209
level of NADPH. Cadmium has a negative impact on digestion, transportation, synthesis of fatty acids, and even on the metabolism of fatty acids [38].
Arsenic
Sources and Exposure
Arsenic is naturally present in the earth’s crust and it is a very toxic element in an
inorganic form that is present in air, land, and water. Exposure of arsenic to human
beings (Fig. 13.3) is mostly through drinking contaminated water, using this contaminated water in the preparation of food and processing in the industries [40].
Arsenic contents are also found in the smoke of a cigarette. It is proved that by
smoking a single cigarette, about 0.25 μg inhalation of arsenic occurs. Arsenic can
be exposed to humans by the skin when there is the frequent use of cosmetic products [41].
Effect Arsenic on Carbohydrates Metabolism
Arsenic has the potential to inhibit the activity of hexokinase [42] production of
ATP by substituting the phosphate group of ATP with arsenate, this process is
known as arsenolysis [43]. The ability of arsenic to replace the phosphate group is
due to its structural similarity with the phosphate group [44]. This process may
occur during oxidative phosphorylation and as a result, adenosine diphosphate arsenate is produced (Fig. 13.4). Arsenic can react with glucose to form glucose-6arsenate. Similarly, when arsenic reacts with gluconate it can produce
6-arsenogluconate [45]. Trivalent arsenicals can inhibit many enzymes that participate in the metabolism of carbohydrates such as α-ketoglutarate dehydrogenase,
pyruvate dehydrogenase, and succinyl COA synthase. One of these following
enzymes, pyruvate dehydrogenase is highly sensitive to arsenic toxicity. This causes
a reduction in the production of ATP [12].
Arsenic-Induced Diabetes Mellitus
The subjects that are exposed to arsenic show similar symptoms as a patient suffering from type 2 diabetes mellitus [46].This is due to the same pathophysiology of
T2DM which is induced by arsenic toxicity (Fig. 13.4). The possible pathway
through which arsenic can induce diabetes mellitus has been well determined [47].
13 Role of Heavy Metals in Metabolic Disorders
level of NADPH. Cadmium has a negative impact on digestion, transportation, synthesis of fatty acids, and even on the metabolism of fatty acids [38].
Arsenic
Sources and Exposure
Arsenic is naturally present in the earth’s crust and it is a very toxic element in an
inorganic form that is present in air, land, and water. Exposure of arsenic to human
beings (Fig. 13.3) is mostly through drinking contaminated water, using this contaminated water in the preparation of food and processing in the industries [40].
Arsenic contents are also found in the smoke of a cigarette. It is proved that by
smoking a single cigarette, about 0.25 μg inhalation of arsenic occurs. Arsenic can
be exposed to humans by the skin when there is the frequent use of cosmetic products [41].
Effect Arsenic on Carbohydrates Metabolism
Arsenic has the potential to inhibit the activity of hexokinase [42] production of
ATP by substituting the phosphate group of ATP with arsenate, this process is
known as arsenolysis [43]. The ability of arsenic to replace the phosphate group is
due to its structural similarity with the phosphate group [44]. This process may
occur during oxidative phosphorylation and as a result, adenosine diphosphate arsenate is produced (Fig. 13.4). Arsenic can react with glucose to form glucose-6arsenate. Similarly, when arsenic reacts with gluconate it can produce
6-arsenogluconate [45]. Trivalent arsenicals can inhibit many enzymes that participate in the metabolism of carbohydrates such as α-ketoglutarate dehydrogenase,
pyruvate dehydrogenase, and succinyl COA synthase. One of these following
enzymes, pyruvate dehydrogenase is highly sensitive to arsenic toxicity. This causes
a reduction in the production of ATP [12].
Arsenic-Induced Diabetes Mellitus
The subjects that are exposed to arsenic show similar symptoms as a patient suffering from type 2 diabetes mellitus [46].This is due to the same pathophysiology of
T2DM which is induced by arsenic toxicity (Fig. 13.4). The possible pathway
through which arsenic can induce diabetes mellitus has been well determined [47].
13 Role of Heavy Metals in Metabolic Disorders