The suppressive effect of S-
methyl methanethiosulfonate (
MMTS) on
aflatoxin B1 (AFB1)- or
methyl methanesulfonate (MMS)-induced
chromosome aberrations (CA) in rat bone marrow cells was studied.
MMTS significantly suppressed CA induced by both AFB1 (an indirect-acting
carcinogen) and MMS (a direct-acting
carcinogen). Suppression was observed at all periods (6, 12, 18, 24 and 48 h) after AFB1 or MMS treatment and in all doses of AFB1 (5, 10 and 20 mg/kg) or MMS (50, 75 and 100 mg/kg) investigated. AFB1-induced CA was potently suppressed by
MMTS given between 2 h before and 6 h after the AFB1 injection. The suppression of AFB1-induced CA by
MMTS paralleled the dose of
MMTS when
MMTS was given in a dose range of 1-20 mg/kg
body weight. MMS-induced CA was potently suppressed by
MMTS given between 2 h before and 2 h after the MMS injection. The suppressive effect of
MMTS on MMS-induced CA paralleled the dose of
MMTS when
MMTS was given in a dose range of 1-15 mg/kg
body weight.
Diphenyl disulfide, which modifies -SH groups in
proteins like
MMTS, also significantly suppressed both AFB1- and MMS-induced CA. Although other mechanisms are not excluded, the suppression of
carcinogen-induced CA by
MMTS may result from the ability of
MMTS to modify -SH groups in
proteins. The juices of cabbage and onion, which contain considerable amounts of
MMTS and
S-methyl-L-cysteinesulfoxide (the precursor of
MMTS), also significantly suppressed AFB1- or MMS-induced CA. These results suggest that
MMTS is a possible chemopreventive agent against
cancer.