title: New class of acetylcholinesterase inhibitors from the stem bark of Knema laurina and their structural insights.
abstract: Bioassay-guided extraction of the stem bark of Knema laurina showed the acetylcholinesterase (AChE) inhibitory activity of DCM and hexane fractions. Further repeated column chromatography of hexane and DCM fractions resulted in the isolation and purification of five alkenyl phenol and salicylic acid derivatives. New compounds, (+)-2-hydroxy-6-(10'-hydroxypentadec-8'(E)-enyl)benzoic acid (1) and 3-pentadec-10'(Z)-enylphenol (2), along with known 3-heptadec-10'(Z)-enylphenol (3), 2-hydroxy-6-(pentadec-10'(Z)-enyl)benzoic acid (4), and 2-hydroxy-6-(10'(Z)-heptadecenyl)benzoic acid (5) were isolated from the stem bark of this plant. Compounds (1-5) were tested for their acetylcholinesterase inhibitory activity. The structures of these compounds were elucidated by the 1D and 2D NMR spectroscopy, mass spectrometry and chemical derivatizations. Compound 5 showed strong acetylcholinesterase inhibitory activity with IC(50) of 0.573 ± 0.0260 μM. Docking studies of compound 5 indicated that the phenolic compound with an elongated side chain could possibly penetrate deep into the active site of the enzyme and arrange itself through π-π interaction, H-bonding, and hydrophobic contacts with some critical residues along the complex geometry of the active gorge.
authors.affiliation: Laboratory of Natural Products, Institute of Bioscience, University Putra Malaysia, Malaysia.
authors.forename: Muhammad Nadeem
authors.initials: MN
authors.lastname: Akhtar
authors.forename: Kok Wai
authors.initials: KW
authors.lastname: Lam
authors.forename: Faridah
authors.initials: F
authors.lastname: Abas
authors.lastname: Maulidiani
authors.forename: Syahida
authors.initials: S
authors.lastname: Ahmad
authors.forename: Syed Adnan Ali
authors.initials: SA
authors.lastname: Shah
authors.lastname: Atta-Ur-Rahman
authors.forename: M Iqbal
authors.initials: MI
authors.lastname: Choudhary
authors.forename: Nordin Hj
authors.initials: NH
authors.lastname: Lajis
mesh_terms: D001665:Binding Sites; D002800:Cholinesterase Inhibitors / Q000737:chemistry*; D020128:Inhibitory Concentration 50; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D026324:Myristicaceae / Q000737:chemistry*; D018547:Plant Stems / Q000737:chemistry*
chemical_list: D002800:Cholinesterase Inhibitors