Flavonoids: antioxidants or signalling molecules?

The Role of Oxidative Stress and Therapeutic Potential of Antioxidants in Graves' Ophthalmopathy

Graves’ ophthalmopathy (GO) is the most common extrathyroidal manifestation of Graves’ disease. It is characterized initially by an inflammatory process, followed by tissue remodeling and fibrosis, leading to proptosis, exposure keratopathy, ocular motility limitation, and compressive optic neuropathy. The pathogenic mechanism is complex and multifactorial. Accumulating evidence suggests the involvement of oxidative stress in the pathogenesis of GO. Cigarette smoking, a major risk factor for GO, has been shown to induce reactive oxygen species (ROS) generation and oxidative damage in GO orbital fibroblasts. In addition, an elevation in ROS and antioxidant enzymes is observed in tears, blood, and urine, as well as orbital fibroadipose tissues and fibroblasts from GO patients. In vitro and in vivo studies have examined the efficacy of various antioxidant supplements for GO. These findings suggest a therapeutic role of antioxidants in GO patients. This review summarizes the current understanding of oxidative stress in the pathogenesis and potential antioxidants for the treatment of GO.

Double-responsive hyaluronic acid-based prodrugs for efficient tumour targeting

Hyaluronic acid (HA)-based prodrugs bearing double-responsive (acid pH or oxidation) boronates of catechol-containing drugs were used to treat xenografted human prostate tumours (LNCaP) in SCID mice. The HA prodrugs accumulated significantly only in tumours (impressively, up to 40% of the injected dose after 24 h) and in liver, with negligible - actually anti-inflammatory - consequences in the latter. A quercetin-HA prodrug significantly slowed down tumour growth, in a dose-dependent fashion and with a much higher efficacy (up to 4 times) than equivalent doses of free quercetin. In short, boronated HA appears to be a very promising platform for targeted chemotherapy.

Chemopreventive potential of plant-derived epigenetic inhibitors silibinin and quercetin: an involvement of apoptotic signaling cascade modulation

Background

Epigenetic deregulation of the cellular apoptotic mechanism is the common hallmark of cancer. Silibinin (SBN) and quercetin (QCT) are two bioflavonoids well known for their epigenetic inhibition property. The objective of the present study was to explore the preventive anti-cancer efficacy of the SBN and QCT in both in vitro as well as in vivo tumor xenograft model through regulating cellular apoptotic signaling pathway.

Results

SBN and QCT inhibited the growth of A549 and MDA-MB-468 cancer cells in the concentration dependent manner. The treatment caused significant (p < 0.05) reduction of the size and the number of colonies formed by the cancer cells. In vitro apoptosis assay using the fluorescence microscopy revealed that the treatment noticeably increased the percentage of apoptotic cells as compared to the untreated control. Dosing with SBN (200mg/kg), QCT (100mg/kg) alone and in combination was initiated in 3-week-old C57BL6 mice. Interestingly, the treatment prevented tumor progression significantly (p < 0.05) in adult mice without causing any toxicity. Furthermore, SBN and QCT triggered apoptosis via modulating p53 and Bcl2 gene expression and the SOD enzyme activity.

Conclusion

Daily oral intake of SBN and QCT alone and in combination from the very early stage of life might prevent tumor growth in adult mice through activating cellular apoptotic signaling cascade.

A flavonoid, quercetin, is capable of enhancing long-term memory formation if encountered at different times in the learning, memory formation, and memory recall continuum

A major extrinsic factor influencing memory and neuro-cognitive performances across taxa is diet. Studies from vertebrates have shown the effects of a flavonoid rich diet on cognitive performance, but the mechanism underlying this action is still poorly understood. A common and abundant flavonoid present in numerous food substances is quercetin (Q). The present study provides the first support for Q-modulated enhancement of cognitive function in an invertebrate model, the pond snail Lymnaea stagnalis, after an operant conditioning procedure. We found that when snails were exposed to Q 3 h before or after a single 0.5 h training session, which typically results in memory lasting ~ 3 h, they formed a long-term memory (LTM) lasting for at least 24 h. Additionally, we assessed the effects of the combined presentation of a single reinforcing stimulus (at 24 h post-training or 24 h before training) and Q-exposure on both LTM formation and reconsolidation. That is, when applied within 3 h of critical periods of memory, Q regulates four different phases: (1) acquisition (i.e., a learning event), (2) consolidation processes after acquisition, (3) memory recall, and (4) memory reconsolidation. In all these phases Q-exposure enhanced LTM persistence.

Nutrition, Physical Activity, and Other Lifestyle Factors in the Prevention of Cognitive Decline and Dementia

Multiple factors combined are currently recognized as contributors to cognitive decline. The main independent risk factor for cognitive impairment and dementia is advanced age followed by other determinants such as genetic, socioeconomic, and environmental factors, including nutrition and physical activity. In the next decades, a rise in dementia cases is expected due largely to the aging of the world population. There are no hitherto effective pharmaceutical therapies to treat age-associated cognitive impairment and dementia, which underscores the crucial role of prevention. A relationship among diet, physical activity, and other lifestyle factors with cognitive function has been intensively studied with mounting evidence supporting the role of these determinants in the development of cognitive decline and dementia, which is a chief cause of disability globally. Several dietary patterns, foods, and nutrients have been investigated in this regard, with some encouraging and other disappointing results. This review presents the current evidence for the effects of dietary patterns, dietary components, some supplements, physical activity, sleep patterns, and social engagement on the prevention or delay of the onset of age-related cognitive decline and dementia.

Plant Extract of Limonium gmelinii Attenuates Oxidative Responses in Neurons, Astrocytes, and Cerebral Endothelial Cells In Vitro and Improves Motor Functions of Rats after Middle Cerebral Artery Occlusion

There are numerous publications demonstrating that plant polyphenols can reduce oxidative stress and inflammatory processes in the brain. In the present study we have investigated the neuroprotective effect of plant extract isolated from the roots of L. gmelinii since it contains a rich source of polyphenols and other biologically active compounds. We have applied an oxidative and inflammatory model induced by NMDA, H₂O₂, and TNF-α in human primary neurons and astrocytes, and mouse cerebral endothelial cell (CECs) line in vitro. The levels of ROS generation, NADPH oxidase activation, P-selectin expression, and activity of ERK1/2 were evaluated by quantitative immunofluorescence analysis, confocal microscopy, and MAPK assay. In vivo, sensorimotor functions in rats with middle cerebral artery occlusion (MCAO) were assessed. In neurons NMDA induced overproduction of ROS, in astrocytes TNF-α initiated ROS generation, NADPH oxidase activation, and phosphorylation of ERK1/2. In CECs, the exposure by TNF-α induced oxidative stress and triggered the accumulation of P-selectin on the surface of the cells. In turn, pre-treatment of the cells with the extract of L. gmelinii suppressed oxidative stress in all cell types and pro-inflammatory responses in astrocytes and CECs. In vivo, the treatment with L. gmelinii extract improved motor activity in rats with MCAO.

The effect of Luteolin on DNA damage mediated by a copper catalyzed Fenton reaction

Luteolin has been reviewed as a flavonoid possessing potential cardioprotective, anti-inflammatory, anti-cancer activities. Having multiple biological effects, luteolin may act as either an antioxidant or a pro-oxidant. In this work, the protective role of copper(II)-chelation by luteolin on DNA damage via the Cu-Fenton reaction was studied. EPR and UV-vis spectroscopic data demonstrated that the luteolin, lacking 3-OH group, chelates to Cu(II) via the 5-OH and 4-CO groups, respectively. EPR spin trapping experiments using DMPO spin trap confirmed that the coordination of luteolin to Cu(II) significantly suppressed formation of hydroxyl and superoxide radicals (by 80%) in a Cu-Fenton system. Absorption titrations showed that the chelation of Cu(II) by luteolin slightly increased the mild intercalation strength of its interaction with DNA, as compared with free luteolin. Comparison with kaempferol and quercetin revealed, that the strength of the interaction between the free flavonoids/Cu-flavonoid complexes with DNA is only mildly affected by the presence/absence of 3-OH group. Due to the differences in the sensitivities of absorption titrations and viscometry, the latter confirmed weaker DNA intercalating efficiency of Cu-luteolin complex than does free luteolin. A dose dependent protective effect of luteolin against ROS-induced DNA damage was observed using gel electrophoresis. This effect was more pronounced compared to quercetin and kaempferol. In conclusion, the administration of luteolin to patients suffering from oxidative stress-related diseases with disturbed Cu-metabolism such as Alzheimer's diseases (antioxidant effect) and certain cancers (prooxidant effect) may have several health benefits.

