Reactive dicarbonyl compounds in soft drinks....

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Olafur Pall Olafsson...

Posted: Tue May 06, 2008 9:48 pm

Guest

Non surprisingly carbonated beverages usually contain a lot of
reactive dicarbonyl compounds. The main source appears to be the high
fructose corn syrup.

Ann N Y Acad Sci. 2008 Apr;1126:72-75.
Related Articles, Links
Click here to read
Methylglyoxal: Its Presence in Beverages and Potential Scavengers.

Tan D, Wang Y, Lo CY, Sang S, Ho CT.

Department of Food Science, Rutgers University, 65 Dudley Road,
New Brunswick, NJ 08901-8529. ho at (no spam) aesop.rutgers.edu.

Nonenzymic glycation, also known as the Maillard reaction, is a
complex series of reactions between reducing sugars and amino
compounds. Previous studies have demonstrated that reactive dicarbonyl
compounds (e.g., methylglyoxal [MG] and glyoxal [GO]), formed as
intermediate products of the Maillard reaction, irreversibly and
progressively modify proteins over time and yield advanced glycation
end products (AGEs), which are thought to contribute to the
development of diabetes mellitus and its complications. Several
studies have shown that higher levels of MG are present in diabetic
patients' plasma than in healthy people's plasma. Thus, decreasing the
levels of MG and GO will be an effective approach to reduce the
formation of AGEs and the development of diabetic complications. Here,
we briefly describe our effort in searching for non- or less-toxic
trapping agents of reactive dicarbonyl species from dietary sources.
In addition, we have discovered that commercial beverages contain
extremely high levels of MG. The potential hazardous effects of
dietary MG on humans remain to be explored.

PMID: 18448797 [PubMed - as supplied by publisher]

Related Articles

* Tea polyphenol (-)-epigallocatechin-3-gallate: a new
trapping agent of reactive dicarbonyl species. [Chem Res Toxicol.
2007]
* Reaction of metformin with dicarbonyl compounds. Possible
implication in the inhibition of advanced glycation end product
formation. [Biochem Pharmacol. 1999]
* Immunological evidence that non-carboxymethyllysine advanced
glycation end-products are produced from short chain sugars and
dicarbonyl compounds in vivo. [Mol Med. 2000]
* Increase in three alpha,beta-dicarbonyl compound levels in
human uremic plasma: specific in vivo determination of intermediates
in advanced Maillard reaction. [Biochem Biophys Res Commun. 1999]
* New biomarkers of Maillard reaction damage to proteins.
[Nephrol Dial Transplant. 1996]
* >> See all Related Articles...

This quote from the full text below reports the level of methylglyoxal
in diabetic subjects compared to normal subjects. To put it into
perspective, the carbonated drinks tested in the study had
concentrations of MG ranging from about 7-14ìg/dL, which is almost as
high as the concentration reported in the blood of diabetic patients.
The exception to this were two carbonated drinks that did not contain
high fructose corn syrup but instead had aspartame as a sweetener.

"Several studies have shown that diabetic patients have higher levels
of GO and MG in their plasma than healthy individuals.5-7 In a recent
report,7 the amount of MG from diabetic patients was found to be 16-27
ìg/dL, while the amount found in normal subjects was 3.0-7.0 ìg/dL.
Thus, decreasing the levels of GO and MG may provide a useful approach
for preventing the formation of AGEs."

Here is another quote from the full text:

"The rate of MG formation is approximately 120 ìmol/d, which is about
0.1% of the flux of glucose under normal conditions measured in in
vitro red blood cells.18,19 Even with such a small fraction, MG is of
importance and a threat because of its high reactivity. MG presence in
most foods and beverages may come from sugars and lipids. Intake of MG
has been shown to induce hypertension in animal studies.20,21 Our
study on the measurement of MG levels in commercial beverages shows
that regular carbonated beverages containing HFCS have astonishing
high levels of MG."

Below is another study (not found on pubmed) that lends further
support to high fructose corn syrup being the major source of
dicarbonyl compounds in soft drinks.

