*1.1.1.2.5 Glutathione (GSH and GSSG)*

Glutathione, which eliminates the effects of harmful compounds in the body, is found in all cells. GSH is reduced glutathione and serves as a substrate for antioxidant enzymes by acting as a radical scavenger during radical cell damage. Glutathione is a very important molecule, especially for the activities of peroxidase and reductase enzymes. GSSG is produced by the oxidation of GSH. During oxidative stress, GSH levels are decreased, and the GSSG levels are increased. H2O2 and organic hydroperoxides, which are produced during oxidative stress, are removed by the action of glutathione peroxidase and glutathione reductase [25].

**115**

*Antioxidants and Periodontal Diseases DOI: http://dx.doi.org/10.5772/intechopen.81815*

*1.1.1.2.6 Cysteine*

less teeth [30].

*1.1.1.2.7 Uric acid*

*1.1.1.2.8 Glucose*

*1.1.1.2.9 Albumin*

*1.1.1.2.10 Bilirubin*

*1.1.2.1 Vitamin A*

*1.1.2 Exogenous antioxidants*

association being stronger in severe disease [37].

been demonstrated [34].

processes, thus damaging the periodontium [28].

GSH plays a critical role in keeping enzymes and other cellular components from being reduced. Most of the GSH is synthesized in the liver, and approximately 40% of GSH is excreted through bile. It is suggested that the GSH in the bile protects the body against dietary xenobiotics, prevents lipid peroxidation in the lumen of the intestine, and defends the intestinal epithelium against oxygen radicals [27]. Glutathione is the most important redox regulator that controls inflammatory

Cysteine is a superoxide and hydroxyl radical scavenger [29]. The measurement of salivary cysteine may be useful for identifying periodontitis patients with hope-

Uric acid, which is synthesized as the final product of purine metabolism, functions as an endogenous free radical scavenger and antioxidant. It is found in body fluids at a concentration of approximately 0.5 mmol/L [31]. In a recent study, uric acid levels in periodontitis patients have been found to be higher than in gingivitis patients. Moreover, uric acid has many roles in periodontitis than in gingivitis as an antioxidant agent [32].

Glucose is a hydroxyl radical scavenger [33]. The relationship between the periodontal disease and the blood glucose level among type II diabetic patients has

It defends against free radicals and is therefore regarded as an important part of the extracellular antioxidant defense system [22]. An inverse relationship between the serum albumin concentration and the chronic periodontal disease has been evaluated [35].

Bilirubin is an important scavenger of peroxyl radicals [36]. Serum concentrations of bilirubin were found to be inversely associated with periodontitis and the

Carotenoids are recognized as substances that give color to vegetables and fruits, and their antioxidant effects as vitamin A precursors are well-known. Most important carotenoids are α-carotene, β-carotene, lycopene, crocetin, canthaxanthin, and fucoxanthin. β-carotene is a combination of two molecules of vitamin A (also known as retinol). When dietary β-carotene is absorbed by the small intestinal mucosa, it is converted into retinol [5, 38]. Retinol and other retinoids have potential hormone-like effects on cell growth and differentiation [39]. It has been reported that in the case of retinol deficiency, predisposition to

some types of cancer including oral cavity cancer is increased [40].

#### *Antioxidants and Periodontal Diseases DOI: http://dx.doi.org/10.5772/intechopen.81815*

GSH plays a critical role in keeping enzymes and other cellular components from being reduced. Most of the GSH is synthesized in the liver, and approximately 40% of GSH is excreted through bile. It is suggested that the GSH in the bile protects the body against dietary xenobiotics, prevents lipid peroxidation in the lumen of the intestine, and defends the intestinal epithelium against oxygen radicals [27]. Glutathione is the most important redox regulator that controls inflammatory processes, thus damaging the periodontium [28].
