Antioxidant capacity of flavonoids in hepatic microsomes is not reflected by antioxidant effects in vivo

Comprehensive and critical view on the anti-inflammatory and immunomodulatory role of natural phenolic antioxidants

The immune response encompasses innate and adaptive immunity, each with distinct and specific activities. The innate immune system is constituted by phagocytic cells, macrophages, monocytes and neutrophils, the cascade system, and different classes of receptors such as toll-like receptors that are exploited by the innate immune cells. The adaptive immune system is antigen-specific, encompassing memory lymphocytes and the corresponding specific receptors. Inflammation is understood as an activation of different signaling pathways such as toll-like receptors or nuclear factor kappa-light-chain-enhancer of activated B cells, with an increase in nitric oxide, inflammatory cytokines and chemokines. Increased oxidative stress has been identified as main source of chronic inflammation. Phenolic antioxidants modulate the activities of lymphocytes and macrophages by impacting cytokines and nitric oxide release, exerting anti-inflammatory effect. The nuclear-factor kappa-light-chain-enhancer of activated B cells signaling pathway and the mitogen-activated protein kinase pathway are targeted, alongside an increase in nuclear factor erythroid 2-related factor mediated antioxidant response, triggering the activity of antioxidant enzymes. The inhibitive potential on phospholipase A2, cyclooxygenase and lipoxygenase in the arachidonic acid pathway, and the subsequent reduction in prostaglandin and leukotriene generation, reveals the potential of phenolics as inflammation antagonists. The immunomodulative potential encompasses the capacity to interfere with proinflammatory cytokine synthesis and with the expression of the corresponding genes. A diet rich in antioxidants can result in prevention of inflammation-related pathologies. More investigations are necessary to establish the role of these antioxidants in therapy. The appropriate delivery system and the prooxidant effects exhibited at large doses, or in the presence of heavy metal cations should be regarded.

In Vitro-In Vivo Study of the Impact of Excipient Emulsions on the Bioavailability and Antioxidant Activity of Flavonoids: Influence of the Carrier Oil Type

The influence of the carrier oil type on the bioavailability and bioactivity of flavonoids (quercetin, kaempferol, and apigenin) was examined using in vitro digestion, in situ intestinal perfusion, and pharmacokinetic studies. Here, medium-chain triglycerides (MCTs), long-chain triglycerides (LCTs), or MCT/LCT mixtures (1:1, w/w) served as the oil phase of excipient emulsions. Overall, the bioavailability and antioxidant activity of flavonoids increased when they were coingested with excipient emulsions. The in vitro bioaccessibility of flavonoids was affected by the carrier oil: LCT (17.9-22.8%) > MCT/LCT (12.1-13.7%) > MCT (9.2-12.6%). These differences were mainly attributed to the fact that the mixed micelles formed after the digestion of LCTs had larger hydrophobic domains to solubilize more flavonoids. However, in vivo pharmacokinetic experiments showed that the flavonoid concentrations in rat serum were comparable for all carrier oils (p > 0.05). Our results assist in formulating excipient emulsions to enhance the efficacy of flavonoids.

Flavonoid profile and antioxidant properties of Algerian common yew (Taxus baccata L.)

Background

In humans, various diseases are associated with the accumulation of free radicals. The antioxidants can scavenge free radicals and reduce their impact; thus, the search for effective natural antioxidants of plant origin is indispensable. The present study aims to determine, for the first time, the flavonoid compounds profile and to investigate the free radical scavenging and antioxidant properties of the methanolic extract of Taxus baccata L. from Algeria.

Methods

The determination of the flavonoid compound profile of the methanolic extract of Taxus baccata L. was established using high-performance liquid chromatography with diode-array detection coupled to electrospray ionization tandem mass spectrometry (HPLC–DAD–ESI–MS/MS). The total flavonoid content (TFC) was performed according to the aluminum chloride colorimetric method, while the free radical scavenging and antioxidant activities were carried out using three methods, namely 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical assay, 2,2'-azino-bis3-ethylbenzothiazoline-6-sulphonic acid (ABTS) radical assay and ferric reducing antioxidant power (FRAP) Assay.

