A Switch between Antioxidant and Prooxidant Properties of the Phenolic Compounds Myricetin, Morin, 3',4'-Dihydroxyflavone, Taxifolin and 4-Hydroxy-Coumarin in the Presence of Copper(II) Ions: A Spectroscopic, Absorption Titration and DNA Damage Study

Novel thiazole-based cyanoacrylamide derivatives: DNA cleavage, DNA/BSA binding properties and their anticancer behaviour against colon and breast cancer cells

A novel series of 2-cyano-3-(pyrazol-4-yl)-N-(thiazol-2-yl)acrylamide derivatives (3a-f) were synthesized using Knoevenagel condensation and characterized using various spectral tools. The weak nuclease activity of compounds (3a-f) against pBR322 plasmid DNA was greatly enhanced by irradiation at 365 nm. Compounds 3b and 3c, incorporating thienyl and pyridyl moieties, respectively, exhibited the utmost nuclease activity in degrading pBR322 plasmid DNA through singlet oxygen and superoxide free radicals' species. Furthermore, compounds 3b and 3c affinities towards calf thymus DNA (CT-DNA) and bovine serum albumin (BSA) were investigated using UV-Vis and fluorescence spectroscopic analysis. They revealed good binding characteristics towards CT-DNA with Kb values of 6.68 × 104 M-1 and 1.19 × 104 M-1 for 3b and 3c, respectively. In addition, compounds 3b and 3c ability to release free radicals on radiation were targeted to be used as cytotoxic compounds in vitro for colon (HCT116) and breast cancer (MDA-MB-231) cells. A significant reduction in the cell viability on illumination at 365 nm was observed, with IC50 values of 23 and 25 µM against HCT116 cells, and 30 and 9 µM against MDA-MB-231 cells for compounds 3b and 3c, respectively. In conclusion, compounds 3b and 3c exhibited remarkable DNA cleavage and cytotoxic activity on illumination at 365 nm which might be associated with free radicals' production in addition to having a good affinity for interacting with CT-DNA and BSA.

Effects of Strawberry Tree Water Leaf Extract and Arbutin on Biochemical Markers and DNA Integrity in Brain Cells of Lewis Rats

There is growing evidence that arbutin and plant extracts rich in arbutin, such as extracts of the strawberry tree (Arbutus unedo L.), exert a range of beneficial effects, including cyto- and genoprotective properties. This study evaluated the effects of strawberry tree water leaf extract (STE) and arbutin in the brain tissue of Lewis rats. STE or arbutin were administered per os to male and female rats at a dose of 200 mg/kg body weight/day for 14 or 28 days. Treatment outcomes were evaluated using biochemical markers (lipid peroxidation and the activities of the antioxidative enzymes catalase and superoxide dismutase). The effects of the tested substances on DNA integrity in brain cells were evaluated using the alkaline comet assay. The results suggest a high biocompatibility of both tested substances with rat brain tissue. No significant harmful disturbances were observed in the oxidative/antioxidative status or impairments of DNA integrity in the rat brain cells. Nearly all post-treatment values were within tolerable limits as compared to the matched control rats. Such encouraging findings support further research using other subtle biomarkers to clarify the safety aspects of arbutin and STE prior to the development of specific nutraceutical products.

Experimental Parkinson models and green chemistry approach

Parkinson's is the most common neurodegenerative disease after Alzheimer's. Motor findings in Parkinson's occur as a result of the degeneration of dopaminergic neurons starting in the substantia nigra pars compacta and ending in the putamen and caudate nucleus. Loss of neurons and the formation of inclusions called Lewy bodies in existing neurons are characteristic histopathological findings of Parkinson's. The disease primarily impairs the functional capacity of the person with cardinal findings such as tremor, bradykinesia, etc., as a result of the loss of dopaminergic neurons in the substantia nigra. Experimental animal models of Parkinson's have been used extensively in recent years to investigate the pathology of this disease. These models are generally based on systemic or local(intracerebral) administration of neurotoxins, which can replicate many features of Parkinson's mammals. The development of transgenic models in recent years has allowed us to learn more about the modeling of Parkinson's. Applying animal modeling, which shows the most human-like effects in studies, is extremely important. It has been demonstrated that oxidative stress increases in many neurodegenerative diseases such as Parkinson's and various age-related degenerative diseases in humans and that neurons are sensitive to it. In cases where oxidative stress increases and antioxidant systems are inadequate, natural molecules such as flavonoids and polyphenols can be used as a new antioxidant treatment to reduce neuronal reactive oxygen species and improve the neurodegenerative process. Therefore, in this article, we examined experimental animal modeling in Parkinson's disease and the effect of green chemistry approaches on Parkinson's disease.

Autophagy-induced cell death by aqueous and polyphenol-enriched extracts of honeybush (Cyclopia spp.) in liver and colon cancer cells

The anti-cancer potential of Cyclopia species (honeybush) has been demonstrated in several models. The present study investigated the effects of aqueous and polyphenol-enriched (PE) extracts of C. subternata and C. genistoides, as well as mangiferin and hesperidin, on different cell growth parameters in human liver (HepG2) and colon (HT-29) cancer cells. Mangiferin and hesperidin were most abundant in C. genistoides and C. subternata, respectively. Cyclopia subternata extracts had the highest ferric-reducing antioxidant capacity. Following exposure of the cells to the extracts and compounds, cell viability, proliferation, and death (apoptosis and autophagy) were determined. Cyclopia subternata extracts reduced cell viability and inhibited cell proliferation the most, associated with depletion of ATP. In HepG2 cells, the PE extracts were less effective than the aqueous extracts in reducing cell viability but more effective in inhibiting cell proliferation. Despite disrupting cell growth, none of the extracts induced apoptosis. The aqueous extracts affected autophagy in both cancer cells. Disruption of mitochondrial membrane integrity by the different extracts, presumably via polyphenol/iron interactions, is postulated to be involved; however, mangiferin and hesperidin had no effect, suggesting that other polyphenols and/or complex interactions between compounds are likely responsible for the differential cytotoxic and/or cytoprotective effects of the extracts.

Targeting Peroxisome Proliferator-Activated Receptor-β/δ, Reactive Oxygen Species and Redox Signaling with Phytocompounds for Cancer Therapy

Significance: Peroxisome proliferator-activated receptors (PPARs) have a moderately preserved amino-terminal domain, an extremely preserved DNA-binding domain, an integral hinge region, and a distinct ligand-binding domain that are frequently encountered with the other nuclear receptors. PPAR-β/δ is among the three nuclear receptor superfamily members in the PPAR group. Recent Advances: Emerging studies provide an insight on natural compounds that have gained increasing attention as potential anticancer agents due to their ability to target multiple pathways involved in cancer development and progression. Critical Issues: Modulation of PPAR-β/δ activity has been suggested as a potential therapeutic strategy for cancer management. This review focuses on the ability of bioactive phytocompounds to impact reactive oxygen species (ROS) and redox signaling by targeting PPAR-β/δ for cancer therapy. The rise of ROS in cancer cells may play an important part in the initiation and progression of cancer. However, excessive levels of ROS stress can also be toxic to the cells and cancer cells with increased oxidative stress are likely to be more vulnerable to damage by further ROS insults induced by exogenous agents, such as phytocompounds and therapeutic agents. Therefore, redox modulation is a way to selectively kill cancer cells without causing significant toxicity to normal cells. However, use of antioxidants together with cancer drugs may risk the effect of treatment as both act through opposite mechanisms. Future Directions: It is advisable to employ more thorough and detailed methodologies to undertake mechanistic explorations of numerous phytocompounds. Moreover, conducting additional clinical studies is recommended to establish optimal dosages, efficacy, and the impact of different phytochemicals on PPAR-β/δ.

Multifunctional in vitro, in silico and DFT analyses on antimicrobial BagremycinA biosynthesized by Micromonospora chokoriensis CR3 from Hieracium canadense

Among the actinomycetes in the rare genera, Micromonospora is of great interest since it has been shown to produce novel therapeutic compounds. Particular emphasis is now on its isolation from plants since its population from soil has been extensively explored. The strain CR3 was isolated as an endophyte from the roots of Hieracium canadense, and it was identified as Micromonospora chokoriensis through 16S gene sequencing and phylogenetic analysis. The in-vitro analysis of its extract revealed it to be active against the clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) and Candida tropicalis (15 mm). No bioactivity was observed against Gram-negative bacteria, Escherichia coli ATCC 25922, and Klebsiella pneumoniae ATCC 706003. The Micromonospora chokoriensis CR3 extract was also analyzed through the HPLC-DAD-UV-VIS resident database, and it gave a maximum match factor of 997.334 with the specialized metabolite BagremycinA (BagA). The in-silico analysis indicated that BagA strongly interacted with the active site residues of the sterol 14-α demethylase and thymidylate kinase enzymes, with the lowest binding energies of - 9.7 and - 8.3 kcal/mol, respectively. Furthermore, the normal mode analysis indicated that the interaction between these proteins and BagA was stable. The DFT quantum chemical properties depicted BagA to be reasonably reactive with a HOMO-LUMO gap of (ΔE) of 4.390 eV. BagA also passed the drug-likeness test with a synthetic accessibility score of 2.06, whereas Protox-II classified it as a class V toxicity compound with high LD50 of 2644 mg/kg. The current study reports an endophytic actinomycete, M. chokoriensis, associated with H. canadense producing the bioactive metabolite BagA with promising antimicrobial activity, which can be further modified and developed into a safe antimicrobial drug.

