RESUMEN
INTRODUCTION: Sennosides are the main active constituents of the dried leaves and/or pods of Senna alexandrina Mill. that are used as laxatives. A hypothesis is that aglycones are formed during the degradation of sennosides. However, it is unknown, whether this happens under visible light exposure and how photosensitive sennosides behave in solution. OBJECTIVES: Pure anthraquinone glycosides were tested on their behaviour during sample preparation in the lab under visible light exposure in dependence on the instability of the solvent. MATERIALS AND METHODS: Samples before and after exposure were analysed using UHPLC with UV/Vis and MS detection. RESULTS: Under visible light protection, the solutions were stable for 14 days at room temperature whereas a loss of 20%-60% was measured after 1 day of light exposure. The loss of sennosides due to degradation can be as fast as up to 2%-2.5% per hour, which might have a tremendous impact on phytochemical analysis results during the course of an analysis. The formation of aglycones was not observed in the degradation of sennosides and rhein-8-O-glucoside. CONCLUSION: Aglycones could not be found as a result of the forced degradation. The solutions of sennosides clearly need to be protected from light to obtain reliable analytical results, and light protection is a major point for the stability of liquid preparations.
