Background
Ultraviolet B (UVB) causes photoaging of the skin, the appearance of wrinkles, spots, and alteration of the skin barrier. The main cells in the most superficial layer of the skin are the ...keratinocytes; these cells play an important role in protecting this organ.
Objective
The present study aimed to investigate the antioxidant activity of the hydrolysates from kafirin to inhibit UVB‐induced responses in human keratinocytes cells (HaCaT).
Methods
Kafirin hydrolysates were produced by enzymatic hydrolysis with alcalase. The activity of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), in the HaCaT cell line in the presence of UVB and the effects of the hydrolysates against the UVB‐induced response were evaluated. Furthermore, the peptides that were generated by hydrolysis were identified in silico using the BIOPEP database.
Results
Two protein sequences were identified (α‐kafirin and the precursor protein of α‐kafirin), in the kafirin extract. A degree of hydrolysis of 18.8% was obtained by hydrolyzing the kafirin extract with alcalase. The kafirin hydrolysates avoided the decrease in endogenous antioxidant enzymes such as SOD, CAT, and GPx reducing the oxidative stress generated by UVB. Using the BIOPEP‐UWM database, we found 102 peptide sequences, and it has shown that the peptides have a large amount of hydrophobic amino acids such as proline, alanine, and glutamine, and amino acids with high antioxidant capacity.
Conclusion
These results suggest that the kafirin hydrolysates can be used as antioxidant agents to ameliorate UVB‐induced skin keratinocytes cells' response in vitro, providing an alternative against UVB‐induced photoaging.
•Peptide extracts were produced enzymatically from sorghum kafirins.•Peptide extracts exhibited protective effects in UVB-exposed human skin organotypic cultures.•Peptide extracts showed antioxidant, ...anti-inflammatory and anti-skin aging properties.•Sorghum has potential as a new source of anti-photoaging agents for the skin.
In recent years, the cosmetic industry has developed products that provide beneficial functions on the skin, with an increase in the production of cosmeceuticals which has generated great scientific and industrial interest in the search for alternative bioactive ingredients. The objective of this research was to determine the protective effects (antioxidant, anti-inflammatory, and anti-aging) of peptide extracts of the grain of white sorghum Sorghum bicolor (L.) Moench against the damage induced by exposure to ultraviolet B irradiation (UVB) in organotypic cultures of human skin. The kafirins (α, β, and γ-kafirin) fraction extracted from the sorghum grain was hydrolyzed with alcalase to produce crude hydrolysates. Then, by ultrafiltration, two peptide extracts with molecular weight 1–3 kDa (PE-3) and < 1 kDa (PE-1) were prepared. Bioassays were performed on organotypic skin cultures (exposed and not exposed to UVB). The results revealed that the treatments with both extracts (PE-3 and PE-1) significantly reduce the damage caused by UVB, by attenuating the depletion of the activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx), as well as by maintaining or increasing the activity of catalase (CAT). Also, PE-3 and PE-1 decreased the levels of pro-inflammatory cytokines such as interleukin 1-β (1L-β), interferon-γ (IFN-γ), and tumor necrosis factor-α (TNF-α). Furthermore, PE-3 and PE-1 inhibited collagenase, elastase, and tyrosinase activities. In general, PE-1 exhibited a greater protective effect than PE-3 and like that obtained with glutathione. Therefore, the enzymatic production of PE-3 and PE-1 with protective functions of the skin could be a promising strategy to generate potential ingredients that can be incorporated in new cosmeceutical formulations.
The standardization of secondary electrolytic conductivity cells requires the use of a certified reference material. The accepted certification method involves electrochemical impedance spectroscopy ...(EIS) to estimate the material’s solution resistance. This method normally assumes that the impedance’s imaginary component can be neglected; and hence, the measured impedance approximates the real impedance. Thus, a linear extrapolation of the impedance versus the period (inverse frequency) yields solution resistance. However, experimental impedance data usually do not exhibit a linear behavior over the spectra of frequency, which strongly suggest that the ideal capacitive assumption may not strictly apply. To account for the observed nonlinear behavior, we have proposed to introduce the concept of a constant phase element (CPE) to the analysis of impedance. This approach leads to the development of a relationship that improves the fitting of experimental data and improves the accuracy of the estimation, by establishing a critical frequency where extrapolation should be done. Finally, we are presenting simulated results to demonstrate how sizeable capacitive effects can influence the determination of solution resistance, and a final analysis to estimate the impact on constant cell or electrolytic conductivity values.
