Phenethylamine alkaloids are a group of non-heterocyclic compounds widely distributed in plants. The main representative molecules of this class are ephedrine (isolated from Ephedra species) and synephrine (isolated from Citrus species). Products containing E. sinica or C. aurantium have been widely used for the treatment of obesity or for increasing performance in body-building. However, these products have shown side-effects on the cardiovascular system by means of adrenergic stimulation. Considering the variability in the quality composition of the secondary metabolites of Ephedra and Citrus natural products, continued research effort is desired toward the application of fully validated methods to monitor the quality of crude drugs, extracts and dietary supplements. There have been many reports on the HPLC determination of phenethylamine alkaloids in plant material and natural products. RP-HPLC with UV detection is usually employed for the determination of these analytes and most separations are based on ion-pairing. In recent years, RP-HPLC stationary phases that contain polar groups as part of their structure often succeed in retaining and resolving compounds that C18 phases do not, because they can interact with analytes by mechanisms that are not possible with C18 alkyl chains. Of many such phases currently available, the pentafluorophenylpropyl (PFPP) stationary phase has shown wide applicability. In this study, the chromatographic performance of the fluorinated stationary phase was investigated to develop reliable HPLC methods for the separation and quantitative determination of phenethylamine alkaloids in Ephedra and Citrus natural products. The proposed methods were carefully optimised and fully validated in agreement with ICH guidelines. The practical applicability of the developed techniques was demonstrated by the analysis of Ephedra and Citrus natural products. Furthermore, due to the difference in the pharmacological effect between the two enantiomeric forms of synephrine, an efficient method for the enantioselective separation and determination of this compound in Citrus natural products was optimized and validated.
Recent advances in the chromatographic analysis of phenethylamine alkaloids in natural products / Pellati, Federica; Benvenuti, Stefania. - STAMPA. - 1:(2009), pp. 67-67. (Intervento presentato al convegno Recent Developments in Pharmaceutical Analysis 13th International Meeting (RDPA 2009) tenutosi a Milano, Italy nel September 9-12, 2009).