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Title: Cytotoxic, antioxidative and anti-human papillomavirus (HPV) activities of selected Allium SPP.
Authors: Chan, Pek Yue
Keywords: Anti-human papillomavirus
HPV
Selected Allium SPP.
Cytotoxic
Antioxidative
Issue Date: 2008
Publisher: University Malaya
Abstract: At the present time, the Allium genus onsists of about 1,250 species, making it one of the largest plant genera in the world. Each member of the Allium genus is distinct in their appearance, colour and taste but is similarly close in their biochemical, phytochemical and nutraceutical content. This genus is revered to possess health benefiting properties and many studies have ascertained that Alliums play an important role in the prevention and treatment of cardiovascular disease, infectious diseases and cancers. Although Alliums are widely distributed and commonly used as spices and cultivated for therapeutic purposes, limited or no comprehensive data was available on their cytotoxic, antioxidant and anti-human papillomavirus (HPV) activities of its members. Hence, the present study was taken to screen and evaluate the cytotoxic, antioxidative and anti-HPV activities of 21 crude petroleum ether, chloroform and methanol extracts of selected Alliums from the local market, namely Allium cepa L., Allium fistulosum L., A. porrum L., A. sativum L., A. ursinum L. and two variants of A. tuberosum Rottl. (i.e. bunga kuchai and daun kuchai). In the cytotoxicity study, the normal human lung cell line (MRC-5), human epidermal carcinoma of cervix HPV type-16 contained-cell line (CaSki) and human colon carcinoma cell line (HCT-116) were used to screen for the cytotoxic activities of the selected Allium spp. using the Neutral Red (NR) assay. This assay is fast, simple, accurate and sensitive in screening the toxicity of crude extracts. Crude extracts that registered effective inhibition concentration to suppress 50% cell growth in cultures (IC50) of 20.0 μg/ml or less are considered as active. All crude extracts were not active against the three cell lines; however three crude extracts managed to register an IC50 value. The antioxidative potentials of the crude Allium extracts were comprehensively evaluated using four different antioxidant bioassays namely the β-carotene bleaching inhibition assay, ferric thiocyanate (FTC) assay, 1,1-diphenyl-2-picrylhydrazyl hydrate (DPPH) radical scavenging assay and the reducing power assay. The total phenolic and flavonoid contents of the selected Allium spp. were also determined. The β-carotene bleaching inhibition assay and FTC assay were used to measure the inhibition of lipid peroxidation (LPO) and initial production of peroxides of the crude Allium extracts respectively. The DPPH radical scavenging assay was used to investigate the free radical scavenging ability of the crude extracts. The reduction of ferric ions by the crude extracts was tested using the reducing power assay. The Folin-Ciocalteau reagent and the aluminium chloride (AlCl3) colorimetric assay were respectively used to determine the total phenolic and flavonoid contents of the crude extracts. Overall, the petroleum ether extracts of the Alliums studied were most active in inhibiting LPO while the chloroform extracts of Alliums were more effective in inhibiting initial production of peroxides. The petroleum ether extracts of A. tuberosum Rottl. (daun kuchai) and chloroform extracts of both A. cepa L., and A. ursinum L. effectively scavenged DPPH radicals by registering inhibition concentration that causes a 50% decrease in the initial amount of free radicals (IC50) of 3.89 mg/ml, 4.20 mg/ml and 4.55 mg/ml respectively. The methanol extracts of Allium spp. were better reducing agents when compared to its petroleum ether and chloroform counterparts. Chloroform extracts of A. cepa L. possessed the highest total phenolic content of 820±0.00 mg GAEs/100 g sample while the methanol extracts of A. porrum L. demonstrated the highest total flavonoid content at 56.48±0.00 mg QEs/100 g sample. Based on the persistent fact that HPV type 16 is the main causal factor of cervical cancer, and that the principal gene that is responsible for HPV replication is E6, the present study attempts to evaluate the anti-HPV type 16 E6 oncoprotein activities of the selected Allium spp. against CaSki cells using the simple and rapid immunocytochemistry (ICC) technique. The results showed that 20 of the Allium extracts was tested positive of anti-HPV type 16 E6 oncoprotein activities. The results also indicated that the methanol extracts of A. porrum L. induced the expression of E6 oncoprotein with increasing concentrations of extracts used. In summary, the crude extracts of Alliums were not active against MRC-5, CaSki and HCT-116 cell lines. However, the extracts demonstrated promising antioxidative and anti-HPV type 16 E6 oncoprotein activities. Hence, the consumption of Allium spp. Can be promoted for its potential in cancer and HPV infection chemoprevention.
Description: Dissertation (M.C.S.) -- Faculty of Science, University of Malaya, 2008.
URI: http://dspace.fsktm.um.edu.my/handle/1812/509
Appears in Collections:Masters Dissertations : Science

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