Results

A total of 26 compounds including flavon-3-ols, flavanonols, flavones, flavonols and bioflavonoids were characterized and identifiedusing HPLC–DAD–ESI–MS/MS analysis, five were reported for the first time such as taxifolin, apigenin, apigenin 7-O-glucoside, isorhamnetin 3-O-rutinoside and robustaflavone. The plant extract exhibited high total flavonoid content (TFC = 204.26 ± 6.02 mg RE/g dry extract) which corresponded to its strong radical scavenging activities [(DPPH IC50 = 35.31 ± 0.29 µg/ml and ABTS IC50 = 8.27 ± 0.52 µg/ml)] as compared to the synthetic antioxidant BHT [(DPPH IC50 = 78.96 ± 5.70 µg/ml and ABTS IC50 = 13.56 ± 0.06 µg/ml)]. However, the methanolic extract of T. baccata showed the lowest ferric reducing ability as compared to the positive controls (BHT, BHA, ascorbic acid, trolox and quercetin).

Conclusion

Our results imply that the Taxus Baccata L. might be a potential source for the isolation of natural antioxidant compounds.

Myricetin inhibits pseudorabies virus infection through direct inactivation and activating host antiviral defense

Myricetin, a polyhydroxyflavone compound, is one of the main ingredients of various human foods and therefore also known as dietary flavonoids. Due to the continuous emergence of resistant strains of herpesviruses, novel control measures are required. In the present study, myricetin exhibited potent antiviral activity against pseudorabies virus (PRV), a model organism of herpesvirus. The suppression rate could reach up to 96.4% at a concentration of 500 μM in cells, and the 50% inhibitory concentration (IC₅₀) was 42.69 μM. Moreover, the inhibitory activity was not attenuated by the increased amount of infective dose, and a significant reduction of intracellular PRV virions was observed by indirect immunofluorescence. A mode of action study indicated that myricetin could directly inactivate the virus in vitro, leading to inhibition of viral adsorption, penetration and replication in cells. In addition to direct killing effect, myricetin could also activate host antiviral defense through regulation of apoptosis-related gene expressions (Bcl-2, Bcl-xl, Bax), NF-κB and MAPK signaling pathways and cytokine gene expressions (IL-1α, IL-1β, IL-6, c-Jun, STAT1, c-Fos, and c-Myc). In PRV-infected mouse model, myricetin could enhance the survival rate by 40% at 5 days post infection, and viral loads in kidney, liver, lung, spleen, and brain were significantly decreased. The pathological changes caused by PRV infection were improved by myricetin treatment. The gene expressions of inflammatory factors (MCP-1, G-CSF, IL-1α, IL-1β, and IL-6) and apoptotic factors (Bcl-xl, Bcl-2, and Bax) were regulated by myricetin in PRV-infected mice. The present findings suggest that myricetin can effectively inhibit PRV infection and become a candidate for development of new anti-herpesvirus drugs.

Variations in Morphological Characters and Antioxidant Potential of Different Plant Parts of Four Ziziphus Mill. Species from the Cholistan

Genus Ziziphus (Z.) contains various important species in tropical and subtropical regions that are globally famous for their food and medicinal uses. However, no comprehensive study was available on the morphology and phytochemistry of Ziziphus species, mainly under different growth conditions, i.e., irrigated and desert (Cholistan). Therefore, this study was carried out to evaluate the morphological and phytochemical characteristics of Ziziphus species, i.e., Z. jujuba, Z. mauritiana, Z. spina-christi, and Z. nummularia, found in the irrigated and desert conditions. Our results revealed significant variations for most of the measured parameters, showing a large-scale diversity among Ziziphus species under irrigated and desert conditions. Specifically, Ziziphus species showed better morphology of all measured parameters of leaves and fruits under irrigated conditions compared to desert conditions, indicating that the optimum water availability in irrigated conditions improved the morphological parameters of Z. species. Meanwhile, among all Ziziphus species, the maximum leaf length (7.4 cm), leaf width (4.1 cm), leaf area (30.6 cm²), and leaf petiole length (1.3 cm) were observed for Z. jujuba, and the highest leaf dry weight (55.4%) was recorded for Z. mauritiana. Similarly, the highest fruit length (3.9 cm), fruit stalk length (1.5 cm), fruit diameter (3.6 cm), fruit width (3.8 cm), fruit area (66.1 cm²), seed length (2 cm), and seed diameter (1.1 cm) were measured for species Z. jujuba, while the maximum fruit dry weight (49.9%) and seed width (1.4 cm) were recorded for species Z. nummularia. Interestingly, compared to irrigated conditions, higher values of bioactive contents, i.e., phenol, flavonoid, and antioxidant activity, in fruits and leaves of Ziziphus species under desert conditions indicated the positive impact of desert climate on the phytochemistry of the Z. plants. Among Ziziphus species, Z. nummularia accumulated the maximum fruit phenols (304.4 mg GAE/100 g), leaf phenols (314.2 mg GAE/100 g), fruit flavonoids (123.7 mg QE/100 g), and leaf flavonoids (113.4 mg QE/100 g). Overall, this study demonstrated the significant morphological and phytochemical variations of the Ziziphus species under irrigated and desert conditions, which could be utilized for future studies to improve the production and medicinal potential of the Ziziphus, especially in desert areas.