Food Chemistry
Volume 107, Issue 3, 1 April 2008, Pages 1099-1105

Reactive dicarbonyl compounds and 5-(hydroxymethyl)-2-furfural in
carbonated beverages containing high fructose corn syrup

Chih-Yu Lo, Shiming Lib, Yu Wangb, Di Tanb, Min-Hsiung Panc, Shengmin
Sangd and Chi-Tang Hob

Abstract

greek small letter alpha-Dicarbonyl compounds, namely glyoxal (GO),
methylglyoxal (MGO) and 3-deoxyglucosone (3-DOG), as well as 5-
(hydroxymethyl)-2-furfural (5-HMF) were found and measured in
carbonated soft drinks (CSD). It was realized that high fructose corn
syrup (HFCS) in regular CSDs was the major source of greek small
letter alpha-dicarbonyl compounds in beverages after comparison of
levels in regular and diet CSDs. In two most commonly used HFCS
formulas, 42% and 55% HFCS, the highest level of dicarbonyl found was
3-DOG, followed by MGO, and then GO. The stability of dicarbonyls in
CSDs containing HFCS and (-)-epigallocatechin gallate (EGCG) which
were incubated at 35 and 45 °C was investigated. It was found that
EGCG decreased from 1 mg/mL to 0.5 and 0.3 mg/mL for 35 and 45 °C,
respectively, in 16 days storage. Moreover, the reactions of EGCG with
MGO, 3-DOG and 5-HMF were observed from the comparison of storage CSDs
with and without EGCG under acidic conditions.

Paul Antonik Wakfer...

Posted: Wed May 07, 2008 3:33 am

Guest

On May 7, 3:48 am, Olafur Pall Olafsson <olafurp... at (no spam) yahoo.com> wrote:

Quote:

Please either send me the full paper or quote the portions of the
study which refer to:

"Here, we briefly describe our effort in searching for non- or less-
toxic
trapping agents of reactive dicarbonyl species from dietary sources."

--Paul Wakfer

MoreLife for the rational - http://morelife.org
Reality based tools for more life in quantity and quality
The Self-Sovereign Individual Project - http://selfsip.org
Self-sovereignty, rational pursuit of optimal lifetime happiness,
individual responsibility, social preferencing & social contracting

Olafur Pall Olafsson...

Posted: Wed May 07, 2008 1:34 pm

Guest

On May 7, 1:33 pm, Paul Antonik Wakfer <p... at (no spam) morelife.org> wrote:

Quote:

On May 7, 3:48 am, Olafur Pall Olafsson <olafurp... at (no spam) yahoo.com> wrote:

Non surprisingly carbonated beverages usually contain a lot of
reactive dicarbonyl compounds. The main source appears to be the high
fructose corn syrup.

Ann N Y Acad Sci. 2008 Apr;1126:72-75.
Related Articles, Links
Click here to read
Methylglyoxal: Its Presence in Beverages and Potential Scavengers.

Tan D, Wang Y, Lo CY, Sang S, Ho CT.

Department of Food Science, Rutgers University, 65 Dudley Road,
New Brunswick, NJ 08901-8529. h... at (no spam) aesop.rutgers.edu.

Nonenzymic glycation, also known as the Maillard reaction, is a
complex series of reactions between reducing sugars and amino
compounds. Previous studies have demonstrated that reactive dicarbonyl
compounds (e.g., methylglyoxal [MG] and glyoxal [GO]), formed as
intermediate products of the Maillard reaction, irreversibly and
progressively modify proteins over time and yield advanced glycation
end products (AGEs), which are thought to contribute to the
development of diabetes mellitus and its complications. Several
studies have shown that higher levels of MG are present in diabetic
patients' plasma than in healthy people's plasma. Thus, decreasing the
levels of MG and GO will be an effective approach to reduce the
formation of AGEs and the development of diabetic complications. Here,
we briefly describe our effort in searching for non- or less-toxic
trapping agents of reactive dicarbonyl species from dietary sources.
In addition, we have discovered that commercial beverages contain
extremely high levels of MG. The potential hazardous effects of
dietary MG on humans remain to be explored.