Cytotoxic Activity of the Red Grape Polyphenol Resveratrol against Human Prostate Cancer Cells: A Molecular Mechanism Mediated by Mobilization of Nuclear Copper and Generation of Reactive Oxygen Species

Resveratrol, a polyphenolic compound found primarily in red grapes and pomegranates is known as an antioxidant but can act as a pro-oxidant when copper ions are present. Here, resveratrol is demonstrated to reduce cell growth (as evaluated by MTT assay) and promote apoptosis-like cell death (as measured by Histone/DNA ELISA) in prostate cancer cell lines PC3 and C42B. This effect is effectively inhibited by a copper chelator (neocuproine) and reactive oxygen species (ROS) scavengers (thiourea for hydroxyl radical, superoxide dismutase for superoxide anion, and catalase for hydrogen peroxide). These inhibitory effects provide evidence that intracellular copper reacts with resveratrol within cancer cells, resulting in DNA damage via the generation of reactive oxygen species. Additionally, it has been demonstrated that non-tumorigenic epithelial cell lines (MCF-10A) grown in media supplemented with copper are more susceptible to growth inhibition by resveratrol, as confirmed by the observed reduction in cell proliferation. Copper supplementation induces enhanced expression of the copper transporter CTR1 in MCF-10A cells, which is reduced by the addition of resveratrol to the media. The selective cell death of cancer cells generated by copper-mediated and ROS mechanisms may help to explain the anticancer properties of resveratrol.

Several lines of antioxidant defense against oxidative stress: antioxidant enzymes, nanomaterials with multiple enzyme-mimicking activities, and low-molecular-weight antioxidants

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are well recognized for playing a dual role, since they can be either deleterious or beneficial to biological systems. An imbalance between ROS production and elimination is termed oxidative stress, a critical factor and common denominator of many chronic diseases such as cancer, cardiovascular diseases, metabolic diseases, neurological disorders (Alzheimer's and Parkinson's diseases), and other disorders. To counteract the harmful effects of ROS, organisms have evolved a complex, three-line antioxidant defense system. The first-line defense mechanism is the most efficient and involves antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). This line of defense plays an irreplaceable role in the dismutation of superoxide radicals (O2•-) and hydrogen peroxide (H2O2). The removal of superoxide radicals by SOD prevents the formation of the much more damaging peroxynitrite ONOO- (O2•-  + NO• → ONOO-) and maintains the physiologically relevant level of nitric oxide (NO•), an important molecule in neurotransmission, inflammation, and vasodilation. The second-line antioxidant defense pathway involves exogenous diet-derived small-molecule antioxidants. The third-line antioxidant defense is ensured by the repair or removal of oxidized proteins and other biomolecules by a variety of enzyme systems. This review briefly discusses the endogenous (mitochondria, NADPH, xanthine oxidase (XO), Fenton reaction) and exogenous (e.g., smoking, radiation, drugs, pollution) sources of ROS (superoxide radical, hydrogen peroxide, hydroxyl radical, peroxyl radical, hypochlorous acid, peroxynitrite). Attention has been given to the first-line antioxidant defense system provided by SOD, CAT, and GPx. The chemical and molecular mechanisms of antioxidant enzymes, enzyme-related diseases (cancer, cardiovascular, lung, metabolic, and neurological diseases), and the role of enzymes (e.g., GPx4) in cellular processes such as ferroptosis are discussed. Potential therapeutic applications of enzyme mimics and recent progress in metal-based (copper, iron, cobalt, molybdenum, cerium) and nonmetal (carbon)-based nanomaterials with enzyme-like activities (nanozymes) are also discussed. Moreover, attention has been given to the mechanisms of action of low-molecular-weight antioxidants (vitamin C (ascorbate), vitamin E (alpha-tocopherol), carotenoids (e.g., β-carotene, lycopene, lutein), flavonoids (e.g., quercetin, anthocyanins, epicatechin), and glutathione (GSH)), the activation of transcription factors such as Nrf2, and the protection against chronic diseases. Given that there is a discrepancy between preclinical and clinical studies, approaches that may result in greater pharmacological and clinical success of low-molecular-weight antioxidant therapies are also subject to discussion.

Protective effects of myricetin and morin on neurological damage in Aβ1-42/Al3+ -induced Alzheimer's disease model of rats

Alzheimer's disease (AD) is a degenerative neurological disorder with unclear pathogenesis. Single-target drugs have very limited efficacy in treating AD, but synthetic multi-target drugs have poor efficacy and safety. Therefore, finding suitable natural multi-target drugs against AD is of great interest for research studies. We chose two flavonols, myricetin and morin, for the relevant study. In this study, we used microinjection of Aβ1-42 oligomers into the CA1 region of rat hippocampus, combined with gavage of Aluminum chloride hexahydrate (AlCl3·6H2O) solution to establish AD rat models, and myricetin and morin were selected as intervening drugs to explore the protective effects against neurological impairment. Experimental results showed that myricetin or morin could reduce the production of Aβ, Tubulin-associated unit (Tau), and Phosphorylated tubulin-associated unit (p-Tau), down-regulate the expression of relevant inflammatory factors, reduce hippocampal cell apoptosis in rats. There was a significant increase in the activity of adenosine triphosphatase, catalase, total superoxide dismutase, and the content of glutathione in the brain tissue. However, the content of malondialdehyde, inducible nitric oxide synthase, and the activity of acetylcholinesterase were decreased in the brain tissue. These two flavonols can regulate the imbalance of monoamine and amino acid neurotransmitter levels. In conclusion, Myricetin or morin can effectively improve learning and memory dysfunction in AD rats induced by Aβ1-42/Al3+ through anti-oxidative stress and anti-apoptotic features.

Comparative Analysis of Fluorescence Emission in Myricetin, Kaempferol, and Quercetin Powders and Solutions

Myricetin is a flavonol with high antioxidant properties. In this research, the fluorescence emission of myricetin powder and its solutions in different solvents were measured and analyzed by comparing with the results of calculations. Comparison of the calculated and measured characteristic wavelengths allowed the identification of all the spectral features in the fluorescence spectra of myricetin powder and solutions with different concentrations. The computation was based on modeling the process of the excited state intermolecular proton transfer, which predicts the formation of tautomeric forms of the flavonol molecule. Characteristic emission wavelengths were obtained using TDDFT/M06-2X/6-31++G(d,p). To understand the influence of the hydroxyl groups in the B-ring of the flavonol molecule on the emission spectrum, we also compared the fluorescence spectra of myricetin with those of kaempferol and quercetin. Moreover, based on the analysis of the changes in the shape of the FL spectra with the concentration of the solution, a criterion for the complete dissolution of the flavonol powders was established, which is important for bioavailability of flavonoids.

Variability in morphology, phytochemicals and antioxidant activity in Bistorta amplexicaulis (D. Don) Greene populations under variable habitats and altitudes

Phytochemicals have become significantly important for scientific research since these possess incredibly remarkable health benefits, especially antioxidant potential to scavenge free radicals and combat the harmful effects of oxidative stress caused by adverse environmental factors. The efficacy and quantity of these phytochemicals relies upon numerous factors including the extraction method, solvent polarity and the habitat features in which the plant is growing. In this study we emphasized on phytochemical analysis and antioxidant activity of Bistorta amplexicaulis, an important medicinal plant species from Kashmir Himalaya. We evaluated antioxidant activity using different assays from all the selected sites to enumerate the impact of habitat. The sites were selected based on varying habitat features and altitude. Our results revealed that Ethyl acetate is the potent solvent for the extraction of phytochemicals. Below ground parts exhibited better scavenging activity than the above ground parts. Amongst the sites, we found the maximum antioxidant potential at Site I. A positive correlation was found between antioxidant activity and altitude while soil attributes (OC, OM, N, P, and K) and most of the morphological traits showed a negative correlation. Overall, our study identified the elite populations that could be utilized for mass propagation and harness the ultimate antioxidant potential of B. amplexicaulis.