Coffee, Tea, and Mammographic Breast Density in Premenopausal Women

Studies have investigated the associations of coffee and tea with mammographic breast density (MBD) in premenopausal women with inconsistent results. We analyzed data from 375 premenopausal women who attended a screening mammogram at Washington University School of Medicine, St. Louis, MO in 2016, and stratified the analyses by race (non-Hispanic White (NHW) vs. Black/African American). Participants self-reported the number of servings of coffee, caffeinated tea, and decaffeinated tea they consumed. Volpara software was used to determine volumetric percent density (VPD), dense volume (DV), and non-dense volume (NDV). We used generalized linear regression models to quantify the associations of coffee and tea intake with MBD measures. Coffee: ≥1 time/day (β = 1.06; 95% CI = 0.93–1.21; p-trend = 0.61) and caffeinated tea: ≥1 time/day (β = 1.01; 95% CI = 0.88–1.17; p-trend = 0.61) were not associated with VPD. Decaffeinated tea (≥1 time/week) was positively associated with VPD in NHW women (β = 1.22; 95% CI = 1.06–1.39) but not in African American women (β = 0.93; 95% CI = 0.73–1.17; p-interaction = 0.02). Coffee (≥1 time/day) was positively associated with DV in African American women (β = 1.52; 95% CI = 1.11–2.07) but not in NHW women (β = 1.10; 95% CI = 0.95–1.29; p-interaction = 0.02). Our findings do not support associations of coffee and caffeinated tea intake with VPD in premenopausal women. Positive associations of decaffeinated tea with VPD, with suggestions of effect modification by race, require confirmation in larger studies with diverse study populations.

Emerging Novel Approaches for the Enhanced Delivery of Natural Products for the Management of Neurodegenerative Diseases

Neurodegenerative diseases (NDs) such as Alzheimer's disease, Parkinson's disease, Huntington disease, amyotrophic lateral sclerosis, and prion disease affect any part of the brain. The complete mechanism of ND is unknown, but there are some molecular mechanism and chemical process. Natural compounds have better compatibility with the human body along with lesser side effects. Moreover, several studies showed that various natural compounds have significant neuroprotective, potent antioxidant, and anti-inflammatory properties, which are effective for treating the different type of ND. In ND, natural compounds act by various mechanisms such as preventing the generation of reactive oxygen species (ROS), eliminating destructed biomolecules before their accumulation affects cell metabolism, and improving the disease conditions. But due to the presence of the blood-brain barrier (BBB) layer and unfavorable pharmacokinetic properties of natural compounds, their delivery into the brain is limited. To minimize this problem and enhance drug delivery into the brain with an effective therapeutic dose, there is a need to develop a practical novel approach. The various studies showed that nanoformulations and microneedles (MN) containing natural compounds such as quercetin, curcumin, resveratrol, chrysin, piperine, ferulic acid, huperzine A, berberine, baicalein, hesperetin, and retinoic acid effectively improved many ND. In this review, the effect of such natural drug-loaded nanoformulation and MN patches on ND management is discussed, along with their merits and demerits. This review aims to introduce different novel approaches for enhancing natural drug delivery into the brain to manage various neurodegenerative diseases.

Anti-Inflammatory Potential of Complex Extracts of Ligularia stenocephala Matsum. & Koidz. and Secale cereale L. Sprout in Chronic Gingivitis: In Vitro Investigation and Randomized Clinical Trial

Complex extracts of Ligularia stenocephala Matsum. & Koidz. (LSE) and Secale cereale L. sprout (SCSE) (TEES-10^®) were prepared. The purposes of the study were to evaluate anti-inflammatory activities of TEES-10^® in vitro and to observe resolution of gingivitis in human with oral administration of TEES-10^®. The effects of TEES-10^® on normal periodontal ligament (PDL) cell viability, lipopolysaccharide (LPS) induced PDL cell viability and the changes of inflammatory mediator expression were evaluated in vitro. In the clinical trial, 150 mg of TEES-10^® powder containing capsule was administered twice daily to the test group, while the control group administered placebos in a total 100 participants with gingivitis. Probing depth (PD), bleeding on probing (BOP), clinical attachment loss, gingival index (GI) and plaque index (PI) were measured at baseline and 4 weeks. Administering TEES-10^® showed significant increase in PDL cell viability compared to administering LSE or SCSE alone. In addition, treating TEES-10^® to LPS induced PDL cell significantly increased PDL cell viability compared to control. TEES-10^® suppressed expression of NF-κB, p-ERK, ERK, COX-2, c-Fos and p-STAT and promoted expression of PPARγ in LPS induced PDL cells. In the clinical trial, significant improvement of GI and BOP was observed in the test group at 4 weeks. In addition, the number of patients diagnosed with gingivitis was significantly reduced in the test group at 4 weeks. Salivary MMP-8 and MMP-9 was also significantly decreased compared to placebo group. Within the limitations of this study, the TEES-10^® would have an anti-inflammatory potential clinically in the chronic gingivitis patients.

Application of the INFOGEST Standardized Method to Assess the Digestive Stability and Bioaccessibility of Phenolic Compounds from Galician Extra-Virgin Olive Oil

The INFOGEST standardized method was applied to assess the potential bioaccessibility and bioaccessibility of the phenolic compounds from a Galician extra-virgin olive oil (EVOO). The in vitro digestion model involves three steps and generates two fractions after each one: an aqueous fraction (namely, water phase (Wp)) and an oily fraction (namely, oily phase (Op)). The results showed that secoiridoids were the most abundant family in the Galician EVOO polar fraction, representing 98% of the total phenolic compounds. After oral digestion, phenolic acids and simple phenols were mainly detected in Wp, while lignans and flavonoids were mostly found in Op. After gastric digestion, extensive hydrolysis of secoiridoids was observed to generate free tyrosol, hydroxytyrosol, and hydroxytyrosol acetate. The instability of secoiridoids after intestinal digestion was again responsible for the release of simple phenols, which were mainly recovered in Wp together with flavonoids. In contrast, lignans were stable to duodenal conditions and remained in Op.

Comparative transcriptome analysis reveals the molecular mechanism of salt tolerance in Apocynum venetum

Apocynum venetum is a traditional Chinese medicinal herb with tolerance to various abiotic stresses, especially, salinity. However, only a few studies have investigated the salt-tolerant mechanism of this non-halophyte under salt stress at phenotypic and physiological levels. To explore the molecular mechanism of salinity tolerance in A. venetum, the global transcriptome profiles of seedling leaves under different salt-stress durations, using 200 mM NaCl, were analyzed. De novo assembly of approximately 715 million high-quality reads and approximately 105.61 Gb sequence data was performed. In total, 2822 differentially expressed genes (DEGs) were identified. DEGs were significantly enriched in flavonoid metabolism-related pathways such as "flavonoid biosynthesis" and "phenylpropanoid biosynthesis". Most of these DEGs were downregulated under salt stress. However, genes encoding the non-selective cation channels and antioxidants were upregulated under salt stress, whereas most cell wall-related DEGs were downregulated. Consequently, the concentration of flavonoids decreased, whereas that of Na⁺ increased with exposure time. Thus, we hypothesized that the accumulation of Na⁺ in the leaves, which resulted in reduced flavonoid concentration under salt stress, directly led to a decrease in the salt tolerance of A. venetum. This was verified by overexpressing four flavonoid synthesis pathway genes in Arabidopsis. The transgenic plants showed higher salt tolerance than the wild-type plants due to the accumulation of total flavonoids. These physiological and transcriptome analyses of A. venetum revealed major molecular underpinnings contributing to the responses of A. venetum to salt stress, thereby improving our understanding of the molecular mechanisms underlying salt tolerance in A. venetum and plants in general. The findings serve as a basis for functional studies on and engineering strategies for plant salinity tolerance.

