Nutr Cancer. 1997;28(2):184-8.  

Modulation of phase I and phase II xenobiotic-metabolizing enzymes by
selenium-enriched garlic in rats.

Ip C, Lisk DJ.

Department of Surgical Oncology, Roswell Park Cancer Institute, Buffalo, NY
14263, USA. cip@sc3101.med.buffalo.edu

Previous research showed that treatment with selenium-enriched garlic
(Se-garlic) was able to inhibit the initiation phase of mammary carcinogenesis
in the dimethyl-benz[a]anthracene (DMBA) model in rats. The present study was
designed to investigate the following parameters: 1) DMBA-DNA adduct formation
in liver and mammary gland, 2) urinary excretion of DMBA metabolites, 3) phase I
and phase II xenobiotic-metabolizing enzymes, and 4) tissue selenium levels as a
function of Se-garlic supplementation. Prior feeding with an
Se-garlic-containing diet (at 3 ppm Se) for two weeks resulted in a consistent
reduction of all DMBA adducts in liver and mammary gland. This was accompanied
by a 40% increase in urinary excretion of DMBA metabolites over a two-day
period. Several liver P-450 enzymes were examined in rats fed a diet
supplemented with 1, 2, or 3 ppm Se. Compared with controls receiving 0.1 ppm
Se, no significant alteration in activity was detected with respect to P-450 1A1
(responsible for DMBA activation), 1A2, 2B1, 2E1, and 3A4. In contrast,
glutathione S-transferase and uridine 5'-diphosphate-glucuronyltransferase
activities were elevated to a maximum of 2- to 2.5-fold in liver and kidney. As
expected, there was a dose-dependent elevation of selenium concentrations in
liver, kidney, mammary gland, and plasma as a function of the level of Se-garlic
supplementation. Our data seem to suggest that an increased detoxification of
carcinogen via the phase II conjugating enzymes might represent a mechanism of
tumor suppression by Se-garlic.

PMID: 9290126 [PubMed - indexed for MEDLINE]