Gallotannins and Tannic Acid: First Chemical Syntheses and In Vitro Inhibitory Activity on Alzheimer's Amyloidβ-Peptide Aggregation.
Angew Chem Int Ed Engl. 2015 Jul 6 ;54(28):8217-21. Epub 2015 May 26. PMID: 26013280
Tahiri Sylla
The screening of natural products in the search for new lead compounds against Alzheimer's disease has unveiled several plant polyphenols that are capable of inhibiting the formation of toxicβ-amyloid fibrils. Gallic acid based gallotannins are among these polyphenols, but their antifibrillogenic activity has thus far been examined using"tannic acid", a commercial mixture of gallotannins and other galloylated glucopyranoses. The first total syntheses of two true gallotannins, a hexagalloylglucopyranose and a decagalloylated compound whose structure is commonly used to depict"tannic acid", are now described. These depsidic gallotannins and simpler galloylated glucose derivatives all inhibit amyloidβ-peptide (Aβ) aggregation in vitro, and monogalloylated α-glucogallin and a natural β-hexagalloylglucose are shown to be the strongest inhibitors.