Neuroprotective Properties of Kempferol Derivatives from Maesa membranacea against Oxidative Stress-Induced Cell Damage: An Association with Cathepsin D Inhibition and PI3K/Akt Activation

As components of the human diet with potential health benefits, flavonols are the subject of numerous studies, confirming their antioxidant, free radical scavenging and anti-inflammatory activity. Taking into consideration the postulated pathogenesis of certain CNS dysfunctions characterized by neuronal degradation, flavonols may prevent the decay of neurons in multiple pathways. Leaves of Maesa membranacea yielded several flavonol glycosides including α-rhamnoisorobin (kaempferol 7-O-α-rhamnoside) and kaempferitrin (kaempferol 3,7-di-O-α-rhamnoside). The latter compound was a major constituent of the investigated plant material. Neuroprotective effects of kaempferitrin and α-rhamnoisorobin were tested in vitro using H₂O₂-, 6-OHDA- and doxorubicin-induced models of SH-SY5Y cell damage. Both undifferentiated and differentiated neuroblastoma cells were used in the experiments. α-Rhamnoisorobin at a concentration range of 1–10 µM demonstrated cytoprotective effects against H₂O₂-induced cell damage. The compound (at 1–10 µM) was also effective in attenuating 6-OHDA-induced neurotoxicity. In both H₂O₂- and 6-OHDA-induced cell damage, kaempferitrin, similar to isoquercitrin, demonstrated neuroprotective activity at the highest of the tested concentrations (50 µM). The tested flavonols were not effective in counteracting doxorubicin-induced cytotoxicity. Their caspase-3- and cathepsin D-inhibitory activities appeared to be structure dependent. Inhibition of the PI3-K/Akt pathway abolished the neuroprotective effect of the investigated flavonols.

Anticancer Activity of Half-Sandwich Ru, Rh and Ir Complexes with Chrysin Derived Ligands: Strong Effect of the Side Chain in the Ligand and Influence of the Metal

An important challenge in the field of anticancer chemotherapy is the search for new species to overcome the resistance of standard drugs. An interesting approach is to link bioactive ligands to metal fragments. In this work, we have synthesized a set of p-cymene-Ru or cyclopentadienyl-M (M = Rh, Ir) complexes with four chrysin-derived pro-ligands with different -OR substituents at position 7 of ring A. The introduction of a piperidine ring on chrysin led to the highly cytotoxic pro-ligand HL4 and its metal complexes L4-M (SW480 and A549 cell lines, cytotoxic order: L4-Ir > L4-Ru ≈ L4-Rh). HL4 and its complexes induce apoptosis and can overcome cis-platinum resistance. However, HL4 turns out to be more cytotoxic in healthy than in tumor cells in contrast to its metal complexes which displayed higher selectivity than cisplatin towards cancer cells. All L4-M complexes interact with double stranded DNA. Nonetheless, the influence of the metal is clear because only complex L4-Ir causes DNA cleavage, through the generation of highly reactive oxygen species (1O2). This result supports the hypothesis of a potential dual mechanism consisting of two different chemical pathways: DNA binding and ROS generation. This behavior provides this complex with a great effectivity in terms of cytotoxicity.

The Role of Polyphenols in Regulation of Heat Shock Proteins and Gut Microbiota in Weaning Stress

Gut microbiota is the natural residents of the intestinal ecosystem which display multiple functions that provide beneficial effects on host physiology. Disturbances in gut microbiota in weaning stress are regulated by the immune system and oxidative stress-related protein pathways. Weaning stress also alters gut microbiota response, limits digestibility, and influences animal productive performance through the production of inflammatory molecules. Heat shock proteins are the molecular chaperones that perform array functions from physiological to pathological point of view and remodeling cellular stress response. As it is involved in the defense mechanism, polyphenols ensure cellular tolerance against enormous stimuli. Polyphenols are nature-blessed compounds that show their existence in plenty of amounts. Due to their wider availability and popularity, they can exert strong immunomodulatory, antioxidative, and anti-inflammatory activities. Their promising health-promoting effects have been demonstrated in different cellular and animal studies. Dietary interventions with polyphenols may alter the gut microbiome response and attenuate the weaning stress related to inflammation. Further, polyphenols elicit health-favored effects through ameliorating inflammatory processes to improve digestibility and thereby exert a protective effect on animal production. Here, in this article, we will expand the role of dietary polyphenol intervention strategies in weaning stress which perturbs gut microbiota function and also paid emphasis to heat shock proteins in gut health. This review article gives new direction to the feed industry to formulate diet containing polyphenols which would have a significant impact on animal health.

Dominant factors that determine the dissolution state of complexes between poorly water-soluble ingredients and casein hydrolysate

Casein hydrolysate (Pep) is a dispersant for poorly water-soluble drugs and nutraceutical ingredients. However, two types of complexes may be between Pep and poorly water-soluble molecules: those that are (1) dispersed as hydrocolloids in aqueous media with a particle size of 100-500 nm; and (2) not hydrocolloids, as indicated by permeability of the complex through an ultrafiltration (UF) membrane and the fact that the particle size is ambiguous by dynamic light scattering. This study was conducted to clarify the factors that determine the dissolution state of the complexes between poorly water-soluble ingredients and casein hydrolysate. We classified the dissolution state of the complexes between poorly water-soluble ingredients and Pep by the permeability using a UF membrane. Complexes containing larger and more-hydrophobic molecules are hydrocolloids and do not permeate the UF membrane, whereas complexes containing comparatively smaller and less-hydrophobic molecules do permeate the UF membrane. A complex containing indomethacin, which has borderline solubility properties, does not permeate the UF membrane at pH values in which the indomethacin carboxylic acid group is protonated, but it is permeable at pH values in which its carboxylic acid group is deprotonated. Furthermore, we determined the stoichiometry and association constant for the complex between a major peptide in Pep and poorly water-soluble resveratrol (Res) based on fluorescence quenching. We calculated the stoichiometry of Res and PepY to be 2:3 and the association constant to be 2.4 × 10⁷ M^-1.

Kaempferol Blocks the Skin Fibroblastic Interleukin 1β Expression and Cytotoxicity Induced by 12-O-tetradecanoylphorbol-13-acetate by Suppressing c-Jun N-terminal Kinase

Kaempferol, a bioflavonoid present in fruits and vegetables, has a variety of antioxidant and anti-inflammatory capacities, but the functional role of kaempferol in oxidative skin dermal damage has yet to be well studied. In this study, we examine the role of kaempferol during the inflammation and cell death caused by 12-O-tetradecanoylphorbol-13-acetate (TPA) in normal human dermal fibroblasts (NHDF). TPA (5 μM) significantly induced cytotoxicity of NHDF, where a robust increase in the interleukin (IL)-1β mRNA among the various pro-inflammatory cytokines. The skin fibroblastic cytotoxicity and IL-1β expression induced by TPA were significantly ameliorated by a treatment with 100 nM of kaempferol. Kaempferol blocked the production of the intracellular reactive oxygen species (ROS) responsible for the phosphorylation of c-Jun N-terminal kinase (JNK) induced by TPA. Interestingly, we found that kaempferol inhibited the phosphorylation of nuclear factor-kappa B (NF-κB) and the inhibitor NF-κB (IκBα), which are necessary for the expression of cleaved caspase-3 and the IL-1β secretion in TPA-treated NHDF. These results suggest that kaempferol is a functional agent that blocks the signaling cascade of the skin fibroblastic inflammatory response and cytotoxicity triggered by TPA.

