Thesis Abstract

Medicinal plants have been assumed to be good in detoxifications because they contain bioactive compounds capable of doing this. However, some plants are very toxic to both humans and animals with the potential of damaging certain organs in the body. Many plant-derived substances, collectively termed “phytochemicals,” are becoming increasingly known for their antioxidant activity. This study is aimed at investigating the toxic and as well as the antioxidant profile of methanol extract of Senna siamea leaves, extensively used in Nigeria folk medicine to manage various ailments. The potent metabolites were quantified using standard methods and the antioxidant scavenging potentials of the extract on DPPH and superoxide radicals were also determined. Both acute and sub-acute toxicity profile were evaluated by determining the LD50, liver and kidney function tests, which was then correlated and confirmed with histopathologic techniques of hepatocytes and kidney cells. Furthermore, haematological parameters of the test rats were determined. The qualitative phytochemical screening of the leaves of S. siamea revealed the presence of proteins, carbohydrates, tannins, alkaloids, steroids, glycosides, flavonoids, reducing sugars, terpenoids and quinones in the leaves. The result of these tests also indicates that tannin, carbohydrates, reducing sugar, terpenoids, alkaloids, total phenols, glycosides and flavonoids were contained in various amounts when quantified. The antioxidant vitamin contents of the extract was also quantified and this showed that vitamin E was significantly higher (p< 0.05), (181.70±2.47 mg/100g) when compared to vitamin A (40.35±13.60 mg/100g) and vitamin C (4.11±0.06 mg/100g). The extract scavenged DPPH and superoxide radicals in concentration dependent manner. The EC50 of DPPH., superoxide radical were 12.59±0.00 and 39.38±0.01 respefreeresearchproject.com.ngctively. Acute toxic test shows no death was observed in any group of the mice used, indicating that the extract could be tolerated by the mice at 5000mg/kg bw, the highest concentration used. The liver marker enzymes AST and ALP showed significantly increased (p<0.05) in their serum activity while ALP activity showed no significant changes (p>0.05) when compared to the control. Furthermore, bilirubin concentration were significantly increased (p<0.05) during the 3rd and 4th week of administration of extract to the 4th group. The kidney function test showed a significant increase (p<0.05) in creatinine concentration was observed in the first and second week. A significant increase (p<0.05) in serum urea concentration was observed in the 1st week of group 4. The result of the blood electrolytes showed no significant difference (p>0.05) in sodium ion but significant changes (p<0.05) were observed in the levels of Potassium and chloride ion. The hematological parameters (White Blood Cell, Hemoglobin and packed cell volume) did not produce any significant changes (p>0.05). Significant reduction (p< 0.05) was observed in catalase activities of the 2nd and 3rd weeks of extract administration. These results obtained indicate that the extract could be toxic to hepatocytes and kidney cells at higher concentration.

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