Antioxidants vs carotenoids. Inhibitors or promoters of experimental colorectal cancers.
The organospecific, 1,2-dimethylhydrazine-induced murine tumor model was used to test the effects on tumor formation of the following dietary supplements: (1) ascorbic acid, 7% per weight; (2) alpha tocopherol, 1% per weight; (3) beta carotene, 1% per weight; and (4) canthazanthin, 1% per weight. Following a four-week dietary acclimation, a 16-week 1,2-dimethylhydrazine induction, and a four-week hiatus, the animals were killed, underwent autopsies, and tumor formation was recorded. The antioxidant supplements of ascorbic acid and alpha tocopherol resulted in a significant decrease in tumor formation when compared with control groups. In contrast, the beta carotene group showed no difference in tumor formation, and canthazanthin, a non-provitamin A carotenoid, resulted in an increase in tumor formation when compared with controls. In addition, the K-gel powder control diet (a carrier medium for alpha tocopherol acetate) had a significantly higher rate of tumor formation than the regular chow and placebo beadlet control diets. In sum, ascorbic acid and alpha tocopherol demonstrated a clear chemopreventive effect, whereas beta carotene had no effect, and canthazanthin appeared to function as a promoter in this organospecific tumor model.
Colacchio
T A
TA
Department of Surgery, Dartmouth Medical School, Hanover, NH 03755.
Memoli
V A
VA
Hildebrandt
L
L
D019813:1,2-Dimethylhydrazine; D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage*; D001205:Ascorbic Acid / Q000008:administration & dosage; D016644:Canthaxanthin; D002338:Carotenoids / Q000008:administration & dosage* / Q000031:analogs & derivatives; D015179:Colorectal Neoplasms / Q000139:chemically induced / Q000517:prevention & control*; D004127:Dimethylhydrazines; D008297:Male; D051381:Rats; D014810:Vitamin E / Q000008:administration & dosage; D019207:beta Carotene
D000975:Antioxidants; D004127:Dimethylhydrazines; D019207:beta Carotene; D014810:Vitamin E; D002338:Carotenoids; D016644:Canthaxanthin; D019813:1,2-Dimethylhydrazine; D001205:Ascorbic Acid