Thymoquinone protects against 5-Fluorouracil-induced mucositis by NF-κβ and HIF-1 mechanisms in mice

Mucositis is among the most common side effects of 5-Fluorouracil (5-FU) and other cancer therapeutic drugs. Thymoquinone (TQ), a bioactive constituent extracted from Nigella sativa, has antioxidant and anti-inflammatory properties and can modify acute gastrointestinal injury. To investigate the effects of TQ on mucositis induced by 5-FU, studied animals were divided into four groups: control, 5-FU unit dose (300 mg/kg) to cause oral and intestinal mucositis (OM and IM), TQ (2.5 mg/kg) and TQ (2.5 mg/kg) plus 5-FU. Due to The molecular mechanisms, it was confirmed that the expression of NF-κβ and HIF-1 increases in OM. The serum levels of malondialdehyde (MDA), catalase (CAT), and superoxide dismutase (SOD), as well as pathological parameters, were assessed. Based on our results, the nuclear factor-kappa β gene expression in the tongue was downregulated significantly in the 5-FU + TQ compared to the 5-FU. TQ treatment can diminish MDA, and a reduction in oxidative stress was shown. TQ could also reduce the severity of tissue destruction and damaging effects induced by 5-FU on the tongue and intestine. We also observed lower villus length and width in the intestine of the 5-FU group compared to the control group. According to our research's pathological, biochemical, and molecular results, treatment with TQ as an anti-inflammatory and antioxidant compound may be the potential to improve and treat 5-FU-induced OM and IM, and TQ could be used against cancer treatment drugs and exhibit fewer adverse effects.     

Elucidation of molecular mechanisms underlying the protective effects of thymoquinone against rheumatoid arthritis

Thymoquinone (TQ) is the major active compound derived from the medicinal Nigella sativa. A few studies have shown that TQ exhibits anti‐inflammatory activities in experimental models of rheumatoid arthritis (RA) through mechanisms that are not fully understood. The aim of this work was to evaluate the in vitro and in vivo effects of TQ and to investigate its influence on the major signalling pathways involved in pathophysiological RA changes. We used isolated human RA fibroblast‐like synoviocytes (FLS) and a rat adjuvant‐induced arthritis model of RA. In isolated RA FLS, TQ (0–10 µM) was not cytotoxic and inhibited slightly lipopolysaccharide (LPS)‐induced FLS proliferation and strongly H₂O₂‐induced 4‐hydroxynonenal (HNE) generation. By studying different inflammatory and catabolic factors, we determined that TQ significantly abolished LPS‐induced interleukin‐1beta (IL‐1β), tumour necrosis factor‐alpha (TNFα), metalloproteinase‐13, cyclooxygenase‐2, and prostaglandin E₂. Furthermore, LPS‐induced the phosphorylation of p38 mitogen‐activated protein kinase, extracellular‐regulated kinases ½, and nuclear factor‐kappaB‐p65 were also blocked by TQ in time‐dependent manner. In our experimental RA model, the oral administration of TQ 5 mg/kg/day significantly reduced the serum levels of HNE, IL‐1β and TNFα as well as bone turnover markers, such as alkaline phosphatase and tartrate‐resistant acid phosphatase. The protective effects of TQ against RA were also evident from the decrease in arthritis scoring and bone resorption. In conclusion, the fact that TQ abolishes a number of factors known to be involved in RA pathogenesis renders it a clinically valuable agent in the prevention of articular diseases, including RA. J. Cell. Biochem. 112: 107–117, 2011. © 2010 Wiley‐Liss, Inc.     

