In humans will the sugar moiety be metabolised after cleavage of anthocyanins?
Normally the aglycone is absorbed from the intestine, does the same happen to the sugar moiety?
Good afternoon Terun Desai,
Yes, the sugar moiety is also metabolised by the human organism.
In fact, in the anthocyanin molecule, the sugar moiety is only a "sugar residue" linked to tha anthocianidin part by a glicosidic link.
But when the hydrolisis occours, a water molecule is added, and reconstitutes tha hole sugar molecule, that can be metabolised as any other sugar molecule.
Hello Terun Desai,
I am sorry, I only realize to-day you asked this question.
The answer of Paulo is quite clear and does not need further comment. Hydrolysis of anthocyanins gives back anthocyanidins and the free sugar moiety.
However, I am just willing to tell you that almost all those natural heterosides (including anthocyanins) are of "bêta"-configuration, and, we (animals) have no enzymes that could hydrolyze such heterosidic bounds. Only gut microflora do possess the necessary bêta-glycosidases, and can metabolize such bêta-O-heterosides. Therefore, to my opinion, the sugar moiety has almost no chance to be metabolized by humans (after resorption). It will be rather used by gut microflora (thus, metabolized, as Paulo told you).
By the way, what about the "freed" anthocyanidins: it still is a cation (quite acidic compound) whom resorption by the colon is not obvious at all ... Would you have any information on its fate?
At the same time, because of the higher chemical instability caused by the formation of the free OH group at the C-3 position. the pyrilium ring could easily degrade: opening leads to alpha dicarbonyl derivatives, that further break down in 2 parts! We have shown earlier that human flora implanted into gnotoxenic mice could metabolize such "flavonoids" into acid-phenols, phenyl-lactones ... which were found into the blood (resorption):
C. Brezillon, S. Rabot, C. Philippe, J. Durao, C. Cheze, J. Vercauteren, in Polyphenols Communications 98, XIXth International Conference on Polyphenols, Lille (France), 1–4 sept. 1998, F. Charbonnier, J.-M. Delacotte, C. Rolando, Eds., Lille, 1998, vol. 1, p 11–12).
Philippe, C., S. Rabot, C. Brézillon, J. Durao, C. Chèze and J. Vercauteren, Excretion pattern of dietary catechin in gnotobiotic rats associated with a human intestinal microflora, in Polyphenols Communications 98, F. Charbonnier, J.-M. Delacotte, and C. Rolando, Editors. 1998: Lille. p. 67-68.
Deprez, S., C. Brezillon, S. Rabot, C. Philippe, I. Mila, C. Lapierre and A. Scalbert, Polymeric proanthocyanidins are catabolized by human colonic microflora into low-molecular-weight phenolic acids. J Nutr, 2000. 130(11): p. 2733-8.
Good luck for your research.
Joseph Vercauteren
Hello Terun Desai
Thank you for putting the question, which is of interest. I have also learned something from the excellent response of Joseph, with his explanation about the metabolism of the aglicone in human body.
As Joseph says, the connection between anthocyanidin and sugar is beta-type, so it is difficult to metabolize, since an enzyme (beta-glucosidase) is not present in adult humans.
The same happens with cellulose (polysaccharide) and with lactose (disaccharide), where the glycoside bond is also beta-type.
In the case of cellulose, it is not metabolized by humans, as you know, but only by ruminants, which also have a compartment in the stomach (the rumen) reserved for the hydrolysis of cellulose into glucose through the microbial flora.
In the case of lactose, I believe that only babies have this enzyme, and if adult humans do not have enough gut flora, they may not metabolize lactose.
Therefore, the question of the metabolism of anthocyanins by humans is less simple than it seems, as says Joseph Vercauteren.
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