Identification of new alpha-synuclein fibrillogenesis inhibitor using in silico structure-based virtual screening

Abnormal aggregation and accumulation of alpha-synuclein (αSN) in existing neurons is associated with Parkinson's disease (PD) as one of the age-related neurodegenerative disorders. Inhibition of αSN fibrillogenesis could be considered as a solution for PD diseases treatment. Here, virtual screening (VS) approach was used to investigate available ligands in PubChem library with structural similarity with Dihydromyricetin (DHM) (as a recently introduced suitable candidate for designing of novel antiPD drugs) against aggregation of αSN chains. Primary screening identified 314 promising molecules for αSN monomer, which were further analyzed in details by their binding energy and binding modes through molecular docking method. Evidently, the compound with PubChem ID of 100968625 displayed the lowest free binding energy with ΔG⁰ = -7.1 kcal.mol^-1 and was selected for further analysis using molecular dynamics (MD) simulation method. Analysis of MD trajectories showed that molecules of the selected ligand interact with αSN trimer via H-bond interaction and destabilize the compact structure of αSN trimer. Further, prompt in vivo testing to validate the antiPD inhibition efficiency by this molecule can save lives.

Protein Adducts and Protein Oxidation as Molecular Mechanisms of Flavonoid Bioactivity

There are tens of thousands of scientific papers about flavonoids and their impacts on human health. However, despite the vast amount of energy that has been put toward studying these compounds, a unified molecular mechanism that explains their bioactivity remains elusive. One contributing factor to the absence of a general mechanistic explanation of their bioactivity is the complexity of flavonoid chemistry in aqueous solutions at neutral pH. Flavonoids have acidic protons, are redox active, and frequently auto-oxidize to produce an array of degradation products including electrophilic quinones. Flavonoids are also known to interact with specificity and high affinity with a variety of proteins, and there is evidence that some of these interactions may be covalent. This review summarizes the mechanisms of flavonoid oxidation in aqueous solutions at neutral pH and proposes the formation of protein-flavonoid adducts or flavonoid-induced protein oxidation as putative mechanisms of flavonoid bioactivity in cells. Nucleophilic residues in proteins may be able to form covalent bonds with flavonoid quinones; alternatively, specific amino acid residues such as cysteine, methionine, or tyrosine in proteins could be oxidized by flavonoids. In either case, these protein-flavonoid interactions would likely occur at specific binding sites and the formation of these types of products could effectively explain how flavonoids modify proteins in cells to induce downstream biochemical and cellular changes.

Fast Antioxidant Reaction of Polyphenols and Their Metabolites

The negative correlation between diets rich in fruits and vegetables and the occurrence of cardiovascular disease, stroke, cancer, atherosclerosis, cognitive impairment and other deleterious conditions is well established, with flavonoids and other polyphenols held to be partly responsible for the beneficial effects. Initially, these effects were explained by their antioxidant ability, but the low concentrations of polyphenols in tissues and relatively slow reaction with free radicals suggested that, instead, they act by regulating cell signalling pathways. Here we summarise results demonstrating that the abandonment of an antioxidant role for food polyphenols is based on incomplete knowledge of the mechanism of the polyphenol-free radical reaction. New kinetic measurements show that the reaction is up to 1000 times faster than previously reported and lowers the damaging potential of the radicals. The results also show that the antioxidant action does not require phenolic groups, but only a carbon-centred free radical and an aromatic molecule. Thus, not only food polyphenols but also many of their metabolites are effective antioxidants, significantly increasing the antioxidant protection of cells and tissues. By restoring an important antioxidant role for food polyphenols, the new findings provide experimental support for the advocacy of diets rich in plant-derived food.

Comparative analysis of metabolic variations, antioxidant potential and cytotoxic effects in different parts of Chelidonium majus L

Metabolic variations, antioxidant potential and cytotoxic effects were investigated in the different plant parts like the leaf, stem, flower, pod, and root of C. majus L. using spectroscopic and chromatographic methods. Total phenolics and flavonoids were studied in the different parts of C. majus L., leaf showed higher flavonoid content (137.43 mg/g), while the pod showed the highest phenolic (23.67 mg/g) content, when compared with the stem, flower and root. In the ABTS antioxidant assay, the flower extract showed 57.94% effect, while the leaf, pod and root extract exhibited 39.10%, 36.08% and 28.88% activity, respectively. The pod and leaf extracts demonstrated the potential effect, exhibiting 45.46 and 41.61% activity, respectively, for the DPPH assay. Similar to the phosphomolybdenum assay, the flower revealed higher antioxidant activity (46.82%) than the other plant parts. The in vitro SRB assay facilitated evaluation of the cytotoxic effect against the HeLa and CaSki human cervical cancerous cells. The extract displayed dose-dependent inhibitory effect on both the cell lines. The highest cytotoxic effect was observed in the pod and flower extracts post 48 h of exposure at 1000 μg/mL. The results of C. majus L. offered new insights in the preliminary steps regarding the development of a high value product for phytomedicine applications though promising metabolic variations with antioxidant and anticancer potentials.

Quercetin as a Novel Therapeutic Approach for Lymphoma

Lymphoma is a name for malignant diseases of the lymphatic system including Hodgkin's lymphoma and non-Hodgkin's lymphoma. Although several approaches are used for the treatment of these diseases, some of them are not successful and have serious adverse effects. Therefore, other effective treatment methods might be interesting. Studies have indicated that plant ingredients play a key role in treating several diseases. Some plants have already shown a potential therapeutic effect on many malignant diseases. Quercetin is a flavonoid found in different plants and could be useful in the treatment of different malignant diseases. Quercetin has its antimalignant effects through targeting main survival pathways activated in tumor cells. In vitro/in vivo experimental studies have demonstrated that quercetin possesses a cytotoxic effect on lymphoid cancer cells. Regardless of the optimum results that have been obtained from both in vitro/in vivo studies, few clinical studies have analyzed the antitumor effects of quercetin in lymphoid cancers. Thus, it seems that more clinical studies should introduce quercetin as a therapeutic, alone or in combination with other chemotherapy agents. Here, in this study, we reviewed the anticancer effects of quercetin and highlighted the potential therapeutic effects of quercetin in various types of lymphoma.

Phytochemicals, Trace Element Contents, and Antioxidant Activities of Bark of Taleh (Acacia seyal) and Desert Rose (Adenium obesum)

Acacia seyal and Adenium obesum are used in traditional medicines by indigenous communities of the Asir region of Saudi Arabia. The present study aimed to acquire the phytochemical profiles, quantify the trace element contents and the total phenolic (TPC) and flavonoid (TFC) contents, and evaluate the antioxidant activity of the two species. Phytochemical screening was conducted to detect the presence of the phytochemical constituents. Bark samples were digested with a microwave, and ICP-MS was used for the elemental analysis. The antioxidant capacities in DPPH, H₂O₂, and FRAP assays and the TPC and TFC were determined by spectrophotometry, and their correlation with the IC₅₀ of the DPPH and H₂O₂ and the EC₅₀ of the FRAP capacities were analyzed by Pearson's correlation. Both plant extracts contain a variety of phytochemicals. A. obesum had the highest concentrations of all 11 elements measured. In both plants, manganese was found at the highest concentration, and cadmium exhibited the lowest concentration. The aqueous-methanolic extract of A. seyal showed the highest TPC (309.32 ± 2.15 mg gallic acid equivalent/g), whereas the aqueous-methanolic extract of A. obesum exhibited the highest TFC (32.16 ± 3.16 mg quercetin equivalent/g). Significant differences in the IC₅₀ and EC₅₀ values were observed among the tested plant extracts. The highest antioxidant activity was found in aqueous-methanolic extract of A. obesum. Correlation analysis showed significant correlations between the DPPH and FRAP activities and the TFC. The present findings highlight that these plants are good sources of phenolic compounds and essential elements and support their therapeutic use as antioxidant drugs.

