Protective effect of quercetin on the reproductive toxicity of 4-nitrophenol in diesel exhaust particles on male embryonic chickens

4-Nitrophenol at environmentally relevant concentrations mediates reproductive toxicity in Caenorhabditis elegans via metabolic disorders-induced estrogen signaling pathway

4-Nitrophenol (4-NP), as a toxic and refractory pollutant, has generated significant concern due to its adverse effects. However, the potential toxic effects and mechanism remained unclear. In this study, the reproduction, development, locomotion and reactive oxygen species (ROS) production of Caenorhabditis elegans were investigated to evaluate the 4-NP toxicity. We used metabolomics to assess the potential damage mechanisms. The role of metabolites in mediating the relationship between 4-NP and phenotypes was examined by correlation and mediation analysis. 4-NP (8 ng/L and 8 µg/L) caused significant reduction of brood size, ovulation rate, total germ cells numbers, head thrashes and body bends, and an increase in ROS. However, the oosperm numbers in uterus, body length and body width were decreased in 8 µg/L. Moreover, 36 differential metabolites were enriched in the significant metabolic pathways, including lysine biosynthesis, β-alanine metabolism, tryptophan metabolism, pentose phosphate pathway, pentose and glucuronate interconversions, amino sugar and nucleotide sugar metabolism, starch and sucrose metabolism, galactose metabolism, propanoate metabolism, glycerolipid metabolism, and estrogen signaling pathway. The mechanism of 4-NP toxicity was that oxidative stress caused by the perturbation of amino acid, which had effects on energy metabolism through disturbing carbohydrate and lipid metabolism, and finally affected the estrogen signaling pathway to exert toxic effects. Moreover, correlation and mediation analysis showed glycerol-3P, glucosamine-6P, glucosamine-1P, UDP-galactose, L-aspartic acid, and uracil were potential markers for the reproduction and glucose-1,6P2 for developmental toxicity. The results provided insight into the pathways involved in the toxic effects caused by 4-NP and developed potential biomarkers to evaluate 4-NP toxicity.

PM2.5 from diesel exhaust attenuated fisetin mediated cytoprotection in H9c2 cardiomyocytes subjected to ischemia reoxygenation by inducing mitotoxicity

The impact of PM2.5 from diesel exhaust (termed as diesel particulate matter (DPM)) on ischemia re-oxygenation (IR) injury and the consequent effect of fisetin to attenuate this injury remains unclear. IR was induced in H9c2 cells after 24 hrs of fisetin treatment. The cells when incubated with 100 µg/mL of DPM followed by IR, induced 60% cell death which was escalated to 78% with DPM exposure. Fisetin significantly attenuated IR induced cytotoxicity, improved mitochondrial activity and reduced oxidative stress in normal cells but failed to render protection against IR in presence of DPM. Isolated mitochondria experiment confirmed the mitotoxic effect of DPM. Immunoblot analysis established the failure of fisetin to activate PI3K/Akt signaling pathway. Based on the above observations, we concluded that fisetin mediated protection against IR was abrogated with DPM exposure due to augmented mitochondrial dysfunction and inactivation of PI3K/Akt signaling pathway.

Dietary quercetin and vitamin E supplementation modulates the reproductive performance and antioxidant capacity of aged male breeder chickens

Aged male chickens experience rapid declines in spermatogenesis, antioxidant capacity, immunity, and hormone synthesis. Vitamin E plays a significant role in reproduction, nervous system function, and disease resistance in animals. Quercetin also exerts many biological effects, such as antioxidant ability, immunostimulation, and protection of spermatozoal plasma membranes. This study evaluated the effects of combining dietary quercetin (Q) and vitamin E (VE) on sperm quality, antioxidant capacity, immunity, and expression of genes related to spermatogenesis, immunity, apoptosis, and inflammation in aged male chickens. A total of 120 Tianfu breeder male chickens (65 wk old) were randomly allotted to 4 treatments with 3 replicates (10 birds each). The birds were fed diets containing Q (0.4g/kg), VE (0.2g/kg), Q+VE (0.4g/kg + 0.2g/kg), and a basal diet for 11 wk. At the end of the experimental period, blood, semen, liver, testes, and spleen samples were collected from 2 birds per replicate. Serum hormones, antioxidant parameters, cytokines, and immunoglobulins were evaluated; and the mRNA expression of genes related to spermatogenesis, apoptosis, and inflammation are determined in the testes and liver tissues.