PMID: 18448797

Please either send me the full paper or quote the portions of the
study which refer to:

"Here, we briefly describe our effort in searching for non- or less-
toxic
trapping agents of reactive dicarbonyl species from dietary sources."

They are referring to catechins in green tea, theaflavins in black tea
and a couple of dipeptides in that quote.

Below are the relevant quotes from the full text article. In the
quotes reference no. 11 is http://pmid.us/17103374 , no. 12 is
http://pmid.us/18001060 no. 13 is not found on pubmed, no. 14 is
http://pmid.us/15309567 , no. 15 is http://pmid.us/8853285 and no. 16
is not found on pubmed.

"In our recent studies to find non- or less-toxic trapping agents of
reactive dicarbonyl species from dietary sources, we compared the
trapping effect of MG by four major catechins in green tea and three
major theaflavins in black tea under physiological conditions (pH 7.4,
37 °C). Our results indicated that all the test compounds could
efficiently trap MG with theaflavin 3,3'-digallate (TF-3) in
theaflavins and (-)-EGC in tea catechins showing the highest trapping
activity.11

To better understand the reaction trend of TF3 and MG, a time course
study has been carried out with the same molar amount of TF3 and MG in
an hour. The time course of the reaction of TF-3 and MG showed that
TF-3 started the MG scavenging reaction rapidly. At the first
measurement at 3 min, more than one-third of the MG was trapped. The
reaction of MG with TF3 has almost been completed during the time of
our experiment.

In addition, the major adduct between EGCG and MG has been identified.
11 The 1:1 adduct formation between EGCG and MG dominantly occurs at
either the C8- or C6-position in the A ring of EGCG, and the gallate
ring did not play an important role in the trapping of reactive
dicarbonyl species.11,12"

"The formation of pyrazinone between dipeptides and GO was first
proposed by van Chuyen et al.13 who observed that a series of
pyrazinones, 2-(3'-alkyl-2-oxo-pyrazin-1'-yl) alkanoic acid, were
generated at the cooking condition, 100 °C and pH 5.0. Recently, the
pyrazinones produced between tripeptide and GO and MG have also been
reported at physiological conditions (pH 7.4, 37 °C).14 For the
reaction between MG and dipeptides, MG first adds to the primary amino
group forming a Schiff base. After tautomerization, the amido nitrogen
of the first peptide bond attacks the remaining carbonyl C-atom. It is
finally followed by an elimination of a second molecule of water. It
has been observed that 5-methylpyrazinone derivative is the main
product in the reaction between Gly-Ala-Phe and MG.14 This is
supported with the observation that the aldehyde group of MG is
hydrated in aqueous solution,15 as it is the ketone group and not the
aldehyde group that is targeted by the primary amino group at the
first step. It was shown that the reactivity of trapping MG by N-
terminal of the peptide and the guanidino function of arginine were
similar under both separate and mixing incubation.14

We have selected dipeptides, Gly-Cys, Gly-Gly, Gly-Leu, Gly-Phe, Gly-
Pro, and Gly-Ser with the N-terminal glycine and triglycine (TG) to
compare their reactivity with MG. In one day incubation, the MG
scavenging efficiency is in the order of Gly-Cys (53.42%) > Gly-Gly-
Gly (47.01%) > Gly-Phe (16.19%) > Gly-Gly (12.19%) > Gly-Ser (11.92%)

Quote:

Gly-Pro (8.92%) > Gly-Leu (5.75%). Gly-Cys has a much higher
scavenging efficiency than all the other peptides we tested, which may

indicate a very different mechanism for scavenging. Moreover, TG
showed relatively high trapping efficiency compared to most
dipeptides, including diglycine.16 This may imply that elements other
than the properties of side-chain groups influence the trapping of MG.

