Twenty polyphenols were synthesized and evaluated for their effect on Helicobacter pylori urease. Among these compounds, 4-(p-hydroxyphenethyl)pyrogallol (15) (IC50 = 0.03 mM) and 7,8,4'-trihydroxyisoflavone (19) (IC50 = 0.14 mM) showed potent inhibitory activities, and inhibited Helicobacter pylori urease in a time-dependent manner. The structure-activity relationship of these polyphenols revealed: the two ortho hydroxyl groups were essential for inhibitory activity of polyphenol. When the C-ring of isoflavone was broken, the inhibitory activity markedly decreased. As for deoxybenzoin, the carboxyl group was clearly detrimental. (c) 2007 Elsevier Ltd. All rights reserved.
Amines and oximes derived from deoxybenzoins as Helicobacter pylori urease inhibitors
Twenty amines and oximes from deoxybenzoins were prepared and evaluated for their inhibitory activity against Helicobacter pylori urease. Among these compounds, high inhibitory activities were observed in amines and oximes, especially amines 1b (IC50 = 0.011 mM) and 6b (IC50 = 0.047 mM) exhibited good in vitro activities, and were comparable to acetohydroxamic acid (AHA). The hydroxyl groups on deoxybenzoin skeleton may be responsible for the inhibitory activity and coordinate with the nickel (active site) on enzyme. A direct interaction may exist between the OH group of hydroxylamines or NH group of amines and His alpha 323 of H. pylori urease, which is on the flap of the enzyme active site. (C) 2008 Elsevier Masson SAS. All rights reserved.
The synthesis, structure and activity evaluation of pyrogallol and catechol derivatives as Helicobacter pylori urease inhibitors
Some pyrogallol and catecholderivatives were synthesized, and their urease inhibitory activity was evaluated by using acetohydroxamic acid (AHA), a well known Helicobacter pylori urease inhibitor, as positive control. The assay results indicate that many compounds have showed potential inhibitory activity against H. pylori urease. 4-(4-Hydroxyphenethyl)phen-1,2-diol (2a) was found to be the most potent
In the presence of boron trifluoride diethyl etherate (BF3·OEt2), direct acylation of phenols with free carboxylic acid is chemoselective and regioselective and no demethylation, if any, was observed. The para-directing effect of BF3·OEt2 is attributed to the large steric hindrance of the boron trifluoride-phenolic hydroxyl group complex, which blocks the ortho-acylation from occurrence. Microwave irradiation could not change the regioselectivity of BF3·OEt2 except the reaction time being greatly shortened.