ANTIMUTAGENIC EFFECTS OF TANNIC ACID ON SOMATIC AND GERM CELLS OF RATS

Abstract

There is increasing interest in identification of naturally occurring substances that may be capable in diminishing genotoxicity of the environmental carcinogens and still serve as leads for the development of novel pharmacological agents. Many such medicinal plants have hepatoprotective, neuroprotective, antiinflammatory and also antioxidant or radical-scavenging properties (Najmi et al., 2010; Zhang et al., 2010). Phenolic acids are secondary metabolites widely distributed in the plant kingdom and they come in the second priority after flavonoids in terms of their dominance. Tannic acid is a plant polyphenol which is found, along with other condensed tannins, in several beverages including red wine, beer, coffee, black tea, green tea, and many foodstuffs such as grapes, pears, bananas, sorghum, black-eyed peas, lentils and chocolate (Erexson, 2003; Bennett et al., 2010). Similar to many polyphenols, tannic acid has been shown to possess antioxidant (Ferguson, 2001; Wu et al., 2004; Andrade et al., 2005), antimutagenic (Ferguson, 2001; Chen and Chung, 2000) and anticarcinogenic properties (Huang et al., 2010; van der Logt et al., 2003). The antioxidant mechanism of tannic acid is still far from being fully understood; therefore, it requires further investigation. For example, in the presence of copper ions, tannic acid acts either as a prooxidant, promoting DNA damage (Ferguson, 2001; Khan et al., 2000), or as an antioxidant, suppressing hydroxyl radical formation (Andrade et al., 2005). Tannic acid is always used as a food additive. Its safe dosage ranges from 10 to 400 mg, depending on the type of food to which it is added (Chen and Chung, 2000). Also, several authors have demonstrated that tannic acid and other polyphenols have antimutagenic and anticarcinogenic activities (Ferguson, 2001; Andrade et al., 2005; Huang et al., 2010; van der Logt et al., 2003). Moreover, the consumption of polyphenol-rich fruits, vegetables, and beverages, such as tea and red wine, has been linked with inhibitory and preventive effects in various human cancers and cardiovascular diseases, which may be related-at least in part-with the antioxidant activity of polyphenols (Andrade et al., 2005). Phenolic acids have been shown to be anti-oxidant and it is a potent antagonist of the mutagenicity of polycyclic aromatic hydrocarbons (PAHs) such as benzo(a)pyrene (BaP) (Mansour et al., 2007). Benzo(a)pyrene is a semi-volatile, lipophilic, high molecular weight compound that belongs to the polycyclic aromatic hydrocarbon (PAH) family. Benzo(a)pyrene and other PAHs are products of combustion and can accumulate in crops via absorption from contaminated soils (ATSDR, 1995). Exclusive sources for BaP contamination of the environment and consequently human exposures include industrial and automobile emissions, hazardous waste sites, cigarette smoke, biomass burning, municipal incinerators, volcanic eruptions, home heating, and consumption of charcoal broiled and smoked foods (ATSDR, 1995; WHO, 1998). Food ingestion and inhalation are the major routes of entry into the human body for a large section of the general population exposed to PAHs (Ramesh et al., 2004). The previous experimental data has shown that PAHs must be metabolically activated by peroxy radical dependent pathway and the electrophilic bay-region diol-epoxides act as the ultimate carcinogenic metabolites of PAH (Li et al., 2004). This study aimed to investigate the multifunctional antioxidant properties of tannic acid on BaP-induced genotoxicity in somatic and germ cells of rats.