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  • Open access
  • 11 Reads
Ohmic heating effect on the bioaccessibility of proteins from ohmic-heated nixtamalized tortillas

This research aimed to assess protein bioaccessibility of traditionally (TN) or ohmic heating (OH)-nixtamalized sorghum tortillas using two sorghum varieties (82w21/8133) processed at several conditions (110/120 V, 85/90 ºC). The 82w21 variety (120 V/85 ºC) displayed the highest yield (1.82 kg tortilla/kg masa) and the best sensory parameters (rollability/puffiness). A higher tannin decrease (-27.77%) was obtained compared to TN. The highest protein bioaccessibility (58.23 %) was found for OH-tortillas at 60 min in the digestible fraction, while TN showed the highest permeation rates. Concluding, OH is an environmentally friendly procedure to obtain nixtamalized sorghum flours to manufacture highly-bioaccessible protein tortillas

  • Open access
  • 9 Reads
Effects of extrusion cycles on the formation of type 3 resistant starch
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The present work was to evaluate the formation of type III resistant starch in Hylon VII starch by the cycle’s extrusion process. The starch was subjected to three extrusion cycles. Starch viscosity, structural and thermal properties were determined. Results have shown that thermal properties had a decrease in the enthalpy, a decrease in the viscosity, and a loss in the crystallinity pattern because of the cycle’s extrusion. The type III resistant starch decreased for each extrusion cycle, due to the gelatinization process that occurred during the extrusion cycles.

  • Open access
  • 28 Reads
Glycopeptide antibiotic-loaded poly(vinyl alcohol)/polycaprolactone co-axial wet-spun fibrous scaffolds for infection control in diabetic ulcers

Annually, the incidence of diabetic foot ulcers (DFUs) varies between 9.1 to 26.1 million worldwide, with numbers increasing each year. About 25% of diabetic patients develop DFUs, with near 70% of those requiring lower limb amputation. DFUs often fail to progress past the inflammatory phase due to increased bacterial colonization and recurrent infection. Over the last decades, technology breakthroughs have demonstrated the impact of bioactive 3D, fiber-based scaffolding systems in the treatment of DFUs (DOI: 10.1016/j.ijpharm.2021.120423). In the present project, co-axial wet-spun microfibrous scaffolds are proposed as drug delivery platforms for infection control in DFUs-prevalent bacteria infested environments.

Microfibers with a shell made of poly(vinyl alcohol) (PVA) at 10wt.% in water and a core of polycaprolactone (PCL) at 10wt.% in dimethylformamide were engineered via wet-spinning in a 8wt.% Na2SO4 and 4wt.% NaOH coagulation bath. Ceftazidime and vancomycin minimum bactericidal concentrations (MBC) against S. aureus and P. aeruginosa were determined at 32.0µg/mL and 7.8µg/mL, respectively. Antibiotics were loaded at 2×MBC at the shell of the microfibers. PCL was used to sustain the scaffolding structure and convey mechanical resilience, while PVA was used primarily as a drug carrier, maintaining a local moist environment and absorbing exudates. The microfibers co-axial structure was confirmed via brightfield microscopy. Both polymers and antibiotics presence were verified via Fourier-transform infrared spectroscopy (FTIR) and UV-visible spectroscopy, following antibiotic release up to 24h in phosphate buffer (PBS, pH 7.4). Artificial exudates were used to attest the scaffold swelling capacity and map its degradation profile. Scaffolds could maintain >80% of their mass up to 28 days of incubation in dynamic conditions. Antimicrobial testing revealed the drug diffusion abilities of the scaffolding system, forming zones of inhibition in single and co-culture settings. Time-kill kinetics studies established this drug delivery platform as effective for infection control in non-sterile DFUs-mimicking environments within a 24h period.

  • Open access
  • 7 Reads
Coaxial wet-spun fibers loaded with AAPV – a viable option for chronic wound healing

Chronic wounds (CW) are a worldwide concern, causing serious strives on the health and quality of patients’ life. In CW, human neutrophil elastase (HNE) enzyme gets highly expressed during inflammation, reaching abnormally elevated concentrations. Additionally, prevalence of Staphylococcus aureus-induced infections remains very high and difficult to treat. Considering these phenomena, a drug delivery system made of co-axial wet-spun fibers, loaded with the tetrapeptide Ala-Ala-Pro-Val (AAPV, a known inhibitor of HNE activity) and N-carboxymethyl chitosan (NCMC, responsive to neutral-basic pH’s, characteristic of CW and endowed with antibacterial features), was proposed.

