Solid-State 15N NMR Studies of Tobacco Leaves

Nitrogen-containing compounds are one important class of constituents in tobacco because of various pharmacological and biological properties. Three types of tobacco leaves (burley, bright, and oriental) were studied using solid-state 15N NMR cross polarization with magic-angle spinning, dipolar dephasing and five π replicated magic angle turning (FIREMAT) experiments. The results show that burley tobacco leaves contain significantly more pyridinic nitrogen than that of bright or oriental tobacco leaves. The principal values of 15N chemical shift tensors of nitrogen functional groups were obtained from the FIREMAT data. Possible assignments of solid-state 15N NMR resonances were made using nitrogen chemical shift tensors in some model compounds or isotropic chemical shift values from liquid NMR results. To the best of our knowledge, this is the first solid-state 15N NMR study of tobacco plant material. Keywords: Solid-state 15N NMR; tobacco leaves; nitrogen compounds; FIREMAT