Comparison of different Rhodiola species using NMR- metabolomics, HPTLC and DNA barcoding techniques

Medicinal Rhodiola species, including Rhodiola rosea L. and Rhodiola crenulata (Hongjingtian红景天) have been widely used as herbal medicines with numerous claims for their therapeutic effects. These products are registered by a number as pharmaceuticals and throughout China Rhodiola is also taken for wellness and is registered as a self-medicated wellness product for ‘blood-boosting and heart-strengthening.’ However other species exist that may be found as adulterants in the value chain, these include Rhodiola quadrifida (Pall.) Fisch. & C.A.Mey, Rhodiola sachalinensis Borris, and Rhodiola fastigiata (Hook. f. & Thomson) S.H. Fu. Faced with resource depletion, environment destruction and higher demand, R. rosea and R. crenulata are becoming scarce around theworld. This scarcity may add to their economic value, but also increases the risk of adulteration and poor quality (Booker et al. 2015)

Comparison of different Rhodiola species using NMR-metabolomics, HPTLC and DNA barcoding techniques

The fast developing international trade of products based on local and traditional knowledge and their associated value chains have become an important aspect of the ethnopharmacological debate. The structure and diversity of value chains and their impact on the phytochemical composition of herbal medicinal products (HMPs) has been overlooked in quality issues in transnational trade. Medicinal Rhodiola species, including R. rosea L. and R. crenulata (Hook.f. & Thomson) H.Ohba, abbreviate genus have been widely used as traditional herbal medicines with numerous claims for their therapeutic effects [1]. Faced with resource depletion and environment destruction, R. rosea and R. crenulata are becoming endangered, making them more economically valuable to collectors and middlemen, and also increasing the risk of adulteration and low quality. This study compares the phytochemical differences among Rhodiola raw materials available on the market and provides a practical method for Rhodiola authentication. Nuclear magnetic resonance (NMR) spectroscopy coupled with multivariate analysis software and high performance thin layer chromatography (HPTLC) techniques were used to analyse the phytochemical differences between five Rhodiola species. We compared the phytochemical composition of collected Rhodiola samples to authenticated samples. Rosavin and rosarin were mainly present in R. rosea whereas an unknown compound was only present in R. crenulata. 30% of the Rhodiola samples purchased from the Chinese market were adulterated by other Rhodiola spp. 7% of the raw-material samples were not labelled properly and the species information was not clearly illustrated. Both 1H-NMR and HPTLC methods provided an integrated analysis of the phytochemical differences between the species studied. This study provided an identification method for R. rosea and R. crenulata and provided further analytical data that could form the basis for the identification of other species. The integrated identification approach combining these two analytical platforms offers an innovative and practical way of assessing the chemical variability along the value chains of medicinal plants