We have reported protective effects of dietary administration of a powder "
CHRP" containing high amounts of beta-cryptoxanthin and hesperidin prepared
from a Satsuma mandarin (Cirrus unshiu Marc.) juice on azoxymethane (AOM)-
induced rat aberrant crypt foci through suppression of crypt: cell prolifer
ation and/or induction of detoxifying enzymes. In the present study, we inv
estigated the modifying effects of a commercial Satsuma mandarin (Citrus un
shiu Marc.) juice (MJ) and those of MJ2 and MJ5, which were prepared from M
J and are richer in beta-cryptoxanthin and hesperidin than MJ, on the occur
rence of colonic tumors induced by AOM in male F344 rats. Rats were given 2
weekly s,c. injections of AOM (20 mg/kg body weight) to induce colonic neo
plasms. They also received MJ, MJ2, or MJ5 as a drinking water at night for
36 weeks, starting 1 week after the last dosing of AOM. AOM exposure produ
ced colonic adenocarcinoma with an incidence of 69% and a multiplicity of 0
.76 +/- 0.57/rat at week 38, MJ, MJ2, and MJ5 administration significantly
reduced the frequency of colonic carcinoma [M]: 35% (49% reduction), p < 0.
02; MJ2: 20% (64% reduction), p = 0.0028; and MJ5: 15% (78% reduction), p <
0.00021] and multiplicity [MJ: 0.40 +/- 0.58 (47% reduction), p < 0.05; MJ
2: 0.25 +/- 0.43 (67% reduction), p < 0.005; and MJ5: 0.15 +/- 0.36 (80% re
duction), p < 0.0011, Also, the numbers of cancer cells positive for prolif
erative cell nuclear antigen (PCNA) and cyclin D1 in colonic tumors were lo
wered by these treatments. In addition, treatment with MJ, MJ2, or MJ5 sign
ificantly increased apoptotic index in colonic adenocarcinoma. These findin
gs might suggest effective chemopreventive ability of MJs, especially MJ5,
in colon tumorigenesis. (C) 2000 Wiley-Liss, Inc.