HPLC analysis of mesembrine-type alkaloids in Sceletium plant material used as an african traditional medicine

Abstract

Purpose. Sceletium plant species have been reported to contain psychoactive alkaloids, specifically belonging to mesembrine-type alkaloids. Sceletium is presently marketed through health shops and on the internet as dried plant powder and as pharmaceutical dosage forms and purported to be useful in the treatment of psychological disorders. However, there are no validated analytical methods and reference standards of the relevant alkaloids are not commercially available for use in the analysis and quality control of Sceletium products and dosage forms. Hence, the objective of this research was to isolate and characterize appropriate analytical markers for use in the assay and as well as markers for fingerprinting by high performance liquid chromatography (HPLC). Methods. The separation of the relevant alkaloids was carried out on a C18 column and detected at a UV wavelength of 228nm. The method was validated and used to assay the mesembrine-type alkaloids namely Δ7 mesembrenone, mesembranol, mesembrenone, mesembrine and epimesembranol. Results. The calibration curves were found to be linear over the entire concentration range of 400-60,000 ng/ml with correlation coefficients >0.99. The accuracies of the relevant alkaloids were found to be between 94.8 and 103.6% with an inter-day relative standard deviation (RSD) of less than 2.8%. The precision studies showed inter-day RSD's of less than 3%. The recoveries were all within the range of 95 and 105% (RSD<4.5%) and the limits of quantitation (LOQ) and detection (LOD) were found to be 100 and 200 ng/ml respectively using the respective S/N ratios of 3 and 10. Conclusions. An HPLC method for the quantitative analysis of Δ7 mesembrenone, mesembranol, mesembrenone, mesembrine and epimesembranol in Sceletium plant material has been developed and validated. This assay method can be applied for the quality control of Sceletium plant material which is used as an African Traditional Medicine for the treatment of psychological disorders.