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Extract of lotus root (Nelumbo nucifera rhizome) causes necrotic damage to human colorectal cancer cells in culture

Hideki Arimochi, Eiji Sawada, Keiko Kataoka, Naoyoshi Nishibori, Mari Itoh, Kyoji Morita

Lotus root (a rhizome of Nelumbo nucifera) is known to contain various bioactive phytochemicals, and traditionally used for medical treatment in East Asia. However, this plant is mainly used as a food material, and the joint part of this plant is dumped as an agricultural waste in Japan. Then, to use it as medicinal resources, the aqueous extracts were prepared from the edible and joint parts of lotus root, and the direct effects of these extracts on human colorectal cancer cells were examined. The joint part extract reduced the viabilities ofHT29 and HCT116 cells by causing the oxidative damage to these cells. The aqueous extracts prepared from both parts of lotus root contained large amounts of polyphenolic compounds, and their concentrations in the joint part extract were higher as compared with the edible part extract. Furthermore, the joint part extractwas shown to liberate hydrogen peroxide in the culture medium, which might be derived from polyphenolic compounds contained in the extract, thus suggesting that the joint part extractmay directly act on the cells as a pro-oxidant, resulting in the oxidative damage to the cells, whichmight be unexpectedlymediated through the necrotic rather than the apoptotic pathway.