Olive Pomace Phenolic Compounds and Extracts Can Inhibit Inflammatory- and Oxidative-Related Diseases of Human Ocular Surface Epithelium

Oxidative- and inflammatory-related ocular surface diseases have high prevalence and are an emerging issue in ophthalmology. Olive pomace (OP) is the olive oil's industry main by-product, and is potentially environmentally hazardous. Nevertheless, it contains phenolic compounds with important bioactivities, like oleuropein (OL) and hydroxytyrosol (HT). The antioxidant and anti-inflammatory effects of four OP extracts (CONV, OPT(1-3)), pure OL and HT, and mixtures thereof were screened on human corneal (HCE) and conjunctival epithelial (IM-ConjEpi) cells. CONV was conventionally extracted, while OPT(1-3) were produced by pressurized liquid extraction. Thanks to their improved activity, CONV and OPT3 (HT-enriched) were selected for dose-dependent studies. Cells were stimulated with tumor necrosis factor-α or ultraviolet-B radiation, measuring interleukin (IL)-1β, IL-6, IL-8, and IL-17A as well as interferon γ-induced protein [IP]-10 secretion or intracellular ROS production, respectively. On HCE, both extracts and HT inhibited the secretion of most measured ILs, demonstrating a strong anti-inflammatory effect; while in IM-ConjEpi, all samples decreased IP-10 secretion. Moreover, HT, OL, and both extracts showed strong dose-dependent antioxidant activity in both cell lines. Compared with CONV, OPT3 was active at lower concentrations, demonstrating that intensified extraction techniques are selective towards targeted biomarkers. Hence, a high-value application as potential ocular surface therapy was proposed for the OP valorization.

Therapeutic Promises of Medicinal Plants in Bangladesh and Their Bioactive Compounds against Ulcers and Inflammatory Diseases

When functioning properly, the stomach is the center of both physical and mental satisfaction. Gastrointestinal disorders, or malfunctioning of the stomach, due to infections caused by various biological entities and physiochemical abnormalities, are now widespread, with most of the diseases being inflammatory, which, depending on the position and degree of inflammation, have different names such as peptic or gastric ulcers, irritable bowel diseases, ulcerative colitis, and so on. While many synthetic drugs, such as non-steroidal anti-inflammatory drugs, are now extensively used to treat these diseases, their harmful and long-term side effects cannot be ignored. To treat these diseases safely and successfully, different potent medicinal plants and their active components are considered game-changers. In consideration of this, the present review aimed to reveal a general and comprehensive updated overview of the anti-ulcer and anti-inflammatory activities of medicinal plants. To emphasize the efficacy of the medicinal plants, various bioactive compounds from the plant extract, their experimental animal models, and clinical trials are depicted.

Quercetin relaxes human gastric smooth muscles directly through ATP-sensitive potassium channels and not depending on the nitric oxide pathway

BACKGROUND

Quercetin has recently become a remarkably popular subject of research due to its broad beneficial pharmacological properties. The goal of our study was to observe its effects on contractility of human gastric smooth muscles in reference to the NO pathway and direct influence of potassium channels.

METHODS

Tissues were obtained from patients undergoing sleeve gastrectomy due to morbid obesity (n = 10 aged 24-56; BMI 47.16 ± 1.84). The following parameters were evaluated in the recordings: area under the curve (AUC), average baseline muscle tone, and relative change in muscle contraction.

KEY RESULTS

Quercetin induced noticeable, dose-dependent relaxation of the carbachol treated gastric strips. The substantial effect was noted at concentrations higher than 10^-7  mol/L and maximal at 10^-4  mol/L (81.82 ± 3.32%; n = 10; p < 0.0001) of the control. Neither NOS blockers nor guanylyl cyclase blockers had inhibitory effects on the relaxation of strips induced by examined polyphenol. Glibenclamide inhibited the relaxing effect of quercetin, significant at concentrations higher than 5⋅10^-5  mol/L. Preincubation with charybdotoxin or apamin extended the relaxing effect of quercetin (from 10^-6  mol/L). Tamoxifen, in turn, significantly increased muscle relaxation at all quercetin concentrations.

CONCLUSIONS & INFERENCES

In conclusion, the current study was the first to show that quercetin-induced relaxation of human gastric smooth muscle occurs directly through K⁺_ATP channels and independently to NO pathways. The present results suggest that quercetin is a potential nutraceutical in the treatment of functional gastrointestinal dyspepsia and other minor gastric muscle motility disturbance.

Olive Polyphenols: Antioxidant and Anti-Inflammatory Properties

Oxidative stress and inflammation triggered by increased oxidative stress are the cause of many chronic diseases. The lack of anti-inflammatory drugs without side-effects has stimulated the search for new active substances. Plant-derived compounds provide new potential anti-inflammatory and antioxidant molecules. Natural products are structurally optimized by evolution to serve particular biological functions, including the regulation of endogenous defense mechanisms and interaction with other organisms. This property explains their relevance for infectious diseases and cancer. Recently, among the various natural substances, polyphenols from extra virgin olive oil (EVOO), an important element of the Mediterranean diet, have aroused growing interest. Extensive studies have shown the potent therapeutic effects of these bioactive molecules against a series of chronic diseases, such as cardiovascular diseases, diabetes, neurodegenerative disorders and cancer. This review begins from the chemical structure, abundance and bioavailability of the main EVOO polyphenols to highlight the effects and the possible molecular mechanism(s) of action of these compounds against inflammation and oxidation, in vitro and in vivo. In addition, the mechanisms of inhibition of molecular signaling pathways activated by oxidative stress by EVOO polyphenols are discussed, together with their possible roles in inflammation-mediated chronic disorders, also taking into account meta-analysis of population studies and clinical trials.

Phytochemicals as Therapeutic Interventions in Peripheral Artery Disease

Peripheral artery disease (PAD) affects over 200 million people worldwide, resulting in significant morbidity and mortality, yet treatment options remain limited. Among the manifestations of PAD is a severe functional disability and decline, which is thought to be the result of different pathophysiological mechanisms including oxidative stress, skeletal muscle pathology, and reduced nitric oxide bioavailability. Thus, compounds that target these mechanisms may have a therapeutic effect on walking performance in PAD patients. Phytochemicals produced by plants have been widely studied for their potential health effects and role in various diseases including cardiovascular disease and cancer. In this review, we focus on PAD and discuss the evidence related to the clinical utility of different phytochemicals. We discuss phytochemical research in preclinical models of PAD, and we highlight the results of the available clinical trials that have assessed the effects of these compounds on PAD patient functional outcomes.

Natural Products for Neurodegeneration: Regulating Neurotrophic Signals

Neurodegenerative disorders (NDs) are heterogeneous groups of ailments typically characterized by progressive damage of the nervous system. Several drugs are used to treat NDs but they have only symptomatic benefits with various side effects. Numerous researches have been performed to prove the advantages of phytochemicals for the treatment of NDs. Furthermore, phytochemicals such as polyphenols might play a pivotal role in rescue from neurodegeneration due to their various effects as anti-inflammatory, antioxidative, and antiamyloidogenic agents by controlling apoptotic factors, neurotrophic factors (NTFs), free radical scavenging system, and mitochondrial stress. On the other hand, neurotrophins (NTs) including nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), NT4/5, and NT3 might have a crucial neuroprotective role, and their diminution triggers the development of the NDs. Polyphenols can interfere directly with intracellular signaling molecules to alter brain activity. Several natural products also improve the biosynthesis of endogenous genes encoding antiapoptotic Bcl-2 as well as NTFs such as glial cell and brain-derived NTFs. Various epidemiological studies have demonstrated that the initiation of these genes could play an essential role in the neuroprotective function of dietary compounds. Hence, targeting NTs might represent a promising approach for the management of NDs. In this review, we focus on the natural product-mediated neurotrophic signal-modulating cascades, which are involved in the neuroprotective effects.