Goethite-titania (α-FeOOH-TiO
) composites were prepared by co-precipitation and mechanical milling. The structural, morphological and optical properties of as-synthesized composites were ...characterized by X-ray powder diffraction, scanning electron microscopy and UV-Vis diffuse reflectance spectroscopy, respectively. α-FeOOH-TiO
composites and TiO
-P25, as reference, were evaluated as photocatalysts for the disinfection of
under UV or visible light in a stirred tank reactor. α-FeOOH-TiO
exhibited better photocatalytic activity in the visible region than TiO
-P25. The mechanical activation increased the absorption in the visible range of TiO
-P25 and the photocatalytic activity of α-FeOOH-TiO
. In the experiments with UV light and α-FeOOH-TiO
, mechanically activated, a 5.4 log-reduction of bacteria was achieved after 240 min of treatment. Using visible light the α-FeOOH-TiO
and the TiO
-P25 showed a 3.1 and a 0.7 log-reductions at 240 min, respectively. The disinfection mechanism was studied by ROS detection and scavenger experiments, demonstrating that the main ROS produced in the disinfection process were superoxide radical anion, singlet oxygen and hydroxyl radical.
Goethite-titania (α-FeOOH-TiO
2
) composites were prepared by co-precipitation and mechanical milling. The structural, morphological and optical properties of as-synthesized composites were ...characterized by X-ray powder diffraction, scanning electron microscopy and UV-Vis diffuse reflectance spectroscopy, respectively. α-FeOOH-TiO
2
composites and TiO
2
-P25, as reference, were evaluated as photocatalysts for the disinfection of
Escherichia coli
under UV or visible light in a stirred tank reactor. α-FeOOH-TiO
2
exhibited better photocatalytic activity in the visible region than TiO
2
-P25. The mechanical activation increased the absorption in the visible range of TiO
2
-P25 and the photocatalytic activity of α-FeOOH-TiO
2
. In the experiments with UV light and α-FeOOH-TiO
2
, mechanically activated, a 5.4 log-reduction of bacteria was achieved after 240 min of treatment. Using visible light the α-FeOOH-TiO
2
and the TiO
2
-P25 showed a 3.1 and a 0.7 log-reductions at 240 min, respectively. The disinfection mechanism was studied by ROS detection and scavenger experiments, demonstrating that the main ROS produced in the disinfection process were superoxide radical anion, singlet oxygen and hydroxyl radical.
A photocatalytic mechanism for FeOOH-TiO
2
composite is proposed under UV-Vis light, the FeOOH-TiO
2
composite showed higher photocatalytic activity than TiO
2
-P25.
Mercury (Hg), a global contaminant, is emitted mainly in its elemental form Hg⁰ to the atmosphere where it is oxidized to reactive HgII compounds, which efficiently deposit to surface ecosystems. ...Therefore, the chemical cycling between the elemental and oxidized Hg forms in the atmosphere determines the scale and geographical pattern of global Hg deposition. Recent advances in the photochemistry of gas-phase oxidized HgI and HgII species postulate their photodissociation back to Hg⁰ as a crucial step in the atmospheric Hg redox cycle. However, the significance of these photodissociation mechanisms on atmospheric Hg chemistry, lifetime, and surface deposition remains uncertain. Here we implement a comprehensive and quantitative mechanism of the photochemical and thermal atmospheric reactions between Hg⁰, HgI, and HgII species in a global model and evaluate the results against atmospheric Hg observations. We find that the photochemistry of HgI and HgII leads to insufficient Hg oxidation globally. The combined efficient photoreduction of HgI and HgII to Hg⁰ competes with thermal oxidation of Hg⁰, resulting in a large model overestimation of 99% of measured Hg⁰ and underestimation of 51% of oxidized Hg and ∼66% of HgII wet deposition. This in turn leads to a significant increase in the calculated global atmospheric Hg lifetime of 20 mo, which is unrealistically longer than the 3–6-mo range based on observed atmospheric Hg variability. These results show that the HgI and HgII photoreduction processes largely offset the efficiency of bromine-initiated Hg⁰ oxidation and reveal missing Hg oxidation processes in the troposphere.
The Chemistry of Mercury in the Stratosphere Saiz‐Lopez, Alfonso; Acuña, A. Ulises; Mahajan, Anoop S. ...