In Vitro Safety and Efficacy Evaluation of a Juniperus communis Callus Culture Extract and Matricaria recutita Processing Waste Extract Combination as a Cosmetic Ingredient

For skin health promotion and cosmetic applications, combinations of plant cell extracts are extensively utilized. As most natural ingredient suppliers offer crude extracts from individual plants or specific isolated compounds, the potential interactions between them are assessed in the development phase of cosmetic products. The industry seeks extract combinations that have undergone optimization and scrutiny for their bioactivities. This study presents a combination of two sustainably produced botanical ingredients and outlines their chemical composition, in vitro safety, and bioactivity for skin health enhancement. The amalgamation comprises the extract of Matricaria recutita processing waste and the extract from Juniperus communis callus culture. Chemical analysis revealed distinct compounds within the extracts, and their combination led to a broader array of potentially synergistic compounds. In vitro assessments on skin cells demonstrated that the combination possesses robust antioxidant properties and the ability to stimulate keratinocyte proliferation, along with regulating collagen type I and matrix metalloproteinase 1 (MMP-1) production by dermal fibroblasts. The identified traits of this combination render it an appealing cosmetic component. To the best of our knowledge, this represents the first case when the extracts derived from medicinal plant processing waste and biotechnological plant cell cultivation processes have been combined and evaluated for their bioactivity.

Hypericum alpestre extract exhibits in vitro and in vivo anticancer properties by regulating the cellular antioxidant system and metabolic pathway of L-arginine

Conventional treatment methods are not effective enough to fight the rapid increase in cancer cases. The interest is increasing in the investigation of herbal sources for the development of new anticancer therapeutics. This study aims to investigate the antitumor capacity of Hypericum alpestre (H. alpestre) extract in vitro and in vivo, either alone or in combination with the inhibitors of the  l-arginine/polyamine/nitric oxide (NO) pathway, and to characterize its active phytochemicals using advanced chromatographic techniques. Our previous reports suggest beneficial effects of the arginase inhibitor NG-hydroxy-nor- l-arginine and NO inhibitor NG-nitro-Larginine methyl ester in the treatment of breast cancer via downregulation of polyamine and NO synthesis. Here, the antitumor properties of H. alpestre and its combinations were explored in vivo, in a rat model of mammary gland carcinogenesis induced by subcutaneous injection of 7,12-dimethylbenz[a]anthracene. The study revealed strong antiradical activity of H. alpestre aerial part extract in chemical (DPPH/ABTS) tests. In the in vitro antioxidant activity test, the H. alpestre extract demonstrated pro-oxidant characteristics in human colorectal (HT29) cells, which were contingent upon the hemostatic condition of the cells. The H. alpestre extract expressed a cytotoxic effect on HT29 and breast cancer (MCF-7) cells measured by the MTT test. According to comet assay results, H. alpestre extract did not exhibit genotoxic activity nor possessed antigenotoxic properties in HT29 cells. Overall, 233 substances have been identified and annotated in H. alpestre extract using the LC-Q-Orbitrap HRMS system. In vivo experiments using rat breast cancer models revealed that the H. alpestre extract activated the antioxidant enzymes in the liver, brain, and tumors. H. alpestre combined with chemotherapeutic agents attenuated cancer-like histological alterations and showed significant reductions in tumor blood vessel area. Thus, either alone or in combination with Nω -OH-nor- l-arginine and Nω -nitro- l-arginine methyl ester, H. alpestre extract exhibits pro- and antioxidant, antiangiogenic, and cytotoxic effects.

Stability of Coumarins and Determination of the Net Iron Oxidation State of Iron-Coumarin Complexes: Implications for Examining Plant Iron Acquisition Mechanisms

Coumarins are exuded into the soil environment by plant roots in response to iron (Fe) deficiency. Previous studies have shown that coumarins can increase the Fe solubility upon interaction with sparsely soluble Fe(III) (hydr)oxide. However, the chemical mechanisms of Fe(III) (hydr)oxide dissolution by coumarins remain unclear. The high redox instability of dissolved coumarins and the interference of coumarins in determining the Fe redox state hinder the quantitative and mechanistic investigation of coumarin-induced Fe mobilization. In this study, we investigated the oxidative stability of three coumarins that have been found in root exudates, esculetin, scopoletin, and fraxetin, over a broad pH range under oxic and anoxic conditions. Our results show that the oxidation of coumarins is irreversible under oxic conditions and that oxidative degradation rates increased with increasing pH under both oxic and anoxic conditions. However, the complexation of Fe protects coumarins from degradation in the circumneutral pH range even under oxic conditions. Furthermore, we observed that Ferrozine, which is commonly used for establishing Fe redox speciation, can facilitate the reduction of Fe(III) complexed by coumarins, even at circumneutral pH. Reduction rates increased with decreasing pH and were larger for fraxetin than for scopoletin and esculetin. Based on these observations, we optimized the Ferrozine method for determining the redox state of Fe complexed by coumarins. Understanding the stability of dissolved coumarins and using a precise analytical method to determine the redox state of Fe in the presence of coumarins are critical for investigating the mechanisms by which coumarins enhance the availability of Fe in the rhizosphere.

Anti-tumor activity of silymarin nanoliposomes in combination with iron: In vitro and in vivo study

Combination therapy represents a promising strategy in cancer management by reducing chemotherapy resistance and associated side effects. Silymarin (SLM) has been extensively investigated due to its potent antioxidant properties and demonstrated efficacy against cancer cells. Under certain conditions however, polyphenolic compounds may also exhibit prooxidant activity by elevating intracellular reactive oxygen species (ROS), which can harm the target cells. In this study, we hypothesized that the simultaneous administration of iron (Fe) could alter the antioxidant characteristic of SLM nanoliposomes (SLM Lip) to a prooxidant state. Hence, we first developed a SLM Lip preparation using lipid film method, and then investigated the anti-oxidant properties as well as the cytotoxicity of the liposomal preparation. We also explored the efficacy of concomitant administration of iron sucrose and SML Lip on the tumor growth and survival of mice bearing tumors. We observed that exposing cells to iron, and consecutive treatment with SLM Lip (Fe + SLM Lip) could induce greater toxicity to 4 T1 breast cancer cells compared to SLM Lip. Further, Fe + SLM Lip combination demonstrated a time-dependent effect on reducing the catalase activity compared to SLM Lip, while iron treatment did not alter cell toxicity and catalase activity. In a mouse breast cancer model, the therapeutic efficacy of Fe + SLM Lip was superior compared to SLM Lip, and the treated animals survived longer. The histopathological findings did not reveal a significant damage to the major organs, whereas the most significant tumor necrosis was evident with Fe + SLM Lip treatment. The outcomes of the present investigation unequivocally underscored the prospective use of Fe + SLM combination in the context of cancer therapy, which warrants further scrutiny.

Analysis of Softwood Lignans by Comprehensive Two-Dimensional Liquid Chromatography

Lignans constitute a large group of phenolic plant secondary metabolites possessing high bioactivity. Their accurate determination in plant extracts with a complex chemical composition is challenging and requires advanced separation techniques. In the present study, a new approach to the determination of lignans in coniferous knotwood extracts as the promising industrial-scale source of such compounds based on comprehensive two-dimensional liquid chromatography separation and UV spectrophotometric detection is proposed. First and second-dimension column screening showed that the best results can be obtained using a combination of non-polar and polar hydroxy group embedded octadecyl stationary phases with moderate (~40%) "orthogonality". The optimization of LC × LC separation conditions allowed for the development of a new method for the quantification of the five lignans (secoisolariciresinol, matairesinol, pinoresinol, 7-hydroxymatairesinol, and nortrachelogenin) in knotwood extracts with limits of quantification in the range of 0.27-0.95 mg L-1 and a linear concentration range covering at least two orders of magnitude. Testing the developed method on coniferous (larch, fir, spruce, and pine) knotwood extracts demonstrated the high selectivity of the analysis and the advantages of LC × LC in the separation and accurate quantification of the compounds co-eluting in one-dimensional HPLC.

