Essential features for antioxidant capacity of ascorbic acid (vitamin C)

A systematic DFT study of structure and electronic properties of titanium dioxide

DFT functionals are of paramount importance for an accurate electronic and structural description of transition metal systems. In this work, a systematic analysis using some well-known and commonly used DFT functionals is performed. A comparison of the structural and energetic parameters calculated with the available experimental data is made in order to find the adequate functional for an accurate description of the TiO2 bulk and surface of both anatase and rutile structures. In the absence of experimental data on the surface energy, the theoretical predictions obtained using the high-accuracy HSE06 functional were used as a reference to compare against the surface energy values calculated with the other DFT functionals. A clear improvement in the electronic description of both anatase and rutile was observed by introducing the Hubbard U correction term to PBE, PW91, and OptPBE functionals. The OptPBE-U4 functional was found to offer a good compromise between accurately describing the structural and electronic properties of titania.

Efficient Estimation of Ascorbic Acid in Vitamin C Tablets Enabled by Phase-Transfer Strategy

In this paper, we introduced a novel phase-transfer strategy tailored for the efficient batch detection of ascorbic acid in vitamin C tablets. This method entailed the reaction between ascorbic acid and an excess of potassium permanganate. Subsequent reaction of the residual potassium permanganate with sodium oxalate in an acidic medium led to the generation of carbon dioxide. The quantification of the produced carbon dioxide was achieved using headspace GC, enabling the indirect measurement of ascorbic acid. The obtained findings revealed that the headspace method exhibited satisfied precision with a relative standard deviation of less than 2.11% and high sensitivity with a limit of quantitation of 0.27 μmol. These results firmly establish the reliability of this innovative approach for determining ascorbic acid. In addition, the highly automated feature of headspace method significantly enhances the efficiency of batch sample detection and reduces the errors caused by human operation. Thus, the adoption of the transformed phase strategy has demonstrated its effectiveness in assessing ascorbic acid, especially for large-scale sample analysis in industrial applications, owing to its efficiency, precision, and sensitivity.

K. P, Kim CH, Li Y, Park JH. Dual Stimuli-Responsive Nanoprecursor of Ascorbic Acid and Quinone Methide Disrupting Redox Homeostasis for Cancer Treatment

Disrupting the redox balance through reactive oxygen species (ROS) generation and intracellular glutathione (GSH) depletion presents a promising strategy for cancer therapy. Megadoses of ascorbic acid (AA) can induce oxidative stress in cancer cells, leading to cell death. However, achieving enhanced oxidative stress using ultrahigh doses of AA is challenging because of the intricate delivery of high-concentration AA to the targeted sites while the cancer cells could also re-establish more robust redox homeostasis by upregulating antioxidants such as GSH. Recently, quinone methide and its analogues (QMs) have been recognized as effective GSH scavengers, offering a new dimension to accelerate oxidative stress. In this study, we formulated a dual stimuli-responsive nanoprecursor of AA and QM using gold nanoparticles. The nanoprecursor can release AA in response to the intracellular acidic pH in tumor cells, elevating the intracellular ROS levels and triggering the production of ample QMs to quench excessive GSH. This positive feedback mechanism significantly amplifies oxidative stress and disrupts redox homeostasis in cancer cells at a relatively low concentration of AA, leading to selective apoptosis without affecting normal cells. These results highlight the potential of the nanoprecursor as an effective anticancer therapeutic.

Post-COVID-19 approach to teaching an undergraduate laboratory class focused on experimental design and data interpretation

To best prepare students for the real-world research environment, key skills, including experimental design, data analysis, communication of results, and critical thinking, should be key components of undergraduate science courses. Furthermore, the impact of the COVID-19 pandemic on in-person teaching has resulted in a need to develop courses that enable flexible learning. This paper details the laboratory component of a senior-level toxicology class that was developed to emphasize all these skills and allow for flexible learning. The aim of the laboratory class was for students to determine how curcumin protected against acetaminophen-induced hepatoxicity. To stimulate critical thinking, students were required to choose a maximum of four experiments from the six on offer. Before conducting an experiment, students stated a hypothesis and selected the appropriate treatment groups. Once an experiment was completed, students were given access to a complete dataset, on which they performed statistical analysis and drew conclusions. Students who were unable to attend the laboratory session in person were able to complete the required pre-lab work and access the dataset. Following each experiment, students could write a lab summary, and receive thorough feedback. The final assessment was a written manuscript of their findings as well as a chance to respond to reviewer comments. This teaching approach prioritized the critical thinking, analysis, and experimental design aspects of scientific research. Overall, this structure was well received by students and it could easily be adapted for use on other life science courses.

