Conformational Analysis of a New Cytochalasin Using Molecular Mechanics and Nuclear Magnetic Resonance Spectroscopic Data

No Thumbnail Available



Journal Title

Journal ISSN

Volume Title


Addis Ababa Universty


This projeot uses moleoular mechanics teohniques with the aid of NMR data to determine low-energy oonformations (threedimensional structures) of a novel cytochalasin isolated from fungus XYlaria Obovota[lj. Although the two-dimensional struoture for this substituted hydrogenated isoindole unit fused to an II-membered ring has been postulated, no study of the three-dimensional struoture has been made. Molecular mecanics teohniques, the force field equations, and conformational searching algorithms: the stoohastic search (random search method) on cartesian and internal coordinates have been applied. A total of 22 conformations were generated within 10 kcal/mol to the global minimum. The calculated proton coupling constants, averaged over the first six lowest-energy conformations, were compared with the experimental values. The geometry parameters, the calculated coupling constants, the structure of the isoindole unit, the macrocycle and overall structure of the cytochalasin were also compared with similar cytochalasins whose struotures were determined from x-ray and related experimental techniques. Comparison of the calculated coupling constants and the various torsion angles for this novel fungal cytochalasin revealed similarity in the conformations of the structures generated from the analysis and those determined experimentally.



moleoular mechanics teohniques