Reactive oxygen species, toxicity, oxidative stress, and antioxidants: chronic diseases and aging

A physiological level of oxygen/nitrogen free radicals and non-radical reactive species (collectively known as ROS/RNS) is termed oxidative eustress or "good stress" and is characterized by low to mild levels of oxidants involved in the regulation of various biochemical transformations such as carboxylation, hydroxylation, peroxidation, or modulation of signal transduction pathways such as Nuclear factor-κB (NF-κB), Mitogen-activated protein kinase (MAPK) cascade, phosphoinositide-3-kinase, nuclear factor erythroid 2-related factor 2 (Nrf2) and other processes. Increased levels of ROS/RNS, generated from both endogenous (mitochondria, NADPH oxidases) and/or exogenous sources (radiation, certain drugs, foods, cigarette smoking, pollution) result in a harmful condition termed oxidative stress ("bad stress"). Although it is widely accepted, that many chronic diseases are multifactorial in origin, they share oxidative stress as a common denominator. Here we review the importance of oxidative stress and the mechanisms through which oxidative stress contributes to the pathological states of an organism. Attention is focused on the chemistry of ROS and RNS (e.g. superoxide radical, hydrogen peroxide, hydroxyl radicals, peroxyl radicals, nitric oxide, peroxynitrite), and their role in oxidative damage of DNA, proteins, and membrane lipids. Quantitative and qualitative assessment of oxidative stress biomarkers is also discussed. Oxidative stress contributes to the pathology of cancer, cardiovascular diseases, diabetes, neurological disorders (Alzheimer's and Parkinson's diseases, Down syndrome), psychiatric diseases (depression, schizophrenia, bipolar disorder), renal disease, lung disease (chronic pulmonary obstruction, lung cancer), and aging. The concerted action of antioxidants to ameliorate the harmful effect of oxidative stress is achieved by antioxidant enzymes (Superoxide dismutases-SODs, catalase, glutathione peroxidase-GPx), and small molecular weight antioxidants (vitamins C and E, flavonoids, carotenoids, melatonin, ergothioneine, and others). Perhaps one of the most effective low molecular weight antioxidants is vitamin E, the first line of defense against the peroxidation of lipids. A promising approach appears to be the use of certain antioxidants (e.g. flavonoids), showing weak prooxidant properties that may boost cellular antioxidant systems and thus act as preventive anticancer agents. Redox metal-based enzyme mimetic compounds as potential pharmaceutical interventions and sirtuins as promising therapeutic targets for age-related diseases and anti-aging strategies are discussed.

Polyphenols in Plants: Structure, Biosynthesis, Abiotic Stress Regulation, and Practical Applications (Review)

Phenolic compounds or polyphenols are among the most common compounds of secondary metabolism in plants. Their biosynthesis is characteristic of all plant cells and is carried out with the participation of the shikimate and acetate-malonate pathways. In this case, polyphenols of various structures are formed, such as phenylpropanoids, flavonoids, and various oligomeric and polymeric compounds of phenolic nature. Their number already exceeds 10,000. The diversity of phenolics affects their biological activity and functional role. Most of their representatives are characterized by interaction with reactive oxygen species, which manifests itself not only in plants but also in the human body, where they enter through food chains. Having a high biological activity, phenolic compounds are successfully used as medicines and nutritional supplements for the health of the population. The accumulation and biosynthesis of polyphenols in plants depend on many factors, including physiological-biochemical, molecular-genetic, and environmental factors. In the review, we present the latest literature data on the structure of various classes of phenolic compounds, their antioxidant activity, and their biosynthesis, including their molecular genetic aspects (genes and transfactors). Since plants grow with significant environmental changes on the planet, their response to the action of abiotic factors (light, UV radiation, temperature, and heavy metals) at the level of accumulation and composition of these secondary metabolites, as well as their metabolic regulation, is considered. Information is given about plant polyphenols as important and necessary components of functional nutrition and pharmaceutically valuable substances for the health of the population. Proposals on promising areas of research and development in the field of plant polyphenols are presented.

Hybrids of Sterically Hindered Phenols and Diaryl Ureas: Synthesis, Switch from Antioxidant Activity to ROS Generation and Induction of Apoptosis

The utility of sterically hindered phenols (SHPs) in drug design is based on their chameleonic ability to switch from an antioxidant that can protect healthy tissues to highly cytotoxic species that can target tumor cells. This work explores the biological activity of a family of 45 new hybrid molecules that combine SHPs equipped with an activating phosphonate moiety at the benzylic position with additional urea/thiourea fragments. The target compounds were synthesized by reaction of iso(thio)cyanates with C-arylphosphorylated phenols containing pendant 2,6-diaminopyridine and 1,3-diaminobenzene moieties. The SHP/urea hybrids display cytotoxic activity against a number of tumor lines. Mechanistic studies confirm the paradoxical nature of these substances which combine pronounced antioxidant properties in radical trapping assays with increased reactive oxygen species generation in tumor cells. Moreover, the most cytotoxic compounds inhibited the process of glycolysis in SH-SY5Y cells and caused pronounced dissipation of the mitochondrial membrane of isolated rat liver mitochondria. Molecular docking of the most active compounds identified the activator allosteric center of pyruvate kinase M2 as one of the possible targets. For the most promising compounds, 11b and 17b, this combination of properties results in the ability to induce apoptosis in HuTu 80 cells along the intrinsic mitochondrial pathway. Cyclic voltammetry studies reveal complex redox behavior which can be simplified by addition of a large excess of acid that can protect some of the oxidizable groups by protonations. Interestingly, the re-reduction behavior of the oxidized species shows considerable variations, indicating different degrees of reversibility. Such reversibility (or quasi-reversibility) suggests that the shift of the phenol-quinone equilibrium toward the original phenol at the lower pH may be associated with lower cytotoxicity.

The role of redox active copper(II) on antioxidant properties of the flavonoid baicalein: DNA protection under Cu(II)-Fenton reaction and Cu(II)-ascorbate system conditions

The antioxidant properties of flavonoids are mediated by their functional hydroxyl groups, which are capable of both chelating redox active metals such as iron, copper and scavenging free radicals. In this paper, the antioxidant vs. prooxidant and DNA protecting properties of baicalein and Cu(II)-baicalein complexes were studied under the conditions of the Copper-Fenton reaction and of the Copper-Ascorbate system. From the relevant EPR spectra, the interaction of baicalein with Cu(II) ions was confirmed, while UV-vis spectroscopy demonstrated a greater stability over time of Cu(II)-baicalein complexes in DMSO than in methanol and PBS and Phosphate buffers. An ABTS study confirmed a moderate ROS scavenging efficiency, at around 37%, for both free baicalein and Cu(II)-baicalein complexes (in the ratios 1:1 and 1:2). The results from absorption titrations are in agreement with those from viscometric studies and confirmed that the binding mode between DNA and both free baicalein and Cu-baicalein complexes, involves hydrogen bonds and van der Waals interactions. The DNA protective effect of baicalein has been investigated by means of gel electrophoresis under the conditions of the Cu-catalyzed Fenton reaction and of the Cu-Ascorbate system. In both cases, it was found that, at sufficiently high concentrations, baicalein offers some protection to cells from DNA damage caused by ROS (singlet oxygen, hydroxyl radicals and superoxide radical anions). Accordingly, baicalein may be useful as a therapeutic agent in diseases with a disturbed metabolism of redox metals such as copper, for example Alzheimer's disease, Wilson's disease and various cancers. While therapeutically sufficient concentrations of baicalein may protect neuronal cells from Cu-Fenton-induced DNA damage in regard to neurological conditions, conversely, in the case of cancers, low concentrations of baicalein do not inhibit the pro-oxidant effect of copper ions and ascorbate, which can, in turn, deliver an effective damage to DNA in tumour cells.

Hepatoprotective role of myricitrin isolated from Mimusops elengi Linn. leaves extract on γ-radiation-induced liver damage in rats: Phyto-biochemical investigations

The hepatoprotective effects of methanol extract of Mimusops elengi Linn. (M. elengi L.) leaves and isolated pure myricitrin (3-, 4-, 5-, 5, 7-five hydroxyflavone-3-O-α-l-rhamnoside) (Myr) were evaluated in male rats exposed to γ-irradiation. The extraction of M. elengi L. leaves was performed using ethyl acetate (EtOAC). Seven groups of rats were used: control group, irradiated (IRR) group (6 Gy of γ-rays in a single dose), vehicle group (oral administration of 0.5% carboxymethyl cellulose for 10 days), EtOAC extract group (100 mg/kg body weight of extract, orally for 10 days), EtOAC + IRR group (administration of extract and exposure to γ-rays on Day 7), Myr group (50 mg/kg body weight Myr, orally for 10 days), and Myr + IRR group (administration of Myr and exposure to γ-rays on Day 7). High-performance liquid chromatography and 1H-nuclear magnetic resonance were used to isolate and characterize the compounds from M. elengi L. leaves. Enzyme-linked immunosorbent assay was used for biochemical analyses. Identified compounds were Myr, myricetin 3-O-galactoside, myricetin 3-O-rahmnopyranoside (1 → 6) glucopyranoside, quercetin, quercitol, gallic acid, α-,β-amyrin, ursolic acid, and lupeol. Serum aspartate transaminase and alanine transaminase activities were significantly increased, while serum protein and albumin levels were significantly decreased after irradiation. Hepatic levels of tumor necrosis factor-α, prostaglandin 2, inducible nitric oxide synthase, interleukin-6 (IL-6), and IL-12 were increased following irradiation. Improvements were observed in most serological parameters after treatment with extract or pure Myr, with histological analyses confirming decreased liver injury in treated rats. Our study demonstrates that pure Myr has a greater hepatoprotective effect than M. elengi leaf extracts against irradiation-induced hepatic inflammation.

