Special Issue "Flavonoids and Their Disease Prevention and Treatment Potential": Recent Advances and Future Perspectives

Different behavior of food-related benzoic acids toward iron and copper

Benzoic acids, which are commonly found in food, are also produced by human microbiota from other dietary phenolics. The aim was to investigate the interactions of 8 food-related benzoic acids with the physiological metals iron and copper under different (patho)physiologically relevant pH conditions in terms of chelation, reduction, impact on the metal-based Fenton chemistry, and copper-based hemolysis. Only 3,4-dihydroxybenzoic acid behaved as a protective substance under all conditions. It chelated iron, reduced both iron and copper, and protected against the iron and copper-based Fenton reaction. Conversely, 2,4,6-trihydroxybenzoic acid did not chelate iron and copper, reduced both metals, potentiated the Fenton reaction, and worsened copper-based hemolysis of rat red blood cells. The other tested compounds showed variable effects on the Fenton reaction. Interestingly, prooxidative benzoic acids mildly protected human erythrocytes against Cu-induced lysis. In conclusion, 3,4-dihydroxybenzoic acid seems to have a protective effect against copper and iron-based toxicity under different conditions.

Ameliorative role of catechin to combat against lindane instigated liver toxicity via modulating PI3K/PIP3/Akt, Nrf-2/Keap-1, NF-κB pathway and histological profile

Lindane (LDN) is a well-known herbicidal drug that exerts deleterious impacts on vital body organs including the liver. Catechin (CTN) is a plant-based flavonoid that demonstrates various pharmacological abilities. This trial was executed to evaluate the ameliorative efficacy of CTN to combat LDN instigated hepatotoxicity in male albino rats (Rattus norvegicus). Thirty-two rats were categorized into four groups including control, LDN (30 mg/kg), LDN (30 mg/kg) + CTN (40 mg/kg) and CTN (40 mg/kg) alone treated group. It was observed that LDN dysregulated the expressions of PI3K/PIP3/Akt and Nrf-2/Keap-1 pathway. Moreover, the activities of catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD), heme‑oxygenase-1 (HO-1) and glutathione reductase (GSR) were subsided after LDN intoxication. Besides, the levels of reactive oxygen species (ROS), malondialdehyde (MDA), ALT (Alanine aminotransferase), AST (Aspartate transaminase), Gamma-glutamyl transferase (GGT) and ALP (Alkaline phosphatase) were increased whereas reduced the levels of albumin and total proteins in response to LDN exposure. Additionally, LDN administration escalated the levels of Interleukin-6 (IL-6), Nuclear factor kappa-B (NF-κB), Interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and the activity of cyclooxygenase-2 (COX-2). Furthermore, the gene expressions of Bcl-2-associated X protein (Bax) and Cysteinyl aspartate-acid proteases-3 (Caspase-3) were enhanced whereas the expression of B-cell lymphoma-2 (Bcl-2) was lowered following the LDN treatment. LDN instigated various histological impairments in hepatic tissues. Nonetheless, concurrent administration of CTN remarkably ameliorated liver impairments via regulating aforementioned disruptions owing to its antioxidant, anti-apoptotic and histo-protective potentials.

Potential antioxidant and cytotoxic impacts of defatted extract rich in flavonoids from Styphnolobium japonicum leaves growing in Egypt

Styphnolobium japonicum leaves are considered a rich source of flavonoids, which are the prospective basis for various therapeutic effects. However, there has been a lack of comprehensive cytotoxic studies conducted on these leaves. Therefore, this ongoing investigation aimed to detect and isolate the flavonoids present in S. japonicum leaves, and assess their antioxidant and anticancer properties. The defatted extract from S. japonicum leaves was analyzed using HPLC, which resulted in the identification of seven phenolics and six flavonoids. Rutin and quercetin were found to be the most abundant. Furthermore, a comprehensive profile of flavonoids was obtained through UPLC/ESI-MS analysis in negative acquisition mode. Fragmentation pathways of the identified flavonoids were elucidated to gain relevant insights into their structural characteristics. Furthermore, genistein 7-O-glucoside, quercetin 3-O-rutinoside, and kaempferol 3-O-α-L-rhamnopyranosyl-(1 → 6)-β-D-glucopyranosyl-(1 → 2)-β-D-glucopyranoside were isolated and characterized. The defatted extract rich in flavonoids exhibited significant antioxidant, iron-reducing, free radicals scavenging impacts, and remarkable cytotoxicity against the liver cell line (IC50 337.9μg/ mL) and lung cell line (IC50 55.0 μg/mL). Furthermore, the antioxidant and anticancer capacities of the three isolated flavonoids have been evaluated, and it has been observed that their effects are concentration-dependent. The findings of this research highlight the promising impact of flavonoids in cancer therapy. It is recommended that future scientific investigations prioritize the exploration of the distinct protective and therapeutic characteristics of S. japonicum leaves, which hold significant potential as a valuable natural resource.

Advanced Application of Polymer Nanocarriers in Delivery of Active Ingredients from Traditional Chinese Medicines

Active ingredients from Traditional Chinese Medicines (TCMs) have been a cornerstone of healthcare for millennia, offering a rich source of bioactive compounds with therapeutic potential. However, the clinical application of TCMs is often limited by challenges such as poor solubility, low bioavailability, and variable pharmacokinetics. To address these issues, the development of advanced polymer nanocarriers has emerged as a promising strategy for the delivery of TCMs. This review focuses on the introduction of common active ingredients from TCMs and the recent advancements in the design and application of polymer nanocarriers for enhancing the efficacy and safety of TCMs. We begin by discussing the unique properties of TCMs and the inherent challenges associated with their delivery. We then delve into the types of polymeric nanocarriers, including polymer micelles, polymer vesicles, polymer hydrogels, and polymer drug conjugates, highlighting their application in the delivery of active ingredients from TCMs. The main body of the review presents a comprehensive analysis of the state-of-the-art nanocarrier systems and introduces the impact of these nanocarriers on the solubility, stability, and bioavailability of TCM components. On the basis of this, we provide an outlook on the future directions of polymer nanocarriers in TCM delivery. This review underscores the transformative potential of polymer nanocarriers in revolutionizing TCM delivery, offering a pathway to harness the full therapeutic potential of TCMs while ensuring safety and efficacy in a modern medical context.