Antioxidant,antiproliferative, and apoptotic activity of thymoquinone against benzo(a)pyrene-induced experimental lung cancer

Several studies have suggested that increased consumption of phytochemicals is a comparatively easy and practical strategy to significantly decrease the incidence of cancer. In the present study, we have reported the protective effect of a natural compound, thymoquinone (TQ) against benzo(a)pyrene (B(a)P)-induced lung carcinogenesis in Swiss albino mice. B(a)P (50 mg/kg body weight) was administered twice weekly for four successive weeks and left until 20 weeks to induce lung cancer in mice. TQ (20 mg/kg body weight) was given orally as a pretreatment and posttreatment drug to determine its chemopreventive and therapeutic effects. B(a)P-induced lung cancer-bearing animals displayed cachexia-like symptoms along with an abnormal increase in lung weight and the activities of marker enzymes adenosine deaminase, aryl hydrocarbon hydroxylase, gamma-glutamyl transpeptidase, 5′-nucleotidase and lactate dehydrogenase; tumor marker carcinoembryonic antigen levels. Furthermore, B(a)P-induced animals showed elevated levels of lipid peroxides with subsequent depletion in the antioxidant status and histological aberrations. These anomalies were accompanied by increased expressions of proliferating cell nuclear antigen and cyclin D1 in the lung sections derived from B(a)P-induced animals. On TQ treatment, all the above alterations were returned to near normalcy. Furthermore, TQ administration in B(a)P-induced animals downregulated phosphatidylinositol 3-kinase/protein kinase B signaling pathway and induced apoptosis as evidenced by a decrease in cytochrome c, proapoptotic Bax, caspase-3, and p53 with a parallel increase in antiapoptotic Bcl-2. Our present results demonstrate the potential effectiveness of TQ as an antioxidant, antiproliferative, and apoptotic agent against B(a)P-induced experimental lung tumorigenesis.     

Protection of half sulfur mustard gas–induced lung injury in guinea pigs by antioxidant liposomes

The purpose of this study was to develop antioxidant liposomes as an antidote for mustard gas–induced lung injury in a guinea pig model. Five liposomes (LIP‐1, LIP‐2, LIP‐3, LIP‐4, and LIP‐5) were tested with differing levels of phospholipid, cholesterol, phosphatidic acid, tocopherol (α, γ, δ), N‐acetylcysteine (NAC), and glutathione (GSH). A single dose (200 µL) of liposome was administered intratracheally 5 min or 1 h after exposure to 2‐chloroethyl ethyl sulfide (CEES). The animals were sacrificed either 2 h after exposure (for lung injury study) or 30 days after exposure (for histology study). The liposomes offered 9%–76% protection against lung injury. The maximum protection was with LIP‐2 (71.5% protection) and LIP‐4 (75.4%) when administered 5 min after CEES exposure. Delaying the liposome administration 1 h after CEES exposure decreased the efficacy. Both liposomes contained 11 mM α‐tocopherol, 11 mM γ‐tocopherol, and 75 mM NAC. However, LIP‐2 contained additionally 5 mM δ‐tocopherol. Overall, LIP‐2 and LIP‐4 offered significant protection by controlling the recruitment of neutrophils, eosinophils, and the accumulation of septal and perivascular fibrin and collagen. However, LIP‐2 showed better protection than LIP‐4 against the accumulation of red blood cells in the bronchi, alveolar space, arterioles and veins, and fibrin and collagen deposition in the alveolar space. The antifibrotic effect of the liposomes, particularly LIP‐2, was further evident by a decreased level of lipid peroxidation and hydroxyproline in the lung. Thus, antioxidant liposomes containing both NAC and vitamin E are an effective antidote against CEES‐induced lung injury. © 2009 Wiley Periodicals, Inc. J Biochem Mol Toxicol 23:143–153, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/jbt.20279     

New Methoxyflavone from Casimiroa sapota and the Biological Activities of Its Leaves Extract against Lead Acetate Induced Hepatotoxicity in Rats

