Sunny O. Abarikwu

Kolaviron, a natural flavonoid from the seeds of Garcinia kola, reduces LPS-induced inflammation in macrophages by combined inhibition of IL-6 secretion, and inflammatory transcription factors, ERK1/2, NF-κB, p38, Akt, p-c-JUN and JNK.

BACKGROUND Kolaviron (Kol-v), an important component of Garcinia kola seed has a variety of biologic activities, including anti-inflammatory properties. METHODS We tested the ability of Kol-v to block signalling pathways implicated in lipopolysaccharide (LPS)-induced inflammatory gene expression in RAW 264.7 macrophage cell line. RESULTS When macrophages pre-treated with Kol-v (15 and 25μM) were activated with LPS, phosphorylation of p38 and p-c-JUN but not IκBα degradation and phosphorylation of NF-κB (p65), ERK1/2, and IκBα were blocked. Furthermore, Kol-v suppressed LPS-induced increase in the expression of IL-18 gene and LPS-induced decrease in the mRNA expression of IP-10 but it had no effect on the LPS-induced decrease in the gene expression levels of IL-1α, IL-33, IL-1β, and IFNβ1-1. When macrophages pre-treated with Kol-v (50 and 100μM) were activated with LPS, phosphorylation of Akt, ERK1/2, IκBα, and NFκB (p65) but not that of CREB was blocked by Kol-v. The protective effect of Kol-v on the LPS-induced phosphorylation of the mitogen activated protein kinase (MAPK) family member JNK was only observed at 100μM. At all concentrations of Kol-v (0-100μM) tested in this study, there was no effect of Kol-v on LPS-induced secretion of the pro-inflammatory cytokine TNF-α but a concentration dependent inhibition of Kol-v on IL-6 secretion was observed. CONCLUSION Kol-v interferes with LPS signalling by reducing the activation of several inflammatory transcription factors and that its inhibitory action on IL-6 secretion correlates with inhibition of ERK1/2, p38, Akt, p-c-JUN and JNK signalling pathways. GENERAL SIGNIFICANCE The anti-inflammatory potential of Kol-v via inhibition of IL-6 secretion in RAW macrophage was established in this study.

Rutin Ameliorates Cyclophosphamide-induced Reproductive Toxicity in Male Rats.

Cyclophosphamide (CYC) as an anticancer alkylating agent has been known as a male reproductive toxicant. This study was aimed to evaluate the protective effect of rutin (RUT) on CYC-induced reproductive toxicity. Sexually mature Wistar rats (weighing 199 ± 10 g with five animals in each group) were given CYC (15 mg/kg) and/or RUT (30 mg/kg) twice a week via gavage for 4 weeks. The sperm counts, sperm motility, sperm morphology, daily sperm production (DSP), testicular, and epididymal antioxidant systems: superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH), glutathione reductase (GR), glutathione-S-transferase (GST), glutathione peroxidase (GSH-Px), malondialdehyde (MDA), and testicular steroidogenic enzymes (3β-hydroxysteroid dehydrogenase and 17β-HSD and spermatogenesis marker enzymes (lactate dehydrogenase (LDH), sorbitol dehydrogenase (SDH), alkaline phosphatase (ALP), acid phosphatase (ACP) in the testes, epididymis and seminal vesicles were investigated at the end of the fourth week. By the end of the fourth week, RUT prevented lower sperm counts, sperm motility, DSP, and higher abnormal sperm numbers induced by CYC. In testes, RUT decreased SOD, LDH, and SDH and increased CAT, 3β-HSD, 17β-HSD, ALP, and ACP induced by CYC. In epididymis, RUT increased SOD, CAT, GSH, GSH-Px, GR, GST SDH, ALP and ACP and decreased MDA and LDH induced by CYC. In seminal vesicles, marker enzymes were unchanged in rats given CYC alone or in combination with RUT. It appears that RUT ameliorates CYC reproductive toxicity at the investigated dose.

Protective effect of quercetin on atrazine-induced oxidative stress in the liver, kidney, brain, and heart of adult wistar rats.

Background: The conflicting roles of quercetin against tissue pathologies associated with oxidative stress are known. Objective: To evaluate the effect of quercetin at doses of 5 mg/kg (Q5) or 10 mg/kg (Q10) against atrazine (120 mg/kg, ATZ)-induced oxidative stress in various tissues of rats. Materials and Methods: Adult male albino Wistar rats were administered ATZ, Q5, and Q10 alone or in combination for 16 days. At the end of the 16th day, the animals were sacrificed by cervical dislocation; and the blood, heart, brain, kidney and liver were collected and used for biochemical determinations and histopathological examination. Results: Q10 but not Q5 attenuated ATZ-induced increase in the levels of serum enzyme markers sorbitol dehydrogenase (SDH), acid phosphatase (ACP), alkaline phosphatase (ALP), and aspartate aminotransferase (AST). The heart was less susceptible to ATZ-induced oxidative stress than the liver, kidney, and brain of treated animals, and there were tendencies for synergistic effects in the heart and liver of Q5 + ATZ-treated rats. Oxidative stress-induced by ATZ in terms of increased lipid peroxidation level and superoxide dismutase (SOD) activity was decreased in the brain of the Q5 + ATZ-treated rats but not that of the Q10 + ATZ-treated rats. Conversely, histopathological changes and oxidative stress-induced by ATZ in terms of elevated lipid peroxidation level, decreased SOD, and catalase (CAT) activities were prevented in the kidney and liver of the Q10 + ATZ-treated rats but not that of the Q5 + ATZ-treated rats. Conclusion: Quercetin at the investigated doses and especially the low dose may not protect against ATZ-induced oxidative stress in rat tissues in an overall sense.

