Use this URL to cite or link to this record in EThOS:
Title: Evaluation of plant extracts for anticancer potential in in vitro assays using colon cancer cell-lines
Author: Borkowski, Tomasz
ISNI:       0000 0004 2721 5108
Awarding Body: University of Ulster
Current Institution: Ulster University
Date of Award: 2009
Availability of Full Text:
Access from EThOS:
Colorectal cancer is one of the most prevailing cancers worldwide with particularly high incidence and mortality rates in the Western countries. Compelling evidence indicates that diet is considered as an important etiological factor of colorectal cancer risk. Consumption of vegetables has been shown in numerous epidemiological, case-control and prospective studies to be inversely associated with the pathogenesis of several cancers including cancers of colon and rectum. Leguminous and cruciferous vegetables abundant in every day diet are a rich source of many bioactive compounds. Some of those phytochemicals such as glucosinolates and their derivatives, flavonoids - especially isoflavones and saponins have been demonstrated to be potent chemoprotective agents with an ability to inhibit carcinogenesis. Recently, sprouting seed of many plants has been popularized as a healthy and nutritious food plentiful in proteins, minerals, vitamins and a range of phytochemicals. The germination process results in significant increases in concentrations of particular compounds as compared to the mature plants and may contribute to enhanced anticancer activity of sprouts. The focus of this study was primarily to evaluate the anti-cancer effects of the extracts prepared from leguminous (alfalfa, red clover) and cruciferous (Raab broccoli, Daikon radish) sprouts on key stages of colon carcinogenesis, namely initiation, promotion and invasion using in vitro model systems. The shoots were investigated as a commercial product - BroccoShoots sprouts mixture which were processed following extraction methods to obtain crude juice, methanol and in vitro digested extracts to assess how changes in the chemical characteristics could affect the biological activity of the samples. BroccoShoots extract at the highest concentrations (100, 150, 200 ug/ml) inhibited growth of CaCo-2 cells. At non-toxic range of concentrations (0 - 50 ug/ml) BroccoShoots extracts reduced H202 induced DNA damage in CaCo-2 cells and significantly inhibited migration and invasion of the HT115 cell-line. These effects appeared to be stronger for the crude juice extracts than for the other two types of extracts. There were no evident changes in the epithelial integrity of CaCo-2 cells (measured as trans-epithelial electrical resistance) and in cell cycle progression (24 hours) after exposure to the extracts. Then individual plants were prepared as crude juice extracts to examine the extent to which particular species contributed to the overall activity of the mixture. It was found that anti-genotoxic, anti-proliferative, anti-migrative and anti-invasive effects observed for Daikon radish extracts were the highest among all individual sprouts. Further, Daikon radish extracts at non-toxic concentrations (35, 50 ug/ml) were shown to induce G2/M phase cell cycle arrest in CaCo-2 cells and significantly reduce cell proliferation (over 144 hours) due to cytostatic effects. Thus, it was postulated that anti- cancer effects exerted by BroccoShoots mixture were mainly mediated by activity of Daikon radish extracts. These results demonstrate that sprouts and notably Daikon radish sprouts were effective in inhibiting several stages of colon carcinogenesis in vitro. Also, hypothesis was proposed that lymphocytes could be used as a surrogate biomarker of colonic tissue in assessment of DNA hypermethylation status of genes involved in colon carcinogenesis and that supplementation with folate rich watercress could affect promoter methylation of these genes. However, no detectable levels in promoter methylation ofp16INK4a, MGMT, CDX-2 and C-Myc genes were found in lymphocytes from healthy volunteers. Moreover, there was no evidence that watercress consumption could change methylation status of investigated genes. This indicates that lymphocytes may not be a suitable marker for measurement of DNA hypermethylation in the selected genes.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available