Flavonoids are agents with strong antioxidant properties and ameliorate many diseases associated with oxidative stress. Leaves of Casimiroa sapota were investigated for components and antioxidant/anti‐inflammatory activities against lead acetate ((AcO)₂Pb) induced hepatotoxicity in rats. Three groups of male albino rats were administrated orally with vehicle or C. sapota (100 and 200 mg/kg b.w/day) for 28 days; other group was injected with sub‐acute dose (100 mg/kg b.w/day) of (AcO)₂Pb. Three protective groups were injected with (AcO)₂Pb (100 mg/kg b.w/day) for 7 days at day 22 after treatment with either C. sapota (100 or 200 mg/kg b.w/day) or silymarin (SILY) for 28 days. We isolated and identified, from C. sapota, a new compound for the 1st time in nature; 5,6,2′,3′‐tetramethoxyflavone in addition to the rare compound 5,6,3′‐trimethoxyflavone (second report of isolation from nature) and the known compound 5,6,2′,3′,4′‐pentamethoxyflavone. There is an improvement in all hemato‐biochemical parameters, antioxidant defense system and anti‐inflammatory cytokines of protective groups, which received C. sapota in dose dependent manner. The percentage of changes in all parameters measured in (AcO)₂Pb groups that received vehicle, CS100, CS200 or SILY were 109.2, 37.3, 12.5%, and 1.2% compared with the healthy control group. The C. sapota groups confer a better antioxidant activity by preventing oxidative stress and inflammation in (AcO)₂Pb treated rats. The compounds isolated are responsible at least in part for the observed protective effects.     

Protective effects of caffeic acid phenethyl ester and thymoquinone on toluene induced liver toxicity

Toluene is an organic solvent that is toxic to humans. Caffeic acid phenethyl ester (CAPE) and thymoquinone (TQ) exhibit antioxidant and antitoxic effects. We investigated the protective effects of CAPE and TQ on toluene induced hepatotoxicity. Wistar albino rats were divided into seven groups of eight. The animals were injected intraperitoneally (i.p.) with 0.1 ml/10 g/day corn oil (control I), 0.1 ml/10 g/day corn oil + 2 ml/kg/day 10% ethanol (control II), 20 mg/kg/day TQ dissolved in 0.1 ml/10 g corn oil (TQ), 10 µmol/kg/day CAPE dissolved in 10% ethanol (CAPE), 500 mg/kg/day toluene (T), toluene and TQ together (T + TQ), or toluene and CAPE together (T + CAPE). All rats were sacrificed on day 15. Liver samples were obtained for histological analysis. Serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were measured to evaluate liver function. Liver sections from the control I and TQ groups exhibited normal histology. Sections from the T group exhibited sinusoid dilation, hemorrhage, vacuolization and necrosis. TQ and CAPE protected against toluene induced histopathological changes. AST and ALT levels were increased significantly in T group compared to both control groups. CAPE decreased significantly the toluene induced increase in AST and ALT levels, while TQ did not. CAPE and TQ exhibited some antitoxic and hepato-protective effects on toluene induced liver damage.     

Terpene Conjugates of the Nigella sativa Seed‐Oil Constituent Thymoquinone with Enhanced Efficacy in Cancer Cells

Thymoquinone (TQ; 1 ) is a weak anticancer constituent of black seed oil. Derivatives bearing terpene‐terminated 6‐alkyl residues were tested in cells of human HL‐60 leukemia, 518A2 melanoma, multidrug‐resistant KB‐V1/Vbl cervix, and MCF‐7/Topo breast carcinomas, as well as in non‐malignant human foreskin fibroblasts. Derivatives with a short four‐atom spacer between quinone and cyclic monoterpene moieties were more antiproliferative than analogues with longer spacers. 6‐(Menthoxybutyryl)thymoquinone ( 3a ) exhibited single‐digit micromolar IC₅₀ (72 h) values in all four cell lines. It was seven times more active than TQ ( 1 ) in 518A2 melanoma cells and four times in KB‐V1/Vbl cervix carcinoma cells, while only half as toxic in the fibroblasts. Compound 3a was also not a substrate for the P‐gp and BCRP drug transporters of the resistant cancer cells. The caryophyllyl and germacryl conjugates 3e and 3f specifically inhibited the growth of the resistant MCF‐7 breast carcinoma cells. Conjugation of TQ with the triterpene betulinic acid via the OH group as in 3g led to a loss in activity, while conjugation via the carboxylic acid afforded compound 4 with nanomolar IC₅₀ (72 h) activity against HL‐60 cells. All anticancer‐active derivatives of TQ ( 1 ) induced apoptosis associated with DNA laddering, a decrease in mitochondrial membrane potential and a slight increase in reactive oxygen species.     

