Publications

Abstract The purpose of this study was to examine the neuroprotective effects of caffeic acid hexyl (CAF6) and dodecyl (CAF12) amide derivatives on the early stage of retinopathy in streptozotocin-induced diabetic rats. Animals were divided in five groups (n=8/group); one group consisted of non-diabetic rats as control, while the other four were diabetic animals either non-treated or treated with CAF6, CAF12 or resveratrol intravitreally for four weeks. Retinal superoxide dismutase (SOD) activity and 8-iso-prostaglandin F-2 alpha (iPF(2 alpha)) levels were evaluated by an ELISA assay. Phosphorylation of ERK1/2 and AKT was determined by immunoblotting in retinal homogenates. Retinal morphology was also examined using light microscopy. Treatment with CAF6 and CAF12 increased retinal SOD activity, while it decreased iPF(2 alpha) levels in diabetic rats. Phosphorylation of ERK1/2 was increased, while AKT phosphorylation was decreased in diabetic rats compared to normal control and these alterations were significantly reversed in diabetic rats treated with CAF6 and CAF12. Furthermore, thickness of the whole retinal layer, outer nuclear layer, and ganglion cell count were decreased in diabetic rats compared to control and CAF6 and CAF12 treatments prevented these changes. CAF6 and CAF12 seem to be effective agents for treatment of diabetic retinopathy via attenuation of retinal oxidative stress and improvement of neuronal survival signaling.

Abstract The conspicuous absence of novel and effective strategies to control microbial growth, both in the food and healthcare industries and evidence of increasing microbial resistance to conventional biocides has led to a search for novel antimicrobials and growth prevention strategies. In this study, 15 phytochemicals and derivatives, structurally-related to cinnamic acid and cinnamaldehyde, were assessed for their effects on the growth of Escherichia colt, Staphylococcus aureus and Enterococcus hirae. Their effects were compared to seven commonly used biocides (hydrogen peroxide, sodium hypochlorite, chlorhexidine, cetyltrimethylammonium bromide, triclosan, o-phthalaldehyde and lactic acid). All phytochemicals and derivatives increased lag phase and culture doubling time of the tested bacteria. Cinnamic acid and other derivatives inhibited bacterial growth. The MIC of cinnamaldehyde was comparable to o-phthalaldehyde and sodium hypochlorite and lower than hydrogen peroxide and lactic acid. The effect of methyl trans-cinnamate on bacterial growth was more evident against Gram-negative bacteria. It also inhibited quorum sensing in Chromobacterium violaceum. The effect of phytochemicals against sessile bacteria was low: < 1 log CFU.cm(-2). Inhibition of quorum sensing and of bacterial growth supports the fact that phytochemicals are an interesting source of antimicrobials with potential use as biocides or more likely as additives to improve the efficacy of current biocidal formulations and preservative systems.

Abstract This paper, reports for the first time the green synthesis of the polymorphs I and II of new pharmaceutical co-crystals lamivudine:theophylline in solid-phase, through the mixture between lamivudine and theophylline (both active pharmaceutical ingredients-APIs) in the proportion of 1:1 by neat grinding and liquid assisted grinding (10 mu L ethanol). Fourier transform-infrared (FT-IR) spectroscopy and multivariate curve resolution with alternating least-squares (MCR-ALS) were employed as non-invasive analytical methodology for the at-line green synthesis monitoring of the novels lamivudine:theophylline co-crystals. By MCR-ALS it was possible to identify each component present in a complex matrix, with strong spectral overlapping, containing lamivudine, theophylline, and the novel lamivudine:theophylline co-crystal with high confidence based on the comparison of the pure and recovered spectral and concentration profiles. This model allowed to identify the end of the reaction and understand the mechanism involved in the synthesis through the identification of the intermediates present in the synthesis process. Also, MCR-ALS model estimated the concentration of co-crystal polymorph I with a root mean square error of prediction (RMSEP) and the percentage relative error of prediction (REP%) equal to 3.323 (w/w) and 9.9%, respectively. These were good results since the spectral profile of cocrystal and the physical mixture of its APIs present strong spectral overlapping in their spectral domain. Therefore, the quantification of the co-crystal between its APIs (lamivudine and theophylline) certified that the co-crystal as final product was obtained, collaborating with the results obtained by differential scanning calorimetry (DSC) and X-ray powder diffraction (XRPD).

Abstract Here we report the near-infrared-upconversion (NIR-UC) luminescence of the organic dye fluorescein, without the need of metal-based NIR-UC materials or the use of high-energy and high-cost two-photon absorption excitation (TPA) systems. Fluorescein upconverts NIR light (lambda = 920 nm) to visible light (lambda = 545 nm) in aqueous solutions, with a pH-dependent light-intensity, by using a low-energy and low-cost nanosecond pulsed laser. The NIR-UC of fluorescein is explained with a triplet-triplet annihilation (TTA) mechanism, assisted by molecular vibrations. This work opens the door for deep-penetration bioimaging and photodynamic therapy, as well for NIR-excited TTA, photocatalysis and photovoltaics, by using solely high quantum yield organic molecules.