Potentiation of Cisplatin Cytotoxicity in Resistant Ovarian Cancer SKOV3/Cisplatin Cells by Quercetin Pre-Treatment

Previously, we demonstrated that the overexpression of antioxidant enzymes (SOD-1, SOD-2, Gpx-1, CAT, and HO-1), transcription factor NFE2L2, and the signaling pathway (PI3K/Akt/mTOR) contribute to the cisplatin resistance of SKOV-3/CDDP ovarian cells, and treatment with quercetin (QU) alone has been shown to inhibit the expression of these genes. The aim of this study was to expand the previous data by examining the efficiency of reversing cisplatin resistance and investigating the underlying mechanism of pre-treatment with QU followed by cisplatin in the same ovarian cancer cells. The pre-incubation of SKOV-3/CDDP cells with quercetin at an optimum dose prior to treatment with cisplatin exhibited a significant cytotoxic effect. Furthermore, a long incubation with only QU for 48 h caused cell cycle arrest at the G1/S phase, while a QU pre-treatment induced sub-G1 phase cell accumulation (apoptosis) in a time-dependent manner. An in-depth study of the mechanism of the actions revealed that QU pre-treatment acted as a pro-oxidant that induced ROS production by inhibiting the thioredoxin antioxidant system Trx/TrxR. Moreover, QU pre-treatment showed activation of the mitochondrial apoptotic pathway (cleaved caspases 9, 7, and 3 and cleaved PARP) through downregulation of the signaling pathway (mTOR/STAT3) in SKOV-3/CDDP cells. This study provides further new data for the mechanism by which the QU pre-treatment re-sensitizes SKOV-3/CDDP cells to cisplatin.

Probing the binding of morin with alpha-2-macroglobulin using multi-spectroscopic and molecular docking approach : Interaction of morin with α2M

Alpha-2-macroglobulin (α2M) is an essential antiproteinase that is widely distributed in human plasma. The present study was aimed at investigating the binding of a potential therapeutic dietary flavonol, morin, with human α2M using a multi-spectroscopic and molecular docking approach. Recently, flavonoid-protein interaction has gained significant attention, because a majority of dietary bioactive components interact with proteins, thereby altering their structure and function. The results of the activity assay exhibited a 48% reduction in the antiproteolytic potential of α2M upon interaction with morin. Fluorescence quenching tests unequivocally confirmed quenching in the fluorescence of α2M in the presence of morin, conforming complex formation and demonstrating that the binding mechanism involves a dynamic mode of interaction. Synchronous fluorescence spectra of α2M with morin showed perturbation in the microenvironment around tryptophan residues. Furthermore, structural changes were observed through CD and FT-IR, showing alterations in the secondary structure of α2M induced by morin. FRET further supports the results of the dynamic mode of quenching. Moderate interaction is shown by binding constant values using Stern-Volmer's fluorescence spectroscopy. Morin binds to α2M at 298 K with a binding constant of 2.7 × 104 M-1, indicating the strength of the association. The α2M-morin system was found to have negative ΔG values, which suggests that the binding process was spontaneous. Molecular docking also reveals the different amino acid residues involved in this binding process, revealing that the binding energy is -8.1 kcal/mol.

Natural flavonols: actions, mechanisms, and potential therapeutic utility for various diseases

Background

Flavonols are phytoconstituents of biological and medicinal importance. In addition to functioning as antioxidants, flavonols may play a role in antagonizing diabetes, cancer, cardiovascular disease, and viral and bacterial diseases. Quercetin, myricetin, kaempferol, and fisetin are the major dietary flavonols. Quercetin is a potent scavenger of free radicals, providing protection from free radical damage and oxidation-associated diseases.

Main body of the abstract

An extensive literature review of specific databases (e.g., Pubmed, google scholar, science direct) were conducted using the keywords "flavonol," "quercetin," "antidiabetic," "antiviral," "anticancer," and "myricetin." Some studies concluded that quercetin is a promising antioxidant agent while kaempferol could be effective against human gastric cancer. In addition, kaempferol prevents apoptosis of pancreatic beta-cells via boosting the function and survival rate of the beta-cells, leading to increased insulin secretion. Flavonols also show potential as alternatives to conventional antibiotics, restricting viral infection by antagonizing the envelope proteins to block viral entry.

Short conclusion

There is substantial scientific evidence that high consumption of flavonols is associated with reduced risk of cancer and coronary diseases, free radical damage alleviation, tumor growth prevention, and insulin secretion improvement, among other diverse health benefits. Nevertheless, more studies are required to determine the appropriate dietary concentration, dose, and type of flavonol for a particular condition to prevent any adverse side effects.

Synthesis, Structural Elucidation and Pharmacological Applications of Cu(II) Heteroleptic Carboxylates

Six heteroleptic Cu(II) carboxylates (1-6) were prepared by reacting 2-chlorophenyl acetic acid (L¹), 3-chlorophenyl acetic acid (L²), and substituted pyridine (2-cyanopyridine and 2-chlorocyanopyridine). The solid-state behavior of the complexes was described via vibrational spectroscopy (FT-IR), which revealed that the carboxylate moieties adopted different coordination modes around the Cu(II) center. A paddlewheel dinuclear structure with distorted square pyramidal geometry was elucidated from the crystal data for complexes 2 and 5 with substituted pyridine moieties at the axial positions. The presence of irreversible metal-centered oxidation reduction peaks confirms the electroactive nature of the complexes. A relatively higher binding affinity was observed for the interaction of SS-DNA with complexes 2-6 compared to L¹ and L². The findings of the DNA interaction study indicate an intercalative mode of interaction. The maximum inhibition against acetylcholinesterase enzyme was caused for complex 2 (IC₅₀ = 2 µg/mL) compared to the standard drug Glutamine (IC₅₀ = 2.10 µg/mL) while the maximum inhibition was found for butyrylcholinesterase enzyme by complex 4 (IC₅₀ = 3 µg/mL) compared to the standard drug Glutamine (IC₅₀ = 3.40 µg/mL). The findings of the enzymatic activity suggest that the under study compounds have potential for curing of Alzheimer's disease. Similarly, complexes 2 and 4 possess the maximum inhibition as revealed from the free radical scavenging activity performed against DPPH and H₂O₂.

Bacterial Lux Biosensors in Genotoxicological Studies

The aim of this study was to assess the applicability of the bacterial lux biosensors for genotoxicological studies. Biosensors are the strains of E. coli MG1655 carrying a recombinant plasmid with the lux operon of the luminescent bacterium P. luminescens fused with the promoters of inducible genes: recA, colD, alkA, soxS, and katG. The genotoxicity of forty-seven chemical compounds was tested on a set of three biosensors pSoxS-lux, pKatG-lux and pColD-lux, which allowed us to estimate the oxidative and DNA-damaging activity of the analyzed drugs. The comparison of the results with the data on the mutagenic activity of these drugs from the Ames test showed a complete coincidence of the results for the 42 substances. First, using lux biosensors, we have described the enhancing effect of the heavy non-radioactive isotope of hydrogen deuterium (D₂O) on the genotoxicity of chemical compounds as possible mechanisms of this effect. The study of the modifying effect of 29 antioxidants and radioprotectors on the genotoxic effects of chemical agents showed the applicability of a pair of biosensors pSoxS-lux and pKatG-lux for the primary assessment of the potential antioxidant and radioprotective activity of chemical compounds. Thus, the results obtained showed that lux biosensors can be successfully used to identify potential genotoxicants, radioprotectors, antioxidants, and comutagens among chemical compounds, as well as to study the probable mechanism of genotoxic action of test substance.

