title: Cholinesterase-inhibiting withanolides from Ajuga bracteosa.
abstract: Three new withanolides, bracteosin A (= (22R)-5beta,6beta : 22,26-diepoxy-4beta,28-dihydroxy-3beta-methoxyergost-24-ene-1,26-dione; 1), bracteosin B (= (22R)-5beta,6beta : 22,26-diepoxy-4beta,28-dihydroxy-3beta-methoxy-1,26-dioxoergost-24-en-19-oic acid; 2), and bracteosin C (= (22R)-22,26-epoxy-4beta,6beta,27-trihydroxy-3beta-methoxyergost-24-ene-1,26-dione; 3), have been isolated from the whole plants of Ajuga bracteosa. Their structures were deduced by spectral analysis, including 1D- and 2D-NMR techniques. In addition, dihydroclerodin-1, clerodinin A, lupulin A, and dihydroajugapitin have also been isolated for the first time from this species. Compounds 1-3 exhibited evident inhibitory potential against cholinesterase enzymes in a concentration-dependent fashion.
authors.affiliation: International Centre for Chemical Sciences, H.E.J. Research Institute of Chemistry, University of Karachi, Karachi-75270, Pakistan.
authors.forename: Naheed
authors.initials: N
authors.lastname: Riaz
authors.forename: Abdul
authors.initials: A
authors.lastname: Malik
authors.forename: Sarfraz Ahmad
authors.initials: SA
authors.lastname: Nawaz
authors.forename: Pir
authors.initials: P
authors.lastname: Muhammad
authors.forename: M Iqbal
authors.initials: MI
authors.lastname: Choudhary
mesh_terms: D031328:Ajuga / Q000201:enzymology*; D000818:Animals; D002800:Cholinesterase Inhibitors / Q000737:chemistry / Q000302:isolation & purification*; D004593:Electrophorus; D004875:Ergosterol / Q000737:chemistry / Q000302:isolation & purification*; D006736:Horses; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification; D018514:Plant Structures; D032341:Withania / Q000201:enzymology*
chemical_list: D002800:Cholinesterase Inhibitors; D010936:Plant Extracts; D004875:Ergosterol