FUJIKI Hirota National Cancer Research Institute, Director, がん予防研究部, 部長 (60124426)
MORI Kazuko Faculty of Pharmaceutical Sciences Okayama University, Asst., 薬学部, 助手 (20032823)
HATANO Tsutomu Faculty of Pharmaceutical Sciences Okayama University, Asst., 薬学部, 助手 (50127578)
YOSHIDA Takashi Faculty of Pharmaceutical Sciences Okayama University, Ass.Prof., 薬学部, 助教授 (20025696)
Tannins and related polyphenols which are expected to show anti-chemical carcinogenic activities were isolated from various medicinal plants of Japan and China. Inhibition of tumor promotors were also investigated.
Main plants investigated are as follows; Liquidambar formosana, Coriaria japonica, Geranium thunbergi Acer nikoense, Perilla frutescens, Rhus succedanea, Artemisia princeps, Saxifraga stolonifera, Camp to theca acuminata, Hippophae rhamnoides, Psidium guajava, Euphorbia hirta, Pyrola japonica, Rosa roxburghii, Pistacia chinesis, Bergenia purpurascens, Tibouchina semidecandra, Medinilla magnifica, Euphorbia maculata, Euphorbia supina, Diospyros kaki, Licorice,and several other species belonging to Aceracea, Labiatae, Anacardiaceae, Melastomataceae, Euphorbiaceae and Compositae (Artemisia species).
New methods such as centrifugal partition chromatography etc. were apllied to isolation of tannins from these plants.
Examples of isolated new tannins are as follows: Camp to thin A, B
, roxbin A, B, nobotanin C, E, Euphorbin A ( oligomeric hydrolyzable tannins ); hippophaenin A, B, liquidambin ( C-glucosidic tannins and related tannins ); guavin A,C,D ( complex tannins ), ascorgeraniin ( ascorbic acid-geraniin condensate); gallotannins having quinic acid ; flavonoid derivatives having tannic activities.
Most of eighteen tested compounds among these tannins and related polyphenols inhibited specific binding of [ <^3H> ] TPA to a mouse skin particulate in vitro. Among them, pentagalloylglucose and (-)-epi-gallocatechin gallate were tested for inhibition of tumor promotion in the two-stage carcinogenesis experiment in mouse skin treated with 7,12-dimethylbenz (a)anthracene (DMBA) plus teleocidin.
The treatment with pentagalloylglucose before that with teleocidin reduced the number of tumor bearing mice to about a half, and the same treatment with EGCG reduced it to about one-third. The average numbers of tumors per mouse were also markedly reduced ( to about 1/20 by the latter treatment). Less