Authentication of Eleuthero and Rhodiola Supplements in the United Kingdom

Eleuthero (Siberian ginseng, Eleutherococcus senticosus, Araliaceae) and Rhodiola (Rhodiola Rosea, Crassulaceae) roots are popular herbal supplements that are used to improve overall health resilience to conditions such as stress and exhaustion. The purpose of this study was to authenticate eleuthero and Rhodiola herbal supplements utilizing DNA barcoding techniques and determine whether there is evidence for adulteration.

The authors obtained a total of 39 single-ingredient herbal supplements that contained either eleuthero (n=25) or Rhodiola (n=14) powdered root or standardized extract from both online and brick and mortar retailers in the United Kingdom. DNA was extracted several times from all samples. In eleuthero samples, a portion of the matK region was amplified with polymerase chain reaction (PCR), sequenced, and compared to reference standards. In samples where DNA data from the matK region were inconclusive, the ITS2 region was used. Rhodiola samples were treated in a similar fashion, with ITS2 as the target region.

In eleuthero samples, a species-specific single nucleotide polymorphism (SNP), two base pairs in the matK region, was used to differentiate between species. All 25 eleuthero products contained at least one DNA extraction with this SNP. However, nine out of 25 products (36%) contained SNPs that were either variable or altogether different at this site, indicating the presence of Eleutherococcus species other than E. senticosus.

In Rhodiola samples, DNA was recovered and sequenced from 13 out of the 14 products. Of these, only five matched the reference sequences. Another five had sequences that were significantly different from R. rosea but still belonged to the genus Rhodiola (R. himalensisR. wallichianaR. crenulata, or R. gelida). In three products, no Rhodiola spp. were detected, and only sequences most likely belonging to fenugreek (Trigonella foenum-graecum, Fabaceae) or alfalfa (Medicago sativa, Fabaceae) were recovered.

The results suggest all of the tested eleuthero products contained E. senticosus; however, a substantial amount also contained another Eleutherococcus species. In another survey of Japanese and Chinese products, E. sessiliflorus was estimated to occur in about 30% of claimed eleuthero-containing supplements.1

Authentication with Rhodiola supplements was more problematic. In half of the tested supplements, R. rosea was not detected but other Rhodiola species were. Rhodiola root is often wild-harvested in regions that contain other species with similar morphology, potentially complicating identification at the source of the supply chain. It is also understood that extraction and manufacturing processes degrade DNA material, posing challenges for DNA barcoding as a method of authentication.

The authors declare no conflicts of interest.

Reference

1Maruyama T, Kamakura H, Miyai M, et al. Authentication of the traditional medicinal plant Eleutherococcus senticosus by DNA and chemical analyses. Planta Med. June 2008; 74(7):787–789. doi: 10.1055/s-2008-1074537.

Ruhsam M, Hollingsworth PM. Authentication of Eleutherococcus and Rhodiola herbal supplement products in the United Kingdom. J Pharm Biomed Anal. February 2018;149:403-409. doi: 10.1016/j.jpba.2017.11.025.

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