The results showed that the combination quercetin and vitamin E significantly promoted the sperm count and motility, as well as elevated the levels of testosterone, follicle-stimulating hormone, and luteinizing hormone, antioxidant enzymes (Superoxide dismutase, Glutathione, and Total antioxidant capacity), and serum immunoglobulins (IgA and IgM) in the aged male chickens; also Q+VE showed protective effects on the liver against injury. In addition, Q+VE significantly increased the expression of genes related to spermatogenesis (AR, pgk2, Cyclin A1, and Cyclin A2), immunity (IFN-γ and IL-2), and anti-inflammatory cytokines (IL-10) (P < 0.05), whereas the expression of proinflammatory cytokines (IL-1β and IL-6) was decreased (P < 0.05). Taken together, these data indicate that the combination of quercetin and vitamin E improved reproductive characteristics such as spermatogenesis, sperm quality, and hormone regulation, as well as promoted antioxidant defense, hepatoprotective capacity, and immune response in aged male chickens without any detrimental effects.

Flavonols as potential antiviral drugs targeting SARS-CoV-2 proteases (3CLpro and PLpro), spike protein, RNA-dependent RNA polymerase (RdRp) and angiotensin-converting enzyme II receptor (ACE2)

The novel coronavirus outbreak (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) represents the actual greatest global public health crisis. The lack of efficacious drugs and vaccines against this viral infection created a challenge for scientific researchers in order to find effective solutions. One of the promising therapeutic approaches is the search for bioactive molecules with few side effects that display antiviral properties in natural sources like medicinal plants and vegetables. Several computational and experimental studies indicated that flavonoids especially flavonols and their derivatives constitute effective viral enzyme inhibitors and possess interesting antiviral activities. In this context, the present study reviews the efficacy of many dietary flavonols as potential antiviral drugs targeting the SARS-CoV-2 enzymes and proteins including Chymotrypsin-Like Protease (3CLpro), Papain Like protease (PLpro), Spike protein (S protein) and RNA-dependent RNA polymerase (RdRp), and also their ability to interact with the angiotensin-converting enzyme II (ACE2) receptor. The relationship between flavonol structures and their SARS-CoV-2 antiviral effects were discussed. On the other hand, the immunomodulatory, the anti-inflammatory and the antiviral effects of secondary metabolites from this class of flavonoids were reported. Also, their bioavailability limitations and toxicity were predicted.

Effects of P-nitrophenol exposure on the testicular development and semen quality of roosters

The widespread use of P-nitrophenol (PNP) as a raw material in pesticides, medicines and dyes has led to environmental pollution. PNP is a well-known endocrine disruptor in mammals and quails. This study investigated the effects of long-term PNP exposure on the testicular development and semen quality of roosters. Pubescent and postpubescent animals were given drinking water supplemented with (0 mg/L, 1 mg/L, 10 mg/L, or 100 mg/L) PNP for eight weeks or sixteen weeks. The relative testis weight, antioxidant index, serum hormone concentration, morphological changes, semen quality and expression of major steroidogenic genes were measured. The results showed that eight weeks of PNP exposure decreased CAT activity and increased H₂O₂ level in serum and testes in the 10 mg/L and 100 mg/L PNP-treated groups. Detached sperm cells were also found in the testicular tissues of the 100 mg/L PNP-treated group. After sixteen weeks of PNP exposure, daily weight gain, sperm motility, serum testosterone concentration and 3β1-hydroxysteroid dehydrogenase (HSD3β1) mRNA expression were decreased in the 100 mg/L PNP-treated group. Some vacuoles in the seminiferous epithelium in the testicular tissues were found in the 10 mg/L and 100 mg/L PNP-treated groups. In conclusion, as an endocrine disruptor, PNP exposure impaired antioxidant capacity, reduced testosterone synthesis, caused morphological changes in testes, and ultimately decreased semen quality in the roosters. The reproductive damage of PNP to roosters depended on the length of exposure time and the administered dose.