Effect of co-administration of gallic acid and quercetin or gallic acid and rutin on impaired spermatogenesis and oxidative damage in a busulfan-treated rat model

Gallic acid (GAL), rutin (RUT), and quercetin (QUE) are common antioxidant agents in fruits and vegetables with intriguing pharmacological effects. In the present study, we compared the therapeutic outcomes of GAL + QUE in comparison with GAL + RUT co-treatment in a busulfan (BUS) model of testicular injury in Wistar rats. BUS (4 mg kg-1 body weight (b.w) was injected intraperitoneally daily for 4 days. GAL + RUT or GAL + QUE (20 mg kg-1 b. w) was delivered by oral gavage for 52 days. Examination of the testes of BUS-treated rats both biochemically and under light microscopy revealed an increased level of lipid peroxidation, DNA fragmentation, glutathione-S-transferase, lactate dehydrogenase, gamma-glutamyl transpeptidase, alkaline phosphatase and acid phosphatase with a concomitant decrease in the level of antioxidants: glutathione, ascorbic acid, superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase activities, suggesting testicular injury. Tissue sections confirmed the testicular injury-induced by BUS, including diminished spermatogenesis score index, tubular diameter, gonado-somatic index, testis weight, epithelia thickness and higher percentage of aberrant tubules. GAL + QUE co-administration had better recovery effects than GAL + RUT on the biochemical markers and protected against BUS-induced testicular damage. GAL + QUE treatment regimen has better capacity to maintain the antioxidant capacity of the testes and is more potent at reducing BUS-induced oxidative damage compared to GAL + RUT.

In silico discovery of potent and selective Janus kinase 3 (JAK3) inhibitors through 3D-QSAR, covalent docking, ADMET analysis, molecular dynamics simulations, and binding free energy of pyrazolopyrimidine derivatives

Rheumatoid arthritis is a prevalent and debilitating chronic disease worldwide. Targeting Janus kinase 3 (JAK3) has emerged as a crucial molecular strategy to treat this condition. In this study, we employed a comprehensive theoretical approach that included 3D-QSAR, covalent docking, ADMET, and molecular dynamics to propose and optimize new anti-JAK3 compounds. We investigated a series of 28 1H-pyrazolo[3.4-d]pyrimidin-4-amino inhibitors and developed a highly accurate 3D-QSAR model using comparative molecular similarity index analysis (COMSIA). The model predicted with Q2 = 0.59, R2 = 0.96, and R2(Pred) = 0.89, was validated using Y-randomization and external validation methods. Our covalent docking studies identified T3 and T5 as highly potent inhibitors of JAK3 compared to the reference ligand 17. Additionally, we evaluated the ADMET properties and drug similarity of our newly developed compounds and reference ligand, providing critical insights for further optimization of anti-JAK3 medications. Furthermore, MM-GBSA analysis showed promising results for the designed compounds. Finally, we validated our docking results using molecular dynamics simulations, which confirmed the stability of hydrogen bonding contacts with key residues required to block JAK3 activity. Our findings offer new chemical scaffolds and insights that could lead to the development of novel and effective JAK3 therapeutic targets for treating rheumatoid arthritis.Communicated by Ramaswamy H. Sarma.

The Expression of Key Ethylene and Anthocyanin Biosynthetic Genes of 'Honeycrisp' Apples Subjected to the Combined Use of Reflective Groundcovers and Aminoethoxyvinylglycine in the Mid-Atlantic US

The decreased profitability of important apple cultivars, such as 'Honeycrisp', results from the poor red skin coloration and high fruit drop in the mid-Atlantic US. Apple red skin coloration is determined by the anthocyanin concentration. Reflective groundcovers promote red skin coloration, whereas aminoethoxyvinylglycine (AVG) decreases the ethylene production and fruit drop, thus reducing the coloration. Although our previous study showed that combinations of these practices impact the fruit quality and color, research is lacking regarding their effects at the gene and metabolite levels. In this work, for two years, we compared the differences in the internal ethylene concentration (IEC), red skin coloration, fruit drop, transcript accumulation of key ethylene and anthocyanin biosynthetic pathway-related genes, and total anthocyanin concentration of 'Honeycrisp' apples. The fruit was treated with combinations of reflective groundcover (Extenday) and AVG (130 mg L-1) and was assessed throughout ripening. Extenday-only-treated fruit displayed the highest upregulation of ethylene and anthocyanin biosynthetic-related genes and of total anthocyanins, exceeding 50% blush, while boosting the IEC. In contrast, AVG significantly decreased the expression of key ethylene and anthocyanin biosynthetic-related genes and total anthocyanins, thus preventing apples from reaching 50% blush, while also decreasing the IEC and fruit drop. The combination of Extenday x AVG fine-tuned the transcript accumulation of ethylene and anthocyanin biosynthetic-related genes as well as the total anthocyanins, allowing the 'Honeycrisp' fruit to exceed 50% blush, while increasing the IEC moderately and reducing the fruit drop (as compared to Extenday-only and control), thus enhancing the fruit economic value.

