280 4 Carbohydrates
(4.79)(4.80)instable compounds which undergo reactions
with other amino components. In the pres-
ence of mainly primary amines (amino acids),
aminoreductones are formed (pyrrolinones,
Formula 4.79) and in the presence of sec-
ondary amino acids, relatively stable carbocyclic
compounds (Formula 4.80).
The following compounds were detected in re-
action mixtures containing proline and hydroxy-
proline. Their formation must proceed via the
1-deoxyosones as well:
(4.81)The pyrrolidino- and dipyrrolidinohexose reduc-
tones were characterized as bitter substances
obtained from heated proline/saccharose mix-
tures (190◦C, 30 min, molar ratio 3:1; csbi:0. 8
and 0.03 mmol/l).4.2.4.4.5 Secondary Products of 4-Deoxyosones
As shown in Formula 4.38, 2-hydroxyacetyl-
furan is one the reaction products of 4-deoxy-
osone. However, this compound is preferentially
formed in carbohydrate degradation in the ab-
sence of amine components. If it is formed from
theAmadoriproduct in accordance with For-
mula 4.57, the amino acid remains in the reaction
product, producing furosine (Formula 4.82). In
the presence of higher concentrations of primary
amines, the formation of 2-hydroxyacetylfuran
(and also furosine) is significantly suppressed
in favor of the corresponding pyrrole and pyri-
diniumbetaine (Formula 4.84). The reason for
this is that the triketo structures formed from
4,5-dideoxyosone by enolization react with
primary amines, amino acids or ammonia to give
pyrrole and pyridine derivatives (Formula 4.83).(4.82)