Unexpected Value of Honey Color for Prediction of a Non-Enzymatic H2O2 Production and Honey Antibacterial Activity: A Perspective

Hydrogen peroxide is the principal antibacterial compound of honey and its concentration determines honey bacteriostatic (MIC) and bactericidal (MBC) potencies. Levels of H₂O₂ produced are highly relevant to honey therapeutic potential, but they vary extensively among honey with reasons not immediately apparent. According to a traditional view, H₂O₂ is produced as a by-product of glucose oxidation by the honey bee enzyme, glucose oxidase; however, significant levels of H₂O₂ could be produced in a non-enzymatic way via polyphenol autooxidation. The aim of this study was to evaluate the potential for such an alternative pathway by re-examining evidence from many experimental and correlative studies in order to identify factors and compounds required for pro-oxidant activity. Unexpectedly, the color intensity was found to be the main indicator separating honey varieties based on the quantitative differences in the polyphenolic content, antioxidant activity and the content of transition metals, Fe, Cu and Mn, the main factors required for pro-oxidant effects. The color-impeding polyphenolics and their oxidation products (semiquinones and quinones) further contributed to color development through multiple chemical conjugations with proteins, phenolic oxidative polymerization, chelation or the reduction of metal ions. Moreover, quinones, as an intrinsic part of polyphenol redox activity, play an active role in the formation of higher-order structures, melanoidins and colloids in honey. The latter structures are also known to chelate metal ions, potentially contributing to H₂O₂ production. Thus, the color intensity appears as a major parameter that integrates polyphenol-dependent pro-oxidant reactions resulting in H₂O₂ generation.

Insights into Feruloylated Oligosaccharide Impact on Gel Properties of Oxidized Myofibrillar Proteins Based on the Changes in Their Spatial Structure

Polyphenolic compounds can protect against myofibrillar protein (MP) oxidation in meat products. In this study, the inhibitory effect of feruloyl oligosaccharides (FOs) on MP oxidation was investigated, and the gel properties of MPs were further studied. The results showed that 50–100 μmol/g protein of FOs could effectively inhibit damage to amino acid side chains by reducing carbonyl contents by 60.5% and increasing sulfhydryl and free amine contents by 89.5% and 66%, which may protect the secondary and tertiary structures of MPs. Additionally, FOs at 50 μmol/g protein had better effects on the crosslinking of MPs, leading to effective improvements in the gel properties, which can be seen in the rheology properties, scanning electron microscope (SEM) photographs, and the distribution of water in the MP gel. On the contrary, 150–200 μmol/g protein of FOs showed peroxidative effects on oxidatively stressed MPs, which were detrimental to MPs and contributed to their denaturation in the electrophoresis analysis and irregular aggregation in the SEM analysis. The concentration-dependent effects of FOs depended on MP-FOs interactions, indicating that an appropriate concentration of FOs has the potential to protect MPs from oxidation and enhance the gelation ability of pork meat during processing.

Antitumor Activity of PEGylated and TEGylated Phenothiazine Derivatives: Structure–Activity Relationship

The paper aims to investigate the antitumor activity of a series of phenothiazine derivatives in order to establish a structure–antitumor activity relationship. To this end, PEGylated and TEGylated phenothiazine have been functionalized with formyl units and further with sulfonamide units via dynamic imine bonds. Their antitumor activity was monitored in vitro against seven human tumors cell lines and a mouse one compared to a human normal cell line by MTS assay. In order to find the potential influence of different building blocks on antitumor activity, the antioxidant activity, the ability to inhibit farnesyltransferase and the capacity to bind amino acids relevant for tumor cell growth were investigated as well. It was established that different building blocks conferred different functionalities, inducing specific antitumor activity against the tumor cells.

Biosensors Based on Phenol Oxidases (Laccase, Tyrosinase, and Their Mixture) for Estimating the Total Phenolic Index in Food-Related Samples

Plant phenolic compounds demonstrate bioactive properties in vitro and/or in vivo, which creates demand for their precise determination in life sciences and industry. Measuring the concentration of individual phenolic compounds is a complex task, since approximately 9000 plant phenolic substances have been identified so far. The determination of the total phenolic content (TPC) is less laborious and is used for the qualimetric evaluation of complex multicomponent samples in routine analyses. Biosensors based on phenol oxidases (POs) have been proposed as alternative analytical devices for detecting phenolic compounds; however, their effectiveness in the analysis of food and vegetal matrices has not been addressed in detail. This review describes catalytic properties of laccase and tyrosinase and reports on the enzymatic and bienzymatic sensors based on laccase and tyrosinase for estimating the total phenolic index (TPI) in food-related samples (FRSs). The review presents the classification of biosensors, POs immobilization, the functions of nanomaterials, the biosensing catalytic cycle, interference, validation, and some other aspects related to TPI assessment. Nanomaterials are involved in the processes of immobilization, electron transfer, signal formation, and amplification, and they improve the performance of PO-based biosensors. Possible strategies for reducing interference in PO-based biosensors are discussed, namely the removal of ascorbic acid and the use of highly purified enzymes.

Anaerobic Degradation of the Invasive Weed Solidago canadensis L. (goldenrod) and Copper Immobilization by a Community of Sulfate-Reducing and Methane-Producing Bacteria

The weed Solidago canadensis L. poses a global threat to the environment as it spreads uncontrollably on roadsides, in forests, fields, meadows, and farmland. Goldenrod emits toxic substances that suppress other plants on the site, displacing wild ones. Thus, goldenrod conquers huge areas very quickly. The use of herbicides and mechanical methods does not solve the problem of the spontaneous spread of goldenrod. On the other hand, many scientists consider goldenrod as a valuable source of biologically active substances: flavonoids, phenolic compounds, vitamins, etc. In this study, we consider Solidago plants as a promising, free (cheap), and renewable substrate for the production of methane gas. The goal of the study was to identify the main patterns of degradation of the Solidago canadensis L. plant by methane-producing and sulfate-reducing bacteria with methane gas production and simultaneous detoxification of toxic copper. The composition of the gas phase was monitored by gas chromatography. The pH and redox potential parameters were determined potentiometrically; metal concentrations were measured by photometry. The concentration of flavonoids, sugars and phenolic compounds in plant biomass was determined according to well-known protocols. As a result of the study, high efficiencies of methane degradation in the Solidago plant and copper detoxification were obtained. Methane yield has reached the value of 68.2 L kg^-1 TS of Solidago canadensis L. biomass. The degradation coefficient (K_d) was also high at 21.4. The Cu(II) was effectively immobilized by methanogens and sulfate reducers during the goldenrod degradation at the initial concentrations of 500 mg L^-1. Thus, a new method of beneficial application of invasive plants was presented. The result confirms the possibility of using methanogenic microorganisms to produce methane gas from invasive weeds and detoxification of toxic metals.

Design, Synthesis, Calculation and Biological Activity Studies Based on Privileged Coumarin Derivatives as Multifunctional Anti-AD Lead Compound

Coumarins and their derivatives possessed a variety of biological activities and some of coumarin-based drugs have been approved by the US Food and Drug Administration. Alzheimer's disease (AD) has caused great losses to human society. However, due to its complex pathogenesis, the ideal therapeutic approach has not been found yet. Free radical scavenging activity which is one of the main activities of coumarin core structure is closely related to other anti-AD activities. Therefore, in this work coumarins were chosen as privileged lead compounds for the development of anti-AD drugs based on strategy of multi-target directed ligands (MTDLs). Derivatives 1-3 which could modulate multiple targets simultaneously, including ROS, cholinesterase, βamyloid (Aβ) aggregation, and metal dyshomeostasis were designed and for the first time synthesized. Their anti-AD activities were studied both in vitro and in silico. Results showed that 1-3 possessed potent antioxidant activities and 7-OH group did change the electron distribution of the molecule and enhance the antioxidant activities. They also have good inhibition activities on acetylcholinesterase (AChE) and Aβ aggregation and compound 1 had the strongest AChE inhibitory effect among the three compounds (AChE IC₅₀ =11.15 μM). Compound 1-3 could also selectively chelate with Cu²⁺ and Al³⁺ to regulate the metal homeostasis. In silico simulations, including molecular docking and prediction of ADMET performance, indicated that 1-3 could interact with target proteins and cross the blood brain barrier. In conclusion, 1-3 could be promising MTDLs applied as anti-AD candidate drugs.

New Perspectives of Taxifolin in Neurodegenerative Diseases

Neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), cerebral amyloid angiopathy (CAA), and Huntington's disease (HD) are characterized by cognitive and motor dysfunctions and neurodegeneration. These diseases have become more severe over time and cannot be cured currently. Until now, most treatments for these diseases are only used to relieve the symptoms. Taxifolin (TAX), 3,5,7,3,4-pentahydroxy flavanone, also named dihydroquercetin, is a compound derived primarily from Douglas fir and Larix gemelini. TAX has been confirmed to exhibit various pharmacological activities, including anti-inflammation, anti-cancer, anti-virus, and regulation of oxidative stress effects. In the central nervous system, TAX has been demonstrated to inhibit Aβ fibril formation, protect neurons and improve cerebral blood flow, cognitive ability, and dyskinesia. At present, TAX is only applied as a health additive in clinical practice. This review aimed to summarize the application of TAX in neurodegenerative diseases and the underlying neuroprotective mechanisms, such as suppressing inflammation, attenuating oxidative stress, preventing Aβ protein formation, maintaining dopamine levels, and thus reducing neuronal loss.

