Synthesis and Antioxidant Efficiency of a New Copolymer Containing Phosphorylated Myo-Inositol

Glycerylphytate compounds with tunable ion affinity and osteogenic properties

Phytic acid (PA) is a natural-occurring antioxidant, which plays an important role in many biological processes. PA is recognized as a potent inhibitor of lipid peroxidation because of its high affinity to multivalent cations, and it can play a role in osteogenic processes. However, its powerful chelating capacity is controversial because it can lead to a severe reduction of mineral availability in the organism. For this reason, compounds with beneficial biological properties of PA, but a modular ion binding capacity, are of high interest. In this work, we report the synthesis and physicochemical characterization of two hydroxylic derivatives of PA, named glycerylphytates (GPhy), through a condensation reaction of PA with glycerol (G). Both derivatives present antioxidant properties, measured by ferrozine/FeCl₂ method and chelating activity with calcium ions depending on the content of glyceryl groups incorporated. Besides, the hydroxylic modification not only modulates the ion binding affinity of derivatives but also improves their cytocompatibility in human bone marrow mesenchymal cells (MSCs). Furthermore, GPhy derivatives display osteogenic properties, confirmed by COL1A and ALPL expression depending on composition. These positive features convert GPhy compounds into potent alternatives for those skeletal diseases treatments where PA is tentatively applied.

Water-soluble antioxidant derivative poly(triethylene glycol methyl acrylate-co-α-tocopheryl acrylate) as a potential prodrug to enable localized neuroprotection

Implantable microelectrode arrays (MEA) hold enormous hope for individuals with sensory or motor deficits. However, long-term function of MEA remains a critical hurdle. The objective of this study was to synthesize an antioxidant prodrug that can be delivered to the neural tissue around the implant and present a pharmacological depot to combat the injurious oxidative stress around the MEA. In this report, monomers of triethylene glycol methyl acrylate and α-tocopheryl acrylate, a synthetic derivative of the antioxidant α-tocopherol (vitamin E, Ve), were copolymerized to obtain poly(triethylene glycol methyl acrylate-co-α-tocopheryl acrylate) (PVT) with different compositions. In contrast to the poor water solubility of Ve, solubility of the PVT prodrug in water can reach as high as 3.1 mg ml(-1) (equivalent to 500 μM Ve) by tuning the copolymer composition. To demonstrate the applicability of the prodrug for MEA implants, PVT was successfully deposited on silicon substrates with poly(acrylic acid) (PAA) or tannic acid (TA) using the layer-by-layer technique mediated by hydrogen bonding. Ellipsometry and quartz crystal microbalance data showed that the multilayers of PAA/PVT were destructible at physiological pH. In contrast, multilayers of TA/PVT were stable. The PVT prodrug was non-cytotoxic toward A172 human astrocytes. Furthermore, PVT was able to protect astrocytes against oxidative stress exerted by H(2)O(2) in vitro. Using a free radical scavenging assay, the protection mechanism was attributed to the hydrolysis of the labile ester linkage and release of the active Ve.

Preparation, characterization and efficacy evaluation of synthetic biocompatible polymers linking natural antioxidants

The purpose of this work was the synthesis, characterization and efficacy evaluation of new biocompatible antioxidant polymers linking trans-ferulic acid or α-lipoic acid. In particular, ferulic or lipoic acid were introduced in the preformed polymeric backbone. The new antioxidant biopolymers were characterized by Fourier transform infrared spectroscopy and gel permeation chromatography. The degree of functionalization (moles of antioxidant per gram of polymer) was determined by the Gaur-Gupta method for free amino group determination and by the Folin method for the phenolic groups. Their ability to inhibit lipid peroxidation were estimated in rat liver microsomal membranes induced in vitro by tert-BOOH (tert-butyl hydroperoxide), as a source of free radicals. The DPPH (1,1-diphenyl-2-picrylhydrazyl) radical-scavenging effect was also evaluated. The obtained systems, with different solubility, showed strong antioxidant and antiradical activities, suggesting potential use as packaging materials for foods, cosmetics, pharmaceuticals and personal care products. Moreover, the cytotoxicity of the synthesized polymers was also evaluated on Caco-2 cell cultures in order to verify their biocompatibility when exposed to an absorptive epithelial cell line.

