**1.10 Green tea**

*Camellia sinensis* or green tea is a widely consumed beverage across the globe and it has antioxidant, anti-inflammatory, antiarthritic, and antiangiogenic effects. It is a mixture of polyphenols (the major class of active compounds) including catechins (also known as flavan-3-ols) which constitute about 30% (mass fraction) of green tea leaves. The major catechins in green tea are (+) -catechin, (−) -epicatechin, (−) -epigallocatechin, (−) -epicatechin-3-gallate, (−) -gallocatechin, (−) -gallocatechin gallate, and (−) -epigallocatechin-3-gallate (EGCG). EGCG is the most abundant catechin accounting for 50% of total polyphenols; thus, it is the main biological active compound of green tea [87]. However, polyphenols are not the only compounds that green tea exerts its antioxidant activity with through. The amino acid, L-theanine, in green tea accounts for 1–2% of the leaf dry weight that is synthetized in the roots of green tea and is concentrated in the leaves. Studies have reported that L-theanine protects the cell by maintaining its GSH levels in cancer and neurotoxic diseases [88]. The intake of green tea can be considered safe unless its consumption exceeds 1–2 cups a day. And higher consumption such as in attempts to lose weight resulted in hepatotoxicity [87]. At normal doses, Pérez-Vargas et al. [88] found that the main amino acid of green tea, L-theanine, reduced expression of NF-kB and downregulated IL-1β and IL-6 and the cytokines TGF-β and CTGF. Halegoua-De Marzio et al. [89] tested a single high dose of green tea (400 mg), in patients with HCV-induced cirrhosis and found that it is well tolerated by patients and beneficial for treating cirrhosis.

#### **1.11 L-Carnitine**

L-Carnitine (LC), B-hydroxy-y-trimethylaminobutyric acid, is a water-soluble molecule important in mitochondrial oxidation of fatty acids in mammalian

**133**

**Figure 4.**

*coenzyme A [90].*

*Dietary Antioxidants in Experimental Models of Liver Diseases*

metabolism (**Figure 4**). LC can exist in three different forms: as free LC, acetyl-Lcarnitine (ALC), or other carnitine esters. About 25% of carnitine is obtained from methionine biosynthesis, but most LC is provided by the diet, especially through red meat and milk consumption [91]. LC acts as a carrier of fatty acids across the inner mitochondrial membrane for β-oxidation and ATP production. Apart from its role in the lipid metabolism, LC is also a potent antioxidant, and it protects tissues from oxidative damage. Reduced concentrations of LC in the body are mostly due to the accumulating toxic metabolites and also because of lack of protein in restricted diets. Thus, LC supplementation could be useful not only to supply the tissues in presence of but also in avoiding oxidative damage as a result of increased amounts of reactive species. Since LC can easily cross the blood-brain barrier, LC supplementation may also be beneficial in preventing oxidative injury-related neurological damage and further studies are needed in order to clearly establish LC's role in

Lycopene (LYC) is an acyclic isomer of beta-carotene which has great antioxidant activities. It is synthesized by plants or autotrophic bacteria but not by animals. Red fruits and vegetables, such as tomatoes, watermelons, pink grapefruits, apricots, pink guavas, and papaya, contain LYC. Studies show that LYC consumption not only reduces the risk of cancer of many organs but also retards the growth of tumors. LYC has been shown to have protective effects on other pathologies such as cardiovascular diseases, osteoporosis, male infertility, and this action is mainly mediated by LC's ability to inhibit other toxic agents (**Figure 5**). Numerous *in vitro*

*The mitochondrial carnitine system. Abbreviations: CPT I, carnitine-palmitoyl transferase I; CACT, carnitine acyl carnitine transferase; CPT II, carnitine-palmitoyl transferase II; CAT, carnitine acyl transferase; CoA,* 

*DOI: http://dx.doi.org/10.5772/intechopen.83485*

neurological diseases [92].

**1.12 Lycopene**

#### *Dietary Antioxidants in Experimental Models of Liver Diseases DOI: http://dx.doi.org/10.5772/intechopen.83485*

metabolism (**Figure 4**). LC can exist in three different forms: as free LC, acetyl-Lcarnitine (ALC), or other carnitine esters. About 25% of carnitine is obtained from methionine biosynthesis, but most LC is provided by the diet, especially through red meat and milk consumption [91]. LC acts as a carrier of fatty acids across the inner mitochondrial membrane for β-oxidation and ATP production. Apart from its role in the lipid metabolism, LC is also a potent antioxidant, and it protects tissues from oxidative damage. Reduced concentrations of LC in the body are mostly due to the accumulating toxic metabolites and also because of lack of protein in restricted diets. Thus, LC supplementation could be useful not only to supply the tissues in presence of but also in avoiding oxidative damage as a result of increased amounts of reactive species. Since LC can easily cross the blood-brain barrier, LC supplementation may also be beneficial in preventing oxidative injury-related neurological damage and further studies are needed in order to clearly establish LC's role in neurological diseases [92].
