Conformational analysis of capsaicin using 13 C, 15 N MAS NMR, GIAO DFT and GA calculations

摘要: Abstract Capsaicin produced by plants from genus Capsicum exerts multiple pharmacological effects and has found applications in food pharmaceutical industry. The alkaloid was studied a combined approach: solid-state NMR, GA conformational search GIAO DFT methods. 13 C CPMAS NMR spectra were recorded using variable contact time dipolar dephasing experiments. results of cross-polarization (CP) kinetics, such as T CP values long 1ρ H (100–200 ms), indicated that the capsaicin molecule is fairly mobile, especially at end aliphatic chain. 15 N MAS spectrum showed one narrow signal at −255 ppm. Genetic algorithm (GA) with multi modal optimization used to find low-energy conformations capsaicin. Theoretical calculations performed different basis sets characterize five selected conformations. validation method experimental chemical shifts compared those calculated for stable conformers. Conformational analysis suggests side chain can be bent or extended. A comparison indicates solid does not have same structure established PWXRD.