Atrazine induces transcriptional changes in marker genes associated with steroidogenesis in primary cultures of rat Leydig cells

Reproductive toxicity of atrazine (ATZ) is well reported in mammals. However, the underlying mechanisms are poorly understood and need to be explored. Thus, we investigate ATZ induced transcriptional changes in selected markers of steroidogenesis in primary cultures of rat interstitial Leydig cells (ILCs). Cytotoxic studies were carried out by exposing the cells to ATZ (0.5-50 μg/mL or 2.32-232 μM) for 24-72 h, whereas; the exposure period of expression studies was for 2 h. ATZ exposure of (25 and 50 μg/ml) for 48 h onwards was found to be cytotoxic in MTT (dimethylthiazol-diphenyl tetrazolium bromide salt) assay, while in NRU (neutral red uptake) assay, cytotoxicity could be recorded at 50 μg/ml exposure of 72 h only. A significant dose dependent induction in the levels of mRNA expression of genes of steroidogenic acute regulatory protein (STAR), cytochrome P45011A1, 3β-hydroxysteroid dehydrogenase (3β-HSD), and other steroidogenic proteins were observed in cells exposed to ATZ. Our data suggest the applicability of these selected marker genes of steroidogenesis as an indicator of short term exposure of ATZ induced testicular toxicity in rats interstitial Leydig cells (ILCs).

Kolaviron protects apoptotic cell death in PC12 cells exposed to Atrazine

Abstract Kolaviron (KV), a natural biflavonoid obtained from the seeds of Garcinia kola, has been documented for its wide pharmacological window, including anti-apoptotic activities. However, the underlying mechanisms are poorly understood at the cellular level. This study investigates the anti-apoptotic activity of KV in PC12 cells, a rat pheochromocytoma, exposed to endocrine disruptor-atrazine (ATZ). KV (60 μM) treatment for 24 h shows significant anti-apoptotic responses in PC12 cells exposed to ATZ (232 μM) for 24 h. KV treatment recovers the ATZ-induced levels of malondialdehyde, reactive oxygen species (ROS), caspase-3 activity and depleted levels of glutathione and catalase activity. However, KV was found to be ineffective to restore the ATZ-induced expression (mRNA) and activity of glutathione-peroxidase (GSH-Px) and glutathione reductase (GR). KV treatment also demonstrates significant restoration in ATZ-induced alterations in the expression of apoptosis markers viz., p53, Bax, Bcl2, caspase-3, caspase-9, cyclooxygenase-2 (COX-2), c-Jun and c-fos. Flow cytometric analysis confirms the involvement of ROS in the mediation of ATZ-induced apoptosis in PC12 cells. Together, these data suggest that KV has the therapeutic potential against chemical-induced apoptotic cell death in the neuronal system.

4-Hydroxynonenal Induces Mitochondrial-Mediated Apoptosis and Oxidative Stress in SH-SY5Y Human Neuronal Cells

Excessive and sustained increases in oxidative stress and apoptosis have been implicated in the pathogenesis of many diseases. In this study, we demonstrated that 4-hydroxynonenal (4-HNE), a product of lipid peroxidation in a range of concentration (0.1-50 μM) showed cytotoxic effects on SH-SY5Y cell culture at a concentration >5 μM at 4 hr of exposure. 4-HNE dose dependently decreased cell viability and significantly promoted reactive oxygen species formation and enhanced oxidative stress as reflected in the increased level of lipid peroxidation and catalase activity and decreased glutathione peroxidase activity as well as glutathione levels. 4-HNE-induced oxidative stress was associated with increased transcriptional and translational expressions of Bax and p53 in SH-SY5Y cells. Mitochondrial-mediated apoptosis was confirmed by increased expression and activity of caspase-3. Our data demonstrate that 4-HNE induces neuronal cell death through abnormal expression of apoptotic markers (p53, Bax and caspase-3). Oxidative stress may be involved in the initial priming of SH-SY5Y cells to 4-HNE-induced cytotoxicity in vitro.

Dietary antioxidant, quercetin, protects sertoli-germ cell coculture from atrazine-induced oxidative damage.

Quercetin (QT), a dietary‐derived flavonoid, is ubiquitous in fruits and vegetables and plays an important role in human health by virtue of its antioxidant function. The present study was designed to examine the effects of QT on oxidative damage that was induced by the herbicide, atrazine (ATZ), in mixed cultures of Sertoli‐germ cells. Results showed that treatment with QT increased cell viability and decreased catalase activity, malondialdehyde, and reactive oxygen species (ROS) levels. QT treatment also increased the mRNA expression of glutathione peroxidase (GSH‐Px), glutathione reductase (GR), glutathione‐S‐transferase, and superoxide dismutase‐1 and could not reversed to the control levels ATZ‐induced steady‐state mRNA levels of these antioxidant genes as well as the level of glutathione and activities of GSH‐Px and GR. QT has protective effect against ATZ‐induced oxidative stress through a reduction in ROS levels and lipid peroxidation.

