title: NMR and molecular mechanics study of pyrethrins I and II.
abstract: Bioassay-directed fractionation of the organic extract of the Kenyan pyrethrum flowers (Chrysanthemum cinerariaefolium Vissiani) resulted in the isolation of two natural pyrethrin esters, pyrethrin I (PI) and pyrethrin II (PII) as the major constituents. These esters elicited inhibition of the multiple drug resistant (MDR) Mycobacterium tuberculosis. The high-field (1)H and (13)C nuclear magnetic resonance (NMR) chemical shifts of PI and PII were unequivocally assigned using modern two-dimensional (2D) proton-detected heteronuclear multiple-quantum coherence (HMQC) and heteronuclear multiple-bond correlation (HMBC) experiments. The conformations of both esters were deduced from (1)H-(1)H vicinal coupling constants and confirmed by 2D nuclear Overhauser effect spectroscopy (NOESY). Computer molecular modeling (MM) studies revealed that PI and PII molecules adopt a "love-seat" conformation in chloroform (CDCl(3)) solution.
authors.affiliation: Department of Chemistry, Louisiana State University, Baton Rouge 70803, USA.
authors.forename: J K
authors.initials: JK
authors.lastname: Rugutt
authors.forename: C W
authors.initials: CW
authors.lastname: Henry
authors.forename: S G
authors.initials: SG
authors.lastname: Franzblau
authors.forename: I M
authors.initials: IM
authors.lastname: Warner
mesh_terms: D011723:Chrysanthemum cinerariifolium; D003198:Computer Simulation; D007306:Insecticides / Q000737:chemistry* / Q000302:isolation & purification; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D010936:Plant Extracts / Q000737:chemistry; D011722:Pyrethrins / Q000737:chemistry* / Q000302:isolation & purification
chemical_list: D007306:Insecticides; D010936:Plant Extracts; D011722:Pyrethrins; C009119:pyrethrin I