Thymoquinone-induced platelet apoptosis

Thymoquinone (TQ) is a nutrient with anticarcinogenic activity that stimulates suicidal death of tumor cells. Moreover, TQ triggers suicidal death of erythrocytes or eryptosis, an effect at least partially due to increase in cytosolic Ca²⁺ activity and ceramide formation. The present experiments explored whether TQ influences apoptosis of blood platelets. Cell membrane scrambling was determined utilizing Annexin V binding to phosphatidylserine exposing platelets, cytosolic Ca²⁺ activity utilizing Fluo 3‐AM fluorescence, caspase activity utilizing immunofluorescence and Western blotting of active caspase‐3 and inactive procaspase‐3, mitochondrial potential utilizing DiOC₆ fluorescence and ceramide by FACS analysis of ceramide‐binding antibodies. A 30 min exposure to TQ (≥5 µM) was followed by Annexin V binding, paralleled by caspase activation, increase of cytosolic Ca²⁺ activity, mitochondrial depolarization, and ceramide formation. P‐selectin exposure and integrin α_IIbβ₃ activation did not increase in response to TQ. Nominal absence of extracellular Ca²⁺ blunted but did not fully abolish the TQ‐induced activation of caspase‐3. The effects of TQ on platelets are significantly abolished with phosphoinositide‐3 kinase (PI3K) inhibitor wortmannin and G‐protein coupled receptor (GPCR) inhibitor pertussis toxin treatment prior to TQ stimulation. In conclusion, TQ triggers suicidal death of blood platelets in a PI3K‐dependent manner, possibly through a GPCR family receptor; an effect paralleled by increase of cytosolic Ca²⁺ activity, ceramide formation, mitochondrial depolarization, and caspase‐3 activation. J. Cell. Biochem. 112: 3112–3121, 2011. © 2011 Wiley Periodicals, Inc.     

Thymoquinone protects against carbon tetrachloride hepatotoxicity in mice via an antioxidant mechanism

Thymoquinone (TQ) is the major active component of the volatile oil of Nigella sativa seeds. The effects of TQ on carbon tetrachloride (CCl4)-induced hepatotoxicity was investigated in male Swiss albino mice. Carbon tetrachloride (20 microliters/Kg, i.p.) injected into mice, induced damage to liver cells and was followed by the increase in serum alanine aminotransferase (ALT) activity after 24 h. Oral administration of TQ in a single dose (100 mg/Kg) resulted in significant (p < 0.001) protection against the hepatotoxic effects of CCl4. TQ was tested as a substrate for mice hepatic DT-diaphorase in the presence of NADH. TQ appears to undergo reduction to dihydrothymoquinone (DHTQ). Reduction rates as a function of protein (liver homogenate) and substrate (TQ) concentrations are reported. An apparent K(m) of 0.1 mM and an apparent Vmax of 74 mumol/min/g liver were measured. TQ and DHTQ inhibited the in vitro non-enzymatic lipid peroxidation in liver homogenate (induced by Fe(3+)-ascorbate) in a dose dependent manner. In this in vitro model DHTQ was more potent in comparison with TQ and butylated hydroxytoluene (BHT). The IC50 for DHTQ, TQ and BHT were found to be 0.34, 0.87 and 0.58 microM respectively. The data suggest that the in vivo protective action of TQ against CCl4-induced hepatotoxicity may be mediated through the combined antioxidant properties of TQ and its metabolite DHTQ.     

