Phospholipid hydroperoxide glutathione peroxidase activity of rat class theta glutathione transferase T2-2

Functional diversification of three delta-class glutathione S-transferases involved in development and detoxification in Tribolium castaneum

Glutathione S-transferases (GSTs) are members of a multifunctional enzyme superfamily. Forty-one GSTs have been identified in Tribolium castaneum; however, none of the 41 GSTs has been functionally characterized. Here, three delta-class GSTs, TcGSTd1, TcGSTd2 and TcGSTd3, of T. castaneum were successfully cloned and expressed in Escherichia coli. All of the studied GSTs catalysed the conjugation of reduced glutathione with 1-chloro-2,4-dinitrobenzene. Insecticide treatment showed that the expression levels of TcGSTd3 and TcGSTd2 were significantly increased after exposure to phoxim and lambda-cyhalothrin, whereas TcGSTd1 was slightly upregulated only in response to phoxim. A disc diffusion assay showed that overexpression of TcGSTD3, but not TcGSTD1 or TcGSTD2, in E. coli increased resistance to paraquat-induced oxidative stress. RNA interference knockdown of TcGSTd1 caused metamorphosis deficiencies and reduced fecundity by regulating insulin/target-of-rapamycin signalling pathway-mediated ecdysteroid biosynthesis, and knockdown of TcGSTd3 led to reduced fertility and a decreased hatch rate of the offspring, probably caused by the reduced antioxidative activity in the reproductive organs. These results indicate that TcGSTd3 and TcGSTd2 may play vital roles in cellular detoxification, whereas TcGSTd1 may play essential roles in normal development of T. castaneum. These delta-class GSTs in T. castaneum have obtained different functions during the evolution.

Pro-Apoptotic and Anti-Angiogenesis Effects of Olive Leaf Extract on Spontaneous Mouse Mammary Tumor Model by Balancing Vascular Endothelial Growth Factor and Endostatin Levels

It has been proven that olive associated products such as olive leaf extract (OLE) causes significant reduction in cancer cells viability and proliferation. Female BALB/c adult mice were divided into four groups. Three days prior to oral treatments, tumors were transplanted. First group were treated with distilled water and other three groups were received, respectively, 75, 150, and 225 mg/kg/day of OLE for three weeks. For assessment of anti-angiogenesis and pro-apoptotic effect of OLE on tumor tissue, tumor volume, cell mitosis and apoptosis, and also vascular endothelial growth factor (VEGF) and endostatin levels were assessed. OLE treatment with 150 and 225 mg/kg/day lead to significant reduction in tumor volume and cell mitosis compared with the control group, while the same doses significantly increase tumor cell apoptosis. OLE treatment with 150 mg/kg/day increase endostatin levels, while the same dose did not significantly decrease VEGF levels. The VEGF level is significantly reduced by the treatment with OLE 225 mg/kg/day for three weeks. Although, further studies are needed to clarify anti-angiogenesis and anti-apoptotic mechanism of OLE, consumption of OLE polyphenols after tumor transplantation reduced spontaneous mouse mammary tumor growth.

The effects of polyunsaturated:saturated fatty acids ratios and peroxidisability index values of dietary fats on serum lipid profiles and hepatic enzyme activities in rats

