Enzyme Urease Activity and Phytochemical Investigation of the Leaves of Baissea Mortehanii (Apocynaceae)

Abstract

The phytochemical investigation of a previously unstudied species of the genus Apocynaceae, Baissea mortehanii de Wild was undertaken and eight known secondary metabolites were isolated from leaves of this plant including one alkaloid, N-Feruloyltryptamine (1); one aromatic ester, Dibutyl phthalate (2); two flavonoids, Genistein (3) and Gerontoisoflavone A (4), four sterols, β-Sitosterol (5), Sitosterol-3-O-β-D-glucopyranoside (6), Stigmasterol (7) and Stigmasterol-3-O-β-D glucopyranoside (8). The structures of compounds were determined by means of spectroscopic methods :NMR analysis (1H and13C NMR, 1H-1H-COSY, HSQC, HMBC), spectrometric methods such as UV, IR, ESI-MS, EI, and by comparing their data with those reported in the literature. All the isolated compounds were tested for their potential to inhibit the enzyme urease. Urease activity was determined by measuring ammonia production using the indophenol method and thiourea was used as standard inhibitor of urease. Compounds 5 and 7 showed the best urease inhibition with an IC₅₀ value 17. 2 and 18.5 µM respectively, which is higher than that of the potent inhibitor, thiourea (IC₅₀ = 21.5 µM); Compounds 3, 4, 6 and 8 showed a good urease inhibition with an IC₅₀ value 26.9, 29.7, 32.8 and 34.3 µM respectively; Compounds 1 and 2 showed a moderate urease inhibition with an IC₅₀ value 49.1 and 46.8 µM respectively.