title: Isolation and enzyme-inhibition studies of the chemical constituents from Ajuga bracteosa.
abstract: Bractin A (=(2S,3S,4R,5E)-2-{[(2R)-2-hydroxydodecanoyl]amino}triacont-5-ene-1,3,4-triol; 1) and bractin B (=(2S,3S,4R,5E,8E)-2-{[(2R)-2-hydroxyhexacosanoyl]amino}pentadeca-5,8-diene-3,4,15-triol 1-O-beta-D-glucopyranoside; 2), new sphingolipids, and bractic acid (=(5Z,10Z,15Z)-2-decyl-4,7,8,12,13,17,18-heptahydroxy-20,23-dioxopentacosa-5,10,15-trienoic acid; 3), a long-chain polyhydroxy acid, were isolated from the whole plant Ajuga bracteosa along with four known diterpenoids 4-7. Their structures were deduced by spectral studies including 1D- and 2D-NMR spectroscopy. Compounds 1-3 displayed inhibitory potential against enzyme lipoxygenase, while compounds 4-7 inhibited cholinesterase enzymes in a concentration-dependent manner with IC(50) values in the range 10.0-33.0, 14.0-35.2, and 10.0-19.0 microM for lipoxygenase, acetylcholinesterase, and butyrylcholinesterase, respectively. Lineweaver-Burk, and Dixon plots, and their secondary replots indicated that all compounds exhibit non-competitive type of inhibition with K(i) values in the range of 9.5-35.2, 15.2-36.0, and 11.6-20.5 microM, for lipoxygenase, acetylcholinesterase, and butyrylcholinesterase, respectively.
authors.affiliation: Pharmaceutical Research Centre, PCSIR Laboratories Complex Karachi, Karachi-75280, Pakistan.
authors.forename: Naheed
authors.initials: N
authors.lastname: Riaz
authors.forename: Sarfraz A
authors.initials: SA
authors.lastname: Nawaz
authors.forename: Naveen
authors.initials: N
authors.lastname: Mukhtar
authors.forename: Abdul
authors.initials: A
authors.lastname: Malik
authors.forename: Nighat
authors.initials: N
authors.lastname: Afza
authors.forename: Samar
authors.initials: S
authors.lastname: Ali
authors.forename: Shafi
authors.initials: S
authors.lastname: Ullah
authors.forename: Pir
authors.initials: P
authors.lastname: Muhammad
authors.forename: M Iqbal
authors.initials: MI
authors.lastname: Choudhary
mesh_terms: D031328:Ajuga / Q000737:chemistry*; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D006860:Hydrogen Bonding; D015394:Molecular Structure; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet
chemical_list: D004791:Enzyme Inhibitors