Proanthocyanidins-Based Synbiotics as a Novel Strategy for Nonalcoholic Fatty Liver Disease (NAFLD) Risk Reduction

Nonalcoholic fatty liver disease (NAFLD), the most common liver disease worldwide, is a spectrum of liver abnormalities ranging from steatosis to nonalcoholic steatohepatitis (NASH) characterized by excessive lipid accumulation. The prevalence of NAFLD is predicted to increase rapidly, demanding novel approaches to reduce the global NAFLD burden. Flavonoids, the most abundant dietary polyphenols, can reduce the risk of NAFLD. The majority of dietary flavonoids are proanthocyanidins (PACs), which are oligomers and polymers of the flavonoid sub-group flavan-3-ols. The efficacy of PAC in reducing the NAFLD risk can be significantly hindered by low bioavailability. The development of synbiotics by combining PAC with probiotics may increase effectiveness against NAFLD by biotransforming PAC into bioavailable metabolites. PAC and probiotic bacteria are capable of mitigating steatosis primarily through suppressing de novo lipogenesis and promoting fatty acid β-oxidation. PAC and probiotic bacteria can reduce the progression of steatosis to NASH mainly through ameliorating hepatic damage and inflammation induced by hepatic oxidative stress, endoplasmic reticulum stress, and gut microbiota dysbiosis. Synbiotics of PAC are superior in reducing the risk of NAFLD compared to independent administration of PAC and probiotics. The development of PAC-based synbiotics can be a novel strategy to mitigate the increasing incidence of NAFLD.

Chinese herbal medicines: The modulator of nonalcoholic fatty liver disease targeting oxidative stress

ETHNOPHARMACOLOGICAL RELEVANCE

Plants are a natural treasure trove; their secondary metabolites participate in several pharmacological processes, making them a crucial component in the synthesis of novel pharmaceuticals and serving as a reserve resource foundation in this process. Nonalcoholic fatty liver disease (NAFLD) is associated with the risk of progression to hepatitis and liver cancer. The "Treatise on Febrile Diseases," "Compendium of Materia Medica," and "Thousand Golden Prescriptions" have listed herbal remedies to treat liver diseases.

AIM OF THE REVIEW

Chinese herbal medicines have been widely used for the prevention and treatment of NAFLD owing to their efficacy and low side effects. The production of reactive oxygen species (ROS) during NAFLD, and the impact and potential mechanism of ROS on the pathogenesis of NAFLD are discussed in this review. Furthermore, common foods and herbs that can be used to prevent NAFLD, as well as the structure-activity relationships and potential mechanisms, are discussed.

METHODS

Web of Science, PubMed, CNKI database, Google Scholar, and WanFang database were searched for natural products that have been used to treat or prevent NAFLD in the past five years. The primary search was performed using the following keywords in different combinations in full articles: NAFLD, herb, natural products, medicine, and ROS. More than 400 research papers and review articles were found and analyzed in this review.

RESULTS

By classifying and discussing the literature, we obtained 86 herbaceous plants, 28 of which were derived from food and 58 from Chinese herbal medicines. The mechanism of NAFLD was proposed through experimental studies on thirteen natural compounds (quercetin, hesperidin, rutin, curcumin, resveratrol, epigallocatechin-3-gallate, salvianolic acid B, paeoniflorin, ginsenoside Rg1, ursolic acid, berberine, honokiol, emodin). The occurrence and progression of NAFLD could be prevented by natural antioxidants through several pathways to prevent ROS accumulation and reduce hepatic cell injuries caused by excessive ROS.

CONCLUSION

This review summarizes the natural products and routinely used herbs (prescription) in the prevention and treatment of NAFLD. Firstly, the mechanisms by which natural products improve NAFLD through antioxidant pathways are elucidated. Secondly, the potential of traditional Chinese medicine theory in improving NAFLD is discussed, highlighting the safety of food-medicine homology and the broader clinical potential of multi-component formulations in improving NAFLD. Aiming to provide theoretical basis for the prevention and treatment of NAFLD.

Advanced application of nanotechnology in active constituents of Traditional Chinese Medicines

Traditional Chinese Medicines (TCMs) have been used for centuries for the treatment and management of various diseases. However, their effective delivery to targeted sites may be a major challenge due to their poor water solubility, low bioavailability, and potential toxicity. Nanocarriers, such as liposomes, polymeric nanoparticles, inorganic nanoparticles and organic/inorganic nanohybrids based on active constituents from TCMs have been extensively studied as a promising strategy to improve the delivery of active constituents from TCMs to achieve a higher therapeutic effect with fewer side effects compared to conventional formulations. This review summarizes the recent advances in nanocarrier-based delivery systems for various types of active constituents of TCMs, including terpenoids, polyphenols, alkaloids, flavonoids, and quinones, from different natural sources. This review covers the design and preparation of nanocarriers, their characterization, and in vitro/vivo evaluations. Additionally, this review highlights the challenges and opportunities in the field and suggests future directions for research. Nanocarrier-based delivery systems have shown great potential in improving the therapeutic efficacy of TCMs, and this review may serve as a comprehensive resource to researchers in this field.

Critical review on anthocyanins in blue honeysuckle (Lonicera caerulea L.) and their function

Blue honeysuckle (Lonicera caerulea L.) is an emerging commercial fruit in the world, has been known for its multiple anthocyanins in the berries, cyanidin-3-glucoside (C3G) is a major anthocyanin in berries and it makes up 76-92% of the total anthocyanins content, with high antioxidant capacity, and widely used in food products. In this review, recent studies related to anthocyanins in blue honeysuckle were sorted out, including the current status of research on anthocyanins in blue honeysuckle berries, especially C3G, qualitative and quantitative analysis of anthocyanins in berries, extraction and purification methods of anthocyanins from blue honeysuckle, in addition, biological effects of blue honeysuckle, and recommended utilization. Blue honeysuckle contains polyphenols, flavonoids, anthocyanins, minerals, and multiple bioactive compounds, it has been extensively reported to have significant antioxidant, cardioprotective, anti-inflammatory, neuroprotective, anticancer, and anti-diabetic functions, and has been used in a variety of food products as raw materials.