Geophysical research letters,
28 June 2022, Letnik:
49, Številka:
12
Journal Article
Recenzirano
Odprti dostop
Mercury, a global contaminant, enters the stratosphere through convective uplift, but its chemical cycling in the stratosphere is unknown. We report the first model of stratospheric mercury chemistry ...based on a novel photosensitized oxidation mechanism. We find two very distinct Hg chemical regimes in the stratosphere: in the upper stratosphere, above the ozone maximum concentration, Hg0 oxidation is initiated by photosensitized reactions, followed by second‐step chlorine chemistry. In the lower stratosphere, ground‐state Hg0 is oxidized by thermal reactions at much slower rates. This dichotomy arises due to the coincidence of the mercury absorption at 253.7 nm with the ozone Hartley band maximum at 254 nm. We also find that stratospheric Hg oxidation, controlled by chlorine and hydroxyl radicals, is much faster than previously assumed, but moderated by efficient photo‐reduction of mercury compounds. Mercury lifetime shows a steep increase from hours in the upper‐middle stratosphere to years in the lower stratosphere.
Plain Language Summary
Mercury is a toxic pollutant that is released to the atmosphere as a result of human activities and from natural sources. Due to its long lifetime, mercury can travel around the world and also can be injected to the stratosphere via convective uplift in the tropical regions. Aircraft observations have reported significant concentrations of different forms of mercury in the stratosphere, however, the chemistry of mercury in this region of the atmosphere remains unexplored. This work reports a new chemical framework that sheds light on the chemical cycling of stratospheric mercury. The results reveal the stratosphere as a unique environment for mercury chemistry that has potential implications for the global transport of this metal.
Key Points
A new chemical mechanism for photosensitized mercury oxidation is proposed
Above the UV‐absorbing ozone layer, elemental mercury is quickly oxidized by photosensitized reactions
In the lower stratosphere, the photosensitized oxidation is replaced by much slower thermal oxidation driven by Cl, OH, and Br radicals
Dietary folate intake has been identified as a potentially modifiable factor of gastric cancer (GC) risk, although the evidence is still inconsistent. We evaluate the association between dietary ...folate intake and the risk of GC as well as the potential modification effect of alcohol consumption. We pooled data for 2829 histologically confirmed GC cases and 8141 controls from 11 case-control studies from the international Stomach Cancer Pooling Consortium. Dietary folate intake was estimated using food frequency questionnaires. We used linear mixed models with random intercepts for each study to calculate adjusted odds ratios (OR) and 95% confidence interval (CI). Higher folate intake was associated with a lower risk of GC, although this association was not observed among participants who consumed >2.0 alcoholic drinks/day. The OR for the highest quartile of folate intake, compared with the lowest quartile, was 0.78 (95% CI, 0.67-0.90, P-trend = 0.0002). The OR per each quartile increment was 0.92 (95% CI, 0.87-0.96) and, per every 100 μg/day of folate intake, was 0.89 (95% CI, 0.84-0.95). There was a significant interaction between folate intake and alcohol consumption (P-interaction = 0.02). The lower risk of GC associated with higher folate intake was not observed in participants who consumed >2.0 drinks per day, OR
= 1.15 (95% CI, 0.85-1.56), and the OR
= 1.02 (95% CI, 0.92-1.15). Our study supports a beneficial effect of folate intake on GC risk, although the consumption of >2.0 alcoholic drinks/day counteracts this beneficial effect.
Circulating concentration of arginine, alanine, aspartate, isoleucine, leucine, phenylalanine, proline, tyrosine, taurine and valine are increased in subjects with insulin resistance, which could in ...part be attributed to the presence of single nucleotide polymorphisms (SNPs) within genes associated with amino acid metabolism. Thus, the aim of this work was to develop a Genetic Risk Score (GRS) for insulin resistance in young adults based on SNPs present in genes related to amino acid metabolism. We performed a cross-sectional study that included 452 subjects over 18 years of age. Anthropometric, clinical, and biochemical parameters were assessed including measurement of serum amino acids by high performance liquid chromatography. Eighteen SNPs were genotyped by allelic discrimination. Of these, ten were found to be in Hardy-Weinberg equilibrium, and only four were used to construct the GRS through multiple linear regression modeling. The GRS was calculated using the number of risk alleles of the SNPs in HGD, PRODH, DLD and SLC7A9 genes. Subjects with high GRS (≥ 0.836) had higher levels of glucose, insulin, homeostatic model assessment- insulin resistance (HOMA-IR), total cholesterol and triglycerides, and lower levels of arginine than subjects with low GRS (p < 0.05). The application of a GRS based on variants within genes associated to amino acid metabolism may be useful for the early identification of subjects at increased risk of insulin resistance.
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