Chemical diversity investigation of Stemona species using LC-MS technologies

Abstract

Stemona species (Stemonaceae) are plant resources of traditional Chinese medicine 'baibu', which had long been used as antitussive and insecticidal agents. Stemona alkaloids, featuring a pyrrolo[1,2-α]azepine or pyrido[1,2-α]azepine nucleus, are believed to be responsible for their medicinal usages 1,2. Our previous work has let to the isolation of 90-plus alkaloids from different Stemona species. In our effort to identify alkaloidal constitutents from the extract of a Vietnamese species, an LC-MS method was established for a rapid and sensitive screening of the specific compounds 3. On the basis of more than 90 alkaloids, we established a MS database of all these reference compounds by UPLC/ESI-LTQ. By picking the specific peak in the LC chromatogram, extracting its MS, MS2 and MS3 spectra, and then comparing with those of the standard samples, we can do a rapid identification of main structures in the extract. Such technology was successfully applied for the chemical diversity investigation of three Stemona species – S. sessilifolia Franch. & Sav., S. japonica Franch. & Sav., and S. tuberosa Lour. The results revealed that the alkaloids varied greatly with species and habitats, but not with collecting seasons. S. tuberosa is the commonly-used species while having the most complicated metabolites which structural types were influenced extremely by ecological environment. S. sessilifolia growing in Tsuchou, Anhui province with the highest amount of the most active stemospironine, was determined to the best species for medicinal usage. All these data, combined with the pharmaceutical experiments, supplied the scientific evidence for guiding the usage of TCM baibu.