Effects of Flavonoid Supplementation on Athletic Performance in Healthy Adults: A Systematic Review and Meta-Analysis

Flavonoids, known for their antioxidant properties, can prevent reactive oxygen species (ROS) and influence athletic performance through various physiological and metabolic mechanisms. However, there are conflicting results after summarizing and analyzing the relevant literature. Hence, it is warranted to evaluate the overall impact of flavonoids on athletic performance in healthy adults based on a comprehensive and systematic review and meta-analysis. After searching four databases for literature published since their respective establishments until February 2023 and conducting publication bias and quality assessments, a total of 22 studies were ultimately included. The names and doses of flavonoids, various outcome measurements, as well as types of training, were extracted from included studies. The athletic performance outcomes from the included studies were categorized into 'performance tests' and 'exercise tolerance,' depending on the type of training undertaken. Several statistical results, such as pooled effect size (ES), among others, were implemented by meta-analysis using the random effects model. The results of meta-analysis suggest that there is currently sufficient evidence (ES = -0.28; 95% confidence interval (CI): [-0.50, -0.07]; p = 0.01 and ES = 0.23; 95% CI: [0.07, 0.39]; p = 0.005) to support the notion that flavonoid supplementation enhanced athletic performance in performance tests and exercise tolerance. In addition, among the subgroups, nonsignificant results were observed for athletes (p = 0.28) and acute supplementation (p = 0.41) in performance tests, as well as athletes (p = 0.57) and acute supplementation (p = 0.44) in exercise tolerance. Meanwhile, significant results were found for non-athletes (p = 0.04) and long-term supplementation (p = 0.02) in performance tests, as well as non-athletes (p = 0.005) in performance tests and long-term supplementation (p = 0.006) in exercise tolerance. The nonsignificant results were likely due to the limitation in the number of related papers, sample sizes, optimal dosage, duration, type of flavonoids, and other factors. Therefore, future research should focus on further investigating these relationships with larger sample sizes, optimal dosage, duration, and type of flavonoids to provide more robust conclusions.

Emergence of Nano-Based Formulations for Effective Delivery of Flavonoids against Topical Infectious Disorders

Flavonoids are hydroxylated phenolic substances in vegetables, fruits, flowers, seeds, wine, tea, nuts, propolis, and honey. They belong to a versatile category of natural polyphenolic compounds. Their biological function depends on various factors such as their chemical structure, degree of hydroxylation, degree of polymerization conjugation, and substitutions. Flavonoids have gained considerable attention among researchers, as they show a wide range of pharmacological activities, including coronary heart disease prevention, antioxidative, hepatoprotective, anti-inflammatory, free-radical scavenging, anticancer, and anti-atherosclerotic activities. Plants synthesize flavonoid compounds in response to pathogen attacks, and these compounds exhibit potent antimicrobial (antibacterial, antifungal, and antiviral) activity against a wide range of pathogenic microorganisms. However, certain antibacterial flavonoids have the ability to selectively target the cell wall of bacteria and inhibit virulence factors, including biofilm formation. Moreover, some flavonoids are known to reverse antibiotic resistance and enhance the efficacy of existing antibiotic drugs. However, due to their poor solubility in water, flavonoids have limited oral bioavailability. They are quickly metabolized in the gastrointestinal region, which limits their ability to prevent and treat various disorders. The integration of flavonoids into nanomedicine constitutes a viable strategy for achieving efficient cutaneous delivery owing to their favorable encapsulation capacity and diminished toxicity. The utilization of nanoparticles or nanoformulations facilitates drug delivery by targeting the drug to the specific site of action and exhibits excellent physicochemical stability.

Elnosary M, L. Ashour M, M. Abd El-Moneam N, A. Shreadah M. Flavonoids Biosynthesis in Plants as a Defense Mechanism: Role and Function Concerning Pharmacodynamics and Pharmacokinetic Properties

Flavonoids are a major class of secondary metabolites that comprises more than 6000 compounds that have been identified. They are biosynthesized via the phenylpropanoid metabolic pathway that involves groups of enzymes such as isomerases, hydroxylases, and reductases that greatly affect the determination of the flavonoid skeleton. For example, transferase enzymes responsible for the modification of sugar result in changes in the physiological activity of the flavonoids and changes in their physical properties, such as solubility, reactivity, and interaction with cellular target molecules, which affect their pharmacodynamics and pharmacokinetic properties. In addition, flavonoids have diverse biological activities such as antioxidants, anticancer, and antiviral in managing Alzheimer’s disease. However, most marine flavonoids are still incompletely discovered because marine flavonoid biosynthesis is produced and possesses unique substitutions that are not commonly found in terrestrial bioactive compounds. The current chapter will illustrate the importance of flavonoids’ role in metabolism and the main difference between marine and terrestrial flavonoids.