Effects of Cadmium,Chromium and Lead on Growth,Metal Uptake and Antioxidative Capacity in <Emphasis Type="Italic">Typha angustifolia</Emphasis>

This study investigates the modulation of antioxidant defence system of Typha angustifolia after 30 days exposure of 1 mM chromium (Cr), cadmium (Cd), or lead (Pb). T. angustifolia showed high tolerance to heavy metal toxicity with no visual toxic symptom when exposed to metal stress, and Cd/Pb addition also increased plant height and biomass especially in Pb treatment. Along with increased Cr, Cd, and Pb uptake in metal treatments, there was enhanced uptake of plant nutrients including Ca and Fe, and Zn in Pb treatment. A significant increase in malondialdehyde (MDA) content and superoxide dismutase (SOD) and peroxidase (POD) activities were recorded in plants subjected to Cr, Cd, or Pb stress. Furthermore, Pb stress also improved catalase (CAT), ascorbate peroxidase (APX), and glutathione peroxidase (GPX) activities; whereas Cr stress depressed APX and GPX. The results indicate that enzymatic antioxidants and Ca/Fe uptake were important for heavy metal detoxification in T. angustifolia, stimulated antioxidative enzymes, and Ca, Fe, and Zn uptake could partially explain its hyper-Pb tolerance.     

Hepatoprotective effect of bis(4‐methylbenzoyl) diselenide against CCl4‐induced oxidative damage in mice

From a pharmacological point of view, organoseleniums are compounds with important and interesting antioxidant and biological activities. The aim of this study was to evaluate the hepatoprotective effect of bis(4‐methylbenzoyl) diselenide (BMD) against carbon tetrachloride (CCl₄)–induced oxidative damage in mice. The animals received BMD (25 mg/kg p.o., for 3 days), and after 1 day, CCl₄ (1 mg/kg body weight) was administered by intraperitoneal route. One day after the CCl₄ exposure, the animals were euthanized for biochemical and histological analysis. Treatment with BMD (25 mg/kg p.o.) protected against aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, gamma‐glutamyl transferase and lactate dehydrogenase activity increases induced by CCl₄ plasma exposure. Treatment with BMD (25 mg/kg) protected against increases in thiobarbituric reactive species and decreasing non‐protein thiols and ascorbic acid levels in liver of mice. Catalase and superoxide dismutase activity inhibition in the liver caused by CCl₄ were protected by treatment with BMD (25 mg/kg). Glutathione S‐transferase activity was inhibited by CCl₄ and remained unaltered even after treatment with BMD. Sections of liver from CCl₄‐exposed mice presented an intense infiltration of inflammatory cells and loss of the cellular architecture. BMD (25 mg/kg) attenuated CCl₄‐induced hepatic histological alterations. The results demonstrated the hepatoprotective effects of BMD in the mouse liver, possibly by modulating the antioxidant status. Copyright © 2012 John Wiley & Sons, Ltd.     

Mitigative effects of epigallocatechin gallate in terms of diminishing apoptosis and oxidative stress generated by the combination of lead and amyloid peptides in human neuronal cells

Environmental exposure to lead (Pb) is reported to associate with the development of Alzheimer's disease, where the formation of β‐amyloid peptides (APs) of (1‐40), (1‐42), and (25‐35) is considered as the major risk factor. In this context, we aimed at investigating the effect of epigallocatechin gallate (EGCG), a major flavonoid polyphenol available in green tea, in mitigating the individual and combined toxicity generated by Pb and β‐APs in terms of oxidative stress and apoptosis in human neuronal cells. SH‐SY5Y cells were exposed to Pb and β‐APs of (1‐40) and (25‐35) individually and in different combinations in the presence and absence of EGCG. The results indicated that EGCG mitigated both Pb‐ and β‐AP‐induced oxidative stress in scavenging reactive oxygen species and apoptosis by improving the expression levels of Bax and bcl2 and inhibiting annexin V and caspase‐3. Thus, our study shows that EGCG protects SH‐SY5Y cells against the cytotoxicity induced by Pb and β‐APs by decreasing oxidative stress and inhibiting apoptosis.     