Novel and Extremely Sensitive NiAl2O4-NiO Nanostructures on an ITO Sensing Electrode for Enhanced Detection of Ascorbic Acid

The current study focused on the design of an extremely sensitive electrochemical sensor of ascorbic acid based on a mixture of NiAl2O4-NiO nanoparticles that, produced in a single step using the sol-gel method, on an ITO electrode. This new sensing platform is useful for the detection of ascorbic acid with a wide range of concentrations extending from the attomolar to the molar. SEM micrographs show the porous structure of the NiAl2O4-NiO sample, with a high specific surface area, which is beneficial for the catalytic performance of the nanocomposite. An XRD diffractogram confirmed the existence of two phases, NiAl2O4 and NiO, both corresponding to the face-centred cubic crystal structure. The performances of the modified electrode, as a biomolecule, in the detection of ascorbic acid was evaluated electrochemically by cyclic voltammetry and chronoamperometry. The sensor exhibited a sensitive electrocatalytic response at a working potential of E = +0.3 V vs. Ag/Ag Cl, reaching a steady-state current within 30 s after each addition of ascorbic acid solution with a wide dynamic range of concentrations extending from attolevels (10-18 M) to molar (10 mM) and limits of detection and quantification of 1.2 × 10-18 M and 3.96 × 10-18 M, respectively. This detection device was tested for the quantification of ascorbic acid in a 500 mg vitamin C commercialized tablet that was not pre-treated.

Exosomes isolated from citrus lemon: a promising candidate for the treatment of Alzheimer's disease

Aim: To investigate the efficacy of exosome-like nanovesicles from citrus lemon (EXO-CLs) in combating oxidative stress associated with Alzheimer's disease. Materials & methods: EXO-CLs were isolated through differential ultracentrifugation, characterized for particle size and evaluated for antioxidant activity. Results: EXO-CLs exhibited a mean size of 93.77 ± 12.31 nm, demonstrated permeability across the blood-brain barrier (BBB) and displayed antioxidant activity comparable to ascorbic acid. Additionally, they were found to be non-toxic, with over 80% cell viability observed in SH-SY5Y cells. Conclusion: The study proposes that EXO-CLs could serve as an effective treatment for neurodegenerative diseases. This suggests a promising approach for targeted interventions in brain-related disorders, owing to the antioxidant properties and BBB permeability exhibited by EXO-CLs.

The Browning Properties, Antioxidant Activity, and α-Glucosidase Inhibitory Improvement of Aged Oranges (Citrus sinensis)

Oranges contain many natural active chemicals, organic acids, and polysaccharides. Aging processing is commonly used to modify the color, quality, functional components, and stability of fruits. This study assesses the preparation of aging black oranges using various pre-treatments and solid fermentation. Oranges were aged for six weeks in fresh, non-blanching, blanching, and hot air-assisted aging cycle (AA) groups. The oranges' shrinkage ratio, color difference values, and soluble solids content changed significantly (p < 0.05). Principal component analysis indicated that aging fermentation treatment accelerated glycolysis and increased the ratio of reducing sugars. The enhanced browning can be associated with the oxidation of ascorbic acid (0.66-0.47 mg/g) and the formation of 5-hydroxymethylfurfural (5-HMF) (0.09 mg/g). Furthermore, the presence of free polyphenols led to an increase in the total polyphenol and total flavonoid content. It also had a synergistic effect with 5-HMF in increasing the 2,2-diphenyl-1-picrylhydrazyl free radical-scavenging capacity and ferric ion-reducing antioxidant power (p < 0.05). AA had superior α-glucosidase inhibitory ability increasing from 67.31 to 80.48%. It also reduced the development time by 33%. Therefore, aging technology can enhance the bioactive compounds in oranges and provide a reference for future whole-fruit aging fermentation and health product creation.

Microneedles: A novel clinical technology for evaluating skin characteristics

BACKGROUND

Current methods for evaluating efficacy of cosmetics have limitations because they cannot accurately measure changes in the dermis. Skin sampling using microneedles allows identification of skin-type biomarkers, monitoring treatment for skin inflammatory diseases, and evaluating efficacy of anti-aging and anti-pigmentation products.

MATERIALS AND METHODS

Two studies were conducted: First, 20 participants received anti-aging treatment; second, 20 participants received anti-pigmentation treatment. Non-invasive devices measured skin aging (using high-resolution 3D-imaging in the anti-aging study) or pigmentation (using spectrophotometry in the anti-pigmentation study) at weeks 0 and 4, and adverse skin reactions were monitored. Skin samples were collected with biocompatible microneedle patches. Changes in expression of biomarkers for skin aging and pigmentation were analyzed using qRT-PCR.

