EVALUATION OF LIPID PEROXIDATION AND ANTIOXIDANT ENZYME ACTIVITIES IN TYPE 2 DIABETICPALESTINIAN PATIENTS FROM THE GAZA STRIP

* Ali Abd El-Aal 1 , Mahmoud Sirdah 2 , Eman A. Abd El-Ghffar 1 and Asmaa S. Abughali 1 . 1. Department of Zoology, Faculty of Science, Ain Shams University, Cairo, Egypt. 2. Department of Zoology, Faculty of Science, Al-AzharUniversity,Gaza,Palestine. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History

Several diabetic complications are associated with overproduction of ROS and accumulation of lipid peroxidation products (Palanduz et al., 2001), which is potentially harmful because it's uncontrolled, the self-enhancing process causes disruption of membranes, lipids, and other cell components.
There is not much data available about the relationship between oxidative stress and diabetes in Palestinian type 2 diabetic patients at Gaza strip. Therefore, the aim of the present study is to evaluate oxidative stress by measuring lipid peroxidation and antioxidant enzymes in patients with type 2 diabetes as compared to healthy controls, also to determine the correlations between the pro-oxidant (lipid status) and antioxidant parameters in studied subjects.

Materials and Methods:-
Subjects:The current study was conducted on 40males patients with type 2 diabetes. The patients were chosen from those attending the United Nations Relief and Works Agency for Palestine Refugees in the Near East (UNRWA) health centers in Gaza Strip. Clinical examination was done for all patients to exclude any diabetic complication such as neurologic, cardiac, kidney, and eye complications. All patients were on oral hypoglycemic agents Metformin.Ten healthy subjects (10 males) matching the average age and socioeconomic status were selected randomly as a control group. The healthy subjects were chosen randomly from those working at UNRWA health centers. Clinical examination was also done for all healthy subjects to exclude any health problem that may they suffer from. None of the patients or control subjects reported any intake of dietary supplements such as vitamins or minerals, at least in the last year before launching the study.
Measurements: Weight,height, waist circumference (WC), waist hip ratio (WHR) and blood pressure were measured for each subject then the body mass index was calculated as following: BMI = Body weight (Kg) / height (m 2 ) (Bray, 1987).
Blood samples and biochemical parameters: Blood samples were collected from each subject after an overnight fasting (at least 8-12 hours). Glycosylated hemoglobin (HbA1c) was measured by a direct enzymatic method Statistical Analysis:-Statistical Package of social science (SPSS) version 22 was used for analysis of data. Data was summarized as mean ± standard deviation (SD) and compared between type 2 diabetic patients and healthy controls subjects. Pearson's correlations were also performed to define correlations of individual parameters. All statistical tests were two-tailed. P values ≤ 0.05 were considered statistically significant.

Results:-
The descriptive characteristics of the type 2 diabetic patients and healthy control subjects are shown in Table 1. The type 2 diabetic group significantly differed from the healthy control group in fasting blood glucose level (88.15 ± 3.31vs. 158.82 ± 5.07, P< 0.05) and HbA1c% (5.53± 0.13vs. 8.43 ± 0.214, P<0.05).   There is no significant difference in liver and kidney functions parametersin type 2 diabetic patientswhen compared with healthy control subjects. Table-4. Table 4:-Liver and kidney functions parameters in healthy control and type 2 diabetic subjects.