Abstract Chemical functionalization of multiwalled carbon nanotubes (MWCNTs) is important from the view point of polymer based composite manufacturing. As pristine MWCNTs has certain disadvantage such as they have lower dispersion, they are hydrophobic and are not readily soluble in a solvent, these characteristics makes them unreliable candidate for most of the industrial applications. By doing chemical functionalization of MWCNTs, these shortcomings can be overcome, and the MWCNTs can be used as a filler in composite manufacturing. This has the advantage of better nanofillers’ dispersion and provide the better interfacial bonding. In this study, MWCNTs are functionalized by the carboxylic group, chemical functionalization of MWCNTs is an optimization problem, governed by parameters like mixture acid concentration, temperature, time of heating and amount of MWCNTs used. Material characterization of MWCNTs is done and test specimens are manufactured according to different concentrations of MWCNTs within a bio-based epoxy resin. Mechanical properties are then compared according to different concentrations. These mechanical and material characterizations increase the understanding of chemical functionalization by carboxylic group and the influence of the concentration of MWCNTs dispersed within the bio-based resin matrix.

Abstract Surface disinfection is of utmost importance in the prevention of bacterial infections. This study aims to assess the ability of ten phytochemicals and related derivatives as potentiators of two commonly used biocides-cetyltrimethylammonium bromide (CTAB) and lactic acid (LA). LA in combination with cinnamic, hydrocinnamic, alpha-methylcinnamic, and alpha-fluorocinnamic acids had a factional inhibitory concentration index (FICI) <= 1 for Escherichia coli and Staphylococcus aureus. Several phytochemicals/derivatives in combination with biocides improved the biocidal efficacy against early sessile bacteria. The most effective combination was LA with allyl cinnamate (2.98 +/- 0.76 log CFUcm(-2) reduction) against E. coli. The combination with CTAB was successful for most phytochemicals/derivatives with a maximum bactericidal efficacy against sessile E. coli when combined with allyl cinnamate (2.20 +/- 0.07 log CFUcm(-2) reduction) and for S. aureus when combined with alpha-methylcinnamic acid (1.68 +/- 0.30 log CFUcm(-2) reduction). This study highlights the potential of phytochemicals and their derivatives to be used in biocide formulations.

Abstract Herein, the synthesis of Ho3+ (2 mmol%)/Yb3+ (18 mmol%) doped NaGdF4 up-conversion (UC) phosphor particles via two different chemical routes namely thermal decomposition (sample 1) and hydrothermal (sample 2) methods is done and then the structural and optical properties were studied. The properties of the samples are characterized via different techniques. The UC emission bands are obtained in the visible range at 488 nm, 543 nm, 645 nm and 754 nm wavelengths corresponding to F-5(3) -> I-5(8), F-5(4)/S-5(2) -> I-5(8), F-5(5) -> I-5(8) and I-5(4) -> I-5(8) transitions, respectively. The change in sample internal temperature due to the 980 nm diode laser excitation is calculated for both the samples. The variation in UC emission intensity as a function of the complete cycle of the applied magnetic field (0-1.1 x 10(4) Oe-0) is confirmed the optical bi-stability behavior of the present sample. Sample 1 has found a colloidal stable in water and hence this sample dispersed in the aqueous medium of polyvinyl alcohol (PVA) and thus utilized in security witting demonstration on a bank-note surface. Sample 2 with high emission intensity is demonstrated for latent fingermark detection.

Abstract Aqueous biphasic systems constituted by ionic liquids (IL-based ABSs) are a target of investigation in the separation of high-value biomolecules. However, identification of the molecular-level mechanisms ruling the two-phase formation and extraction performance of these systems is crucial to the successful design of effective separation processes. In this work, IL-based ABSs formed by K2HPO4 and cholinium carboxylate ILs ([Ch] [CnCO2] with n = 1-7, comprising anions with odd and even alkyl chain lengths) were investigated. The corresponding ternary phase diagrams, including binodal curves, tie-lines, tie-line lengths, and critical points, as well as the Setschenow salting-out coefficients (k(s)), which quantitatively describe the two-phase formation ability, were determined at 298 K. The extraction capability of these systems was then evaluated for four amino acids (L-tryptophan, L-phenylalanine, L-tyrosine, and L-3,4-dihydroxyphenylalanine/L-dopa). It was found that ILs composed of anions with even alkyl chains display slightly higher k(s) values, meaning that these ILs are more easily salted out or more easily phase-separated to form ABSs, whereas ABSs formed by ILs with anions comprising odd alkyl chains lead to slightly higher partition coefficients of amino acids. Beyond the neat IL odd-even effect resulting from their nanostructuration, being this a well-known phenomenon occurring in a series of their thermophysical properties, the existence of an odd-even effect displayed by the IL anion aliphatic moiety in aqueous solution is shown here, visible in both the two-phase formation ability and extraction performance of ABSs. These findings contribute to elucidate of the molecular-level mechanisms governing ABS formation and partitioning of biomolecules, ultimately contributing to the design of proficient separation platforms.

Abstract 6-Bromochromone-2-carboxylic acid (3) was synthesized by a microwave-assisted process. The optimization of the reaction was performed varying parameters, such as type of base/number of reagent equivalents, solvent, temperature and reaction time. The yield of the reaction was improved to 87%. The new synthetic route is versatile as several chromone-2-carboxylic acids (compounds 4B-10B) were obtained with good yields (54-93%). Only in the case of the nitro substituent (compound 11B), an ester was obtained instead of the desired carboxylic acid. Following this synthetic route chromone carboxylic acids can be attained with a high degree of purity, without the need of the tedious and expensive purification processes through column chromatography. The reaction is safe, cost-effective, fast and robust, and can be used in the development of concise and diversity-oriented libraries based on chromone scaffold. The overall study can be looked as a step forward to speed-up the discovery of chromone-based multitarget-directed ligands.