1. Introduction

Aerobic organisms possess antioxidant defense system that deals with reactive oxygen species (ROS). ROS is produced by partial reduction of oxygen which is highly reactive substance. They are normally produced in response to both internal and external stimuli ^{[1, 2, 3]}. High levels of ROS or inadequate removal of reactive substances results in oxidative stress, which causes severe malfunction and damage to biological macromolecules ^{[4, 5]}. The mechanism of enzymatic and non-enzymatic functions of antioxidant enzymes which are essential for survival of organisms and their health is complex. ^[9] (Figure 1).

Figure 1. generation of ros & defnse by antioxidant enzymes

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Obesity is a state of excess adipose tissue deposition. The most widely used method to measure obesity is by Body Mass Index (BMI). It is calculated as

Other methods like anthropometry (skin fold thickness), densitometry (underwater weighing), computer tomography (CT) & magnetic resonance Imaging (MRI) are also used as an indices to measure obesity ^[10]. The classification of obesity and waist circumference are shown in (Table 1).

Waist circumference is used as a surrogate marker for upper body obesity. Waist circumference > 102 cm in men and > 88 cm in women increases the risk for metabolic syndrome. Available literature reveals that the prevalence of diabetes is 2.9 times higher in overweight than in normal persons ^{[11, 12]}.

Table 1. The classification of obesity and waist circumference

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This enzyme catalyses dis-mutation of highly reactive superoxide anion to O₂ and less reactive H₂O₂.

It requires metal co-factors like Cu/Zn/Mn/Fe. In humans Cu / Zn SOD is present in cytosol, while Mn SOD is present in mitochondria. There also exists a third form of SOD in Extracellular fluid (ECF) that contains Cu & Zn in its active site. The mitochondrial form of SOD is biologically important. SOD is measured by the Worthington method using inhibiting enzyme by oxygen dependent reaction ^[13].

It is generated from reactive oxygen species (ROS). MDA is reactive and potentially mutagenic, found in heated edible oils like sunflower and Palm oil ^[14]. MDA condenses with two molecules of thiobarbituric acid to give fluorescent red derivative that can be assayed spectrophotometrically ^[15].

The aim of the present study is to identify persons with obesity using BMI/Waist circumference and measure biochemical parameters like fasting blood glucose (FBS), lipid profile, SOD and MDA levels.

2. Materials & Methods

A total of twenty-five subjects (16 males & 9 females) aged >35 years were included in the study. All the study groups including the controls were attending Chalmeda Anand Rao Institute of Medical Sciences (CAIMS) Hospital, Karimnagar, Andhrapradesh, India.

BMI >26 Kg/m^2.

Waist Circumference men > 102cm.

History of obesity in family, diabetes.

Hepatic diseases.

Hepatic diseases.

Renal disorders.

Cardiovascular problems.

Blood samples are collected (5ml) after 12 hours of fasting and were dispensed into a clean dry test tube (3ml), fluoride coated tube (1ml) and EDTA coated tube (1ml). The lipid profile and FBS were performed in fully automated analyzser (BS 300 MINDRAY); SOD and MDA were measured spectrophotometrically.

3. Results

The FBS values of the study subjects were divided into two groups; those having history of diabetes and those who were obese (BMI/Waist circumference) which included both males and females were compared. The mean ± SD values of FBS of samples with history of diabetes (146.3 ± 11.68) and without history of diabetes (95 ± 4.02) compared to controls (88.33 ± 6.78) was statistically significant (p < 0.001). The antioxidant enzyme levels in study groups and controls were SOD (50 ± 4.96) (100 ± 4.62); MDA (619.12 ± 0.91) (240.4 ± 1.14). The comparison of lipid profile of study subjects with controls was also significant (p < 0.001). The detailed values of all the parameters are shown in (Table 2) & (Table 3).

Table 2. The mean ± SD values of all the parameters of the study subjects

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Table 3. The mean ± SD values of all parameters among control subjects

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4. Discussion

The tissues are protected from oxidative injury by expressing stress- response genes and genes coding for anti-oxidant enzymes and also by activating transcriptional regulatory proteins. The anti-oxidant defense system helps in maintaining normal cellular physiology, prevents diseased condition and also promotes immunity ^[16]. In normal healthy individuals there is always redox homeostasis occurring in cell, and any imbalance to this redox homeostasis leads to oxidative stress (OS). OS contributes to over production of ROS and impairs antioxidant defense mechanism ^[17].

Obesity increases the OS by the following mechanisms. (myocardium ^[18], cell injury ^[19], lipid per oxidation ^[20]).

All these mechanisms lead to stimulation of antioxidant enzymes but over a period of time the stores of antioxidant enzymes are depleted and cannot cope with increasing OS ^[21]. In obesity there is excess adipose tissue which contains fatty acids as triglycerides. The enhanced sympathetic state of obesity in turn stimulates lipolysis, releasing excessive quantities of free fatty acids. This leads to lipo toxicity and OS in endoplasmic reticulum and mitochondria. These increased free fatty acids (FFA) inhibit lipogenesis; thus increases triglycerides in serum leading to hypertriglyceridemia ^{[22, 23, 24, 25]}.

In the present study there is increased MDA levels (p < 0.001) in obese individuals due to lipid per oxidation and SOD levels were decreased (p < 0.001) which indicates decline of antioxidant defense capacity among obese individuals. The study results also confirm the altered lipid metabolism in obese individuals.

5. Conclusion

From this study we conclude and re-emphasize the role of obesity in the development of oxidative stress and disturbed lipid metabolism. Therefore early detection of obesity i.e., by BMI / waist circumference or predisposing genetic factors and regular assessment of biochemical parameters including oxidative stress markers is required to minimize the complications arising from type 2 diabetes and obese individuals to increase the life expectancy.

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