Prooxidant-induced glutathione antioxidant response in vitro and in vivo: a comparative study between schisandrin B and curcumin

SOD2, a Potential Transcriptional Target Underpinning CD44-Promoted Breast Cancer Progression

CD44, a cell-adhesion molecule has a dual role in tumor growth and progression; it acts as a tumor suppressor as well as a tumor promoter. In our previous work, we developed a tetracycline-off regulated expression of CD44's gene in the breast cancer (BC) cell line MCF-7 (B5 clone). Using cDNA oligo gene expression microarray, we identified SOD2 (superoxide dismutase 2) as a potential CD44-downstream transcriptional target involved in BC metastasis. SOD2 gene belongs to the family of iron/manganese superoxide dismutase family and encodes a mitochondrial protein. SOD2 plays a role in cell proliferation and cell invasion via activation of different signaling pathways regulating angiogenic abilities of breast tumor cells. This review will focus on the findings supporting the underlying mechanisms associated with the oncogenic potential of SOD2 in the onset and progression of cancer, especially in BC and the potential clinical relevance of its various inhibitors.

Evaluation of Beneficial and Adverse Effects of a Diet Supplemented with Schisandrae Fructus Seed Ethanol Extract on Lipid and Glucose Metabolism in Normal and Hypercholesterolemic/Hyperglycemic Mice

Schisandrae Fructus (SF), the fruit of Schisandra chinensis (Turcz.) Baillon, has been used for the treatment of liver injury and metabolism-related disorders in China. The objective of this study was to investigate the effects of supplementation with ethanol extract of SF seed (EtSF-S) on serum/hepatic lipid and glucose levels as well as fecal total cholesterol (TC) contents in mice fed a normal diet (ND) or high-fat/fructose diet (HFFD) containing 15% lard oil and 15% fructose. Female ICR mice (18–20 g in body weight) were fed with ND or HFFD for 3 months, and then EtSF-S was added to both chow diets at increasing concentrations of 1, 5, and 10% (w/w). Thirty days later, serum and hepatic lipids, including TC, triglyceride (TG), high-density lipoprotein (HDL), low-density lipoprotein (LDL), and glucose, were measured. Dietary supplementation with EtSF-S reduced hepatic TC (36 and 18%) and TG levels (38 and 28%) and increased serum HDL/LDL ratio (16 and 26%) in both ND- and HFFD-fed mice, respectively. Moreover, supplementation with EtSF-S elevated serum HDL (31%) in HFFD-fed mice and reduced serum LDL (27%) in ND-fed mice. EtSF-S treatment reduced fat mass (40%) in ND-fed mice and increased fecal TC contents (33%) in HFFD-fed mice. EtSF-S supplementation decreased hepatic glucose contents (29%) in both ND- and HFFD-fed mice. However, diet supplemented with EtSF-S elevated serum TG levels (up to 123%) and hepatic size (28%), but more importantly, suppressed the body weight gain (approximately 130%) in mice fed with HFFD. These findings suggested that dietary supplementation with EtSF-S as natural herbal function food may be a useful strategy for the treatment of patients with fatty liver disease or overweight without a high intake of sugar and fat.

Schisandrin B attenuates pressure overload-induced cardiac remodeling in mice by inhibiting the MAPK signaling pathway

The aim of the current study was to investigate the effect and mechanism of schisandrin B (Sch B) on myocardial hypertrophy induced by pressure overload in mice. Male C57BL/6J mice were randomly divided into three groups: i) Sham (n=12); ii) transverse aortic constriction (TAC) (n=12); and iii) Sch B-treated (n=12; 80 mg·kg⁻¹·d⁻¹ per gavage). The model of myocardial hypertrophy was established by constricting the descending branch of the aortic arch. Following a 4-week treatment period, cardiac remodeling was evaluated using echocardiography and pathological and molecular analysis. Sch B improved cardiac function in the Sch B-treated group compared with the TAC group. Moreover, the Sch B-treated group had a smaller myocardial cell cross-sectional area and less fibrosis compared with the TAC group. The protein expression levels of cardiac hypertrophy and fibrosis markers in the TAC group were significantly higher compared with those in the sham group. The same markers in the Sch B-treated group were significantly lower compared with those in the TAC group. Additionally, the phosphorylation levels of the mitogen-activated protein kinase (MAPK) signaling pathway-associated proteins extracellular signal-regulated kinase 1/2, c-Jun N-terminal kinase 1/2 and P38 mitogen-activated protein kinase were significantly lower in the Sch B-treated group compared with the TAC group. Further in vitro investigation demonstrated that Sch B prevented the adverse effects of angiotensin II-induced hypertrophy and fibrosis by inhibiting the MAPK signaling pathway in H9c2 cells. In conclusion, Sch B may improve pathological myocardial remodeling and cardiac function induced by pressure overload, and its underlying mechanism may be associated with inhibition of the MAPK signaling pathway.

