GC-MS and q-NMR based chemotaxonomic evaluation of two Leonurus species

Introduction - The genus Leonurus L. (fam: Lamiaceae) is represented in Uzbekistan by two species, L. panzerioides Popov. and L. turkestanicus V. I. Krecz. & Kuprian, which are used to treat nervous disorders and also as sedative and hypotensive agents. Objectives – To establish the taxonomic status of L. panzerioides and L. turkestanicus based on their chemical constituents analyzed by GC-MS and q-NMR. Materials and Methods – Quantitative 1H NMR (q-NMR) was used to identify and quantify known major components in the methanol extracts of these two species. Additionally, the chemical composition of the essential oils obtained from the aerial parts of these plants were analyzed by GC-MS. Results – The q-NMR analyses of L. panzerioides and L. turkestanicus revealed the presence 8-acetylharpagide, harpagide, leonurine and stachydrine as major components. Using the GC-MS method, overall 24 and 39 constituents were identified, respectively, from L. panzerioides and L. turkestanicus oils. The major constituents of the essential oil of L. panzerioides were eugenol (30.9%) and p-vinyl guaiacol (15.8%), whereas thymol (40.1%) and octen-3-ol (13.1%) were the principal compounds in the essential oil of L. turkestanicus. Conclusion – The major components in L. panzerioides and L. turkestanicus as identified by the GC-MS and q-NMR analyses, were similar to those present in other Leonurus species and thus provided chemotaxonomic evidence for the placement of these species under the genus Leonurus