title: Isolation and cholinesterase-inhibition studies of sterols from Haloxylon recurvum.
abstract: Haloxysterols A-D (1-4), new C-24 alkylated sterols, have been isolated from the chloroform soluble fraction of Haloxylon recurvum, along with five known sterols 5-9, which are reported for the first time from this species. Their structures were determined by means of 1D- and 2D-NMR techniques. Compounds 1-9 inhibited cholinesterase enzymes in a concentration-dependent manner with K(i) values ranging between 0.85-25.5 and 1.0-19.0 microM against acetylcholinesterase (AChE; EC 3.1.1.7) and butyrylcholinesterase (BChE; EC 3.1.1.8) enzymes, respectively. Lineweaver-Burk, Dixon plots and their secondary replots indicated that compounds 1-9 are non-competitive inhibitors of both AChE and BChE enzymes.
authors.affiliation: International Center for Chemical Sciences, HEJ Research Institute of Chemistry, University of Karachi, Karachi-75270, Pakistan.
authors.forename: Ejaz
authors.initials: E
authors.lastname: Ahmed
authors.forename: Sarfraz A
authors.initials: SA
authors.lastname: Nawaz
authors.forename: Abdul
authors.initials: A
authors.lastname: Malik
authors.forename: M Iqbal
authors.initials: MI
authors.lastname: Choudhary
mesh_terms: D000110:Acetylcholinesterase / Q000187:drug effects*; D027703:Amaranthaceae / Q000737:chemistry*; D000818:Animals; D001667:Binding, Competitive; D002091:Butyrylcholinesterase / Q000187:drug effects; D002725:Chloroform / Q000737:chemistry; D002800:Cholinesterase Inhibitors / Q000302:isolation & purification* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D009682:Magnetic Resonance Spectroscopy; D008433:Mathematics; D010840:Phytosterols / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology
chemical_list: D002800:Cholinesterase Inhibitors; D010840:Phytosterols; D002725:Chloroform; D000110:Acetylcholinesterase; D002091:Butyrylcholinesterase