Comparative Study on Phytochemical Profile and Antioxidant Activity of an Epiphyte, Viscum album L. (White Berry Mistletoe), Derived from Different Host Trees

The study aimed at evaluating the antioxidant profile of a medicinal epiphyte Viscum album L. harvested from three tree species, namely, Populus ciliata L, Ulmus villosa L., and Juglans regia L. The crude extracts were obtained with ethanol, methanol, and water and were evaluated for the total phenol content (TPC), total flavonoid content (TFC), and antioxidant activities using total reducing power (TRP), ferric reducing antioxidant power (FRAP), 1, 1-diphenyl 1-2-picryl-hydrazyl (DPPH), superoxide radical scavenging (SOR), and hydroxyl radical scavenging (^•OH) assays. Our results showed that crude leaf extracts of plants harvested from the host Juglans regia L. exhibited higher yields of phytochemical constituents and noticeable antioxidative properties. The ethanolic leaf samples reported the highest phenols (13.46 ± 0.87 mg/g), flavonoids (2.38 ± 0.04 mg/g), FRAP (500.63 ± 12.58 μM Fe II/g DW), and DPPH (87.26% ± 0.30 mg/mL). Moreover, the highest values for TRP (4.24 ± 0.26 μg/mL), SOR (89.79% ± 0.73 mg/mL), and OH (67.16% ± 1.15 mg/mL) were obtained from aqueous leaf extracts. Further, Pearson correlation was used for quantifying the relationship between TPC, TFC, and antioxidant (FRAP, DPPH, SOR, OH) activities in Viscum album L. compared to their hosts. It was revealed that the epiphyte showed variation with the type of host plant and extracting solvent.

Pharmacological Potentiality of Bioactive Flavonoid against Ketamine Induced Cell Death of PC 12 Cell Lines: An In Vitro Study

During the past few years, there has been exponential growth in the field of ethnopharmacology in the treatment of different human ailments, including neurological disorders. In our previous study, we isolated, characterized, and reported a novel bioactive compound with therapeutic efficacy in vivo, which was used in the current study. This study was designed to investigate the pharmacological effect and therapeutic mechanism of the natural plant compound 3-(3,4-dimethoxy phenyl)-1-(4-methoxy phenyl)prop-2-en-1-one against ketamine-induced toxicity in PC 12 cell lines. Cell death was induced in PC 12 cell lines by incubating with ketamine, and the protection offered by the compound at different concentrations was studied during pretreatment. The therapeutic efficacy was screened through MTT assay, LDH assay, DCF-DA assay, clonogenic assay, RT-PCR, and densitometric analysis. The bioactive compound caused a significant elevation in cell viability up to approximately 80%, down-regulation of cell damage, reduction in free radical damage caused by intracellular reactive oxygen species, and up-regulation of cell survival ability, which was dysregulated during ketamine induction. In addition, RT-PCR analysis of DOPA-related genes suggests that the compound exerted significant inhibition in the expression of these genes, which were overexpressed during ketamine induction. The current findings provide new insight into the neuroprotective mediation of bioactive factors as a prospective therapy for neurological disorders.

Investigation of genotoxic effects of rhododendron honey using three mammalian bioassays in vivo

Rhododendron honey (RH) is obtained from the rhododendron plants are grown in many regions around the world, causes poisoning in humans due to the grayanotoxin (GTX) compound in its structure. It is used by the public as a therapeutic for some diseases. It was aimed to study the genotoxic and cytotoxic effects of RH in mouse bone-marrow and sperm cells by using three mammalian bioassays. 25, 50 and 75 mg kg^-1 concentrations of RH given to male mice via gavage for 24 and 48 h treatment periods and its active ingredient Grayanatoxin (GTX-III) 0.01 mg kg^-1 by i.p. injection. Chromosome aberrations (CA), polychromatic erythrocytes (PCE)/normochromatic erythrocytes (NCE), micronucleated polychromatic erythrocytes (MNPCE) and sperm abnormalities were investigated. The results demonstrated that all the tested concentrations of RH significantly induced total abnormal cell frequency including chromosomal breaks for two time periods. In the MN assay, 75 mg kg^-1 RH and 0.01 mg kg^-1 GTX-III significantly increased % MNPCE and significantly reduced PCE/NCE ratios after 24 and 48 h treatments on mice demonstrating potential genotoxic and cytotoxic effect. Although there was a concentration-related increase in the percentage of total sperm abnormalities, this increase was not statistically significant compared to control. As a result, microscopic genotoxicity and cytotoxicity marker tests showed that RH and its active ingredient GTX-III have potential genotoxic and cytotoxic effect on mice bone marrow cells. It is understood that RH that is used to treat some diseases by public, should be handled carefully and used in a controlled manner.HighlightsChromosome aberration, micronucleus and sperm morphology assays are recommended as reliable biological indicators.RH and its active ingredient GTX-III have potential genotoxic and cytotoxic effect on mice bone marrow cells.Significant changes were observed upon the treatment of 75 mg kg^-1 MH for MN assay.

Effect of Water Hardness on Catechin and Caffeine Content in Green Tea Infusions

The health benefits of green tea are associated with its high catechin content. In scientific studies, green tea is often prepared with deionized water. However, casual consumers will simply use their local tap water, which differs in alkalinity and mineral content depending on the region. To assess the effect of water hardness on catechin and caffeine content, green tea infusions were prepared with synthetic freshwater in five different hardness levels, a sodium bicarbonate solution, a mineral salt solution, and deionized water. HPLC analysis was performed with a superficially porous pentafluorophenyl column. As water hardness increased, total catechin yield decreased. This was mostly due to the autoxidation of epigallocatechin (EGC) and epigallocatechin gallate (EGCG). Epicatechin (EC), epicatechin gallate (ECG), and caffeine showed greater chemical stability. Autoxidation was promoted by alkaline conditions and resulted in the browning of the green tea infusions. High levels of alkaline sodium bicarbonate found in hard water can render some tap waters unsuitable for green tea preparation.

Metabolites from halophilic bacterial isolates Bacillus VITPS16 are cytotoxic against HeLa cells

The present study was aimed at evaluating the cytotoxic potential of selected halophilic bacterial metabolites. The use of the metabolomics approach in identifying the unexplored bioactive metabolites from halophilic bacterial isolate reduces time and complex experiments. In our study, we used UV/Visible spectroscopy, LC-MS/MS, and NMR to identify the metabolites present in the methanolic extract of the halophilic bacterium Bacillus VITPS16. MTT assay revealed that metabolite fractions (S1-79.61% and S2-85.74%) possess cytotoxic activity. Colonogenic assay confirmed the cytotoxic potential of the fractions and apoptosis assays showed that 83.37% of the cells undergo apoptosis at 10 mg/mL concentration (MF-S2). The DNA binding studies revealed the metabolite fraction interacts with DNA resulting in cytotoxicity. The study states that MF- S2 induced an antiproliferative effect that led to apoptosis through DNA binding as one of the possible pathways. The toxicity analysis using zebrafish indicated that the metabolite fractions are non-toxic even at 10 mg/mL concentration. Fraction MF-S2 is found to contain phosphoethanolamines, glycerophospholipids, sphingolipids, apocarotenoid, enigmol and its analogue, ankaflavin and flavonoid type of metabolites, which have been previously reported to have anti-cancer activity.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-021-02724-9.

