Pz. Yin et al., EXPERIMENTAL STUDIES OF THE INHIBITORY EFFECTS OF GREEN TEA CATECHIN ON MICE LARGE INTESTINAL CANCERS INDUCED BY 1,2-DIMETHYLHYDRAZINE, Cancer letters, 79(1), 1994, pp. 33-38
Three hundred Kunming mice were randomly divided;into six groups (half
males and half females in each group). Group 1 was the positive contr
ol group, Groups 2, 3, 4 and 5 were experimental groups and Group 6 wa
s used as the solvent control group. Mice in Groups 1-4 were injected
with 1,2-dimethylhydrazine (1,2-DMH) (20 mg/kg body wt.) solution subc
utaneously once a week from the 2nd week to the 20th week. From the 1s
t week to the 23rd week, mice in Groups 2, 3 and 4 were given catechin
(1 mg/mouse), catechin (2 mg/mouse) and EGCG (2 mg/mouse), respec tiv
ely, five times a week. Mice in Group 5 received only catechin (3 mg/m
ouse) five times a week from the 1st to the 23rd week. Mice in Group 6
were injected with an equal volume of 1 mmol EDTA solution subcutaneo
usly once a week from the 2nd to the 20th week. At the end of the 27th
week, all the mice were killed by cervical dislocation (Zhu, Q.H. and
Zhu, Q.F. (1991) Laboratory Animal Science, 1st edition. The Junior E
ducational publisher, Guangdong). Pathological examinations indicated
that the incidence of large intestinal cancers occurring in Group 1 wa
s 80%, significantly higher than that in Groups 2, 3 and 4 (P < 0.001)
. No tumors were found in Groups 5 and 6. This might suggest that gree
n tea has preventive effects on large intestinal cancer induction in s
pite of the different doses of catechin. Immunohistochemistry studies
showed that green tea catechins could enhance the activity of superoxi
de dismutase (SOD) in tissues.