Phenolic furanochromene hydrazone derivatives: Synthesis, antioxidant activity, ferroptosis inhibition, DNA cleavage and DNA molecular docking studies

Twenty-four phenolic furanochromene hydrazone derivatives were designed and synthesized in order to evaluate structure-activity relationships in a series of antioxidant-related assays. The derivatives have varying substitution patterns on the phenol ring, with some compounds having one, two or three hydroxy groups, and others containing one hydroxy group in combination with methoxy, methyl, bromo, iodo and/or nitro groups. Antioxidant activity was determined using the DPPH free radical scavenging and CUPRAC assays. Compounds containing ortho-dihydroxy and para-dihydroxy patterns had the highest free radical scavenging activity, with IC50 values ranging from 5.0 to 28 μM. Similarly, derivatives with ortho-dihydroxy and para-dihydroxy patterns, together with a 4-hydroxy-3,5‑dimethoxy pattern, displayed strong copper (II) ion reducing capacity, using Trolox as a standard. Trolox equivalent antioxidant capacity (TEAC) coefficients for these derivatives ranged from 1.75 to 3.97. As further evidence of antioxidant potential, greater than half of the derivatives reversed erastin-induced ferroptosis in HaCaT cells. In addition, twenty-three of the derivatives were effective at cleaving supercoiled plasmid DNA in the presence of copper (II) ions at 1 mM, with the 3,4‑dihydroxy derivative showing cleavage to both the linear and open circular forms at 3.9 uM. The interaction of the phenolic furanochromene derivatives with DNA was confirmed by molecular docking studies, which revealed that all the derivatives bind favorably in the minor groove of DNA.

Insights into chalcone analogues with potential as antioxidant additives in diesel-biodiesel blends

Biodiesel production is one of the promising strategies to reduce diesel consumption and an important contribution to climate change. However, biodiesel stability remains a challenging problem in biofuel use in the global energy matrix. In this context, organic additives have been investigated to minimize these problems and reduce harmful emissions to comply with fuel requirement standards. In this study, we discuss a comprehensive structural description, a behavior of B15 [85% volume of diesel and 15% volume of biodiesel (B100)] stability in the presence of antioxidants (chalcone analogues), and a theoretical calculation to pave the way for clarifying and expanding the potential of title compounds as an antioxidant additive for diesel-biodiesel blends. Finally, a systematic description of the oxidation stability was undertaken using a specialized machine learning computational pySIRC platform.

Physical, Nutritional, and Bioactive Properties of Mandacaru Cladode Flour (Cereus jamacaru DC.): An Unconventional Food Plant from the Semi-Arid Brazilian Northeast

In this study, we evaluated the physical, nutritional, and bioactive properties of mandacaru cladode flour (Cereus jamacaru DC.). The granulometric profile revealed particles with non-uniform geometry, flakiness, a rectangular tendency, and a non-homogeneous surface, with particle sizes ranging from 20 to 60 µm. The flour presented low water activity (0.423), a moisture content of 8.24 g/100 g, high ash (2.82 g/100 g), protein (5.18 g/100 g), and total carbohydrate contents (74.48 g/100 g), and low lipid contents (1.88 g/100 g). Mandacaru flour is an excellent source of insoluble dietary fiber (48.08 g/100 g), calcium (76.33%), magnesium (15.21%), and potassium (5.94%). Notably, ¹H NMR analysis revealed the presence of N-methyltyramine. Using HPLC chromatography, glucose was identified as the predominant sugar (1.33 g/100 g), followed by four organic acids, especially malic acid (9.41 g/100 g) and citric acid (3.96 g/100 g). Eighteen phenolic compounds were detected, with relevant amounts of kaempferol (99.40 mg/100 g), myricetin (72.30 mg/100 g), and resveratrol (17.84 mg/100 g). The total phenolic compounds and flavonoids were 1285.47 mg GAE/100 g and 15.19 mg CE/100 g, respectively. The mean in vitro antioxidant activity values were higher using the FRAP method (249.45 µmol Trolox TEAC/100 g) compared to the ABTS^•+ method (0.39 µmol Trolox TEAC/g). Finally, the ascorbic acid had a content of 35.22 mg/100 g. The results demonstrate the value of mandacaru as a little-explored species and an excellent matrix for the development of flours presenting good nutritional value and bioactive constituents with excellent antioxidant potential.

Effects of Piptoporus betulinus Ethanolic Extract on the Proliferation and Viability of Melanoma Cells and Models of Their Cell Membranes

Piptoporus betulinus is a fungus known for its medicinal properties. It possesses antimicrobial, anti-inflammatory, and anti-cancer activity. In this study, several tests were performed to evaluate the cytotoxic effect of the ethanolic extract of Piptoporus betulinus on two melanoma human cell lines, WM115 primary and A375 metastatic cell lines, as well as Hs27 human skin fibroblasts. The extract proved to affect cancer cells in a dose-dependent manner, and at the same time showed a low cytotoxicity towards the normal cells. The total phenolic content (TPC) was determined spectrophotometrically by the Folin-Ciocalteu method (F-C), and the potential antioxidant activity was measured by ferric-reducing antioxidant power (FRAP) assay. One of the active compounds in the extract is betulin. It was isolated and then its cytotoxic activity was compared to the results obtained from the Piptoporus betulinus extract. To further understand the mechanism of action of the extract's anticancer activity, tests on model cell membranes were conducted. A model membrane of a melanoma cell was designed and consisted of 1,2-dimyristoyl-sn-glycero-3-phosphocholine, disialoganglioside-GD1a and cholesterol: DMPC:GD1a:chol (5:2:3 mole ratio). Changes in a Langmuir monolayer were observed and described based on Π-Amol isotherm and compressibility modulus changes. LB lipid bilayers were deposited on a hydrophilic gold substrate and analyzed by IR and X-ray photoelectron spectroscopy. Our study provides new data on the effect of Piptoporus betulinus extract on melanoma cells and its impact on the model of melanoma plasma membranes.

A simple, cost-effective colorimetric assay for aluminum ions via complexation with the flavonoid rutin

Aluminum has been linked to deleterious health effects with high concentration, chronic exposure, creating a need for innovative detection techniques. Colorimetric assays are an ideal approach since they are simple, cost-effective, and field adaptable. Yet, commercially available colorimetric assays for aluminum are limited since it forms few colored chelation complexes. Flavonoids, a class of polyphenolic compounds, are one of the few examples that create colored aluminum complexes. Aluminum ions (Al3+) are the main constituent in colorimetric assays for flavonoid detection in food or plant samples. Our assay design was based on colorimetric flavonoid assays, where the assay reported herein was optimized. Specifically, the flavonoid rutin concentration and sample-to-rutin volume ratio (295:5 µL) were optimized to detect Al3+ at low µM concentrations in samples. The assay performed comparably, and in some instances better, than those requiring advanced instrumentation and previously reported colorimetric assays, with a linear range (1–8 µM), sensitivity (7.6 nM), limit of detection (79.8 nM), and limit of quantification (266 nM) for Al3+. The colorimetric assay was accurate (99 ≤ 108 ± 4 ≤ 6% Al3+ recovery), precise (low intra- and inter-assay coefficient of variation (CV) of 3.1 ≤ 5.9% and 4.4%, respectively), and selective for Al3+ ions compared to solutions containing a variety of other mono-, di-, and tri-cations at much higher concentrations (10- to 100-fold higher). Lastly, the colorimetric assay was applicable to complex analysis. It was used to generate a chelation curve depicting the Al3+ chelation capacity of sodium alginate, a biologically derived polymer used as a bioink for 3D bioprinting.

Taxifolin increased semen quality of Duroc boars by improving gut microbes and blood metabolites

Taxifolin (TAX), as a natural flavonoid, has been widely focused on due to its strong anti-oxidation, anti-inflammation, anti-virus, and even anti-tumor activity. However, the effect of TAX on semen quality was unknown. The purpose of this study was to analyze the beneficial influences of adding feed additive TAX to boar semen in terms of its quality and potential mechanisms. We discovered that TAX increased sperm motility significantly in Duroc boars by the elevation of the protein levels such as ZAG, PKA, CatSper, and p-ERK for sperm quality. TAX increased the blood concentration of testosterone derivatives, antioxidants such as melatonin and betaine, unsaturated fatty acids such as DHA, and beneficial amino acids such as proline. Conversely, TAX decreased 10 different kinds of bile acids in the plasma. Moreover, TAX increased “beneficial” microbes such as Intestinimonas, Coprococcus, Butyrivibrio, and Clostridium_XlVa at the Genus level. However, TAX reduced the “harmful” intestinal bacteria such as Prevotella, Howardella, Mogibacterium, and Enterococcus. There was a very close correlation between fecal microbes, plasma metabolites, and semen parameters by the spearman correlation analysis. Therefore, the data suggest that TAX increases the semen quality of Duroc boars by benefiting the gut microbes and blood metabolites. It is supposed that TAX could be used as a kind of feed additive to increase the semen quality of boars to enhance production performance.