Research progress of Traditional Chinese Medicine (TCM) in targeting inflammation and lipid metabolism disorder for arteriosclerosis intervention: A review

Atherosclerosis (AS) is a chronic disease caused by inflammation and lipid deposition. Immune cells are extensively activated in the lesions, producing excessive pro-inflammatory cytokines, which accompany the entire pathological process of AS. In addition, the accumulation of lipid-mediated lipoproteins under the arterial intima is a crucial event in the development of AS, leading to vascular inflammation. Improving lipid metabolism disorders and inhibiting inflammatory reactions are the primary treatment methods currently used in medical practice to delay AS progression. With the development of traditional Chinese medicine (TCM), more mechanisms of action of the monomer of TCM, Chinese patent medicine, and compound prescription have been studied and explored. Research has shown that some Chinese medicines can participate in treating AS by targeting and improving lipid metabolism disorders and inhibiting inflammatory reactions. This review explores the research on Chinese herbal monomers, compound Chinese medicines, and formulae that improve lipid metabolism disorders and inhibit inflammatory reactions to provide new supplements for treating AS.

Cytoprotective and genoprotective effects of taxifolin against oxidative damage in HTR-8/SVneo human trophoblast cells

An increase of reactive oxygen species in the placenta and oxidative disbalance has been recognized as a significant factor contributing to pregnancy complications. Dietary intake of food rich in antioxidants during pregnancy could exert a protective role in the prevention of adverse outcomes such as preeclampsia, miscarriage, and others. Flavonoid taxifolin has shown numerous health-promoting effects in a large number of studies conducted on animals, as well as various human cell types in vitro. However, its effects on human placental cells-trophoblasts-have yet to be determined. Therefore, cytoprotective and genoprotective effects of taxifolin on trophoblast cell line HTR-8/SVneo under induced oxidative stress were explored in this study. Cytotoxicity of a range of taxifolin concentrations (1-150 µM) was evaluated using the MTT and crystal violet assays. A model of oxidative stress was achieved by exposing HTR-8/SVneo cells to H2O2. To determine cytoprotective and antigenotoxic effects, the cells were pre-incubated with three concentrations of taxifolin (10, 50, and 100 µM) and then exposed to H2O2. Taxifolin in concentrations of 1, 5, 10, 25, 50, and 100 µM showed no cytotoxic effects on HTR-8/SVneo cells, but 150 µM of taxifolin caused a significant decrease in adherent cell number, as detected by crystal violet assay. Pretreatment with the chosen concentrations of taxifolin showed a significant cytoprotective effect on H2O2-induced cytotoxicity, as determined by the MTT assay. Furthermore, taxifolin showed a significant reduction in H2O2-induced DNA damage, measured by comet assay. This study showed protective effects of taxifolin on human trophoblast cells exposed to oxidative damage. Further studies are needed to explore the underlying mechanisms.

Phytochemical Screening, Antioxidant and Antibacterial Properties of Extracts of Viscum continuum E. Mey. Ex Sprague, a South African Mistletoe

Viscum continuum E. Mey. Ex Sprague is a woody evergreen semi-parasitic shrub that grows on the branches of other trees. It is used by African traditional healers for post-stroke management. This study reports on the qualitative phytochemical screening and the antioxidant and antimicrobial activities of Viscum continuum’s acetone, methanol, hexane and dichloromethane extracts. Standard protocols for the phytochemical screening of extracts were employed. TLC bio-autography was used for qualitative antioxidants analysis. Assays: 2,2-diphenyl-1-picrylhydrazyl, H₂O₂ free-radical scavenging and ferric chloride reducing power were carried out for quantitative antioxidant analysis. The antimicrobial potential of extracts was screened using disc diffusion, bio-autography and broth micro-dilution. The results indicate the presence of alkaloids, phenolics and tannins in all extracts. Acetone and methanol revealed significant amount of saponins, phenolics, tannins and terpenoids. The extracts exhibited significant antioxidant potential on TLC with positive compound bands at an Rf range of 0.05–0.89. DPPH, H₂O₂ and the reduction of Fe³⁺ to Fe²⁺ assays indicated that methanol extract has a strong antioxidant potential, followed by acetone, DCM and lastly hexane. The extracts of Viscum continuum show the potential to be antibacterial agents. It can be concluded that Viscum continuum extracts contain phytochemicals which are capable of mitigating against chronic health conditions such as cancer, stroke and stress-related and infectious diseases.

A Dietary Antioxidant Formulation Ameliorates DNA Damage Caused by γ-Irradiation in Normal Human Bronchial Epithelial Cells In Vitro

Antioxidants can be used as radioprotectants to reduce DNA damage due to exposure to radiation that could result in malignancies, including lung cancer. Mortality rates are consistently higher in lung cancer, which is usually diagnosed at later stages of cancer development and progression. In this preliminary study, we examined the potential of an antioxidant formulation (AOX2) to reduce DNA damage using a cell model of human normal bronchial epithelial cells (BEAS-2B). Cells were exposed to γ-irradiation or smoke-related hydrocarbon 4[(acetoxymethyl)nitrosamino]-1 (3-pyridyl) 1-butanone (NNKOAc) to induce DNA damage. We monitored intracellular reactive oxygen species (ROS) levels and evidence of genotoxic damage including DNA fragmentation ELISA, γ-H2AX immunofluorescence, and comet assays. Pre-incubation of the cells with AOX2 before exposure to γ-irradiation and NNKOAc significantly reduced DNA damage. The dietary antioxidant preparation AOX2 significantly reduced the induction of the tumor suppressor protein p53 and DNA damage-associated γ-H2AX phosphorylation by radiation and the NNKOAc treatment. Thus, AOX2 has the potential to act as a chemoprotectant by lowering ROS levels and DNA damage caused by exposure to radiation or chemical carcinogens.

Changes in ethylene and sugar metabolism regulate flavonoid composition in climacteric and non-climacteric plums during postharvest storage

•

Ethylene metabolism regulated flavonoid (and sugar) contents and composition.