4-nitrophenol exposure in T24 human bladder cancer cells promotes proliferation, motilities, and epithelial-to-mesenchymal transition

Although health hazards of 4-nitrophenol (PNP) exposure have been reported, the adverse effects of PNP exposure on cancer biological features are still unknown. We investigated the effects of administration of PNP in T24 human bladder cancer cells. The results showed that PNP exposure promoted cellular proliferation, migration and invasion, inhibited adhesion and apoptosis in vitro. Using quantitative real-time PCR, we found that (1) the mRNA expression levels of cell-cycle regulators PCNA, cyclin D1 and COX-2 were increased in PNP-treated cells compared to controls, however, that of pro-apoptotic gene Bax was decreased; (2) the expression level of EMT-associated gene E-cadherin was decreased in PNP-treated cells, whereas those of N-cadherin, vimentin, snail, and slug were increased; (3) the expression levels of cancer-promoting genes HIF-1, IL-1β, VEGFα and K-Ras were enhanced, but those of tumor suppressors p53, PTEN and BRCA were decreased. There was a positive association between PNP exposure times and the promotion effects. Finally, we found that the expression level of PPARγ (γ1 isoform) was increased in PNP-treated T24 cells. GW9662, a specific PPARγ antagonist, attenuated PNP-induced cell migration and invasion. These findings indicate that PNP exposure may promote bladder cancer growth and progression involving PPARγ signaling. PPARγ is a potential target for development of novel intervention study on environment pollution. Environ. Mol. Mutagen. 61:316-328, 2020. © 2019 Wiley Periodicals, Inc.

In vitro effects of PNP and PNMC on apoptosis and proliferation in the hen ovarian stroma and prehierarchal follicles

This study aimed to examine the mRNA expression, activity, and immunolocalisation of apoptosis/proliferation regulating factors following in vitro exposure of the stroma, white (WFs), and yellowish (YFs) follicles of the chicken ovary to 4-nitrophenol (PNP) or 3-methyl-4-nitrophenol (PNMC). PNMC increased the mRNA expression of caspase-3, -8, Apaf-1, and cytochrome c in the ovarian stroma. The activity of caspase-3, -8, and -9 decreased in WFs in both nitrophenol-treated groups. PNP reduced the number of caspase-3-positive cells in the stromal connective tissue (CT) and the theca interna and externa layers of WFs. In the stroma, the proliferating index decreased in the wall of primary follicles in both nitrophenol-treated groups, however, in the CT, the effect of PNMC was opposite. In the theca interna of WFs, PNP diminished the proliferating index. These results suggest that nitrophenols might impact the development of chicken ovarian follicles by affecting cell death and proliferation.

4-Nitrophenol (PNP) inhibits the expression of estrogen receptor β and disrupts steroidogenesis during the ovarian development in female rats

4-nitrophenol (PNP), isolated from diesel exhaust particles, has estrogenic and anti-androgenic activities, and affects the hypothalamus-pituitary-gonad axis in male rats. However, the effect of PNP on the reproduction of the female rats is still unknown. The aim of the study was to investigate the effect of neonatal PNP exposure on the ovarian function of female rats. The neonatal female rats were exposed to PNP (10 mg/kg, subcutaneously injection), the ovary and serum samples were collected at postnatal day (PND) 7, 14 and 21. The results showed that the ratio of primordial and primary follicles increased whereas the ratio of antral follicles decreased in the PNP treated ovaries at PND21. Even though no abnormality was observed in cyclicity, there was a significantly delayed timing of vaginal opening in PNP treated rats. The ovarian expression of steroidogenic enzymes including StAR, P450scc, P450c17 and P450arom increased at PND14 in the PNP treated rats compared with the control rats. In consistent with the gene expression, the concentration of estradiol-17β showed the similar pattern. However, PNP exposure failed to cause any significant change in the expression of steroidogenic enzymes in cultured neonatal ovaries. Furthermore, PNP suppressed the expression of estrogen receptor β (ERβ), but not estrogen receptor α (ERα), in cultured ovaries or developmental ovaries. These results suggested that PNP might directly affect the expression of ERβ in the rat ovaries, resulting in the disrupted steroidogenesis during ovarian development and the delayed puberty.