Discussion:-
In the present study, the patients with type 2 diabetes had shown elevation of HbA1c comparing to their agedmatched healthy individuals. It has been reported that various proteins, hemoglobin and LDL, undergo nonenzymatic glycation in diabetes (Klein., 1995). The rate of glycation is proportional to the concentration of blood glucose (Sheelaet al., 1992). In addition, HbA1c has been found to be increased over a long period of time in diabetes (Bunn et al., 1978). Free radical increases proportionally with increased glycation rate (Gupta et al.,  1997). So, the measurement of HbA1c is very sensitive index for glycemic control (Jain et al., 1989).
In the current work, we found that patients with type 2 diabetes were presented with low HDL-C and high triglyceride levels. This result is compatible with the previous studies (Howard, 1987; Taskinen., 1992; Yoshino et al., 1996). The insufficient amounts of anti-atherogenic and antioxidative effects due to the low level of HDL-C, is a key feature for oxidative stress status (Hansel et al., 2004). The reduced HDL-C level is often accompanied with high level of triglyceride (Lamarcheet al., 1996), which is in agreement with the present study. In type 2 diabetes, the increased secretion of apolipoprotein B (apoB) as a result of fatty acid synthesis in the liver (Duvillard et al.,  2000; Krauss et al., 2004), a protein identified as a key component of the VLDL which induced an increase in plasma level of triglyceride and reduce level of HDL-C. Moreover, the elevation of free fatty acid and glucose in type 2 diabetes may decrease the activity of lipoprotein lipase, a pivotal enzyme in the removal of these lipoproteins from the circulation, and control the triglyceride-rich lipoproteins and HDL-C particles (Kastelein et al., 1999).
The present study showed significant increases in MDA, GR, GST, and significant decreases in GSH and GSH-Px levels in patients with type 2 diabetes as compared with the control, which is an indication of marked oxidative stress. The increase of oxidative stress in diabetes mellitus was explained by several mechanisms. These mechanisms fall into two general categories first; Increased production of ROS, second; decreased antioxidant defenses. In diabetes, glucose auto oxidation and glycation products, non-enzymatic protein glycosylation, and changes in antioxidant defense systems can increase production of ROS (Baynes 1991; Inouye et al., 1999;  Bonnefont-Rousselot et al., 2000; Courderot-Masuyeret al., 2000; West, 2000). Increased production of ROS as well as reduced antioxidant defense mechanisms have been suggested to play a role in type 1 and type 2 diabetic patients (Mahboobet al., 2001).   , 2005).The low activity of GSH-Px could be directly explained by the low content of GSH found in patients with the type 2 diabetes since GSH is a substrate and cofactor of GSH-Px. Enzyme inactivation could also contribute to the low GSH-Px activity. GSH-Px is a relatively stable enzyme, but it may be inactivated under conditions of severe oxidative stress. Inactivation of this enzyme may occur through glycation governed by prevailing glucose concentration (Rahbani-Nobar et al., 1999). The increased activity of GR may be a compensatory response to oxidative stress. The changes in GSH-Px and GR activities found in this study may be considered as an adaptation of antioxidant defense against the increased production of ROS.
GSH dependent enzyme activities, such as GSSH-Px, γ-glutamyltranspeptidase, and GST were changed in diabetes (Ballatori et al., 2009). The results showed that patients with the type 2 diabetes had lower GSH concentrations in erythrocytes (RBCs) than observed in the healthy individuals. This result is similar to the finding of Livingstone et al., (2007). The present results showed that GST activity was increased significantly in patients with type 2 diabetes than in the healthy individuals. In RBCs, decreased GSH as well as increased serum total GST levels may be due to a compensatory mechanism of the antioxidants to defense the oxidative stress in diabetic conditions.
Positive correlation between MDA, total cholesterol and LDL-C, as well as positive correlation between GST, triglyceride and VLDL-C were found in patients with the type 2 diabetes. Positive correlations between GSH-Px and LDL-C in healthy individuals could indicate possible association between high lipid concentrations leading to accelerated lipid peroxidation and potentially increased the reduction of the organic hydroperoxides as a consequence of increased activity of GSH-Px. No such correlation was found in patients with the type 2 diabetes, while these were other significant correlations between GSH-Px and triglyceride in the healthy individuals.

Conclusions:-
It was concluded that the Palestinian patients with the type 2 diabetes are presented with a significant increase in lipid peroxidation coupled to a significant decrease in the antioxidant mechanism. The study suggests the evaluation of antioxidant levels as a useful marker in the prevention of the diabetic complications.