•

Ethylene induced anthocyanin and reduced flavonol and flavan-3-ols in plum fruit.

•

Anthocyanins positively correlate with sucrose and galactose metabolic pathways.

•

Flavonol and flavan-3-ols associated with sorbitol, fructose, and glucose contents.

Plums are rich in flavonoids, key contributors to fruit coloration and putative health benefits. We studied the impact of changes in ethylene and sugars in flavonoid metabolism-related pathways of the climacteric Santa Rosa and its non-climacteric mutant Sweet Miriam, throughout the postharvest period. Fruits were harvested at optimal maturity, subjected to ethylene treatments, and evaluated during storage. We examined transcript profiles of structural and regulatory genes of flavonoid-related pathways and their associated metabolites in skin and flesh, integrated with multivariate analyses of ethylene and sugar metabolism. Ethylene treatments were positively correlated with anthocyanin and negatively correlated with flavonol and flavan-3-ol metabolism. Sucrose and galactose were positively associated with anthocyanin concentration, while sorbitol, fructose, glucose and minor sugars were correlated with flavonol and flavan-3-ol metabolism. Our results support the notion that ethylene is playing key roles in shifting plum fruit flavonoid profiles, which are also associated with changes in fruit sugars.

The Mechanism of a Retro-Diels-Alder Fragmentation of Luteolin: Theoretical Studies Supported by Electrospray Ionization Tandem Mass Spectrometry Results

The mechanisms of retro-Diels-Alder fragmentation of luteolin are studied theoretically using the Density Functional Theory method (B3LYP hybrid functional) together with the 6-311++G(d,p) basis set and supported by electrospray ionization tandem mass spectrometry (ESI-MS) results. The reaction paths leading to the formation of 1,3A- and 1,3B- fragment ions observed as the main spectral features in the ESI-MS spectrum are described and discussed, including the structures of the transition states and intermediate products. The heights of the activation energy barriers which have to be overcome along the reaction paths corresponding to 1,3-retrocyclization cleavage of the ionized luteolin are predicted to span the 69-94 kcal/mol range (depending on the initial isomeric structure) for the concerted retrocyclization mechanism and the 60-89 kcal/mol (first barrier) and 24-52 kcal/mol (second barrier) barriers for the stepwise mechanism (also depending on the initial isomeric structure). It is also demonstrated that the final fragmentation products (1,3A- and 1,3B-) are in fact represented by various isomeric systems which are not experimentally distinguishable. In addition, the absence of the spectral feature corresponding to the [M-B]- fragment ion formed by the rupture of the C-C bond connecting luteolin's B and C rings (which does not occur during the ESI-MS experiment) is explained by much larger energy barriers predicted for such a process.

Role of Phytoconstituents as PPAR Agonists: Implications for Neurodegenerative Disorders

Peroxisome proliferator-activated receptors (PPAR-γ, PPAR-α, and PPAR-β/δ) are ligand-dependent nuclear receptors that play a critical role in the regulation of hundreds of genes through their activation. Their expression and targeted activation play an important role in the treatment of a variety of diseases, including neurodegenerative, cardiovascular, diabetes, and cancer. In recent years, several reviews have been published describing the therapeutic potential of PPAR agonists (natural or synthetic) in the disorders listed above; however, no comprehensive report defining the role of naturally derived phytoconstituents as PPAR agonists targeting neurodegenerative diseases has been published. This review will focus on the role of phytoconstituents as PPAR agonists and the relevant preclinical studies and mechanistic insights into their neuroprotective effects. Exemplary research includes flavonoids, fatty acids, cannabinoids, curcumin, genistein, capsaicin, and piperine, all of which have been shown to be PPAR agonists either directly or indirectly. Additionally, a few studies have demonstrated the use of clinical samples in in vitro investigations. The role of the fruit fly Drosophila melanogaster as a potential model for studying neurodegenerative diseases has also been highlighted.

Insights on the Inhibitory Power of Flavonoids on Tyrosinase Activity: A Survey from 2016 to 2021

Tyrosinase is a multifunctional copper-containing oxidase enzyme that initiates melanin synthesis in humans. Excessive accumulation of melanin pigments or the overexpression of tyrosinase may result in skin-related disorders such as aging spots, wrinkles, melasma, freckles, lentigo, ephelides, nevus, browning and melanoma. Nature expresses itself through the plants as a source of phytochemicals with diverse biological properties. Among these bioactive compounds, flavonoids represent a huge natural class with different categories such as flavones, flavonols, isoflavones, flavan-3-ols, flavanones and chalcones that display antioxidant and tyrosinase inhibitor activities with a diversity of mechanistic approaches. In this review, we explore the role of novel or known flavonoids isolated from different plant species and their participation as tyrosinase inhibitors reported in the last five years from 2016 to 2021. We also discuss the mechanistic approaches through the different studies carried out on these compounds, including in vitro, in vivo and in silico computational research. Information was obtained from Google Scholar, PubMed, and Science Direct. We hope that the updated comprehensive data presented in this review will help researchers to develop new safe, efficacious, and effective drug or skin care products for the prevention of and/or protection against skin-aging disorders.