Effect of extracts and isolated compounds derived from Retama monosperma (L.) Boiss. on anti-aging gene expression in human keratinocytes and antioxidant activity

ETHNOPHARMACOLOGICAL RELEVANCE

Moroccan folk medicine treats skin cicatrization with Retama monosperma (L.) Boiss. locally named "Rtem", but the mechanism involved is still not well known. Traditional healers use the plant in small doses as an anthelmintic, disinfectant and an effective abortive. In addition, the cladodes powder mixed with honey is employed as purgative and vermifuge. Equally, the SIRT1 and SIRT3 genes activation and sirtuin proteins expression, which delay cellular senescence, participate in wound healing and skin regeneration especially, SIRT1 the most studied gene, leads to fast skin restoration and cicatrization.

AIM OF THE STUDY

In this study, we evaluated the ability of the Retama monosperma (L.)Boiss. flowers and seeds extracts and the isolated compounds in augmenting the SIRT1 and SIRT3 gene expression in HaCaT cells and expressing the antioxidant activity.

MATERIALS AND METHODS

We examined for quantitative expression levels of SIRT1 and SIRT3 in HaCaT cell by qRT-PCR and the antioxidant activity by four tests (conjugated diene, TBARS assay, DPPH scavenging activity and H₂O₂ radical scavenging assay) of diethyl ether extract of flowers (DEF extract) and ethyl acetate extract of seeds (EAS extract) of R. monosperma(L.) Boiss. and the isolated compounds (quercetin, 6-methoxykaempferol, kaempferol and genistein).

RESULTS

The screening system by EGFP fluorescence revealed that all samples and resveratrol significantly increase SIRT1 and SIRT3 promoters activities in HaCaT cells with p< 0.05. Furthermore, EAS, quercetin, 6-methoxykaempferol and kaempferol increase significantly (p< 0.05) SIRT1 (3.43, 1.18, 2.62, and 1.72 expression quantity, respectively) and SIRT3 (16.27, 5.01, 3.01, and 6.18 expression quantity, respectively) in HaCaT cells. On the other hand, genistein has a moderate activity on SIRT1 and SIRT3 with 1.43 and 2.04 expression levels. For the antioxidant activity, the EAS and the pure compounds exhibited stronger antioxidant activity than BHT. While DEF and genistein have a moderate antioxidant activity when compared with BHT.

CONCLUSIONS

In this study, the expression levels of SIRT1 and SIRT3 in HaCaT cells increase in the presence of extracts of R. monosperma (L.) Boiss. and the pure compounds.