Iron (III) chelation and antioxidant properties of myo-inositol phosphorylated polymeric microspheres

New chelating and antioxidant polymeric microspheres were synthesized through precipitation polymerization of 4-O-(4-vinylbenzyl)-myo-inositol 1,3,5-orthoformate with ethylene glycol dimethacrylate and subsequent exhaustive phosphorylation of the myo-inositol groups with phosphoric acid. Three different microspheres using different molar ratios of the two co-monomers were prepared. The antioxidant properties of these polymers were evaluated in rat liver microsomal membranes. This study showed that the macromolecular systems are very effective at inhibiting iron-dependent lipid peroxidation of the membranes. This antioxidant effect is due to the chelating properties of polyphosphorylated inositol residues in the polymeric devices toward ferric ions. The amount of polyphosphorylated inositol in the microspheres was found to play a crucial role in determining the chelating efficiency of the polymers: the polymer with the greatest amount of polyphosphorylated inositol was the most powerful antioxidant polymer.

Synthesis of antioxidant polymers by grafting of gallic acid and catechin on gelatin

A novel, simple, and cheap method to synthesize antioxidant-protein conjugates by grafting reaction was developed employing a hydrogen peroxide-ascorbic acid pair as radical initiator system. Our challenge was to covalently bind molecules with tested antioxidant activity, as gallic acid (GA) and catechin (CT) to a biomacromolecule, as gelatin, extensively used in the pharmaceutical, cosmetic, and food industry. In this way, two gelatin conjugates, bearing GA and CT covalently bounded to a side chain of protein, were synthesized. Calorimetric, UV-vis, and fluorescence analyses were performed to verify the covalent bond between antioxidant molecules and gelatin, and the antioxidant activity of conjugates was compared to that of a control polymer submitted to the same reaction conditions without antioxidant molecule. The ability of synthesized materials to inhibit 2,2'-diphenyl-1-picrylhydrazyl, hydroxyl radicals, and linoneic acid peroxidation was determined and, to well characterized antioxidant properties of grafted biomacromolecules, disposable phenolic equivalents and total antioxidant activity were calculated. The conjugates showed a good antioxidant activity, confirming the efficiency of the synthetic strategy proposed in this paper. The results clearly showed that antioxidant moieties covalently bounded to a natural polymer allow to introduce in the macromolecule peculiar features for specific industrial applications.

Synthesis and evaluation of novel N-H and N-substituted indole-2- and 3-carboxamide derivatives as antioxidants agents

We have previously reported on the synthesis of novel indole derivatives where some compounds showed significant antioxidant activity. Here, we report the synthesis of novel N-H and N-substituted indole-2- and 3-carboxamide derivatives and investigated their antioxidant role in order to identify structural characteristics responsible for activity. Although all compounds showed a strong inhibitory (95-100%) effect on superoxide anion (SOD) only compounds 4, 5 and 6 showed simliar potency for the inhibition of lipid peroxidation (81-94%) which revealed that compounds 4, 5 and 6 possessed highly potent antioxidant properties. Substitution in the 1-position of the indole ring caused the significant differences between the activity results regarding lipid peroxidation inhibition.

Design and Synthesis of Cellulose Derivatives with Antioxidant Activity

In this study we report the synthesis and characterisation of cellulose ferulate, lipoate and alpha-tocopherulate, and their ability to inhibit lipid peroxidation in rat-liver microsomal membranes, induced in vitro by two different sources of free radicals: tert-butyl hydroperoxide and 2,2'-azobis-(2-amidinopropane). We also compared the antioxidant efficiency of the ferulate derivatives obtained through two different synthetic runs, and of a tocopherulate derivative prepared from 6-carboxycellulose. This study showed that the designed systems, preserving the antioxidant activity of the free substrates, are more effective in protecting from tert-butyl hydroperoxide than from 2,2'-azobis-(2-amidinopropane). Moreover, the cellulose ferulate with the higher degree of substitution acted as the best antioxidant.

Synthesis and Antioxidant Properties of NovelN-H andN-Substituted Propanamide Derivatives

The interest in the application of antioxidants for medical treatment has been growing recently. A lot of evidence has proven the link between the development of human diseases and oxidative stress. Indole derivatives were found to be very effective in protecting against oxidative stress. Recent exciting findings have demonstrated that several indole derivatives (IDs) are strong inhibitors of superoxide anion (SOD) and lipid peroxidation (LP). In this study, a series of novel N-H and N-substituted indole-3-propanamide derivatives (I3PADs) have been prepared and their efficiencies were investigated towards SOD and LP. Among the synthesized I3PADs, compounds 5 and 7-12 significantly inhibited O2*- in the range of 94-100%. In addition, N-H I3PADs showed a stronger inhibitory effect (compounds 1-5, 56-83%) on lipid peroxidation levels than SOD.