Vitamin-Containing Antioxidant Formulation Reduces Carcinogen-Induced DNA Damage through ATR/Chk1 Signaling in Bronchial Epithelial Cells In Vitro

Lung cancer has the highest mortality rate worldwide and is often diagnosed at late stages, requiring genotoxic chemotherapy with significant side effects. Cancer prevention has become a major focus, including the use of dietary and supplemental antioxidants. Thus, we investigated the ability of an antioxidant formulation (AOX1) to reduce DNA damage in human bronchial epithelial cells (BEAS-2B) with and without the combination of apple peel flavonoid fraction (AF4), or its major constituent quercetin (Q), or Q-3-O-d-glucoside (Q3G) in vitro. To model smoke-related genotoxicity, we used cigarette-smoke hydrocarbon 4-[(acetoxymethyl)nitrosamino]-1-(3-pyridyl)-1-butanone (NNKOAc) as well as methotrexate (MTX) to induce DNA damage in BEAS-2B cells. DNA fragmentation, γ-H2AX immunofluorescence, and comet assays were used as indicators of DNA damage. Pre-exposure to AOX1 alone or in combination with AF4, Q, or Q3G before challenging with NNKOAc and MTX significantly reduced intracellular reactive oxygen species (ROS) levels and DNA damage in BEAS-2B cells. Although NNKOAc-induced DNA damage activated ATM-Rad3-related (ATR) and Chk1 kinase in BEAS-2B cells, pre-exposure of the cells with tested antioxidants prior to carcinogen challenge significantly reduced their activation and levels of γ-H2AX (p ≤ 0.05). Therefore, AOX1 alone or combined with flavonoids holds promise as a chemoprotectant by reducing ROS and DNA damage to attenuate activation of ATR kinase following carcinogen exposure.

Bioflavonoid-Induced Apoptosis and DNA Damage in Amastigotes and Promastigotes of Leishmania donovani: Deciphering the Mode of Action

Natural products from plants contain many interesting biomolecules. Among them, quercetin (Q), gallic acid (GA), and rutin (R) all have well-reported antileishmanial activity; however, their exact mechanisms of action are still not known. The current study is a step forward towards unveil the possible modes of action of these compounds against Leishmania donovani (the causative agent of visceral leishmaniasis). The selected compounds were checked for their mechanisms of action against L. donovani using different biological assays including apoptosis and necrosis evaluation, effects on genetic material (DNA), quantitative testing of nitric oxide production, ultrastructural modification via transmission electron microscopy, and real-time PCR analysis. The results confirmed that these compounds are active against L. donovani, with IC₅₀ values of 84.65 µg/mL, 86 µg/mL, and 98 µg/mL for Q, GA, and R, respectively. These compounds increased nitric oxide production and caused apoptosis and DNA damage, which led to changes in the treated cells’ ultrastructural behavior and finally to the death of L. donovani. These compounds also suppressed essential enzymes like trypanothione reductase and trypanothione synthetase, which are critical for leishmanial survival. The selected compounds have high antileishmanial potentials, and thus in-vivo testing and further screening are highly recommended.

An Overview of COVID-19 and the Potential Plant Harboured Secondary Metabolites against SARS-CoV-2: A Review

The SARS-CoV-2 virus causes COVID-19, a pandemic disease, and it is called the novel coronavirus. It belongs to the Coronaviridae family and has been plagued the world since the end of 2019. Viral infection to the lungs causes fluid filling and breathing difficulties, which leads to pneumonia. Pneumonia progresses to ARDS (Acute Respiratory Distress Syndrome), in which fluid fills the air sac and seeps from the pulmonary veins. In the current scenario, several vaccines have been used to control the pandemic worldwide. Even though vaccines are available and their effectiveness is short, it may be helpful to curb the pandemic, but long-term protection is inevitable when we look for other options. Plants have diversified components such as primary and secondary metabolites. These molecules show several activities such as anti-microbial, anti-cancer, anti-helminthic. In addition, these molecules have good binding ability to the SARS-CoV-2 virus proteins such as RdRp (RNA-dependent RNA polymerase), Mpro (Main Protease), etc. Therefore, these herbal molecules could probably be used to control the COVID-19. However, pre-requisite tests, such as cytotoxicity, in vivo, and human experimental studies, are required before plant molecules can be used as potent drugs. Plant metabolites such as alkaloids, isoquinoline ß-carboline, and quinoline alkaloids such as skimmianine, quinine, cinchonine, and dictamine are present in plants and used in a traditional medicinal system.

Polyphenols and Their Effects on Muscle Atrophy and Muscle Health

Skeletal muscle atrophy is the decrease in muscle mass and strength caused by reduced protein synthesis/accelerated protein degradation. Various conditions, such as denervation, disuse, aging, chronic diseases, heart disease, obstructive lung disease, diabetes, renal failure, AIDS, sepsis, cancer, and steroidal medications, can cause muscle atrophy. Mechanistically, inflammation, oxidative stress, and mitochondrial dysfunction are among the major contributors to muscle atrophy, by modulating signaling pathways that regulate muscle homeostasis. To prevent muscle catabolism and enhance muscle anabolism, several natural and synthetic compounds have been investigated. Recently, polyphenols (i.e., natural phytochemicals) have received extensive attention regarding their effect on muscle atrophy because of their potent antioxidant and anti-inflammatory properties. Numerous in vitro and in vivo studies have reported polyphenols as strongly effective bioactive molecules that attenuate muscle atrophy and enhance muscle health. This review describes polyphenols as promising bioactive molecules that impede muscle atrophy induced by various proatrophic factors. The effects of each class/subclass of polyphenolic compounds regarding protection against the muscle disorders induced by various pathological/physiological factors are summarized in tabular form and discussed. Although considerable variations in antiatrophic potencies and mechanisms were observed among structurally diverse polyphenolic compounds, they are vital factors to be considered in muscle atrophy prevention strategies.