Altered gestational outcomes and delayed pubertal onset in prenatally and early postnatally food restricted male and female rats: mitigation by quercetin and kaempferol

Nutrigenomic malnutrition during pregnancy and early postnatal life has serious consequences on original organ-programing, growth pattern, puberty and quality of life. The aim of this was to investigate the effect of two notable flavonoids, quercetin and kaempferol, with nutrigenomic potentials on prenatal and early postnatal food restrictions or both on gestational outcomes and the onset of puberty in male and females Wister rats. In three sets of experiments consisting of prenatal, postnatal food deprivations or both, rats were distributed into various treatment groups (n = 6). Prenatal food restriction (PrNFR) was initiated by 50% of ad libitum available diet in pregnancy (days 1-22) simultaneously with quercetin (50, 100 and 200 mg/kg, p.o./day) or kaempferol (50, 100 and 200 mg/kg, p.o./day) until delivery. However, postnatal food restriction (PsNFR) was simulated by litter-increment to 16 pups per mother from postnatal day 2 together with quercetin (50-200 mg/kg, p.o.) or kaempferol (50-200 mg/kg, p.o.) treatments until weaning (day 24) respectively. The last experiment encompasses both protocols with similar treatment protocols. Kaempferol attenuated PrNFR-induced alterations in gestational length compared to PrNFR-control. Quercetin and kaempferol significantly (P < 0.05) normalized nose-length of pups of rats exposed to PrNFR. Quercetin and kaempferol reduced the number of stillbirths due to PrNFR. Both also reduced the delay in pubertal onset as evidenced by normal onset of balanopreputial-separation and vaginal-opening in the PrNFR, PsNFR and PrNFR-PsNFR male and female rats respectively. Together, quercetin and kaempferol prevents prenatal and postnatal malnutrition-induced altered gestational outcomes and pubertal delays in rats.

Selenium and sulphur derivatives of hydroxytyrosol: inhibition of lipid peroxidation in liver microsomes of vitamin E-deficient rats

PURPOSE

The objective of this study was to evaluate the capacity of modified phenols synthesized from hydroxytyrosol, a natural olive oil phenol, specifically those containing a selenium or sulphur group, to inhibit lipid peroxidation.

METHODS

The compounds' abilities to inhibit lipid peroxidation in liver microsomes obtained from vitamin E-deficient rats were compared to hydroxytyrosol.

RESULTS

All synthetic compounds had a significant higher ability to inhibit lipid peroxidation than hydroxytyrosol. Selenium derivates displayed a higher antioxidant activity than sulphur derivatives. In addition, the antioxidant activity increased with a higher number of heteroatoms in the hydroxytyrosol molecular structure.

CONCLUSION

The study shows, for the first time, the ability of synthetic compounds, derived from the most active phenol present in olives in free form (hydroxytyrosol), and containing one or two atoms of sulphur or selenium, to inhibit the lipid peroxidation of vitamin E-deficient microsomes. The antioxidant activity of five thioureas, a disulfide, a thiol, three selenoureas, a diselenide, and a selenonium were evaluated and the results showed a higher inhibition of lipid peroxidation than the natural phenol. Selenium and sulphur derivatives of hydroxytyrosol are novel antioxidants with the potential to supplement the lack of vitamin E in the diet as natural alternatives for the prevention of diseases related to oxidative damage.

Molecular Mechanisms and Pathways as Targets for Cancer Prevention and Progression with Dietary Compounds

A unique feature of bioactive food ingredients is their broad antioxidant function. Antioxidants having a wide spectrum of chemical structure and activity beyond basic nutrition; display different health benefits by the prevention and progression of chronic diseases. Functional food components are capable of enhancing the natural antioxidant defense system by scavenging reactive oxygen and nitrogen species, protecting and repairing DNA damage, as well as modulating the signal transduction pathways and gene expression. Major pathways affected by bioactive food ingredients include the pro-inflammatory pathways regulated by nuclear factor kappa B (NF-κB), as well as those associated with cytokines and chemokines. The present review summarizes the importance of plant bioactives and their roles in the regulation of inflammatory pathways. Bioactives influence several physiological processes such as gene expression, cell cycle regulation, cell proliferation, cell migration, etc., resulting in cancer prevention. Cancer initiation is associated with changes in metabolic pathways such as glucose metabolism, and the effect of bioactives in normalizing this process has been provided. Initiation and progression of inflammatory bowel diseases (IBD) which increase the chances of developing of colorectal cancers can be downregulated by plant bioactives. Several aspects of the potential roles of microRNAs and epigenetic modifications in the development of cancers have also been presented.