Biflavanone-kolaviron protects human dopaminergic SH-SY5Y cells against atrazine induced toxic insult

Atrazine (ATR) is a widespread agrochemical contaminant frequently detected in water systems and kolaviron (KV) is a seed-derived biflavonoid which is reported to modulate the effects of many mutagens and carcinogens. We investigated the protective effects of KV on ATR-induced cell death in the human neuroblastoma cell line (SHY-SY5Y). KV prevents ATR-induced generation of reactive oxygen species (ROS), cell death and inhibited cell proliferation by reduction of cell proliferation. Further, ATR-induced levels malondialdehyde (MDA), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GR) activities, increased leakage of lactate dehydrogenase (LDH), inhibited cellular LDH activity and depleted glutathione (GSH) levels in SHY-SY5Y cells were blocked by KV. Comparable to the control, KV increased GR but not GSH-Px activities. ATR mediated nuclear changes associated with apoptosis; including nuclear fragmentation, condensation, DNA laddering, and increased caspase-3 activity were blocked on addition of KV. ATR-induced changes in the expressions of p53, Bax, Bcl-2, p21, and mRNA levels of caspase-3 and caspase-9 were prevented by KV. Based on these results, we propose a model for the protective effect of KV on ATR-induced cell injury in neuronal cell.

The protective effects of quercetin on the cytotoxicity of atrazine on rat Sertoli-germ cell co-culture

To evaluate the direct effect of atrazine (ATZ) and the protective effect of quercetin (QT) on testicular cells, we used primary cultures of rat Sertoli-germ cells (SGCs). ATZ (232 μm) up-regulated the mRNA expression of GATA-4, androgen receptor (AR), androgen-binding protein (ABP), steroidogenic acute regulatory protein (StAR), cytochrome P450 side-chain cleavage enzyme (CYP11A1), cyclooxygenase-2 (COX-2) and NF-κappaB (NF-κB) and down-regulated the expression of stem cell factor (SCF) mRNA. There was no change on the mRNA expression of oestrogen receptor-alpha (ER-α). Simultaneous supplementation of QT in the culture normalizes the expression of these genes. The stimulatory action of follicle stimulating hormone (10 ng/mL) on ATZ-induced StAR and CYP11A1 mRNA levels were also prevented by QT. Furthermore, ATZ-stimulatory action on AR mRNA was opposed in a dose-dependent manner in the presence of increasing concentrations of QT (10-50 μm).The dislodgement of germ cells from the Sertoli cells monolayer and decrease in SGCs viability was prevented by QT. To show whether or not the disrupted interactions of Sertoli and germ cells impaired spermatogenesis, adult male rats exposed in vivo to ATZ (50 mg/kg b.wt) for 1 week had their daily spermatozoa production (DSP) per gram testis lowered by 30%. DSP was significantly increased in the QT(10 mg/kg) + ATZ-treated rats as compared with the ATZ-treated rats. Taken together, ATZ can alter SGCs expression of spermatogenesis- and steroiodogenesis-related genes resulting in a decrease in sperm production in the testis as well as cell viability. QT might block these molecular events-induced by ATZ thereby protecting testicular Sertoli-germ cells from ATZ-induced toxicity.

Effects of quercetin on mRNA expression of steroidogenesis genes in primary cultures of Leydig cells treated with atrazine.

The effect of the phytoestrogen, quercetin (QT) on the reproductive toxicity of atrazine (ATZ) was explored in interstitial Leydig cells (ILCs). We measured the mRNA expressions of steroidogenesis genes: steroidogenic acute regulatory protein (StAR), 3β-hydroxysteroid dehydrogenase (3β-HSD), cytochrome-P450 (CYP) 11A1, insulin-like factor 3 (INSL-3), CYP17A1, inhibin-α (INH-α), androgen receptor (AR), estrogen receptor-α (ER-α), and luteinising hormone receptor (LHR) in isolated ILCs by real-time-PCR after cultured cells were treated in vitro with ATZ (232 μM) and QT (50 μM). The mRNA expression of tested genes increased with ATZ treatment and was normalized by quercetin except AR and ER-α expression. Treatment of cells with QT alone (15-50 μM) caused a dose-dependent increase in AR and ER-α mRNA expression. We also found that QT (50 μM) increased the expressions of AR and ER-α in the presence of a sub-threshold level of cyclic-AMP at 1h culture period to the levels seen with maximal stimulation of cyclic-AMP. Furthermore, the expressions of tested genes were unaffected by cyclic-AMP at 6h when the stimulatory effects of ATZ on tested genes were sustained. These findings suggest that ATZ may stimulate the expression of tested steroidogenesis genes in ILCs via a mechanism independent of cyclic-AMP which was partially antagonize by QT.