Induction of Apoptosis in HT-29 Cells by Extracts from Isothiocyanates-rich Varieties of Brassica Oleracea

Abstract:

Among the vegetables with anti-carcinogenic properties, members of the genus Brassica are the most effective at reducing the risk of cancer. This property may be explained by their principle bioactive compounds, isothiocyanates (ITCs). The aim of this study was to measure the amounts of ITCs in extracts from vegetables of the Brasssica genus and assay them for potency of induction of apoptosis in a colorectal cancer cell line (HT-29). ITCs were determined by the cyclocondensation assay with 1,2-benzenedithiol and induction of apoptosis by assessment of cell viability, caspase-3 activity and DNA fragmentation. Purple cabbage extract showed the highest ITC concentration per gram, fresh weight, followed by black cabbage and Romanesco cauliflower. At ITC concentrations of 7.08 μ g/mL these extracts decreased cell viability and induced caspase-3 and DNA fragmentation at 48h. Brussels sprouts showed the strongest effects on cell viability and caspase-3 activity. Varieties of Brassica Oleracea are rich sources of ITCs that potently inhibit the growth of colon cancer cells by inducting apoptosis. All the extracts showed anticancer activity at ITC concentrations of between 3.54 to 7.08 μ g/mL, which are achievable in vivo. Our results showed that ITC concentration and the chemopreventive responses of plant extracts vary among the varieties of Brassica Oleracea studied and among their cultivars.

Acknowledgments and Notes

The authors thank Dr. Josefa Ros of the Cell Culture Service, CDB/IDIBAPS, Hospital Clínico, Barcelona for her advice; and Mr. Josep Faura, manager of the Mercabarna fruit and vegetable market and Mr. Lluís Macià of the Ninot market (Barcelona) for their help in obtaining the varieties of vegetables. This study has been funded by the Danone Institute.

Notes

¹Concentration in the extract.

²Concentration in the vegetable per gram of fresh weight (FW).

¹ITC concentration categories: High ≥ 880; Medium ≥ 350 < 880; Low < 350 μ g/mL in the extract.

²Monofunctional induction categories: High ≥ 4; Medium ≥ 2 < 4; Low ≥ 1.5 < 2 OR of NQO1 activity vs. non-treated cells (5).

³Caspase-3 induction categories; High ≥ 6; Medium > 1.5 < 6; Low ≤ 1.5 OR of caspase-3 activity vs no treated cells.

⁴Other compounds that could explain differences between varieties or cultivars.