Phytochemical, Antioxidant And Anticancer Evaluation Of HydroeThanolic Extracts Of CroTalaria Retusa (L.) And Codiaeum Variegatum (L.) A. Juss Parts.

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2015-11-02
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For centuries now, plants have served as a great source of compounds with pharmacological properties. Some plants like weeds and ornamentals, however, have not been fully exploited for their medicinal value. In this research, the phytochemical, total phenolic content, antioxidant and antiproliferative effect of Codiaeum variegatum, a common ornamental plant used in some parts of the world for treating psoriasis and Crotalaria retusa, a weed reported to have potential to fight tumours were assessed. Standard methods that have been accepted internationally, such as the MTT cell viability and the DPPH assays among others were used to determine the selected properties of both plants. The leaf and stem bark of C. variegatum both showed the presence of general glycosides, tannins, alkaloids, flavonoids and sterols. The seed, pod, flower, stem and leaf of C. retusa were all found to contain saponins, general glycosides, tannins, alkaloids and sterols. Anthracene glycosides were absent from all the two plants. The stem bark of C. variegatum exhibited stronger antioxidant activity with an EC50 value of 0.053±0.004 mg/mL and total phenolic content of 163.0±3.323 mg GAE/g of extract, as compared to its leaf which had EC50 value of 1.396±0.073 mg/mL and total phenolic content of 53.8±0.721 mg GAE/g of extract. With respect to C. retusa, the leaf was found to have the highest concentration of phenols (67.35±1.153 mg GAE/g of extract) and the best free radical scavenging activity with an EC50 value of 0.222±0.004 mg/mL. All the extracts induced cytotoxicity in a dose dependent manner. The antiproliferative effect of C. variegatum indicates that among the components of the plant, the stem bark is most effective in killing the breast (MCF 7), prostate (PC 3) and leukemic (Jurkat) cancer cells. Similarly, the study revealed that the stem of C. retusa exhibited the highest cytotoxicity against the selected cancer cells. However, extracts of both plants were observed to be non-selective towards cancer cells since they were equally toxic to the normal human liver (WRL 68) cells. The Hoechst staining for nuclear morphological changes and flow cytometry assays were used to confirm the apoptotic nature of the C. variegatum stem bark extract at 20 and 40 µg/mL. Further fractionation of the stem bark of C. variegatum and stem of C. retusa into petroleum ether, chloroform, ethyl acetate and hydroethanolic fractions resulted in reduction of cytotoxicity against breast (MCF 7), liver (HepG2) and leukaemic (Jurkat) cancer cell lines for almost all the fractions of both extracts. The chloroform fraction of C. variegatum stem bark, however, recorded an increase in cytotoxicity with an IC50 of 44.71±0.44 µg/mL against Jurkat. These results confirm the cytotoxicity of both plants. Further studies are required to identify the active principle
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A thesis submitted to the Department of Biochemistry and Biotechnology, Kwame Nkrumah University of Science and Technology in partial fulfillment of the requirement for the degree of Master of Philosophy (Biochemistry) College of Science.
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