Abstract:
Experimental studies showed that phytochemicals from Brassicaceae Cruciferae
vegetables possess anticarcinogenic properties. This association is attributed to
glucosinolates molecules, mainly isothiocyanates and indoles released upon
consumption of these vegetables. Two members of this family, namely cabbage
(Brassica oleracea, group Capitata) and kohlrabi (Brassica oleracea, group
Gongylodes) seem to share similar anticarcinogenic characteristics. The aim of this
study is to compare the effect of the ethanolic extracts of the edible parts of these two
plants on the proliferation and apoptosis of HT-29 and Caco-2 colorectal cancer cell
lines. The cytotoxicity of the extracts was assayed using the Trypan Blue Exclusion
method and the IC50 was determined to be higher in kohlrabi compared to cabbage.
Consequently, WST-1 assay was used to assess the effect of these plant extracts on
the proliferation of colorectal cancer cell lines: both extracts exhibited a sharp antiproliferative
effect in a dose and time dependent manner, even though the cell
viability recorded upon kohlrabi treatment was slightly higher. Analysis of cell DNA
content by flow cytomtery revealed the ability of both kohlrabi and cabbage extracts
to induce cell cycle arrest in HT-29 cells at the G phase and S phase in similar
patterns. Furthermore both extracts promoted apoptosis in colorectal cancer cell
lines, as revealed by Cell Death ELISA Assay, as well as Annexin/PI staining
followed by flow cytometry analysis. The apoptotic pathway seems to involve the
pro-apoptotic protein Bax and the anti-apoptotic protein Bcl-2: the expression of
these apoptotic regulatory proteins was altered upon cabbage and kohlrabi treatments
in a dose-dependent manner, with a slightly higher increase in the Bax/Bcl-2 ratio
upon treatment with cabbage extract. As a conclusion, kohlrabi should be considered,
like cabbage, among the potent anti-carcinogenic cruciferous vegetables.