A synthetic cell permeable antioxidant protects neurons against acute oxidative stress

Excessive reactive oxygen species (ROS) can damage proteins, lipids, and DNA, which result in cell damage and death. The outcomes can be acute, as seen in stroke, or more chronic as observed in age-related diseases such as Parkinson’s disease. Here we investigate the antioxidant ability of a novel synthetic flavonoid, Proxison (7-decyl-3-hydroxy-2-(3,4,5-trihydroxyphenyl)-4-chromenone), using a range of in vitro and in vivo approaches. We show that, while it has radical scavenging ability on par with other flavonoids in a cell-free system, Proxison is orders of magnitude more potent than natural flavonoids at protecting neural cells against oxidative stress and is capable of rescuing damaged cells. The unique combination of a lipophilic hydrocarbon tail with a modified polyphenolic head group promotes efficient cellular uptake and moderate mitochondrial enrichment of Proxison. Importantly, in vivo administration of Proxison demonstrated effective and well tolerated neuroprotection against cell loss in a zebrafish model of dopaminergic neurodegeneration.

Biochemical and molecular modulation of CCl4-induced peripheral and central damage by Tilia americana var. mexicanaextracts

Around the world, species from the genus Tilia are commonly used because of their peripheral and central medicinal effects; they are prepared as teas and used as tranquilizing, anticonvulsant, and analgesic agents. In this study, we provide evidence of the protective effects of organic and aqueous extracts (100 mg/kg, i.p.) obtained from the leaves of Tilia americana var. mexicana on CCl4-induced liver and brain damage in the rat. Protection was observed in the liver and brain (cerebellum, cortex and cerebral hemispheres) by measuring the activity of antioxidant enzymes and levels of malondialdehyde (MDA) using spectrophotometric methods. Biochemical parameters were also assessed in serum samples from the CCl4-treated rats. The T. americana var. mexicana leaf extracts provided significant protection against CCl4-induced peripheral and central damage by increasing the activity of antioxidant enzymes, diminishing lipid peroxidation, and preventing alterations in biochemical serum parameters, such as the levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), γ-globulin (γ-GLOB), serum albumin (ALB), total bilirubin (BB), creatinine (CREA) and creatine kinase (CK), relative to the control group. Additionally, we correlated gene expression with antioxidant activity in the experimental groups treated with the organic and aqueous Tilia extracts and observed a non-statistically significant positive correlation. Our results provide evidence of the underlying biomedical properties of T. americana var. mexicana that confer its neuro- and hepatoprotective effects.

Myricetin: A Dietary Molecule with Diverse Biological Activities

Myricetin is a common plant-derived flavonoid and is well recognised for its nutraceuticals value. It is one of the key ingredients of various foods and beverages. The compound exhibits a wide range of activities that include strong anti-oxidant, anticancer, antidiabetic and anti-inflammatory activities. It displays several activities that are related to the central nervous system and numerous studies have suggested that the compound may be beneficial to protect against diseases such as Parkinson's and Alzheimer's. The use of myricetin as a preserving agent to extend the shelf life of foods containing oils and fats is attributed to the compound's ability to protect lipids against oxidation. A detailed search of existing literature revealed that there is currently no comprehensive review available on this important molecule. Hence, the present work includes the history, synthesis, pharmaceutical applications and toxicity studies of myricetin. This report also highlights structure-activity relationships and mechanisms of action for various biological activities.

Bioactive Peptides from Angelica sinensis Protein Hydrolyzate Delay Senescence in Caenorhabditis elegans through Antioxidant Activities

Since excessive reactive oxygen species (ROS) is known to be associated with aging and age-related diseases, strategies modulating ROS level and antioxidant defense systems may contribute to the delay of senescence. Here we show that the protein hydrolyzate from Angelica sinensis was capable of increasing oxidative survival of the model animal Caenorhabditis elegans intoxicated by paraquat. The hydrolyzate was then fractionated by ultrafiltration, and the antioxidant fraction (<3 kDa) was purified by gel filtration to obtain the antioxidant A. sinensis peptides (AsiPeps), which were mostly composed of peptides with <20 amino acid residues. Further studies demonstrate that AsiPeps were able to reduce the endogenous ROS level, increase the activities of the antioxidant enzymes superoxide dismutase and catalase, and decrease the content of the lipid peroxidation product malondialdehyde in nematodes treated with paraquat or undergoing senescence. AsiPeps were also shown to reduce age pigments accumulation and extend lifespan but did not affect the food-intake behavior of the nematodes. Taken together, our results demonstrate that A. sinensis peptides (AsiPeps) are able to delay aging process in C. elegans through antioxidant activities independent of dietary restriction.