Current observations indicate that small peptides may serve as good
scavengers for MG and other reactive carbonyl species. However, more
systematic study is required to better understand the structure–
activity relationship."

jay...

Posted: Sat May 10, 2008 4:20 am

Guest

Quote:

Non surprisingly carbonated beverages usually contain a lot of
reactive dicarbonyl compounds.
The main source appears to be the high fructose corn syrup.

Why would drinks made with HFCS 55 & 42 produce more dicabonyls than
those made with sucrose? Aren't most soft drinks acidic which cause
much of sucrose to break down into fructose and glucose anyways? thx

Olafur Pall Olafsson...

Posted: Sat May 10, 2008 2:40 pm

Guest

On May 10, 2:20 pm, jay <jaym1... at (no spam) hotmail.com> wrote:

Quote:

Non surprisingly carbonated beverages usually contain a lot of
reactive dicarbonyl compounds.
The main source appears to be the high fructose corn syrup.

Why would drinks made with HFCS 55 & 42 produce more dicabonyls than
those made with sucrose?

I am not sure how drinks made with sucrose compare to those made with
HFCS in terms of dicarbonyl content. But based on the facts that
fructose is several times more glycating than glucose and that sucrose
and HFCS contain approximately the same glucose/fructose ratio it is
reasonable to assume that the dicarbonyl content of drinks containing
sucrose is similar to that in those containing a similar concentration
of HFCS. Because of their similar glucose/fructose ratio any
difference in the dicarbonyl content of sucrose and HFCS drinks would
depend mostly on how they are processed during the manufacturing. So
while it is logical to assume that the dicarbonyl content of drinks
containing sucrose and HFCS is similar this is hard to say with any
certainty without a study that directly compares the two in terms of
dicarbonyl content.

In the study I posted 13 soft drinks were tested for methylglyoxal
content. Of those 11 contained HFCS as sweetener and 2 contained
aspartame as a sweetener. But none of the drinks had sucrose as a
sweetener. The reason for this appears to be that, in the US at least,
HFCS is by far the most common sweetener used in soft drinks. I am not
sure how sucrose containing soft drinks compare to HFCS containing
ones in terms of dicarbonyl content. I would need to see a study
testing for dicarbonyl content in sucrose containing soft drinks for
comparison. I have not come across one so far.

Quote:

Aren't most soft drinks acidic which cause
much of sucrose to break down into fructose and glucose anyways? thx

While they are acidic I highly doubt they are acidic enough for any
significant amount of breakdown of sucrose to occur. In any case this
is not that important in vivo since all the sucrose and HFCS will
eventually be broken down to glucose and fructose in the digestive
tract before being absorbed and thus HFCS and sucrose should increase
endogenous production of AGEs by a similar amount. As far as the
dicarbonyl content of the drinks is concerned it depends more on the
processing of the drinks.

jay...

Posted: Sun May 11, 2008 9:25 am

Guest

Quote:

... thus HFCS and sucrose should increase
endogenous production of AGEs by a similar amount. As far as the
dicarbonyl content of the drinks is concerned it depends more on the
processing of the drinks.

In general, can glucose enter endothelial cells without insulin? What
regulates the flow of fructose/galactose from blood to within endo
cells? Can cells process fructose similar to glucose? Which likely is
a bigger factor in diabetes, dietary-AGEs or intracellular-AGEs? See
related abstract below:

Accumulation of endogenous methylglyoxal impaired insulin signaling in
adipose tissue of fructose-fed rats.

