A Survey of Commercial Crude Rhodiola crenulata Raw Materials in China

Reviewed: Xin T, Li X, Yao H, Lin Y, Ma X, Cheng R, Song J, Ni L, Fan C, Chen S. Survey of commercial Rhodiola products revealed species diversity and potential safety issues. Sci Rep. 2015;5:8337. doi: 10.1038/srep08337.

The roots and rhizomes of rhodiola (Rhodiola rosea, Crassulaceae) are widely used in Western phytotherapy, and according to the European Medicines Agency Community Herbal Monograph, a 65-70% hydroalcoholic extract can be used for temporary relief of symptoms of stress, such as fatigue and signs of weakness.¹ In the United States, other species sold under the accepted common name “rhodiola” include R. algida var. tangutica and R. kirilowii.² In China, the only rhodiola species accepted in the Chinese Pharmacopoeia is hong jing tian (R. crenulata), which is considered to invigorate the blood, to free the pulse, and to calm panting.³ Due to the increased popularity of R. crenulata, and subsequent overharvesting in some areas, other species have been sold as hong jing tian in the marketplace. A total of 100 commercial samples from drug stores and hospitals labeled as hong jing tian were submitted to DNA barcode analysis using the ITS2 gene sequence to authenticate the materials and to distinguish from the ITS2 sequences of ten other Rhodiola species which were collected by the researchers. Useful DNA could be obtained from 90% of the samples. Only 36 samples (40%) of the roots and rhizomes analyzed were authentic R. crenulata, while 35 (39%) were found to be R. serrata, nine (10%) were R. rosea, seven (8%) were identified as R. gelida, and the remaining three samples were attributed to other Rhodiola species. The authors suggest that DNA barcoding is a useful tool for authentication of Rhodiola materials in the marketplace.

Comment: This example of R. crenulata illustrates the problem with medicinal plants where the material is mainly gathered in the wild and where a steady supply has become a problem. As evidenced in the survey, substitution with closely related species often represents an alternative for the people collecting the material. In many cases, such substitutions may be acceptable or even supported in official pharmacopeial monographs, while in other cases, they can be problematic since the safety and benefits of these closely related species may not be known. In addition, the Chinese name “hong jing tian” is used not only for R. crenulata, but also for R. rosea, and the Chinese names for R. serrata (chi ye hong jing tian) and R. gelida (chang lin hong jing tian) can also lead to confusion among those unfamiliar with Chinese nomenclature.⁴ According to TCM expert Eric Brand from the Chinese Medicine Teaching and Research Division, School of Chinese Medicine, Hong Kong Baptist University, “Rhodiola is relatively new to Chinese medicine, and many traditional vendors have little specialized experience with it. Several different rhodiola species are wild-harvested from a variety of production regions in China, but it is difficult to distinguish the products on the market down to the species level organoleptically, and they are often not effectively differentiated in trade.”

A similar situation is encountered with the widely used Western medicinal plant R. rosea. Resource shortages of wild R. rosea originating from mountainous or Northern boreal areas have been recognized as well. The situation is aggravated due to the short vegetative seasons and the slow growth of the plant. Roots/rhizomes take 5-7 years of growth to be suitable for medicinal purposes, producing challenges in natural resource management and cultivation. This has increased the risk of adulteration and substitution with other species. For example, Asian Rhodiola species have been reportedly used as admixtures/substitutes in R. rosea-labelled products.⁵ For crude raw material, DNA barcoding may be one of the tools for correct identification of the species, while for extracts, the detection of the characteristic rosavins with chemically based identification methods, such as HPLC-UV or high-performance thin-layer chromatography (HPTLC), will allow authentication of R. rosea.^5,6

References

1.     European Medicines Agency Committee on Herbal Medicinal Products. Community herbal monograph on Rhodiola rosea L., rhizome et radix. London, UK: European Medicines Agency; 2012. Available at: http://www.ema.europa.eu/docs/en_GB/document_library/Herbal_-_Community_herbal_monograph/2012/05/WC500127863.pdf. Accessed May 27, 2015.

2.     McGuffin M, Kartesz JT, Leung AY, Tucker AO, eds. American Herbal Products Association’s Herbs of Commerce, 2^nd ed. Silver Spring, MD: American Herbal Products Association; 2000.

3.     Zhao Z, Chen H. Guo P, Brand E, eds. Chinese Medicinal Identification: An Illustrated Approach. Taos, NM: Paradigm Publications; 2014:123.

4.     Flora of China. eFloras.org website. http://www.efloras.org. Accessed May 27, 2015.

5.     Ma Y-C, Wang X-Q, Hou FF, Ma J, Luo M, Lu S, Jin P, Terevsky N, Chen A, Xu I, Patel AV, Gorecki D. Rapid resolution liquid chromatography (RRLC) analysis for quality control of Rhodiola rosea roots and commercial standardized products. Nat Prod Commun. 2011;6(5):645-650.

6.     Rumalla CS, Avula B, Ali Z, Smillie TJ, Filion V, Cuerrier A, Arnason JT, Khan IA. Quantitative HPTLC analysis of phenylpropanoids in Rhodiola species. Journal of Planar Chromatography – Modern TLC. 2011;24(2):116-120.