Novel Investigations of Flavonoids as Chemopreventive Agents for Hepatocellular Carcinoma

We would like to highlight the application of natural products to hepatocellular carcinoma (HCC). We will focus on the natural products known as flavonoids, which target this disease at different stages of hepatocarcinogenesis. In spite of the use of chemotherapy and radiotherapy in treating HCC, patients with HCC still face poor prognosis because of the nature of multidrug resistance and toxicity derived from chemotherapy and radiotherapy. Flavonoids can be found in many vegetables, fruits, and herbal medicines that exert their different anticancer effects via different intracellular signaling pathways and serve as antioxidants. In this review, we will discuss seven common flavonoids that exert different biological effects against HCC via different pathways.

Attenuating effects of dihydromyricetin on angiotensin II-induced rat cardiomyocyte hypertrophy related to antioxidative activity in a NO-dependent manner

CONTEXT

Dihydromyricetin (DMY) displays a range of biological properties. However, whether DMY attenuates cardiomyocyte hypertrophy is unknown.

OBJECTIVE

To investigate whether DMY had potential therapeutic value to protect against angiotensin II (Ang II)-induced cardiomyocyte hypertrophy.

MATERIALS AND METHODS

Neonatal rat cardiomyocytes were pretreated with DMY (0-320 μM) followed with Ang II (100 nM) stimulation for 24 h, and then degree of hypertrophy was evaluated by cell surface analysis. Levels of reactive oxygen species (ROS) were measured with 2',7'-dichlorfluorescein-diacetate (DCFH-DA) fluorescent staining. Antioxidative activity was evaluated by malondialdehyde (MDA) level, superoxide dismutase (SOD) activity, and total antioxidant capacity (T-AOC). Cyclic guanosine monophosphate (cGMP) was determined with a radioimmunoassay.

RESULTS

Pre-incubation with DMY (20, 40, 80, and 160 μM) for 8 h, 12 h, 24 h, or 48 h decreased cell surface areas. It down-regulated mRNA expression of atrial natriuretic factor (1.95- to 1.24-fold) and β-myosin heavy chains (3.51- to 2.32-fold), reduced levels of MDA as well as increased SOD activity and T-AOC. Expression of SOD and thioredoxin were enhanced by DMY, whereas p22(phox) and phosphorylation of mitogen-activated protein kinases were inhibited. Content of cGMP (0.54- to 0.80-fold) and phosphorylation of endothelial nitric oxide synthase at serine 1177 (0.70- to 1.05-fold) were augmented by DMY. Moreover, attenuating effect of DMY on hypertrophy was abolished when NO production was inhibited by l-NAME.

CONCLUSION

Attenuating effects of DMY on Ang II-induced cardiomyocyte hypertrophy related to antioxidative activity in a NO-dependent manner.

Alteration of antioxidant enzymes and associated genes induced by grape seed extracts in the primary muscle cells of goats in vitro