RESULTS

No adverse events were reported. In the anti-aging study, after 4 weeks, skin roughness significantly improved in 17 out of 20 participants. qRT-PCR showed significantly increased expression of skin-aging related biomarkers: PINK1 in 16/20 participants, COL1A1 in 17/20 participants, and MSN in 16/20 participants. In the anti-pigmentation study, after 4 weeks, skin lightness significantly improved in 16/20 participants. qRT-PCR showed significantly increased expression of skin-pigmentation-related biomarkers: SOD1 in 15/20 participants and Vitamin D Receptor (VDR) in 15/20 participants. No significant change in TFAP2A was observed.

CONCLUSION

Skin sampling and mRNA analysis for biomarkers provides a novel, objective, quantitative method for measuring changes in the dermis and evaluating the efficacy of cosmetics. This approach complements existing evaluation methods and has potential application in assessing the effectiveness of medical devices, medications, cosmeceuticals, healthy foods, and beauty devices.

Carbon Dots from Tire Waste for the Photodegradation of Methyl Orange Dye, Antimicrobial Activity, and Molecular Docking Study

In this study, solvothermal pathway was employed for the synthesis of P, N codoped C-dot using tire waste as a sustainable source of carbon and nitrogen. Comprehensive analyses encompassing X-ray diffraction (XRD) analysis, Transmission Electron Microscopy (TEM), FT-IR, cyclic voltammetry, and UV-Vis spectra were used to assess the crystalline structure, purity, size, fluorescence up-conversion, and morphological attributes of the nanomaterial. Subsequently, the produced C-dots were evaluated for their efficacy in the photocatalytic degradation of methylene blue and methyl orange dyes, demonstrating notable success in degrading methyl orange dye within eight hours in the visible region. Furthermore, the same nanomaterial was applied for carrying out agar disk-diffusion assays against a spectrum of microorganisms. Results revealed substantial inhibition zones against Methicillin-Resistant Staphylococcus aureus (MRSA), Escherichia coli, and Pseudomonas aeruginosa. Elucidating the antimicrobial mechanism, molecular-docking simulations were excuted using on AutoDock Vina with designated ligands. The results indicated a strong binding affinity of the C-dots with certain proteins associated with antibacterial activity. This observation suggests that the synthesized C-dots effectively engage with the active sites of these proteins, indicating their potential as promising antibacterial agents. Importantly, this study implies that C-dots do not induce protein denaturation, thereby warranting further investigation of their utility as antibacterial agents.

Comparative Metabolomic and Transcriptomic Analyses Reveal Distinct Ascorbic Acid (AsA) Accumulation Patterns between PCA and PCNA Persimmon Developing Fruit

Persimmon fruit has a high nutritional value and significantly varies between pollination-constant astringent (PCA) and pollination-constant non-astringent (PCNA) persimmons. The astringency type affects sugar, flavonoids, and tannin accumulation and is well known in persimmon fruit. However, the impact of the fruit astringency type on ascorbic acid (AsA) accumulation is limited. In this study, typical PCA varieties ('Huojing' and 'Zhongshi5') and PCNA varieties ('Yohou' and 'Jiro') of persimmon fruit were sampled at four developing stages (S1-S4) to provide valuable information on AsA content variation in PCA and PCNA persimmon. Persimmon fruit is rich in ascorbic acid; the AsA content of the four varieties 'Zhongshi5', 'Huojing', 'Jiro', and 'Youhou' mature fruit reached 104.49, 48.69, 69.69, and 47.48 mg/100 g. Fruit of the same astringency type persimmon showed a similar AsA accumulation pattern. AsA content was significantly higher in PCA than PCNA fruit at S1-S3. The initial KEGG analysis of metabolites showed that galactose metabolism is the major biosynthetic pathway of AsA in persimmon fruit. There were significant differences in galactose pathway-related metabolite content in developing PCA and PCNA fruit, such as Lactose, D-Tagatose, and D-Sorbitol content in PCA being higher than that of PCNA. Combined gene expression and WGCNA analyses showed that the expression of the GME (evm.TU.contig4144.37) gene was higher in PCA-type than in PCNA-type fruit in S1-S3 and exhibited the highest correlation with AsA content (r = 690 **, p < 0.01). Four hub genes, including the DNA methylation gene, methyltransferase gene, F-box, and Actin-like Protein, were identified as potential regulators of the GME gene. These results provide basic information on how astringency types affect AsA accumulation and will provide valuable information for further investigation on AsA content variation in persimmon fruit.

