Proanthocyanidins can trap reactive carbonyl species
Olafur Pall Olafsson
proanthocyanidins, such as cinnamon, grape seed extract and cocoa, may
potentially help prevent formation of AGEs.
J Agric Food Chem. 2008 Feb 20 [Epub ahead of print]
Related Articles
Cinnamon Bark Proanthocyanidins as Reactive Carbonyl Scavengers To
Prevent the Formation of Advanced Glycation Endproducts.
Peng X, Cheng KW, Ma J, Chen B, Ho CT, Lo C, Chen F, Wang M.
Cinnamon bark has been reported to be effective in the alleviation
of diabetes through its antioxidant and insulin-potentiating
activities. In this study, the inhibitory effect of cinnamon bark on
the formation of advanced glycation endproducts (AGEs) was
investigated in a bovine serum albumin (BSA)-glucose model. Several
phenolic compounds, such as catechin, epicatechin, and procyanidin B2,
and phenol polymers were identified from the subfractions of aqueous
cinnamon extract. These compounds showed significant inhibitory
effects on the formation of AGEs. Their antiglycation activities were
not only brought about by their antioxidant activities but also
related to their trapping abilities of reactive carbonyl species such
as methylglyoxal (MGO), an intermediate reactive carbonyl of AGE
formation. Preliminary study on the reaction between MGO and
procyanidin B2 revealed that MGO-procyanidin B2 adducts are primary
products which are supposed to be stereoisomers. This is the first
report that proanthocyanidins can effectively scavenge reactive
carbonyl species and thus inhibit the formation of AGEs. As
proanthocyanidins behave in a similar fashion as aminoguanidine (AG),
the first AGE inhibitor explored in clinical trials, they show great
potential to be developed as agents to alleviate diabetic
complications.
PMID: 18284204 [PubMed - as supplied by publisher]
Related Links
* Ilex paraguariensis extracts inhibit AGE formation more
efficiently than green tea. [Fitoterapia. 2005]
* Inhibitory effects of Luobuma tea and its components against
glucose-mediated protein damage. [Food Chem Toxicol. 2004]
* A BRIEF COMMUNICATION: Antiglycation Effect of Gliclazide on
In Vitro AGE Formation from Glucose and Methylglyoxal. [Exp Biol Med
(Maywood). 2008]
* [Antioxidant and anti-AGE therapeutics: evaluation and
perspectives] [J Soc Biol. 2001]
* Use of aminoguanidine (Pimagedine) to prevent the formation
of advanced glycation endproducts. [Arch Biochem Biophys. 2003]
* » See all Related Articles...
Paul Antonik Wakfer
There is a thread on Imminst.org to which Scott Miller sent me the
link:
http://www.imminst.org/forum/index.php?showtopic=20097&hl=
which contains the following abstracts with similar conclusions for
other polyphenols.
J Soc Biol. 2007;201(2):189-98.
[Inhibition of advanced glycation by flavonoids. A nutritional
implication for preventing diabetes complications?]
[Article in French]
Urios P, Grigorova-Borsos AM, Peyroux J, Sternberg M.
Département de Biochimie, Faculté de Médecine & Laboratoire de
Pharmacologie, Faculté de Pharmacie, Université René Descartes, Paris,
France. paul....@bch.aphp.fr
Advanced glycation of collagens contributes to development of micro-
and macrovascular complications in diabetes. Since flavonoids are
potent natural antioxidants, it was interesting to examine their
effect on the formation of a cross-linking advanced glycation
endproduct, pentosidine, in collagen incubated with glucose. Monomeric
flavonoids (25 and 250 microM) markedly reduced pentosidine/
hydroxyproline values in a concentration- and structure-dependent
manner. Procyanidin oligomers from grape seed were more active than
pine bark procyanidin oligomers. Oligomers are known to be cleaved
into monomers in the gastric milieu and monomeric flavonoids to be
absorbed and recovered at micromolar concentrations (with a long
plasmatic half-life) in extracellular fluids, in contact with
collagens. In conclusion, flavonoids are very potent inhibitors of
pentosidine formation in collagens, active at micromolar
concentrations; these concentrations might be achieved in plasma of
diabetic patients after oral intake of flavonoids.
PMID: 17978753
Eur J Nutr. 2007 Apr;46(3):139-46.
Flavonoids inhibit the formation of the cross-linking AGE pentosidine
in collagen incubated with glucose, according to their structure.
Urios P, Grigorova-Borsos AM, Sternberg M.
Equipe de recherche "Protéines modifiées, protéases et
physiopathologie de l'endothélium vasculaire", Dépt. de Biochimie,
Faculté de Médecine and Laboratoire de Pharmacologie, Faculté de
Pharmacie, Université René Descartes, Paris, France.
BACKGROUND: Glycoxidation of collagens contributes to development of
vascular complications in diabetes. AIM OF THE STUDY: Since flavonoids
are potent antioxidants present in vegetal foods, it was interesting
to examine their effect on the formation of a cross-linking advanced
glycation endproduct, pentosidine, in collagens. METHODS: Collagen was
incubated with glucose (250 mM), in the presence of different
flavonoids. Pentosidine was measured by HPLC, hydroxyproline
colorimetrically. RESULTS: Monomeric flavonoids (25 and 250 microM)
markedly reduced pentosidine/hydroxyproline values in a concentration-
and structure-dependent manner. In decreasing order of their specific
inhibitory activity, they rank as follows: myricetin > or = quercetin
> rutin > (+)catechin > kaempferol. Thus 3'-OH or 4-oxo + Delta(2-3)
increase the inhibitory activity; conjugation by Rha-Glc on 3-OH
decreases it. Procyanidin oligomers from grape seed were more active
than pine bark procyanidin oligomers: this may be related to the
galloyl residues present in grape seed oligomers only. Procyanidin
oligomers are known to be cleaved into monomers in the gastric milieu
and monomeric flavonoids to be absorbed and recovered at micromolar
concentrations (with a long plasmatic half-life) in extracellular
fluids, in contact with collagens. CONCLUSION: Flavonoids are very
potent inhibitors of pentosidine formation in collagens. They are
active at micromolar concentrations; these might be achieved in plasma
of diabetic patients after oral intake of natural flavonoids.
PMID: 17356796
--Paul Wakfer
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