Enzyme-catalyzed partial deacetylation of 1,6-anhydro-2,3,4-tri-O-acetyl-β-D-glucopyranose

Abstract

Various esterases, lipases, and proteases with esterolytic activity were investigated for their power to catalyse deacetylation of 1,6-anhydro-2,3,4-tri-O-acetyl-β-D-glucopyranose. Out of these, chymotrypsin, esterase ex liver, lipase ex pancreas, and lipase ex wheat-germ have been found to be selective catalysts of deacetylation; chymotrypsin and wheat-germ lipase preferably removed the acetyl at C(3), whereas liver esterase and pancreas lipase the acetyl at C(4). Compared to chemical catalysis, whether by methanolic hydrogen chloride or hydrazine hydrate, the locoselectivity of the enzyme-catalysed deacetylation appear to be much better.

Enzymatic Protecting Group Techniques

“…Therefore, the directed manipulation of their hydroxyl groups is of particular interest. Each of the three OH groups in 1,6-anhydroglucopyranose can be liberated selectively, making use of enzymatic reactions (Figure , Table ). − , Thus, from the triacetate 127a , the 4-protecting group was split off using lipase from porcine pancreas (PPL) 209 or pig liver esterase (PLE). , The acetate in the 3-position could be attacked preferentially using chymotrypsin 209 or lipase from wheat germ (WGL), and the 3,4-diacetate 135 was obtained by hydrolysis with lipase from Rhizopus javanicus (RJL) . In each case, however, other derivatives were formed as undesired byproducts.…”

Biocatalytical Transformations, III [1] Regioselective Enzymic Deacetylations of Laevoglucosane Triacetate

“…Very recently an enzymic deacetylation of 1 was reported, but the pH's had to be different from those which would be optimal for the enzymes used in order to eliminate chemical deacetylations. This resulted in prolonged reaction times [22]. To circumvent these disadvantage, several other, commercially available, enzymes were investigated (Fig.…”

Cholesterol-Lowering Effect of the Mushroom Pleurotus ostreatus in Hereditary Hypercholesterolemic Rats

“…observation] in dry substance. By the inter action of the fiber, particularly of its watersoluble component, or other mushroom components with bile acid in the small intes tine, their enterohepatal circulation is re tarded which, by feedback mechanism, leads to an acceleration of the C catabolism [ 19], It is supposed that the digestive enzymes of the human gastrointestinal tract are able to cata lyze the transformation of chitin into chitosan [20] which is highly capable to bind bile acids [21], The increased degradation of C in the liver is also documented by the lower C accumulation in this organ of animals fed the mushroom-containing diet.…”