Propargyl esters of the C-28 carboxylic acids of pentacyclic triterpenes (oleanolic, ursolic, and maslinic acids) were coupled with 2,3,4,6-tetra-O- acetyl-β-d-glucopyranosyl azide as well as N-(ω-azido-[C-2, C-6, and C-11]alkanoyl)-β-d-glucopyranosylamines under conditions of copper(i)-catalyzed azide-alkyne cycloaddition (CuAAC) to give tethered d-glucose-triterpene heteroconjugates. The O-acetyl protecting groups were removed by base-catalyzed hydrolysis. N-(ω-Azido-[C-2, C-6, C-11, and C-16]alkanoyl)-β-d-glucopyranosylamines were also tethered by 1,7-octadiyne under CuAAC conditions to furnish d-glucose homoconjugates. O-Deacetylation was carried out by the Zemplén protocol. The new compounds were assayed against rabbit muscle glycogen phosphorylase (RMGP) a or b enzymes. Some of the heteroconjugates inhibited the enzyme in the low micromolar range (IC 50 values 40-70 μM), while the homoconjugates proved inefficient as inhibitors.
ASJC Scopus subject areas
- Materials Chemistry