This study was conducted to investigate how the activity and expression of certain paramount antioxidant enzymes respond to grape seed extract (GSE) addition in primary muscle cells of goats. Gluteal primary muscle cells (PMCs) isolated from a 3-week old goat were cultivated as an unstressed cell model, or they were exposed to 100 µM H₂O₂ to establish a H₂O₂-stimulated cell model. The activities of catalase (CAT), superoxide dismutases (SOD) and glutathione peroxidases (GPx) in combination with other relevant antioxidant indexes [i.e., reduced glutathione (GSH) and total antioxidant capacity (TAOC)] in response to GSE addition were tested in the unstressed and H₂O₂-stimulated cell models, and the relative mRNA levels of the CAT, GuZu-SOD, and GPx-1 genes were measured by qPCR. In unstressed PMCs, GSE addition at the dose of 10 µg/ml strikingly attenuated the expression levels of CAT and CuZn-SOD as well as the corresponding enzyme activities. By contrast, in cells pretreated with 100 µM H₂O₂, the expression and activity levels of these two antioxidant enzymes were enhanced by GSE addition at 10 µg/ml. GSE addition promoted GPx activity in both unstressed and stressed PMCs, while the expression of the GPx 1 gene displayed partial divergence with GPx activity, which was mitigated by GSE addition at 10 µg/ml in unstressed PMCs. GSH remained comparatively stable except for GSE addition to H₂O₂-stimulated PMCs at 60 µg/ml, in which a dramatic depletion of GSH occurred. Moreover, GSE addition enhanced TAOC in unstressed (but not H₂O₂-stimulated) PMCs. GSE addition exerted a bidirectional modulating effect on the mRNA levels and activities of CAT and SOD in unstressed and stressed PMCs at a moderate dose, and it only exhibited a unidirectional effect on the promotion of GPx activity, reflecting its potential to improve antioxidant protection in ruminants.

The role of brain-derived neurotrophic factor in comorbid depression: possible linkage with steroid hormones, cytokines, and nutrition

Increasing evidence demonstrates a connection between growth factor function (including brain-derived neurotrophic factor, BDNF), glucocorticoid levels (one of the steroid hormones), and the pathophysiology of depressive disorders. Because both BDNF and glucocorticoids regulate synaptic function in the central nervous system, their functional interaction is of major concern. Interestingly, alterations in levels of estrogen, another steroid hormone, may play a role in depressive-like behavior in postpartum females with fluctuations of BDNF-related molecules in the brain. BDNF and cytokines, which are protein regulators of inflammation, stimulate multiple intracellular signaling cascades involved in neuropsychiatric illness. Pro-inflammatory cytokines may increase vulnerability to depressive symptoms, such as the increased risk observed in patients with cancer and/or autoimmune diseases. In this review, we discuss the possible relationship between inflammation and depression, in addition to the cross-talk among cytokines, BDNF, and steroids. Further, since nutritional status has been shown to affect critical pathways involved in depression through both BDNF function and the monoamine system, we also review current evidence surrounding diet and supplementation (e.g., flavonoids) on BDNF-mediated brain functions.

Myricetin-mediated lifespan extension in Caenorhabditis elegans is modulated by DAF-16

Myricetin is a naturally occurring flavonol found in many plant based food sources. It increases the lifespan of Caenorhabditis elegans, but the molecular mechanisms are not yet fully understood. We have investigated the impact of this flavonoid on the transcription factors DAF-16 (C. elegans FoxO homologue) and SKN-1 (Nrf2 homologue), which have crucial functions in the regulation of ageing. Myricetin is rapidly assimilated by the nematode, causes a nuclear translocation of DAF-16 but not of SKN-1, and finally prolongs the mean adult lifespan of C. elegans by 32.9%. The lifespan prolongation was associated with a decrease in the accumulation of reactive oxygen species (ROS) detected by DCF. Myricetin also decreases the formation of lipofuscin, a pigment consisting of highly oxidized and cross-linked proteins that is considered as a biomarker of ageing in diverse species. The lifespan extension was completely abolished in a daf-16 loss-of-function mutant strain (CF1038). Consistently with this result, myricetin was also not able to diminish stress-induced ROS accumulation in the mutant. These results strongly indicate that the pro-longevity effect of myricetin is dependent on DAF-16 and not on direct anti-oxidative effects of the flavonoid.

Polyphenol compounds in the chicken/animal diet: from the past to the future

Animal feed provides a range of antioxidants that help the body building an integrated antioxidant system responsible for a prevention of damaging effects of free radicals and products of their metabolism. Vitamin E is considered to be the main chain-breaking antioxidant located in the membranes and effectively protecting them against lipid peroxidation. Recently, various polyphenol compounds, especially flavonoids, have received substantial attention because of their antioxidant activities in various in vitro systems. However, it was shown that flavonoid compounds are poorly absorbed in the gut and their concentrations in target tissues are too low to perform an effective antioxidant defences. The aim of the present paper is to review existing evidence about possible roles of various plant extracts provided with the diet in animal/poultry nutrition with a specific emphasis to their antioxidant activities.