Increased accumulation of methylglyoxal (MG) has been linked to
different insulin resistance states including diabetes and
hypertension. In this study, the effects of MG on insulin signaling
pathway were investigated. Following 9 weeks of fructose treatment, an
insulin resistance state was developed in Sprague-Dawley (SD) rats,
demonstrated as increased triglyceride and insulin levels, high blood
pressure, and decreased insulin-stimulated glucose uptake by adipose
tissue. More importantly, we observed a close correlation between the
development of insulin resistance and elevated MG level in serum and
adipose tissue. Both insulin resistance state and the elevated MG
level were reversed by the MG scavenger, N-acetyl cysteine (NAC). When
3T3-L1 adipocytes were treated directly with MG, the impaired insulin
signaling was also observed, indicated by decreased insulin-induced
insulin-receptor substrate-1 (IRS-1) tyrosine phosphorylation and the
decreased kinase activity of phosphatidylinositol (PI) 3-kinase
(PI3K). The ability of NAC to block MG-impairment of PI3K activity and
IRS-1 phosphorylation further confirmed the role of MG in the
development of insulin resistance. In conclusion, the increase in
endogenous MG accumulation impairs insulin-signaling pathway and
decreases insulin-stimulated glucose uptake in adipose tissue, which
may contribute to the development of insulin resistance. PMID: 17660951

Olafur Pall Olafsson...

Posted: Fri May 23, 2008 5:09 pm

Guest

On May 11, 7:25 pm, jay <jaym1... at (no spam) hotmail.com> wrote:

Quote:

Yes. The major glucose-transporting protein in endothelial cells is
GLUT1. Since GLUT1 is not dependent on insulin endothelial cells can
take up glucose without insulin.

Quote:

What
regulates the flow of fructose/galactose from blood to within endo
cells?

Most of the fructose is taken up and metabolized by the liver. I doubt
much if any of the fructose directly enters endothelial cells, the
main glucose transporter in endothelial cells appears to be GLUT1 and
GLUT1 does not transport fructose. With respect to galactose, I am not
sure since I did not find much info on it's uptake and metabolism in
humans.

Quote:

Can cells process fructose similar to glucose?

Cells can metabolize fructose but it's metabolism is distinct from
that of glucose. Most of the fructose is taken up by the liver and
either converted to liver glycogen or to triglycerides.

Quote:

Which likely is
a bigger factor in diabetes, dietary-AGEs or intracellular-AGEs? See
related abstract below:

Intracellular AGEs are generally a much bigger factor in the damage
caused to the body by having diabetes. But in addition to dietary AGEs
and intracellular AGEs there are also extracellular AGEs in the body
such as those in the blood. These are important also and can be
sourced from the diet or endogenously.

With respect to the abstract below, it indicates that MG can directly
cause insulin resistance in adipocytes. The high fructose diet caused
an elevation in both intracellular and extracellular MG an effect that
was partly reversed by NAC. Interestingly the dose used was only 10 mg/
kg/day which corresponds to approximately 200mg of NAC for a 70kg
human.

Olafur

Quote:

Accumulation of endogenous methylglyoxal impaired insulin signaling in
adipose tissue of fructose-fed rats.

Increased accumulation of methylglyoxal (MG) has been linked to
different insulin resistance states including diabetes and
hypertension. In this study, the effects of MG on insulin signaling
pathway were investigated. Following 9 weeks of fructose treatment, an
insulin resistance state was developed in Sprague-Dawley (SD) rats,
demonstrated as increased triglyceride and insulin levels, high blood
pressure, and decreased insulin-stimulated glucose uptake by adipose
tissue. More importantly, we observed a close correlation between the
development of insulin resistance and elevated MG level in serum and
adipose tissue. Both insulin resistance state and the elevated MG
level were reversed by the MG scavenger, N-acetyl cysteine (NAC). When
3T3-L1 adipocytes were treated directly with MG, the impaired insulin
signaling was also observed, indicated by decreased insulin-induced
insulin-receptor substrate-1 (IRS-1) tyrosine phosphorylation and the
decreased kinase activity of phosphatidylinositol (PI) 3-kinase
(PI3K). The ability of NAC to block MG-impairment of PI3K activity and
IRS-1 phosphorylation further confirmed the role of MG in the
development of insulin resistance. In conclusion, the increase in
endogenous MG accumulation impairs insulin-signaling pathway and
decreases insulin-stimulated glucose uptake in adipose tissue, which
may contribute to the development of insulin resistance. PMID: 17660951

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