Functionalised electrospun membranes (TETA-PVC) for the removal of lead(ii) from water

Driven by the need for delivering sustainable water purification solutions for the removal of heavy metals from water, electrospun PVC membranes were functionalised with triethylenetetramine (TETA) and were used to remove lead(ii) ions selectively from water. The membranes were characterised and their adsorption behavior towards the removal of lead from water was investigated. The incorporation of TETA on the membrane's surface significantly improved the removal efficiency of lead(ii) up to 99.8% in 30 minutes and under ambient conditions, with the lowest concentration of 50 ppm. The adsorption mechanism was investigated and kinetic data showed a better correlation with the pseudo-second-order model. Similarly, the equilibrium data best fitted with the Langmuir adsorption isotherm model with a relatively high maximum adsorption capacity of 1250 mg g-1 for lead(ii) ions, larger than recently reported adsorption capacities for similar membranes. The functionalised membrane also showed high selectivity to lead(ii) in a mixed solution containing lead(ii), mercury(ii), cadmium(ii), arsenic(iii), copper(ii), and zinc(ii). The functionalised membrane was regenerated, where desorption of lead(ii) was achieved, under mildly acidic conditions. The removal efficiency of the regenerated membrane after six cycles of adsorption/desorption was maintained at a high level of 98%. The proposed design offers a simple yet effective, sustainable, and environmentally friendly solution for water treatment.

Antioxidative properties of phenolic compounds and their effect on oxidative stress induced by severe physical exercise

Extensive research has found strongly increased generation of reactive oxygen species, free radicals, and reactive nitrogen species during acute physical exercise that can lead to oxidative stress (OS) and impair muscle function. Polyphenols (PCs), the most abundant antioxidants in the human diet, are of increasing interest to athletes as antioxidants. Current literature suggests that antioxidants supplementation can effectively modulate these processes. This overview summarizes the actual knowledge of chemical and biomechanical properties of PCs and their impact as supplements on acute exercise-induced OS, inflammation control, and exercise performance. Evidence maintains that PC supplements have high potency to positively impact redox homeostasis and improve skeletal muscle's physiological and physical functions. However, many studies have failed to present improvement in physical performance. Eleven of 15 representative experimental studies reported a reduction of severe exercise-induced OS and inflammation markers or enhancement of total antioxidant capacity; four of eight studies found improvement in exercise performance outcomes. Further studies should be continued to address a safe, optimal PC dosage, supplementation timing during a severe training program in different sports disciplines, and effects on performance response and adaptations of skeletal muscle to exercise.

Understanding the Prooxidant Action of Plant Polyphenols in the Cellular Microenvironment of Malignant Cells: Role of Copper and Therapeutic Implications

Plant derived polyphenolic compounds are considered critical components of human nutrition and have shown chemotherapeutic effects against a number of malignancies. Several studies have confirmed the ability of polyphenols to induce apoptosis and regression of tumours in animal models. However, the mechanism through which polyphenols modulate their malignant cell selective anticancer effects has not been clearly established. While it is believed that the antioxidant properties of these molecules may contribute to lowering the risk of cancer induction by causing oxidative damage to DNA, it could not be held responsible for chemotherapeutic properties and apoptosis induction. It is a well known fact that cellular copper increases within the malignant cell and in serum of patients harboring malignancies. This phenomenon is independent of the cellular origin of malignancies. Based on our own observations and those of others; over the last 30 years our laboratory has shown that cellular copper reacts with plant derived polyphenolic compounds, by a Fenton like reaction, which generates reactive oxygen species and leads to genomic DNA damage. This damage then causes an apoptosis like cell death of malignant cells, while sparing normal cells. This communication reviews our work in this area and lays the basis for understanding how plant derived polyphenols can behave as prooxidants (and not antioxidants) within the microenvironment of a malignancy (elevated copper levels) and gives rationale for their preferential cytotoxicity towards malignant cells.

Antioxidant Activity and Cytotoxicity of Aromatic Oligosulfides

Natural or synthetic antioxidants with biomimetic fragments protect the functional and structural integrity of biological molecules at a minimum concentration, and may be used as potential chemotherapeutic agents. This paper is devoted to in silico and in vitro evaluation of the antioxidant and cytotoxic properties of synthetic analogues of natural compounds—aromatic oligosulfides. The antiradical and SOD-protective activity of oligosulfides was demonstrated in the reaction with O₂^–• generated in enzymatic and non-enzymatic systems. It was found that phenol-containing disulfides significantly reduced the accumulation level of hydroperoxides and secondary carbonyl thiobarbituric acid reactive substances, which are primary products of oleic acid peroxidation. The antioxidant efficiency of bis(3,5-di-tert-butyl-4-hydroxyphenyl) disulfide increased over time due to the synergistic action of the 2,6-di-tert-butylphenol fragment and the disulfide linker. The highest cytotoxicity on the A-549 and HCT-116 cell lines was found for bis(3,4-dimethoxyphenyl) disulfide. Significant induction of apoptosis in HCT-116 cells in the presence of bis(3,4-dimethoxyphenyl) disulfide indicates the prospect of its use as an antitumor agent. The significant and moderate dependences revealed between various types of activities of the studied aromatic oligosulfides can be used in the development of a strategy for the synthesis and study of target-oriented compounds with predictable biological activity.

The effect of flavonoids on the reduction of cupric ions, the copper-driven Fenton reaction and copper-triggered haemolysis

Flavonoids are considered beneficial, but they may exhibit pro-oxidative effects likely due to metal reducing properties. For the first time, 24 structurally related flavonoids were compared for copper reduction, and modulation of the copper-triggered Fenton reaction and lysis of erythrocytes. The vast majority of flavonoids reduced cupric ions; their behaviour ranged from progressive gradual reduction through bell-shaped, neutral, to a blockade of spontaneous reduction. Similarly, different behaviours were observed with the Fenton reaction. Flavone was the only flavonoid that potentiated copper-triggered haemolysis (155 ± 81 % at twice the amount of Cu²⁺), while 18 flavonoids were at least partly protective in some concentrations. Only 5-hydroxyflavone did not reduce Cu²⁺ and behaved as an antioxidant in both assays (reduction of 60 ± 10 % and 88 ± 1%, respectively, at an equimolar ratio with Cu²⁺). In conclusion, relatively subtle structural differences resulted in very different anti/prooxidant behaviour depending on the model.

Photophysical Behavior of Plant Flavonols Galangin, Kaempferol, Quercetin, and Myricetin in Homogeneous Media and the DMPC Model Membrane: Unveiling the Influence of the B-Ring Hydroxylation of Flavonols

Flavonols have been studied extensively because of their interesting biological activities and excited-state intramolecular proton transfer (ESIPT) behavior. Galangin, kaempferol, quercetin, and myricetin are structurally related flavonols that differ only in the number of B-ring hydroxyl substituents. In this work, we have carried out a detailed study on the photophysical behavior of these structurally related flavonols in various solvents and a 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) small unilamellar vesicles (SUVs) model membrane. We observed that these flavonols exist in different forms in the ground and excited states depending on the nature of the solvent. The weak intrinsic fluorescence of these flavonols gets enhanced in hydrogen-bond-accepting and alcoholic solvents. The phototautomer fluorescence intensity of these flavonols increases significantly in the DMPC membrane compared to water, suggesting ESIPT activation via binding interaction between flavonols and the membrane. According to our findings, both the number of B-ring hydroxy groups and membrane fluidity affect the flavonol binding with the membrane. The steady-state fluorescence intensity, steady-state anisotropy, fluorescence lifetime, and fluorescence anisotropy decay of flavonols were sensitive towards the temperature-induced DMPC membrane phase change. A quenching study has been performed to investigate the location and distribution of flavonols in the DMPC SUVs. Moreover, the antioxidant potential of flavonols in DMPC SUVs has been examined using the DPPH scavenging method. Our results reveal that the B-ring hydroxy groups significantly affect the photophysics, binding affinity, location, distribution, and DPPH scavenging activity of polyhydroxy-flavonols in the DMPC SUVs.