Sugar matters: sugar moieties as reactivity-tuning factors in quercetin O-glycosides

Quercetin, one of the most abundant flavonoids in plant-based foods, commonly occurs in nature in various glycosylated forms. There is still a less explored aspect regarding the cause of diversity of its glycosides, depending on the sugar moiety attached. This work focuses on four wide-spread quercetin glycosides-hyperoside, isoquercitrin, quercitrin and rutin-by testing the property-tuning capacity of different sugar moieties and thus explains and predicts some of their functions in plant-based foods. The electron paramagnetic spectra of the semiquinone anion radicals of these glycosides were interpreted in terms of hyperfine coupling constants and linewidths, highlighting a clear link between spin density trends, the identity of the bound sugar, and their reactivity corroborated with their modelled structures. Redox potential and lipophilicity were connected to a specific flavonoid-enzyme interaction and correlated with their prooxidant reactivity assessed by oxidation of ferrous hemoglobin. Hyperoside and isoquercitin-galactose and glucose glycosides-exhibit the highest prooxidant reactivity owing to their lowest redox potential and lipophilicity whereas rutin and quercitrin-rutinose and rhamnose glycosides-behave vice versa. The ability of the tested glycosides to undergo HAT or SET-type reactions has also been tested using five different analytical assays, including inhibition of cytochrome c-triggered liposome peroxidation. In most cases, rutin proved to be the most unreactive of the four tested glycosides considering either steric or redox reasons whereas the reactivity hierarchy of the other three glycosides were rather assay dependent.

Mechanistic insights and perspectives involved in neuroprotective action of quercetin

Neurodegenerative diseases (NDDs) are the primary cause of disabilities in the elderly people. Growing evidence indicates that oxidative stress, mitochondrial dysfunction, neuroinflammation and apoptosis are associated with aging and the basis of most neurodegenerative disorders. Quercetin is a flavonoid with significant pharmacological effects and promising therapeutic potential. It is widely distributed among plants and typically found in daily diets mainly in fruits and vegetables. It shows a number of biological properties connected to its antioxidant activity. Neuroprotection by quercetin has been reported in many in vitro as well as in in vivo studies. However, the exact mechanism of action is still mystery and similarly there are a number of hypothesis exploring the mechanism of neuroprotection. Quercetin enhances neuronal longevity and neurogenesis by modulating and inhibiting wide number of pathways. This review assesses the food sources of quercetin, its pharmacokinetic profile, structure activity relationship and its pathophysiological role in various NDDs and it also provides a synopsis of the literature exploring the relationship between quercetin and various downstream signalling pathways modulated by quercetin for neuroprotection for eg. nuclear factor erythroid 2-related factor 2 (Nrf2), Paraoxonase-2 (PON2), c-Jun N-terminal kinase (JNK), Tumour Necrosis Factor alpha (TNF-α), Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha (PGC-1α), Sirtuins, Mitogen-activated protein kinases (MAPKs) signalling cascades, CREB (Cyclic AMP response element binding protein) and Phosphoinositide 3- kinase(PI3K/Akt). Therefore, the aim of the present review was to elaborate on the cellular and molecular mechanisms of the quercetin involved in the protection against NDDs.

Promising Green Technology in Obtaining Functional Plant Preparations: Combined Enzyme-Assisted Supercritical Fluid Extraction of Flavonoids Isolation from Medicago Sativa Leaves

To elaborate a complete extraction protocol for the enhanced release of biologically active compounds from plant cells, this study aimed to optimize together the parameters of the supercritical fluid extraction (SFE) process (temperature, pressure, and percentage of cosolvent) and enzymatic treatment of plant material (pH, enzyme concentration, time, and temperature) by response surface methodology (RSM). Medicago sativa L. was selected as a plant material due to its richness in phenolics and flavonoids. HPLC-MS/MS analysis allowed evaluating the content of individual bioactive compounds in obtained extracts. The total content of polyphenolic compounds in the extract obtained after two-step optimization was much higher (546 ± 21 µg/g) than in the extract obtained from non-hydrolyzed material (275 ± 23 µg/g) and in the extract obtained by maceration (162 ± 20 µg/g). Furthermore, it was evidenced that extract with the highest content of polyphenolic compounds can support the cellular antioxidant system both as a free radical scavenger and by stimulating the antioxidant enzyme system.

A review of plant metabolites with metal interaction capacity: a green approach for industrial applications

Rapid industrial development is responsible for severe problems related to environmental pollution. Many human and industrial activities require different metals and, as a result, great amounts of metals/heavy metals are discharged into the water and soil making them dangerous for both human and ecosystems and this is being aggravated by intensive demand and utilization. In addition, compounds with metal binding capacities are needed to be used for several purposes including in activities related to the removal and/or recovery of metals from effluents and soils, as metals' corrosion inhibitors, in the synthesis of metallic nanoparticles and as metal related pharmaceuticals, preferably a with minimum risks associated to the environment. Plants are able to synthesize an uncountable number of compounds with numerous functions, including compounds with metal binding capabilities. In fact, some of the plants' secondary metabolites can bind to various metals through different mechanisms, as such they are excellent sources of such compounds due to their high availability and vast diversity. In addition, the use of plant-based compounds is desirable from an environmental and economical point of view, thus being potential candidates for utilization in different industrial activities, replacing conventional physiochemical methods. This review focuses on the ability of some classes of compounds that can be found in relatively high concentrations in plants, having good metal binding capacities and thus with potential utilization in metal based industrial activities and that can be involved in the progressive development of new environmentally friendly strategies.

Quercetin upregulates CREM gene expression in cyanide-induced endocrine dysfunction

Cyanide is among the ubiquitous chemicals that humans are usually exposed to and it is well documented that cyanide induces infertility in humans and experimental rodents. However, the pathogenesis remains unknown. Likewise, quercetin is an important nutraceutical that detoxifies reactive oxygen species, but its effects on testicular damage is not clear. The present study investigated the role of nutraceutical, quercetin on cyanide-induced testicular toxicity and probable involvement of cAMP-response-element modulator (CREM) which is a transcription factor necessary for the process of spermatogenesis. Thus, this work hypothesized that quercetin will mitigate endocrine dysfunction induced by cyanide. Seventy-two adult male Wistar rats were divided into seven groups (A to G). Groups A, B, C, F and G comprised of eight (8) rats per group while groups D and E comprised of sixteen (16) rats per group. Group A was designated as control while Groups B and C were given 0.5 and 1 mg/kg of cyanide respectively for 56 days. Group D and E received 0.5 and 1 mg/kg body weight cyanide respectively for 30 days. At day 30, eight animals were sacrificed from Group D and E and the remaining eight (8) rats were subdivided into sub-groups (D1 and E1) and were given 20 and 40 mg/kg of quercetin respectively for twenty-six (26) days. Group F and G were given concurrent administration of cyanide and quercetin at a dose of 0.5 + 20 mg/kg and 1 + 40 mg/kg respectively for 56 days. Body and testicular weight were significantly reduced in cyanide treated groups while quercetin modulates the reduction. Significant down-regulation of CREM gene and reduction in serum level of follicle stimulating hormone (FSH), Luteinizing hormone (LH), testosterone, glutathione peroxidase (GPx) and zinc in cyanide-treated groups, whereas administration of quercetin concomitantly with cyanide exposure or post-treated significantly reversed the alterations.