Raising the dietary PUFA:saturated fatty acids (SFA) ratio has been recommended for the prevention of CVD. However, a high PUFA:SFA (P:S) ratio diet enhances oxidative stress because PUFA are highly susceptible to lipid peroxidation. Thus, we focused on the role of the dietary P:S ratio and peroxidisability index (PI) value on serum and liver tissue and investigated the effects of dietary P:S ratios (0.4, 1.0, and 4.8) with a fixed PI value (81) on serum lipid parameters and hepatic enzyme activities (experiment 1). To elucidate whether those phenomena were unique to the P:S ratio, we examined the effects of dietary PI values (36, 81, 126, and 217) with a constant P:S ratio (1.0) (experiment 2). Female Sprague-Dawley rats weighing 240-280 g were fed experimental diets for 4 weeks. When dietary PI value was maintained at 81, serum HDL-cholesterol (HDL-C) increased with increasing dietary P:S ratio. When the P:S ratio was fixed at 1.0, HDL-C was the lowest with mid-low PI (MLPI) (PI value of 81). In both experiments, serum LDL-cholesterol:HDL-C ratio kept in the range of 0-2. The hepatic superoxide dismutase, catalase, and glutathione peroxidase (GSH-Px) activities and thiobarbituric acid reactive substance (TBARS) concentrations were the highest in the lowest dietary P:S ratio group (experiment 1). GSH-Px, glutathione-S-transferase, and TBARS were the lowest in rats fed the MLPI diet (experiment 2). In conclusion, these results indicate that a P:S ratio of 1.0-1.5 and a PI value of 80-90 in the diet are within a favourable range to reduce the risk of CVD.

Relationship between malondialdehyde level and glutathione peroxidase activity in diabetic rats

BACKGROUND

This investigation describes the relationship between glutathione peroxidase activities, an antioxidant enzyme, and the oxidative status in diabetic rat blood.

METHODS

Malondialdehyde level and glutathione peroxidase activity were measured by spectrophotometric techniques.

RESULTS AND CONCLUSIONS

Malondialdehyde content in the diabetic rats group was increased compared to that in the controls [3.08+/-0.32 (mean+/-S.E.) vs. 1.15+/-0.29 mM/g hemoglobin, P>0.01]. Glutathione peroxidase activity in the diabetic rats group was increased compared to that in the control [10.27+/-1.39 (mean+/-S.E.) vs. 3.14+/-0.38 micromol NADPH/min/g hemoglobin, P>0.01]. Our results show a positive correlation between serum glutathione peroxidase and malondialdehyde concentration in diabetic rats.

Antioxidant enzyme activities are decreased in preterm infants and in neonates born via caesarean section

OBJECTIVES

To investigate the antioxidant defense potential of human neonates according to gestational age and mode of delivery.

STUDY DESIGN

Four study groups were established, full-term normal spontaneous vaginal delivery (FT-NSVD, n=24), full-term caesarean section (FT-CS, n=19), preterm normal spontaneous vaginal delivery (PT-NSVD, n=15) preterm caesarean section (PT-CS, n=21). The activity of catalase (CAT), glutathion peroxidase (GPX), Cu/Zn superoxide dismutase (Cu/Zn-SOD) were determined from cord blood. Statistical analysis was made by ANOVA.

RESULTS

CAT activity was significantly higher in full-term than in preterm newborns. In both the categories, neonates born via caesarean section had significantly lower CAT activities. GPX activity was significantly higher in the FT-NSVD group than in any other group. Cu/Zn-SOD activity was significantly higher in full-term neonates than in preterms and no difference was found related to the mode of delivery.

CONCLUSIONS

Prematurity and caesarean section may cause a deficiency of antioxidant defense in human newborn.

Antioxidant enzymes and human diseases

OBJECTIVES

To describe the importance of the antioxidant enzymes superoxide dismutase, glutathione peroxidase, and catalase working together in human cells against toxic reactive oxygen species, their relationship with several pathophysiologic processes and their possible therapeutic implications.

CONCLUSIONS

Reactive oxygen species (ROS) are involved in the cell growth, differentiation, progression, and death. Low concentrations of ROS may be beneficial or even indispensable in processes such as intracellular signaling and defense against micro-organisms. Nevertheless, higher amounts of ROS play a role in the aging process as well as in a number of human disease states, including cancer, ischemia, and failures in immunity and endocrine functions. As a safeguard against the accumulation of ROS, several nonenzymatic and enzymatic antioxidant activities exist. Therefore, when oxidative stress arises as a consequence of a pathologic event, a defense system promotes the regulation and expression of these enzymes.