AAPV was synthesized by solid-phase peptide synthesis, whereas NCMC was synthesized from low molecular weight chitosan in a chloroacetic acid mixture. HNE inhibition tests were conducted to establish the AAPV IC50 in 1.50 µg/mL and the NCMC minimum bactericidal concentration (MBC) against S. aureus in 6.40 mg/mL. These determinations were used to establish fiber loading amounts. Core-shell structures were produced with 10% w/v polycaprolactone (PCL) at the core and 2% w/v sodium alginate (SA) solutions at the shell. NCMC was mixed with SA at 2xMBC so neutral-basic pH-triggered solubility (characteristic of CW) would allow pores to be opened in the outer layer for accessing the core, where AAPV was combined with PCL.

Fourier-transform infrared spectroscopy and brightfield microscopy were used to confirm the presence of the four components on the fibers and the co-axial architecture, respectively. Fibers presented maximum elongations of over 100%. Release kinetics studies conducted via UV-visible absorption spectroscopy mapped NCMC liberation overtime but were uncapable of detecting AAPV, since polymer degradation masked AAPV absorption peaks. Time-kill kinetics studies against S. aureus demonstrated the effectiveness of NCMC in eliminating this bacterium, particularly after 6 h of incubation. On its turn, AAPV guaranteed HNE inhibition. Data demonstrated the potential of SA-NCMC-PCL-AAPV co-axial systems to work as stepwise, pH-triggered delivery platforms.

  • Open access
  • 41 Reads
Development and characterization of calcium carbonate-quince bio-composite for pH triggered release of darfenacin hydrobromide in lower GIT: A green chemistry approach

A green chemistry approach was employed to develop gastric pH resistant bio-composites for colon targeted oral delivery of darfenacin hydrobromide. The FTIR, XRD, DSC and TGA results showed good drug-polymer compatibility. The SEM images showed calcite formation in the quince hydrogel system. The drug release of 80% and 34% were observed in a phosphate buffer 6.8 pH and an acidic media, respectively. The restricted drug permeation (approx. 21.8% only) was observed through gastric membrane in an acidic media. The developed formulation significantly inhibited the development of testosterone induced prostatic hyperplasia. No organ toxicity was observed against all the developed formulations.

  • Open access
  • 12 Reads
Analysis of Lavandula angustifolia compounds obtained by different extraction types by GC-MS technique
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Lavandula angustifolia is a medicinal plant with important benefits for human body, having antimicrobial and antioxidants activities. Scientifical data detalied the fact that lavender extract presented favorable characteristics to health, such as being antibacterial, antifungal, antidepressive or anticancer properties. The aim of this study was to establish the eficiency of extraction methods by identification and determination of compounds extracted from lavender plant. It were used different types of extraction: ultrasound (50°C/2hrs) and magnetic agitation (ambient temp./24hrs), in pure ethanol and hydroalcoholic mixture (ethanol: ultrapure water=50:50 v/v). It was utilised a GC-MS cromatograph equipment for detection and quantitative determination of lavender compounds extracted (ex. eucalyptol, linalool, camphor, terpinenol, linalylacetat, etc), an Elite-5MS (5% diphenyl methyl polysiloxane stationary phase) column and a linalool standard. Were established the optimal GC-MS separation parameters. In conclusion, it was observed that lavender sample extracted in ethanol, thru magnetic aggitation, at room temperature is a more efficient method than the others, because it were observed more compounds (over 20) than in the others laveder extracts samples (approx. 6).

  • Open access
  • 17 Reads
NEW THERMOPHILIC PROTEIN WITH XYLANASE ACTIVITY

Cereal hemicellulose, also called arabinoxylan (AX) or pentosan, is a polysaccharide formed by a linear skeleton of xylose monomers linked by β-1,4 bonds with ramifications due mainly to L-arabinofuranose monomers that bind to the oxygen of the C2 or C3, or even the C2 and C3 oxygen of the same xylose residue. Hemicellulose can be used to obtain different products depending on the degree of hydrolysis of the polysaccharide. The enzymes responsible for the hydrolysis of the xylan chain to xylose are generally called xylanases, the most important being the endo-1,4-β-xylanases, which together with the β-xylosidase enzymes carry out the exhaustive hydrolysis of xylan to xylose.