Thymoquinone protects human retinal pigment epithelial cells against hydrogen peroxide induced oxidative stress and apoptosis

Oxidative stress in retinal pigment epithelium (RPE) cells may contribute to the progression of age-related macular degeneration. Thymoquinone (TQ), an active component derived from Nigella sativa, possesses antioxidative effect. However, the role of TQ in RPE cells under oxidative stress condition remains unclear. The present study aimed to examine the protective effect of TQ against hydrogen peroxide (H₂O₂)-induced oxidative stress in human RPE cells. Our results showed that TQ improved the cell viability and apoptosis in H₂O₂-induced ARPE cells. We also found that the levels of reactive oxygen species and malondialdehyde induced by H₂O₂ were reduced after the pretreatment of TQ. In addition, the inhibitory effect of H₂O₂ on the glutathione (GSH) level and superoxide dismutase activity was markedly attenuated by TQ pretreatment. Moreover, TQ enhanced the activation of Nrf2/heme oxygenase 1 (HO-1) signaling pathway in H₂O₂-induced ARPE cells. Knockdown of Nrf2 abolished the protective effect of TQ on H₂O₂-induced oxidative damage. These results suggested that TQ protected ARPE cells from H₂O₂-induced oxidative stress and apoptosis via the Nrf2/HO-1 signaling pathway.     

EVALUATION OF ANTIOXIDANT DEFENSE RESPONSES TO LEAD STRESS IN HAPALOSIPHON FONTINALIS‐3391

Lead (Pb) is a heavy metal and a potentially hazardous environmental pollutant. In this study, the potential of lead to induce oxidative stress in biological systems was assessed using the cyanobacterium Hapalosiphon fontinalis‐339 as model test organism. The impact of lead toxicity on the cellular antioxidant system and the biochemical modulations that result in generation of antioxidant defense responses were also studied. To determine the effect of Pb toxicity, the test organism was grown in the presence of various concentrations (0.05, 0.10, 0.20, 0.40, 0.80, 1.0, 1.20, and 1.25 mg · L^?1) of exogenous lead chloride (PbCl₂), and its effects on growth were observed in terms of the change in chl content. There was a significant increase in metal uptake by the alga with a concomitant decrease in growth. Lead stress appeared to significantly up‐regulate the levels of stress‐related antioxidant enzymes—such as superoxide dismutase (SOD), ascorbate peroxidase (APX), and glutathione reductase (GR)—while a decrease in catalase (CAT) levels was observed. In addition, the levels of nonenzymatic antioxidants, oxidized and total glutathione, were changed. Our results suggest the existence of a potent antioxidant defense machinery in H. fontinalis‐339 and this organism can be employed to monitor lead toxicity in the environment.     

Protective effects of thymoquinone against cholestatic oxidative stress and hepatic damage after biliary obstruction in rats

The aim of this study was to examine the preventive and therapeutic effects of thymoquinone (TQ) against cholestatic oxidative stress and liver damage in common bile duct ligated rats. A total of 24 male Sprague–Dawley rats were divided into three groups: control, bile duct ligation (BDL) and BDL + received TQ; each group contain 8 animals. The rats in TQ treated groups were given TQ (50 mg/kg body weight) once a day orally for 2 weeks starting 3 days prior to BDL operation. To date, no more biochemical and histopathological changes on common bile duct ligated rats by TQ treatment have been reported. The application of BDL clearly increased the tissue hydroxyproline (HP) content, malondialdehyde (MDA) levels and decreased the antioxidant enzyme [superoxide dismutase (SOD), glutathione peroxidase (GPx)] activities. TQ treatment significantly decreased the elevated tissue HP content, and MDA levels and raised the reduced of SOD, and GPx enzymes in the tissues. The changes demonstrating the bile duct proliferation and fibrosis in expanded portal tracts include the extension of proliferated bile ducts into lobules, mononuclear cells, and neutrophil infiltration into the widened portal areas were observed in BDL group. Treatment of BDL with TQ attenuated alterations in liver histology. The immunopositivity of alpha smooth muscle actin and proliferating cell nuclear antigen in BDL were observed to be reduced with the TQ treatment. The present study demonstrates that oral administration of TQ in bile duct ligated rats maintained antioxidant defenses and reduces liver oxidative damage and ductular proliferation. This effect of TQ may be useful in the preservation of liver function in cholestasis.     