Antioxidant capacity of simplified oxygen heterocycles and proposed derivatives by theoretical calculations

CONTEXT

Some structural properties can be involved in the antioxidant capacity of several polyphenol derivatives, among them their simplified structures. This study examines the contribution of simplified structure for the antioxidant capacity of some natural and synthetic antioxidants. The resonance structures were related to the π-type electron system of carbon-carbon double bonds between both phenyl rings. Trans-resveratrol, phenyl-benzofuran, phenyl-indenone, and benzylidene-benzofuranone are the best basic antioxidant templates among the simplified derivatives studied here. Additionally, the stilbene moiety was found on the molecules with the best antioxidant capacity. Furthermore, our investigation suggests that these compounds can be used as antioxidant scaffold for designing and developing of new promising derivatives.

METHODS

To investigate the structure-antioxidant capacity for sixteen simplified natural and proposed derivatives we have employed density functional theory and used Gaussian 09. Our DFT calculations were performed using the B3LYP functional and the 6-31+G(d,p) basis set. All electron transfer mechanisms were investigated by using values of HOMO, ionization potential, energy affinity, stabilization energies, and spin density distributions.

Tea Polyphenols Inhibit the Activity and Toxicity of Staphylococcus aureus by Destroying Cell Membranes and Accumulating Reactive Oxygen Species

Staphylococcus aureus can cause bacterial food intoxication and seriously affect human health. Tea polyphenols (TP) are a kind of natural, safe, and broad-spectrum bacteriostatic substances, with a wide range of bacteriostatic effects. In the study, we explored the possible bacteriostatic mode of TP. The minimum inhibitory concentration of TP against S. aureus was 64 μg/mL. Protein, DNA, and K+ leak experiments, fluorescence microscopy, and transmission electron microscopy suggested that TP disrupt cell membranes, leading to intracellular component loss. By studying the effect of TP on the toxicity of S. aureus, it was found that the expression levels of two toxin genes, coa and spa, were downregulated by 2.37 and 32.6, respectively. Furthermore, after treatment with TP, a large number of reactive oxygen species (ROS) were propagated and released, leading to oxidative stress in cells. We speculated that the bacteriostatic mechanism of TP may be through the destruction of the cell membrane and ROS-mediated oxidative stress. Meanwhile, the hemolysis activity proved the safety of TP. Our results suggested that TP may be a potential antimicrobial agent for food.

A semiconductor Sc2S3 monolayer with ultrahigh carrier mobility for UV blocking filter application

For humans, ultraviolet (UV) light from sun is harmful to our eyes and eye-related cells. This detrimental fact requires scientists to search for a material that can efficiently absorb UV light while allowing lossless transmission of visible light. Using an unbiased first-principles swarm intelligence structure search, we explored two-dimensional (2D) Sc-S crystals and identified a novel Sc₂S₃ monolayer with good thermal and dynamical stability. The optoelectronic property simulations revealed that the Sc₂S₃ monolayer has a wide indirect bandgap (3.05 eV) and possesses an ultrahigh carrier mobility (2.8 × 10³ cm² V^-1 s^-1). Remarkably, it has almost transparent visible light absorption, while it exhibits an ultrahigh absorption coefficient up to × 10⁵ cm^-1 in the ultraviolet region. Via the application of biaxial strain and thickness modulation, the UV light absorption coefficients of Sc₂S₃ can be further improved. These findings manifest an attractive UV blocking optoelectronic characteristic of the Sc₂S₃ configuration as a prototypical nanomaterial for the potential application in UV blocking filters.

Diverse antitumor effects of ascorbic acid on cancer cells and the tumor microenvironment

Ascorbic acid has attracted substantial attention for its potential antitumor effects by acting as an antioxidant in vivo and as a cofactor in diverse enzymatic reactions. However, solid proof of its clinical efficacy against cancer and the mechanism behind its effect have not been established. Moreover, cancer forms cancer-specific microenvironments and interacts with various cells, such as cancer-associated fibroblasts (CAFs), to maintain cancer growth and progression; however, the effect of ascorbic acid on the cancer microenvironment is unclear. This review discusses the effects and mechanisms of ascorbic acid on cancer, including the role of ascorbic acid concentration. In addition, we present future perspectives on the effects of ascorbic acid on cancer cells and the CAF microenvironment. Ascorbic acid has a variety of effects, which contributes to the complexity of these effects. Oral administration of ascorbic acid results in low blood concentrations (&lt;0.2 mM) and acts as a cofactor for antioxidant effects, collagen secretion, and HIFα degradation. In contrast, intravenous treatment achieves large blood concentrations (&gt;1 mM) and has oxidative-promoting actions that exert anticancer effects via reactive oxygen species. Therefore, intravenous administration at high concentrations is required to achieve the desired effects on cancer cells during treatment. Partial data on the effect of ascorbic acid on fibroblasts indicate that it may also modulate collagen secretion in CAFs and impart tumor-suppressive effects. Thus, future studies should verify the effect of ascorbic acid on CAFs. The findings of this review can be used to guide further research and clinical trials.