4-Nitrophenol induces activation of Nrf2 antioxidant pathway and apoptosis of the germ cells in rat testes

The potential of 4-nitrophenol (PNP) to affect testicular function of rats was assessed by intratesticular injection (IT). The protective effects of phytosterin (PS) on PNP-induced injury were assessed. Rats were sacrificed on days 1, 3, and 7 after IT of PNP (0.1 M, 50 μl). PNP induced hemorrhage in intertubular areas and denudation of germinal epithelium. The expression of caspase-3 and sperm abnormalities were significantly increased (P < 0.05). The concentrations of testosterone in serum were significantly increased (P < 0.05) on the 1st and 3rd day. PNP induced oxidative stress in testes, which manifested increased SOD, CAT, GSH-Px activities, and increases in MDA, GSH, H2O2 concentrations (P < 0.05). The Nrf2 antioxidant pathway was activated as indicated by increased expression of Nrf2, HO-1, and GCLC mRNA (P < 0.05). Moreover, supplementation with PS resulted in an amelioration of PNP-induced oxidative damage. These results suggest that PNP induced activation of Nrf2 antioxidant pathway and apoptosis of the germ cells.

Walnut Polyphenol Extract Attenuates Immunotoxicity Induced by 4-Pentylphenol and 3-methyl-4-nitrophenol in Murine Splenic Lymphocyte

4-pentylphenol (PP) and 3-methyl-4-nitrophenol (PNMC), two important components of vehicle emissions, have been shown to confer toxicity in splenocytes. Certain natural products, such as those derived from walnuts, exhibit a range of antioxidative, antitumor, and anti-inflammatory properties. Here, we investigated the effects of walnut polyphenol extract (WPE) on immunotoxicity induced by PP and PNMC in murine splenic lymphocytes. Treatment with WPE was shown to significantly enhance proliferation of splenocytes exposed to PP or PNMC, characterized by increases in the percentages of splenic T lymphocytes (CD3+ T cells) and T cell subsets (CD4+ and CD8+ T cells), as well as the production of T cell-related cytokines and granzymes (interleukin-2, interleukin-4, and granzyme-B) in cells exposed to PP or PNMC. These effects were associated with a decrease in oxidative stress, as evidenced by changes in OH, SOD, GSH-Px, and MDA levels. The total phenolic content of WPE was 34,800 ± 200 mg gallic acid equivalents/100 g, consisting of at least 16 unique phenols, including ellagitannins, quercetin, valoneic acid dilactone, and gallic acid. Taken together, these results suggest that walnut polyphenols significantly attenuated PP and PNMC-mediated immunotoxicity and improved immune function by inhibiting oxidative stress.

Supplemental dietary phytosterin protects against 4-nitrophenol-induced oxidative stress and apoptosis in rat testes

4-Nitrophenol (PNP), is generally regarded as an environmental endocrine disruptor (EED). Phytosterin (PS), a new feed additive, possesses highly efficient antioxidant activities. The transcription factor, nuclear factor-erythroid 2-related factor 2 (Nrf2), is an important regulator of cellular oxidative stress. Using rats, this study examined PNP-induced testicular oxidative damage and PS-mediated protection against that damage. The generation of MDA and H₂O₂ upon PNP and PS treatment was milder than that upon treatment with PNP alone. This mitigation was accompanied by partially reversed changes in SOD, CAT, GSH and GSH-Px. Moreover, PNP significantly reduced the caudal epididymal sperm counts and serum testosterone levels. Typical morphological changes were also observed in the testes of PNP-treated animals. PNP reduced the transcriptional level of Nrf2, as evaluated by RT-PCR, but it promoted the dissociation from the Nrf2 complex, stabilization and translocation into the nucleus, as evaluated by immunohistochemistry and Western blotting. In addition, PNP enhanced the Nrf2-dependent gene expression of heme oxygenase-1 (HO-1) and glutamate–cysteine ligase catalytic subunit (GCLC). These results suggest that the Nrf2 pathway plays an important role in PNP-induced oxidative damage and that PS possesses modulatory effects on PNP-induced oxidative damage in rat testes.