Role of Dietary Antioxidants in p53-Mediated Cancer Chemoprevention and Tumor Suppression

Cancer arises through a complex interplay between genetic, behavioral, metabolic, and environmental factors that combined trigger cellular changes that over time promote malignancy. In terms of cancer prevention, behavioral interventions such as diet can promote genetic programs that may facilitate tumor suppression; and one of the key tumor suppressors responsible for initiating such programs is p53. The p53 protein is activated by various cellular events such as DNA damage, hypoxia, heat shock, and overexpression of oncogenes. Due to its role in cell fate decisions after DNA damage, regulatory pathways controlled by p53 help to maintain genome stability and thus “guard the genome” against mutations that cause cancer. Dietary intake of flavonoids, a C₁₅ group of polyphenols, is known to inhibit cancer progression and assist DNA repair through p53-mediated mechanisms in human cells via their antioxidant activities. For example, quercetin arrests human cervical cancer cell growth by blocking the G₂/M phase cell cycle and inducing mitochondrial apoptosis through a p53-dependent mechanism. Other polyphenols such as resveratrol upregulate p53 expression in several cancer cell lines by promoting p53 stability, which in colon cancer cells results in the activation of p53-mediated apoptosis. Finally, among vitamins, folic acid seems to play an important role in the chemoprevention of gastric carcinogenesis by enhancing gastric epithelial apoptosis in patients with premalignant lesions by significantly increased expression of p53. In this review, we discuss the role of these and other dietary antioxidants in p53-mediated cell signaling in relation to cancer chemoprevention and tumor suppression in normal and cancer cells.

Topical Nanoemulgel for the Treatment of Skin Cancer: Proof-of-Technology

The present study is a mechanistic validation of ‘proof-of-technology’ for the effective topical delivery of chrysin nanoemulgel for localized, efficient treatment of melanoma-affected skin. Background: Currently available treatments for skin cancer are inefficient due to systemic side effects and poor transcutaneous permeation, thereby presenting a formidable challenge for the development of novel nanocarriers. Methods: We opted for a novel approach and formulated a nanocomplex system composed of hydrophobic chrysin dissolved in a lipid mix, which was further nanoemulsified in Pluronic^® F-127 gel to enhance physicochemical and biopharmaceutic characteristics. Chrysin, a flavone extracted from passion flowers, exhibits potential anti-cancer activities; however, it has limited applicability due to its poor solubility. Pseudo-ternary phase diagrams were constructed to identify the best self-nanoemulsifying region by varying the compositions of oil, Caproyl^® 90 surfactant, Tween^® 80, and co-solvent Transcutol^® HP. Chrysin-loaded nanoemulsifying compositions were characterized for various physicochemical properties. Results: This thermodynamically stable, self-emulsifying drug delivery system showed a mean droplet size of 156.9 nm, polydispersity index of 0.26, and viscosity of 9100 cps after dispersion in gel. Mechanical characterization using Texture Analyzer exhibited that the gel had a hardness of 487 g and adhesiveness of 500 g. Ex vivo permeation through rat abdominal skin revealed significant improvement in percutaneous absorption measured as flux, the apparent permeability coefficient, the steady-state diffusion coefficient, and drug deposition. In vitro cytotoxicity on A375 and SK-MEL-2 cell lines showed a significantly improved therapeutic effect, thus ensuring reduction in dose. The safety of the product was established through biocompatibility testing on the L929 cell line. Conclusion: Aqueous, gel-based, topical, nanoemulsified chrysin is a promising technology approach for effective localized transcutaneous delivery that will help reduce the frequency and overall dose usage and ultimately improve the therapeutic index.

Anti-obesity properties and mechanism of action of flavonoids: A review

Obesity is a major public health problem, and there is increasing scientific interest in its mechanisms, as well as a search for new compounds with antioxidant and anti-inflammatory properties that can minimize the metabolic complications associated with its pathology. One potential source of these compounds is natural products; Among these, flavonoids are a promising group of natural substances. Flavonoids are active constituents with diverse biological activities and are widely found in plants kingdom. Numerous studies have shown that flavonoids can effectively inhibit obesity and related metabolic disorders. The review synthesizes recent evidence in respect of progress in the understanding of the anti-obesity effects of flavonoids. Such effects which occurs through the modulation of proteins, genes and transcriptional factors involved in decreasing lipogenesis, increasing lipolysis, expenditure energy, stimulating fatty acids B-oxidation, digestion and metabolism of carbohydrates. In addition to mitigating inflammatory responses and suppress oxidative stress. A better understanding of the modulating effects and mechanisms of flavonoids in relation to obesity will allow us to better use these compounds to treat or even prevent obesity and its associated comorbidities.

Does Flavonoid Consumption Improve Exercise Performance? Is It Related to Changes in the Immune System and Inflammatory Biomarkers? A Systematic Review of Clinical Studies since 2005

Flavonoids are attracting increasing attention due to their antioxidant, cardioprotective, and immunomodulatory properties. Nevertheless, little is known about their role in exercise performance in association with immune function. This systematic review firstly aimed to shed light on the ergogenic potential of flavonoids. A search strategy was run using SCOPUS database. The returned studies were screened by prespecified eligibility criteria, including intervention lasting at least one week and performance objectively quantified, among others. Fifty-one studies (54 articles) met the inclusion criteria, involving 1288 human subjects, either physically untrained or trained. Secondly, we aimed to associate these studies with the immune system status. Seventeen of the selected studies (18 articles) assessed changes in the immune system. The overall percentage of studies reporting an improved exercise performance following flavonoid supplementation was 37%, the proportion being 25% when considering quercetin, 28% for flavanol-enriched extracts, and 54% for anthocyanins-enriched extracts. From the studies reporting an enhanced performance, only two, using anthocyanin supplements, focused on the immune system and found certain anti-inflammatory effects of these flavonoids. These results suggest that flavonoids, especially anthocyanins, may exert beneficial effects for athletes’ performances, although further studies are encouraged to establish the optimal dosage and to clarify their impact on immune status.