NMR and molecular mechanics study of pyrethrins I and II
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 1H and 13C 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 1H-1H 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 (CDC13) solution.
Publication Source (Journal or Book title)
Journal of Agricultural and Food Chemistry
Rugutt, J., Henry, C., Franzblau, S., & Warner, I. (1999). NMR and molecular mechanics study of pyrethrins I and II. Journal of Agricultural and Food Chemistry, 47 (8), 3402-3410. https://doi.org/10.1021/jf980660b