Thymoquinone supplementation attenuates cyclophosphamide-induced cardiotoxicity in rats

This study examined the possible protective effects of thymoquinone (TQ), the main constituent of the volatile oil of black seed (Nigella sativa), against cyclophosphamide (CP)-induced cardiotoxicity. Adult male Wistar albino rats were divided into four treatment groups. Rats in the first group were served as control. Rats in the second group received TQ (50 mg/L in drinking water) for 12 days. Animals in the third group were injected with a single dose of CP (200 mg/kg, IP) at day 5. Rats in the fourth group received TQ (50 mg/L in drinking water) for 5 days before a single dose of CP (200 mg/kg, IP) and continued thereafter throughout the experiment. On day 13, animals were sacrificed; serum and hearts were isolated and analyzed. Cyclophosphamide resulted in a significant increase in serum creatine kinase, lactate dehydrogenase, cholesterol, triglycerides, creatinine, urea, and tumor necrosis factor-α. In heart tissues, CP resulted in a significant increase in thiobarbituric acid reactive substances and total nitrate/nitrite and a significant decrease in reduced glutathione, glutathione peroxidase, catalase, and adenosine triphosphate levels. Interestingly, TQ supplementation resulted in a complete reversal of all the biochemical changes induced by CP to their control values. Data from this study suggest that TQ supplementation attenuates CP-induced cardiotoxicity by a mechanism related, at least in part, to its ability to decrease oxidative and nitrosative stress and to preserve the activity of antioxidant enzymes as well as its ability to improve the mitochondrial function and energy production. .     

Protective Effect of <Emphasis Type="Italic">Nigella sativa</Emphasis> Extract and Thymoquinone on Serum/Glucose Deprivation-Induced PC12 Cells Death

The serum/glucose deprivation (SGD)-induced cell death in cultured PC12 cells represents a useful in vitro model for the study of brain ischemia and neurodegenerative disorders. Nigella sativa L. (family Ranunculaceae) and its active component thymoquinone (TQ) has been known as a source of antioxidants. In the present study, the protective effects of N. sativa and TQ on cell viability and reactive oxygen species (ROS) production in cultured PC12 cells were investigated under SGD conditions. PC12 cells were cultured in DMEM medium containing 10% (v/v) fetal bovine serum, 100 units/ml penicillin, and 100 μg/ml streptomycin. Cells were seeded overnight and then deprived of serum/glucose for 6 and 18 h. Cells were pretreated with different concentrations of N. sativa extract (15.62–250 μg/ml) and TQ (1.17–150 μM) for 2 h. Cell viability was quantitated by MTT assay. Intracellular ROS production was measured by flow cytometry using 2′,7′-dichlorofluorescin diacetate (DCF-DA) as a probe. SGD induced significant cells toxicity after 6, 18, or 24 h (P < 0.001). Pretreatment with N. sativa (15.62–250 μg/ml) and TQ (1.17–37.5 μM) reduced SGD-induced cytotoxicity in PC12 cells after 6 and 18 h. A significant increase in intracellular ROS production was seen following SGD (P < 0.001). N. sativa (250 μg/ml, P < 0.01) and TQ (2.34, 4.68, 9.37 μM, P < 0.01) pretreatment reversed the increased ROS production following ischemic insult. The experimental results suggest that N. sativa extract and TQ protects the PC12 cells against SGD-induced cytotoxicity via antioxidant mechanisms. Our findings might raise the possibility of potential therapeutic application of N. sativa extract and TQ for managing cerebral ischemic and neurodegenerative disorders.     

