Natural plant products and their derivatives represent more than 50% of all the drugs in clinical use in the world (Ben-Eric, 2002). Dennettiatripetalaalso known as pepper fruit tree is a well-known Nigerian spicy medicinal plant. It is found in the tropical rainforest region of Nigeria and sometimes in Savanna areas (Okwu et al., 2005). It is locally called “Nkarika” by the Efiks of Calabar. The young leaves and fruits have distinctive spicy taste. The mature fruits constitute the main edible portions. Some communities in parts of Southern Nigeria also utilize the leaves and roots, in addition to the fruits for medicinal purpose. Dennettiatripetalahas been found tocontain lots of minerals, vitamins, alkaloids and trace elements which are of medicinal importance. It was also indicated that the rich presence of essential oil (oleoresins) determines the aromatic flavoring, coloring and pungent properties of pepper fruits. (Nwaoguet al., 2007) investigated phytochemical content of Dennettiatripetala and detected the presence of saponins, flavonoids, tannins and cyanogenic glycosides. The intake of flavonoids in any fruit and vegetable tends to decrease cancer risk (Neuhouser, 2004; Grafet al., 2005). Flavonoid contributes to the color of plants, their fruits and flowers. The use of medicinal plants in traditional medicine is not intended in any way to replace modern medical science but rather an aid in conventional therapy (Ben-Eric, 2002).
Carbon tetrachloride (CCl4) is an industrial chemical that does not occur naturally. Most of the carbon tetrachloride produced is used in the production of chlorofluorocarbons (CFCs) and other chlorinated hydrocarbons. It was once used widely as a solvent, cleaner and degreaser, both for industrial and home use. Today, the scientific database on the effects of haloalkanes is so vast that it is no longer employed for such purposes although it is used as a model of experimental liver injury (Weber et al., 2003).
CCl4 is a well-known hepato- and nephrotoxicant (Thrall et al., 2000; Ogeturket al., 2005), and proves highly useful as an experimental model for the study of certain hepatotoxic effects (Muriel et al., 2003; Moreno and Muriel, 2006). CCl4-induced toxicity, depending on dose and duration of exposure, covers a variety of effects. At low doses, transient effects prevail, such as loss of Ca2+ homeostasis, lipid peroxidation, release of noxious or beneficial cytokines (Kyung-Hyun et al., 2006; Muriel, 2007) and apoptotic events followed by regeneration. Other effects, with higher doses or longer exposure, are more serious and develop over a long period of time, such as fatty degeneration, fibrosis, cirrhosis and even cancer (Weber et al., 2003). In addition, acute intoxication with CCl4 at high doses, when the hepatocellular necrosis exceeds the regenerative capacity of the liver, fatal liver failure will ensue. Extreme doses of CCl4 result in nonspecific solvent toxicity, including central nervous system depression and respiratory failure and death.
This study aims at investigating the effect of ethanol extract of Dennettiatripetalaon liver and kidney antioxidant enzyme activity and malondialdehyde concentration of rats exposed to CCl4.
1.1 LITERATURE REVIEW
1.1.0 THE LIVER
The liver is the largest organ of the human body weighing approximately 1500 g, and is located in the upper right corner of the abdomen on top of the stomach, right kidney and intestines and beneath the diaphragm. The liver performs more than 500 vital metabolic functions (Naruseet al., 2007). It is involved in the synthesis of products like glucose derived from glycogenesis, plasma proteins, clotting factors and urea that are released into the bloodstream. It regulates blood levels of amino acids.
Liver parenchyma serves as a storage organ for several products like glycogen, fat and fat soluble vitamins. It is also involved in the production of a substance called bile that is excreted to the intestinal tract. Bile aids in the removal of toxic substances and serves as a filter that separates out harmful substances from the bloodstream and excretes them (Saukonenet al., 2006). An excess of chemicals hinders the production of bile thus leading to the body’s inability to flush out the chemicals through waste.
Smooth endoplasmic reticulum of the liver is the principal ‘metabolic clearing house’ for both endogenous chemicals like cholesterol, steroid hormones, fatty acids and proteins, and exogenous substances like drugs and alcohol. The central role played by liver in the clearance and transformation of chemicals exposes it to toxic injury (Saukonenet al., 2006).
18.104.22.168 FUNCTIONS OF THE LIVER
The liver has three main functions: storage, metabolism, and biosynthesis. Glucose is converted to glycogen and stored; when needed for energy, it is converted back to glucose. Cholesterol uptake also occurs in the liver. Fat, fat-soluble vitamins and other nutrients are also stored in the liver. Fatty acids are metabolized and converted to lipids, which are then conjugated with proteins synthesized in the liver and released into blood stream as lipoproteins. Numerous functional proteins such as, enzymes and blood-coagulating factors are also synthesized by the liver. In addition, the liver, which contains numerous xenobiotic metabolizing enzymes, is the main site of xenobiotic metabolism (Hogson and Levi, 2004).