eCAM Advance Access published online on May 7, 2008
eCAM, doi:10.1093/ecam/nen026
Immunostimulation-Mediated Anti-tumor Activity of Bamboo (Sasa senanensis) Leaf Extracts Obtained Under ‘Vigorous’ Condition
1Graduate School of Science and Technology, 2Department of Microbiology, School of Medicine, Kumamoto University, 3BioDynamics Research Laboratory, Regional Cooperative Research Center of Kumamoto University and 4Laboratory of Microbiology and Oncology, Faculty of Pharmaceutical Sciences, Sojo University, Kumamoto, Japan
Traditional Japanese medicine uses the leaves of Kumaizasa bamboo extracted in hot water at 100°C. For this study, we developed a new, ‘vigorous’ extraction method involving steps at 100, 121 and 196°C. This procedure not only yielded greater amounts of extract but also with significant increase in immunostimulating activity, which induces activation of human natural killer (NK) cells, macrophages and potent induction of IL-2, IL-12 and IFN-
in tumor bearing mice. The efficacy of the extract to facilitate phagocytosis and nitric oxide production by mouse peritoneal macrophages was determined and compared with that of 1,3-β-glucan. Anti-tumor activity was evaluated in vivo in several mouse tumor models (S-180, C38 and Meth-A). Oral administration of the extracts was carried out when tumor reached size of approximately 6 mm at concentrations of 0.05% or higher. The extracts significantly suppressed tumor growth in S-180 and C38 tumor models. Overall survival was significantly prolonged in the treatment group than that of control. Activation of macrophages and NK cells by the extracts suggests that the anti-tumor efficacy of the extract is mediated by immunopotentiation. The extracts resolved into three major fractions (F-I, F-II and F-III) in Sephadex gel chromatography. Fraction F-I consists of 1,3-β-glucan and stimulated both macrophages and NK cells suggesting that it may be the primary immunopotentiating factor in suppressing cancer. Fraction F-III has potent free radical scavenging effects and may play an important role in cancer prevention. These results warrant further translation and clinical investigations.
Keywords: high-temperature/high-pressure extraction – multistep extraction – NK cell activation – macrophage activation – 1,3-β-glucan
For reprints and all correspondence: Professor Hiroshi Maeda, Laboratory of Microbiology and Oncology, Faculty of Pharmaceutical Sciences, Sojo University, 22-1, Ikeda 4-chome, Kumamoto 860-0082, Japan. Tel/Fax: +81-96-326-4114; E-mail: hirmaeda{at}ph.sojo-u.ac.jp
Received September 24, 2007; accepted March 20, 2008