Rapid evolution of antioxidant defence in a natural population of Daphnia magna

Natural populations can cope with rapid changes in stressors by relying on sets of physiological defence mechanisms. Little is known onto what extent these physiological responses reflect plasticity and/or genetic adaptation, evolve in the same direction and result in an increased defence ability. Using resurrection ecology, we studied how a natural Daphnia magna population adjusted its antioxidant defence to ultraviolet radiation (UVR) during a period with increasing incident UVR reaching the water surface. We demonstrate a rapid evolution of the induction patterns of key antioxidant enzymes under UVR exposure in the laboratory. Notably, evolutionary changes strongly differed among enzymes and mainly involved the evolution of UV‐induced plasticity. Whereas D. magna evolved a strong plastic up‐regulation of glutathione peroxidase under UVR, it evolved a lower plastic up‐regulation of glutathione S‐transferase and superoxide dismutase and a plastic down‐regulation of catalase. The differentially evolved antioxidant strategies were collectively equally effective in dealing with oxidative stress because they resulted in the same high levels of oxidative damage (to lipids, proteins and DNA) and lowered fitness (intrinsic growth rate) under UVR exposure. The lack of better protection against UVR may suggest that the UVR exposure did not increase between both periods. Predator‐induced evolution to migrate to lower depths that occurred during the same period may have contributed to the evolved defence strategy. Our results highlight the need for a multiple trait approach when focusing on the evolution of defence mechanisms.     

Tocopherylquinone and tocopherylhydroquinone

Abstract

Tocopherylquinone (TQ) is formed in the antioxidant action of tocopherol (T). TQ was found in human subjects and it was observed that the ratio αTQ/ αT increased in general with increasing oxidative stress. TQ is reduced to tocopheryl hydroquinone (TQH₂) but the ratio TQH₂/TQ in vivo has not been reported. TQH₂ acts as a potent radical-scavenging antioxidant. αTQH₂ is more reactive toward radicals than ubiquinol, a reduced form of coenzyme Q, and αT. The overall efficacy of TQH₂ as an antioxidant is determined by the fate of semiquinone radical formed from TQH₂ as well as the reactivity toward oxygen radicals. Partly substituted γTQ, but not αTQ, exerts cytotoxicity by both redox cycling and reaction with protein thiols and glutathione.     

<Emphasis Type="Italic">Nigella sativa</Emphasis> and Derived Thymoquinone Prevents Hippocampal Neurodegeneration After Chronic Toluene Exposure in Rats

The aim of this study was designed to investigate the possible beneficial effects of Nigella sativa (NS) and derived thymoquinone (TQ) on neurodegeneration in hippocampus after chronic toluene exposure in rats. The rats were randomly allotted into one of four experimental groups: A (control), B (toluene treated), C (toluene treated with NS) and D (toluene treated with TQ); each group contain 10 animals. Toluene treatment was performed by inhalation of 3,000 ppm toluene, in a 8 h/day and 6 day/week order for 12 weeks. Control group received 1 ml serum physiologic and the rats in NS and TQ treated groups (C and D) were given NS (in a dose of 400 mg/kg body weight) and TQ (50 mg/kg body weight) once a day orally by using intra gastric intubation for 12 weeks starting just after toluene exposure respectively. Tissue samples were obtained for histopathological investigation. To date, no histopathological changes of neurodegeneration in hippocampus after chronic toluene exposure in rats by NS and TQ treatment have been reported. In this study, chronic toluene exposure caused severe degenerative changes, shrunken cytoplasma, slightly dilated cisternae of endoplasmic reticulum, markedly swollen mitochondria with degenerated cristae and nuclear membrane breakdown with chromatin disorganization in neurons of the hippocampus. The distorted nerve cells were mainly absent in the TQ and NS-treated rats. We conclude that TQ and especially NS therapy causes morphologic improvement on neurodegeneration in hippocampus after chronic toluene exposure in rats. We believe that further preclinical research into the utility of NS and TQ may indicate its usefulness as a potential treatment on neurodegeneration after chronic toluene exposure in rats.