A metabolomic and phytochemical based study of Rhodiola species sourced from Asia and Europe

Abstract

Rhodiola rosea L. has a long history of use in Europe as an economically valuable medicinal plant. It is used for the treatment of stress-induced fatigue, anxiety and high-altitude sickness [1]. With the increasing demand and over-collection of R. rosea, some adulterated products have been found. According to our investigations, approximately 25% of products claiming to be R. rosea on the European market are adulterated. Adulteration may occur at different stages along the value chain. Therefore the authenticity and quality of raw materials of R. rosea is an important area for investigation. The aim of the project is to investigate the metabolite differences of Rhodiola spp. collected from China and Europe and assess their phytochemical variation. Approximately 45 crude root dried plant specimens were sourced from different suppliers. HPTLC and 1H-NMR analysis was used to evaluate the samples phytochemical variation and metabolites differences. R. crenulata was found to contain no rosavin (a marker compound for R. rosea) but another marker compound, particular to R. crenulata, was identified. Approximately 30% of R. rosea and 27% of R. sachalinesis crude root dried specimens were adulterated with R. crenulata on account of containing no rosavin. R. sachalinesis contains a low concentration of rosavin and salidroside compared with R. rosea. Variations in secondary metabolites of Rhodiola spp. were identified and can be used to distinguish different species of Rhodiola. A marker compound was identified for R. crenulata. Adulteration among these species appears to be commonplace. The method of combining HPTLC and 1H-NMR is shown to be a robust quality control method.