Tetrahydrocurcumin and octahydrocurcumin, the primary and final hydrogenated metabolites of curcumin, possess superior hepatic-protective effect against acetaminophen-induced liver injury: Role of CYP2E1 and Keap1-Nrf2 pathway

Acetaminophen (APAP) overdose-induced hepatotoxicity is tightly associated with oxidative stress. Tetrahydrocurcumin (THC) and octahydrocurcumin (OHC), the primary and final hydrogenated metabolites of curcumin (CUR), possess stronger antioxidant activity in vitro. The present study was performed to investigate the potential and mechanism of OHC and THC against APAP-induced hepatotoxicity in parallel to CUR. Our results showed that OHC and THC dose-dependently enhanced liver function (ALT and AST levels) and alleviated histopathological deterioration. Besides, OHC and THC significantly restored the hepatic antioxidant status by miring level of MDA and ROS, and elevated levels of GSH, SOD, CAT and T-AOC. In addition, OHC and THC markedly suppressed the activity and expressions of CYP2E1, and bound to the active sites of CYP2E1. Moreover, OHC and THC activated the Keap1-Nrf2 pathway and enormously enhanced the translational activation of Nrf2-targeted gene (GCLC, GCLM, NQO1 and HO-1) against oxidative stress, via inhibiting the expression of Keap1 and blocking the interaction between Keap1 and Nrf2. Particularly, OHC and THC exerted superior hepato-protective and antioxidant activities to CUR. In conclusion, OHC and THC possess favorable hepato-protective effect through restoring antioxidant status, inhibiting CYP2E1 and activating Keap1-Nrf2 pathway, which might represent promising antioxidants for the treatment of APAP-induced hepatotoxicity.

The Nrf2-ARE pathway is associated with Schisandrin b attenuating benzo(a)pyrene-Induced HTR cells damages in vitro

As is ubiquitous in the environmental sources, benzo(a)pyrene (BaP) has been reported to induce reprotoxicity in previous studies. Toxicity to trophoblast cells may be one key factor, but evidences were absent. We speculated that BaP can induce cytotoxicity in human trophoblast HTR-8/SVneo (HTR) cells, and Schisandrin B (Sch B) as a potential protector can inhibit the cytotoxicity. MTS assay identified that BaP induced HTR cells death while Sch B played a cytoprotective role. And after Nrf2 interference, the ability of Sch B-induced cytoprotection was declined. Furthermore, PCR, western blot, ELISA, and SOD assays were found that Sch B significantly increased the mRNA and protein expression of Nrf2, HO1, NQO1, and SOD in the Nrf2-ARE pathway, and the extents of increase were declined after Nrf2 interference. These results demonstrated that the Nrf2-ARE pathway plays an important role in Sch B attenuating BaP-induced HTR cells damages in vitro. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1439-1449, 2016.

Schisandrin B: A Double-Edged Sword in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a spectrum of liver lesions ranging from hepatic steatosis, nonalcoholic steatohepatitis, hepatic cirrhosis, and hepatocellular carcinoma. The high global prevalence of NAFLD has underlined the important public health implications of this disease. The pathogenesis of NAFLD involves the abnormal accumulation of free fatty acids, oxidative stress, endoplasmic reticulum (ER) stress, and a proinflammatory state in the liver. Schisandrin B (Sch B), an active dibenzooctadiene lignan isolated from the fruit of Schisandra chinensis (a traditional Chinese herb), was found to possess antihyperlipidemic, antioxidant, anti-ER stress, and anti-inflammatory activities in cultured hepatocytes in vitro and in rodent livers in vivo. Whereas a long-term, low dose regimen of Sch B induces an antihyperlipidemic response in obese mice fed a high fat diet, a single bolus high dose of Sch B increases serum/hepatic lipid levels in mice. This differential action of Sch B is likely related to a dose/time-dependent biphasic response on lipid metabolism in mice. The hepatoprotection afforded by Sch B against oxidative stress, ER stress, and inflammation has been widely reported. The ensemble of results suggests that Sch B may offer potential as a therapeutic agent for NAFLD. The optimal dose and duration of Sch B treatment need to be established in order to ensure maximal efficacy and safety when used in humans.

Hepatoprotective and Nephroprotective Effect of Curcumin Against Copper Toxicity in Rats

Curcumin is a natural anti-inflammatory and antioxidant with several potential health benefits. Although it has been examined in several metals toxicity studies, but its role in the protection against copper toxicity has not been investigated. In this study; the detoxification and antioxidant effect of curcumin were examined to determine its prophylactic/therapeutic role experimentally in rats. Forty albino rats were divided into five groups; control, CuSO4 (4 mg/kg body weight), curcumin (80 mg/kg body weight), curcumin post-treatment (CuSO4 for 15 days followed by curcumin for the next 15 days) and curcumin co-treatment (CuSO4 plus curcumin for 30 days). All rats were treated orally by stomach tube for 30 days/once a day. Changes were observed in hepatic marker enzymes such as: aspartate aminotransferase (AST), alanine transaminase-(ALT), alkaline phosphatase (ALP) and gamma-glutamyltransferase (GGT), besides the serum total protein, urea and creatinine. Concentration of liver and kidney antioxidants such as: catalase (CAT), superoxide dismutase (SOD), reduced glutathione-(GSH) and malondialdehyde (MDA) were measured. An increased in the activities of liver marker enzymes, urea, creatinine and the MDA contents were detected after exposure to CuSO4. Meanwhile, the activities of serum total protein, hepatic and renal antioxidants were decreased. Changes in all biochemical parameters were alleviated by the post-treatment and co-treatment of curcumin. Our finding suggests that the curcumin showed protective effects on CuSO4-induced hepatotoxicity and nephrotoxicity.