The Anticancer Effects of Flavonoids through miRNAs Modulations in Triple-Negative Breast Cancer

Triple- negative breast cancer (TNBC) incidence rate has regularly risen over the last decades and is expected to increase in the future. Finding novel treatment options with minimum or no toxicity is of great importance in treating or preventing TNBC. Flavonoids are new attractive molecules that might fulfill this promising therapeutic option. Flavonoids have shown many biological activities, including antioxidant, anti-inflammatory, and anticancer effects. In addition to their anticancer effects by arresting the cell cycle, inducing apoptosis, and suppressing cancer cell proliferation, flavonoids can modulate non-coding microRNAs (miRNAs) function. Several preclinical and epidemiological studies indicate the possible therapeutic potential of these compounds. Flavonoids display a unique ability to change miRNAs' levels via different mechanisms, either by suppressing oncogenic miRNAs or activating oncosuppressor miRNAs or affecting transcriptional, epigenetic miRNA processing in TNBC. Flavonoids are not only involved in the regulation of miRNA-mediated cancer initiation, growth, proliferation, differentiation, invasion, metastasis, and epithelial-to-mesenchymal transition (EMT), but also control miRNAs-mediated biological processes that significantly impact TNBC, such as cell cycle, immune system, mitochondrial dysregulation, modulating signaling pathways, inflammation, and angiogenesis. In this review, we highlighted the role of miRNAs in TNBC cancer progression and the effect of flavonoids on miRNA regulation, emphasizing their anticipated role in the prevention and treatment of TNBC.

In vitro effects of Capparis spinosa L. extract on human sperm function, DNA fragmentation, and oxidative stress

ETHNOPHARMACOLOGICAL RELEVANCE

Oxidative stress is one of the underlying causes of male infertility. Medicinal plants have many benefits for infertility treatment in men.

AIM OF THE STUDY

In the present study, we evaluated in vitro effects of Capparis spinosa leaf extract on human sperm function, DNA fragmentation, and oxidative stress.

MATERIALS AND METHODS

We conducted this study on the hydroalcoholic extract of C. spinosa. Polyphenol compounds and antioxidant effects of the leaf and fruit extract were determined by HPLC and DPPH method, respectively. Flavones and flavonols, total flavonoid, total phenolic content, tannin, and the total carbohydrate content were determined calorimetrically. Semen samples from 50 healthy men (20-45 years) were divided into control and experimental (15, 30, and 45 ppm of C. spinosa leaf extract) groups. Motility, viability, lipid peroxidation, and DNA fragmentation were evaluated 24 h after incubation.

RESULTS

The antioxidant effect of leaf extract was six times greater than fruit. Progressive and total motility of caper-treated groups (30 and 45 ppm) were crucially higher than the control group. Viability in all treatments was significantly higher than the control group. There was no significant difference in lipid peroxidation. DNA fragmentation in the caper-treated group (45 ppm) was significantly lower than the control group.

CONCLUSIONS

Our results suggest the potential positive in vitro effect of C. spinosa leaf extract on human sperm function. The use of C. spinosa leaf extract or its active metabolites in the sperm culture medium may be beneficial for maintaining motility, vitality, and sperm DNA. Since these effects were observed at very low concentrations of caper, other non-antioxidant mechanisms must be considered.

Flavonoids-Macromolecules Interactions in Human Diseases with Focus on Alzheimer, Atherosclerosis and Cancer

Flavonoids, a class of polyphenols, consumed daily in our diet, are associated with a reduced risk for oxidative stress (OS)-related chronic diseases, such as cardiovascular disease, neurodegenerative diseases, cancer, and inflammation. The involvement of flavonoids with OS-related chronic diseases have been traditionally attributed to their antioxidant activity. However, evidence from recent studies indicate that flavonoids' beneficial impact may be assigned to their interaction with cellular macromolecules, rather than exerting a direct antioxidant effect. This review provides an overview of the recent evolving research on interactions between the flavonoids and lipoproteins, proteins, chromatin, DNA, and cell-signaling molecules that are involved in the OS-related chronic diseases; it focuses on the mechanisms by which flavonoids attenuate the development of the aforementioned chronic diseases via direct and indirect effects on gene expression and cellular functions. The current review summarizes data from the literature and from our recent research and then compares specific flavonoids' interactions with their targets, focusing on flavonoid structure-activity relationships. In addition, the various methods of evaluating flavonoid-protein and flavonoid-DNA interactions are presented. Our aim is to shed light on flavonoids action in the body, beyond their well-established, direct antioxidant activity, and to provide insights into the mechanisms by which these small molecules, consumed daily, influence cellular functions.

Chemical Profiling and Dose-Dependent Assessment of Fear Reducing and Memory-Enhancing Effects of Solanum virginianum in Rats

The current study was planned to investigate the pharmacological basis of Solanum virginianum extract (SV.CR) pertaining to anxiolytic, antidepressant and memory-enhancing effects in rats. The SV.CR was analyzed in-vitro for phytoconstituents, antioxidant potential and anticholinesterase activity. The rats treated in a dose-dependent manner (25, 50 and 100 mg/kg of SV.CR) were subjected to behavioral tests for anxiety, depression and memory judgment followed by biochemical studies. A notable dose-dependent anxiolytic potential of SV.CR was observed in elevated plus maze and open field tests (P < 0.05). The decreased immobility time of the treated rats in the forced swim test (P < 0.01) unveiled the plant’s potential to reduce depression. Moreover, SV.CR treatment also reversed scopolamine-impaired cognition (P < 0.05) in various deployed memory and learning tasks. Biochemical studies of brain homogenates of SV.CR treated animals demonstrated decreased anticholinesterase activity and lipid peroxidation levels whereas increased levels of superoxide dismutase and glutathione peroxidase (P < 0.05 vs scopolamine group) were noted. The scientific validation of the study supported the use of Solanum virginianum in reducing anxiety, depression and amnesia in experimental models. Phytoconstituents in SV.CR such as oleanolic acid and caffeic acid might have played a significant neuroprotective role via modulation of oxidative stress and neurochemical aspects.

Luteolin as a modulator of skin aging and inflammation

Luteolin belongs to the group of flavonoids and can be found in flowers, herbs, vegetables and spices. It plays an important role in defending plants, for example against UV radiation by partially absorbing UVA and UVB radiation. Thus, luteolin can also decrease adverse photobiological effects in the skin by acting as a first line of defense. Furthermore, anti-oxidative and anti-inflammatory activities of luteolin were described on keratinocytes and fibroblasts as well as on several immune cells (e.g., macrophages, mast cell, neutrophils, dendritic cells and T cells). Luteolin can suppress proinflammatory mediators (e.g., IL-1β, IL-6, IL-8, IL-17, IL-22, TNF-α and COX-2) and regulate various signaling pathway (e.g., the NF-κB, JAK-STAT as well as TLR signaling pathway). In this way, luteolin modulates many inflammatory processes of the skin. The present review summarizes the recent in vitro and in vivo research on luteolin in the field of skin aging and skin cancer, wound healing as well as inflammatory skin diseases, including psoriasis, contact dermatitis and atopic dermatitis. In conclusion, luteolin might be a promising molecule for the development of topic formulations and systemic agents against inflammatory skin diseases.

Herbal Medicine in the Treatment of Epilepsy

Epilepsy is one of the most common disorders of the central nervous system. Although epilepsy is common worldwide, approximately 80% of epileptic patients live in the developing countries or those with low-middle income. Up until the second decade of the 20th century, epilepsy was treated mostly by traditional remedies. Today, antiepileptic drugs are used as a general treatment instead to prevent and control epileptic seizures. However, patient access to these drugs is hindered due to the healthcare systems of their countries and a number of other reasons, such as cultural, socio-demographic, and financial poverty. In addition, approximately 30-40%of epileptic patients suffer from refractory epilepsy, additionally, AEDs have adverse side-effects that can lead to treatment failure or reduce the patient's quality of life. Despite recent advances in the treatment of epilepsy, there is still a need for improving medical treatment with a particular focus on efficacy, safety, and accessibility. Since herbal medicines have been used for many centuries around the world for treating epilepsy, it is, therefore, plausible that a rigorous study on herbal medicine and phytochemical components within plants of various species and origin may lead to the discovery of novel AEDs. Nowadays, many medicinal plants used in different cultures and regions of the world have been identified. Most phytochemical components of these plants have been identified and, in some cases, their targets located. Therefore, it is possible that new, effective, and accessible anticonvulsants drugs can be obtained from a medicinal plant.