Evaluation of Hepatoprotective Effect of Aqueous Extract of Bitter Kola (Garcinia Kola) Seeds on Carbon Tetrachloride (Ccl4) Induced Liver Damage in Adult Wistar Rat.
CHAPTER ONE
Objectives of the study
- To evaluate the hepatoprotective effect of aqueous extract of bitter kola seeds on CCL4– induced hepatic toxicity using established hepatoprotective drug, silymarin as a standard.
- To investigate the histological changes of the liver resulting from oral consumption of Garcinia kola extract using H & E stain.
- To investigate the activities liver enzymes (ALT, AST, ALP, SOD, GSH and CAT) using biochemical techniques.
CHAPTER TWO
Literature Review
The Liver
The liver is the largest organ in the body. It weighs approximately 1500g and accounts for one- fortieth of the adult body weight. It lies on the right and left upper quadrants inferior to the diaphragm which separates it from the pleura, lungs, pericardium and heart (Dalley and Moore, 1999). The liver is divided into a larger right and a smaller left lobe, separated superiorly by the falciform ligament and posterior-inferior by an H-shaped arrangement of fossae` (Ellis, 2006).
Functional Parts of the Liver
The liver has functionally independent right and left parts that are approximately equal in size (Dalley and Moore, 1999). Each part has its own blood supply from the hepatic artery and portal vein, and its own venous and biliary drainage. On the visceral surface, the right part of the liver is demarcated from the left by the gall bladder fossa inferiorly and the fossa from the inferior vena cava superiorly (Dalley and Moore, 1999; Ellis, 2006). An imaginary line over the diaphragmatic surface of the liver that runs from the fundus of the gall bladder to the inferior vena cava separates the two parts which includes the caudate and quadrate lobes (Dalley and Moore, 1999).
Porta Hepatis
The porta hepatis is a transverse fissure on the visceral surface of the liver between the caudate and quadrate lobes, where the portal vein and the hepatic artery enter the liver and the hepatic ducts leave. The porta hepatis gives passage to the portal vein, hepatic artery, hepatic nerve plexus, hepatic ducts and lymphatic vessels (Dalley and Moore, 1999).
CHAPTER THREE
Materials and Methods
Plant Material
Garcinia kola seeds were obtained from the Samaru Market in Zaria, Kaduna, Nigeria and was authenticated at the Department of Biological Sciences, Faculty of Sciences, Ahmadu Bello University, Zaria, Nigeria and a voucher number (1783) was obtained.
CHAPTER FOUR
Results
Physical Observation of Animals
During the period of administration of the aqueous extract of Garcinia kola seed, all the experimental animals (Wistar rats) were observed to exhibit normal physical activity. Weight changes were observed in the experimental animals before (day 1) and after (day 14) the experiment, with their weight differences.
Table 4.1 shows body weight changes in experimental animals using one way ANOVA. Weight changes were observed in the groups. Increase in body weights of animals were observed in group I (control), group III (Sil + CCl4), group IV (extract high) and group VI (extract low + CCl4). However, results revealed that animals in groups II (CCl4) and V (extract high + CCl4) exhibited decrease in body weight.
There was significant decrease (p<0.05) in the body weight of group II animals when compared to control. However, results revealed significant increase (p<0.05) in body weights of animals in groups III, IV, and VI when compared to CCl4.
CHAPTER 5
Discussion
Physical Observation
Changes in body weight have been used as an indicator of adverse effect of drugs and chemicals (Mukinda and Syce, 2007). Physical observation of the experimental animals (Wistar rats) revealed changes in the body weights. Marked decrease in the body weight observed in the CCl4 treated group (group II) was as a result of the toxic effects of CCl4 administration. This is in agreement with previous studies on the toxic effect of CCl4 (Obi et al.; 1998; Nevien, 2012).
The observed increase in weight of group I (control) animals is weight increase due to growth. Decrease in body weights of animals treated with CCl4 (group II) and high dose extract + CCl4 (group V) suggests treatment related intoxication. This can also be attributed to the fact that animals in these groups might have reached their peak age (adults), hence the decline in weight.
Observed increase in body weights of extract low + CCl4 treated group (group VI) suggest that the extract is partially potent against CCl4 toxicity. Several studies in relation to herbal and folk medicine reported the hepatoprotective effect of plants against CCl4 – induced hepatotoxicity (Prakesh et al., 2008; Biswas et al., 2010; Osman et al., 2011; Sahreen et al., 2011). This finding is in accordance with the report on the hepatoprotective potential of Garcinia kola extract against CCl4 toxicity (Adaramoye, 2010).
The marked increase in body weight of the extract high group (group IV) shows the extract is safe at this dose (800mg/kg) and does not affect body weight. Reports on the acute toxicity of kola stated non-toxicity at a dose greater than 900mg/ kg and a lethal dose of 6741.43mg/ kg (Duze et al., 2011; Udenze et al., 2012). Observed increase in body weights of the group treated with silymarin + CCl4 implies the protective effect of silymarin as a standard hepatoprotective drug (Prakesh et al., 2008).
CHAPTER SIX
Summary, Conclusion and Recommendation
Summary
The hepatoprotective role of aqueous extract of bitter kola (Garcinia kola) seed on CCl4 induced liver toxicity was conducted using adult Wistar rats.
Aqueous extract of Garcinia kola seeds showed hepatoprotection against CCl4 induced hepatotoxicity through the following mechanisms:
- Aqueous extract of bitter kola seeds showed hepatoprotection on histological sections of the liver in group treated with the extract
- Preservation of the reticular fibres
- Reduction of liver enzyme markers in the serum (ALT, AST and ALP).
- Reduction of oxidative stress through increase in antioxidants (SOD, GSH and CAT).
Conclusion
In conclusion, medicinal plants are essential source of nutrition and the prevention of human diseases. However, their phytochemicals and action mechanisms are poorly understood. Administration of aqueous seed extract of Garcinia kola significantly protected the biochemical and histological alteration to near normal level in liver toxicity-bearing animals and substantially inhibited the liver toxicity incidence in pre-treated groups. From the results it can be inferred that aqueous Garcinia kola seed extract (bitter kola) positively modulated antioxidant activity by reducing and detoxifying the free radicals tissue injuries induced by CCl4.The marked decrease in the levels of lipid peroxides recorded in rats pretreated with Garcinia kola seeds suggest that the seed possess the natural antioxidants necessary for protection against free radical damage induced by CC14 in rat liver.
Garcinia kola seeds extract showed prophylactic effects on the hepatocytes and reticular fibres of the liver. Its effects in CCl4 induced liver damage in rats are mediated through anti- oxidation.
From this study it can be concluded that the aqueous extract of the seeds of Garcinia kola protects liver against oxidative damages and could be used as an effective protector against CCl4 induced hepatic damage.
Recommendation
- Further studies are required to investigate the specific mechanism of action of Garcinia kola seed
- Other methods of extraction of the plant (Garcinia kola) seeds should also be investigated
- Therapeutic principle involved in hepatoprotection and hepatic gene expression to identify the genes responsible for the protective mechanism.
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