M HCl, at 100 °C [1], leading to a versatile multifunctional material (hydrolyzed spent coffee grounds, HSCG). Spectral and morphological analysis suggested that the remarkable potentiation of the antioxidant activity is due to efficient removal of the hydrolyzable components, mainly carbohydrates, making the polyphenol-rich component available for interaction with free radicals and oxidizing species. Based on these results, the possible exploitation of HSCG as an active component in functional food packaging, e.g. for food lipid preservation and stabilization of polymers, or as a food supplement was then invesitgated. HSCG efficiently delays lipid peroxidation in fish and soybean oils. Moreover, films made of polyethylene/2% HSCG blends display greater stability to thermal and photo-oxidative degradation. Regarding the possible use as a food supplement, in other experiments HSCG was subjected to a simulated digestion-fermentation treatment in vitro [2]. The potentially bioaccessible (soluble) fractions obtained exhibit high chemoprotective activity in human hepatocellular carcinoma (HepG2) cells against oxidative stress. Structural analysis of both the indigestible (insoluble) and soluble material revealed partial hydrolysis and release of the lignin components in the potentially bioaccessible fraction following simulated digestion-fermentation. A high prebiotic activity as determined from the increase in Lactobacillus spp. and Bifidobacterium spp. as well as the production of short chain fatty acids following microbial fermentation of HSCG is also observed. HSCG may thus represent an easily accessible and sustainable alternative to currently available antioxidant materials for biomedical, food and technological applications

Natural Phenol Polymers: Recent Advances in Food and Health Applications

Natural phenol polymers are widely represented in nature and include a variety of classes including tannins and lignins as the most prominent. Largely consumed foods are rich sources of phenol polymers, notably black foods traditionally used in East Asia, but other non-edible, easily accessible sources, e.g., seaweeds and wood, have been considered with increasing interest together with waste materials from agro-based industries, primarily grape pomace and other byproducts of fruit and coffee processing. Not in all cases were the main structural components of these materials identified because of their highly heterogeneous nature. The great beneficial effects of natural phenol-based polymers on human health and their potential in improving the quality of food were largely explored, and this review critically addresses the most interesting and innovative reports in the field of nutrition and biomedicine that have appeared in the last five years. Several in vivo human and animal trials supported the proposed use of these materials as food supplements and for amelioration of the health and production of livestock. Biocompatible and stable functional polymers prepared by peroxidase-catalyzed polymerization of natural phenols, as well as natural phenol polymers were exploited as conventional and green plastic additives in smart packaging and food-spoilage prevention applications. The potential of natural phenol polymers in regenerative biomedicine as additives of biomaterials to promote growth and differentiation of osteoblasts is also discussed