Antimicrobial effects on Porphyromonas gingivalis by KAMPO (traditional Japanese herbal medicine) formulas containing Rhei rhizoma, and its active components
Chronic periodontitis is not only an inflammatory disease that destroys the tooth-supporting tissues, but also the risk factor affecting certain chronic systemic diseases. Porphyromonas gingivalis (Pg) is one of the most important pathogens in severe adult periodontitis. Although some Kampo formulas are used to treat tooth ache or oral inflammation, it is not clear whether they are effective to treat periodontitis. In this study, the 128 traditional Kampo preparations, which are registered prescription medicines with the Japan Kampo Medicines Manufacturers Association  and the national health insurance, were examined for their antimicrobial effects on Pg using the paper-disk method. The preparations were purchased from Tsumura & Co. in the form of “ekisu”, a traditional decoction according to Japanese Pharmacopoeia (JP), subsequently spray dried and packed in aluminium covered plastic sachets. In general, a single dose (2.5 – 6.0 g) of these “ekisu” are recommended to be dissolved in 50 – 100 ml hot water, for oral intake. Therefore, the sample solutions were prepared by dissolving 2.5 – 6.0 g of “ekisu” in 50 ml of hot water with sonication. For each disk, 40 µl of the sample solution was added. As a result, 16 Kampo preparations showed remarkable anti-Pg activities. All of them contained Rhei rhizoma, and the intensity was proportional to the amount of Rhei rhizoma in the respective formulation. The strongest was Daiokanzoto  (“Daio” in Japanese is Rhei rhizoma). In JP, Rhei rhizoma is the rhizome of Rheum palmatum, R. tanguticum, R. officinale, R. coreanum or their interspecific hybrids. The MIC (minimum inhibitory concentration) and MBC (ninimum bactericidal concentration) of Daiokanzoto were 156 and 625 µg/ml, respectively. Rhein (MIC and MBC; 0.25 and 31.3 µg/ml), and aloe-emodin (0.12 and 3.9 µg/ml) were found to be the main anti-Pg components of Rhei rhizome, and were more effective than triclosan (15.6 and 15.6 µg/ml), a well-known anti-Pg agent.
Keywords: periodontitis, Porphyromonas gingivalis, Kampo, Rhei rhizoma, Daiokanzoto, Rhein, aloe-emodin, triclosan
 Japan Kampo Medicines Manufactureres Accociation (JKMA), Kampo Formulations for Prescription 2012 -Information in Package Inserts of 148 Formulations -, http://www.nikkankyo.org/kampo/info_pi_english/introduction.pdf
 Tsumura & Co., TSUMURA Daiokanzoto Extract Granules for Ethical Use, http://www.tsumura.co.jp/english/products/pi/JPR_T084.pdf