The Table shows the amount of MeIQx formed and the comparative
mutagenicity of the basic extract in the systems with or without the addition
of xylose-lysine MRPs. The MeIQx content formed in the control group
is expressed as 100%. As 1 or 2 mg of xylose-lysine MRPs was added,
the MeiQx content was reduced to 21.4% and 14.4%, respectively. When
5 or 10 mg of xylose-lysine MRPs was added, the formation of MeIQx
in the model mixture was completely inhibited. When the dose of
xylose-lysine MRPs is within 5 mg, the more xylose-lysine MRPs are
added, the higher extent of the inhibition will be. On the other hand, the
mutagenic activity of the basic extract without MRPs is also expressed as
100%. When 1 or 2 mg of xylose-lysine MRPs was added, the mutagenic
activity of the basic extract was reduced to 93.2% and 87.2%, respectively.
In analyzing the results, when the MeIQx content is reduced, the decrease
in mutagenicity of the basic extract does not correspond to the obvious
decrease in the amount of MeIQx formed. This slightly decrease in
mutagenicity may be caused by the presence of some mutagenic substances
other than MeIQxin the basic extract. Conclusively, there is a trend of
decreasing in mutagenic activity and MeIQx content as the dose of
xylose-lysine MRPs increases. Therefore, there is an apparent correlation
between the inhibition of MeIQx formation and the addition of
xylose-lysine MRPs. In summarizing the above results, it is considered
that the addition of xylose-lysine MRPs (1 mg) can inhibit the formation
ofMeIQx in the heated model mixture of creatinine, glycine, and glucose.
With respect to the report of Jiigerstad et al.,12) some intermediates
formed in the Maillard reaction have been proved to act as the precursors
of mutagenic IQ compounds and other mutagen formation. It is considered
that sufficient xylose-lysine MRPs might inhibit or interfere with the
formation of certain Maillard reaction intermediates. Thus, further study
is required to discover the mechanism of the mutagenic IQ compound
formation via blocking or interfering with the Maillard reaction pathway.