The main objective of this work is to discover new thermoenzymes, mainly xylanases and β-xylosidases. The search for these new thermoenzymes was carried out using culture techniques and construction of metagenomic libraries, from water samples from the thermal spring of Burgas with a temperature of 67º C and from the geothermal spring of Río Caldo with a temperature of more than 77º C, both in the province of Ourense (Spain), using two varieties of wheat straw (Caaveiro and Castilla) as the only carbon source. Using culture techniques, strains positive for the thermophilic enzymes endoxylanase and β-xylosidase have been isolated, while a positive clone corresponding to the enzyme endoxylanase has been obtained through functional metagenomics. The enzyme with endoxylanase activity has been expressed in E. coli and purified by affinity chromatography. The optimal temperature and pH of the purified enzyme have been studied, as well as its thermostability and kinetics.

  • Open access
  • 24 Reads
Identification and characterization of a novel thermostable β-galactosidase discovered through functional metagenomics

β-galactosidases (EC.3.2.1.23), which hydrolyze lactose to glucose and galactose, have two main applications in the food industry: the production of low-lactose milk and dairy goods for lactose intolerant people and the generation of galacto-oligosaccharides (GOS) by transgalactosylation reactions. Due to their thermostability, β-galactosidases from thermophilic microorganisms are very interesting for industrial processes, as the use of high temperatures can increase the initial productivity of the enzyme, gives higher solubility of substrates, and prevents microbial contamination. In this study, a novel thermostable β-galactosidase was obtained through functional screening of a metagenomic library from As Burgas hot spring (Ourense, Spain). The protein shows maximum activity at 80 °C and pH 7 and retains more than 72 % of its activity after incubation at 55 °C for 6 hours. Moreover, it is able to produce up to 48 % (w/w) of GOS from a solution of 40 % (w/v) of lactose at 70 °C after a 4 h reaction. These properties make the new metagenomic-derived enzyme a very suitable catalyst for its industrial application.

  • Open access
  • 35 Reads
A Molecular Dynamics simulation study of the Arg206Cys variant in DNASE1L3 enzyme

Genome-wide association studies (GWAS) have identified that one of the autoimmune disease‑associated loci, predisposing for the development of Systemic Lupus Erythematosus (SLE), Rheumatoid Arthritis (RA) and Systemic Sclerosis (SSc), is the rs35677470 missense variant of the Deoxyribonuclease I like 3 (DNASE1L3) gene, leading to R206C substitution in DNASE1L3 enzyme. Molecular Dynamics (MD) simulations were implemented for the wild type and mutated enzyme, in order to investigate the structural changes and loss of function. Results showed loss of salt bridges, larger fluctuation in active site regions and lower charge of the catalytic and DNA binding sites after the mutation. The present study raises the necessity of in silico methods, in understanding and managing autoimmune diseases.

  • Open access
  • 10 Reads
Effects of Glucocorticoid Receptor Activation on the Expression of Intercellular Adhesion Regulatory Genes in Breast Cancer Cells in vitro

Combinations of common anticancer chemotherapeutics with synthetic glucocorticoids (GCs) are usually used to broaden the therapeutic range of main cytostatics and to diminish the side effects of chemotherapy. However, long-term GC administration may lead to the selection of resistant tumor subclones and the promotion of metastasis. GC effects are mediated by glucocorticoid receptor (GR), which regulating gene expression via DNA-dependent transactivation associated with side effects of GCs, and therapeutically important transrepression, negative interaction between GR and transcription factors.

The main aim of this study was to find out the molecular markers associated with GC-stimulated cell motility and migration potential of breast cancer cells.

Breast cancer cells with epithelial (MCF-7) and mesenchymal-like (MDA-MB-231) phenotype were used as model cells. Cells were treated with Dexamethasone for 24 h. Migration activity were observed in Boyden chamber assay. Expression of 84 specific genes associated with epithelial–mesenchymal transition and cell adhesion (encoding integrin, connexin, cadherin, caveolin, fibullin, desmocolin, interleukin and caveolin protein families) were evaluated by real time q-PCR.

In MCF-7 cells with low metastatic potential, GC induced decrease of claudin, integrin and caveolin family genes. In triple negative breast cancer cell line MDA-MB-231, activation of GR lead to significant decrease in the expression of genes encoding claudins and connexins. In addition, Dexamethasone promote MCF-7 and MDA-MB-231 migration through Boyden chamber.

Thus, we showed that GCs stimulate the invasion and metastasis of breast cancer cells independently from their phenotypes. Moreover, we determined the most significant genetic markers of GC-associated loss of adhesion in breast cancer cells.

Work was partial supported by RSCF (17-75-20124) and RFBR (16-04-01410, 15-04-04006).

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