Manganese superoxide dismutase in cancer prevention

SIGNIFICANCE

Cancer is the second leading cause of death in the United States. Considering the quality of life and treatment cost, the best way to fight against cancer is to prevent or suppress cancer development. Cancer is preventable as indicated by human papilloma virus (HPV) vaccination and tamoxifen/raloxifen treatment in breast cancer prevention. The activities of superoxide dismutases (SODs) are often lowered during early cancer development, making it a rational candidate for cancer prevention.

RECENT ADVANCES

SOD liposome and mimetics have been shown to be effective in cancer prevention animal models. They've also passed safety tests during early phase clinical trials. Dietary supplement-based SOD cancer prevention provides another opportunity for antioxidant-based cancer prevention. New mechanistic studies have revealed that SOD inhibits not only oncogenic activity, but also subsequent metabolic shifts during early tumorigenesis.

CRITICAL ISSUES

Lack of sufficient animal model studies targeting specific cancers; and lack of clinical trials and support from pharmaceutical industries also hamper efforts in further advancing SOD-based cancer prevention.

FUTURE DIRECTIONS

To educate and obtain support from our society that cancer is preventable. To combine SOD-based therapeutics with other cancer preventive agents to obtain synergistic effects. To formulate a dietary supplementation-based antioxidant approach for cancer prevention. Lastly, targeting specific populations who are prone to carcinogens, which can trigger oxidative stress as the mechanism of carcinogenesis.

Novel mouse model of combined hyperlipidemia associated with steatosis and liver injury by a single-dose intragastric administration of schisandrin B/cholesterol/bile salts mixture

Hyperlipidemia is referred to as hypercholesterolemia, hypertriglyceridemia, or both in combined hyperlipidemia. Here, a novel mouse model of combined hyperlipidemia is described. Mice were orally given a single dose of a modeling agent (MA) made of a mixture of schisandrin B/cholesterol/bile salts (1/2/0.5 g/kg) suspended in olive oil. MA treatment increased serum triglycerides (TG) and total cholesterol (TC) (up to 422% and 100% at 12 - 96 h post-treatment, respectively) and hepatic TG and TC (up to 220% and 26%, respectively) in a time- and dose-dependent manner, associated with elevation of high-density lipoprotein and low-density lipoprotein levels. Serum alanine/aspartate aminotransferase activities, indicators of liver cell damage, were also elevated (up to 198%) at 48 and 72 h post-MA treatment. Fenofibrate blocks MA-induced hyperlipidemia, lipid accumulation in the liver, as well as liver injury. Oral administration of a mixture of schisandrin B, cholesterol, and bile salt could generate an interesting mouse model of combined hyperlipidemia associated with hepatic steatosis and steatohepatitis.

Curcumin protection activities against γ-rays-induced molecular and biochemical lesions

Background

Curcumin is a yellow-pigment phenolic compound used as a food spice and has a broad spectrum of antioxidant, anti-carcinogenic, anti-mutagenic and anti-inflammatory properties.

Methods

Radio-protective efficacy of curcumin; diferuloylmethane (C₂₁H₂₀O₆) was evaluated using molecular and biochemical assays in male mice after exposure to 3 Gy γ-rays. Curcumin was given at a dose of 400 μmol/ kg body weight via gastric tubes for 5 following days either pre-, post- or both pre- and post-exposure.

Results

The incidence of aberrant cells and aberration types (mostly chromatids, breaks and fragments) was reduced with curcumin dosage as compared to irradiated group. Thiobarbituric acid reactive substances (TBARS), hydroperoxide (HP), xanthine oxidase (XO) and apoptotic markers (DNA- fragmentation and caspase-3 activation) were increased significantly, whereas levels of glutathione (GSH) and the enzymatic antioxidants [Superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx)] were significantly depleted in γ-irradiated mice. Curcumin treatments of mice groups including the 5 days pre-irradiation treated group (protected), the 5 days post-irradiation treated group (treated), and the curcumin treated group 5 days pre- and post-irradiation (protracted), have attenuated the liver toxic effects of γ-rays as manifested by reducing the levels of TBARS, HP, XO and DNA fragmentation. Curcumin has also rescued the depletion of GSH and the enzymatic-antioxidant status.

Conclusions

Curcumin has significant radio-protective and radio-recovery activities in γ-irradiated mice. It has antioxidant potential against γ-rays-induced cytogenetic, molecular and biochemical lesions in mice.