Zenkeramide: a new iso-benzofuranone propanamide and urease inhibitory constituents of Celtis zenkeri Engl stem bark (Ulmaceae).

A new iso-benzofuranone propanamide: 3-(3-oxo-1, 3-dihydroisobenzofuran-1-yl) propanamide (zenkeramide) (1) along with three known compounds: Trans-N-coumaroyltyramine (2), ß-Sitosterol (3) and ß-sitosterol-3-0-ß-D-glucopyranoside (4) were isolated from the ethyl acetate fraction of the stem-bark of Celtis zenkeri Engl (Ulmaceae). The structure of the new compound was elucidated by extensive spectroscopic analysis. The compounds were examined for Urease Inhibitory Activity. Compounds 1 and 2 showed moderate activities (IC50 values (µM) of 42.3 ± 0.19 and 45.2 ± 0.55, respectively), while compounds 3 and 4 were potent inhibitors of the Jack bean urease (IC50 values (µM) of 20.3 ± 0.37and 27.6 ± 0.52, respectively), when compared to the standard inhibitor (thiourea- IC50 21.5 ± 0.47). The isolation of all the compounds from C. zenkeri and the urease activity of compounds 1 and 2 are reported for the first time.