Hot-compressed-water decomposed products from bamboo manifest a selective cytotoxicity against acute lymphoblastic leukemia cells Hiroki Ando a , Hideki Ohba b, * , Tsuyoshi Sakaki b , Kazunori Takamine a , Yoshitaka Kamino a , Sawako Moriwaki c , Rumiana Bakalova b , Yoshimitsu Uemura d , Yasuo Hatate d a Kagoshima Prefecture Institute of Industrial Technology, 1445-1 Oda Hayato-cho, Aira, Kagoshima 899-5105, Japan b Single-Molecule Bioanalysis Laboratory, National Institute for Advanced Industrial Science and Technology, AIST-Shikoki, 2217-14 Hayashi-cho, Takamatsu, Kagawa-ken 761-0395, Japan c Laboratory of Biochemistry, Kyushu University, 6-10-1 Hakozaki, Fukuoka, Fukuoka 812-0053, Japan d Department of Applied Chemistry and Chemical Engineering, Kagoshima University, Korimoto, Kagoshima, Kagoshima 890-0065, Japan Received 24 December 2003; accepted 15 March 2004 Abstract We examined the effect of hot-compressed-water (HCW) extracted and fractionated bamboo products (named as fractions A and B) on the viability of human cultured cell lines, derived from leukemia patients and human peripheral blood lymphocytes, obtained from normal adults. Fraction A was composed of xylose, xylooligosaccharides and water-soluble lignin, determined by high- performance anion exchange chromatography and spectrophotometry. Fraction B was composed of glucose and celooligosac- charides. It was found that Fraction B expressed a negligible cytotoxic effect against leukemia cells, while Fraction A reduced markedly (in a dose-dependent manner) the viability of leukemia cell lines, derived from acute lymphoblastic leukemia (ALL)–– Jurkat and MOLT-4. Fraction A did not influence the viability of leukemia cells, derived from myelogenous leukemia (ML-2) or lymphoma (SupT-1), as well as the viability of normal lymphocytes. Furthermore, microscopic examination of ALL-derived cells treated with Fraction A showed typical apoptotic morphological changes such as a condensation of nucleus and membrane blebing, as well as phosphatidylserine (PSer) exposure on the cell surface. The effect of decomposed products of commercially available xylan against ALL-derived Jurkat cells was significantly lower than that of Fraction A. These results suggest that the cytotoxic effect of Fraction A may be attributed to apoptosis, induced by xylooligosaccharides and it is specific for ALL-derived cells. We speculate that the water-soluble lignin is an important factor, potentiating the cytotoxic effect of xylan in HCW-extracts from bamboo. Ó 2004 Elsevier Ltd. All rights reserved. Keywords: Decomposed products from bamboo; Cytotoxicity; Leukemia cell; Xylooligosaccharides 1. Introduction There is an increasing interest in dietary fibers be- cause of their benefits for health maintenance and dis- ease prevention (Kritchevsky, 1997; Faivre and Giacosa, 1998; Bingham, 1990, 1999; Jenkins et al., 2000). They are also a component of medical nutrition therapy (Kalandidi et al., 1996; Tzonou et al., 1996). Dietary fibers are a storage of cell wall polysaccharides like cellulose and pectin of plants, and they cannot be hydrolyzed by human digestive enzymes (Kay, 1982; Garcia-Peris and Amblor-Alvarez, 1999). At present, the known dietary fiber materials, which can be utilized for foods, are about 20, and they are mainly obtained from wheat and oat bran derived from cereals. Apart from wheat or oat bran, bamboo (Phyllostachys pubes- cens MAZEL) would be also an utilizable dietary fiber source, because of the similarity of the fundamental components such as hemicellulose, cellulose and lignin, Abbreviations: ALL, acute lymphoblastic leukemia; AML, acute myelogenous leukemia; LY, lymphoma; PBS ()), phosphate buffered saline (Ca 2þ and Mg 2þ free); HCW, hot-compressed-water * Corresponding author. Tel.: +81-942-81-3628/878152523; fax: +81-942-81-3690/878152523. E-mail address: h.ooba@aist.go.jp (H. Ohba). 0887-2333/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.tiv.2004.03.011 Toxicology in Vitro 18 (2004) 765–771 www.elsevier.com/locate/toxinvit