DNA Barcode Authentication of Devil's Claw Herbal Dietary Supplements

Area of Science:

• Pharmacognosy
• Molecular Biology
• Botanical Identification

Background:

• Devil's claw (Harpagophytum procumbens and H. zeyheri) is a medicinal plant genus.
• European pharmacopeia considers H. procumbens and H. zeyheri interchangeable, but they are chemically distinct.
• H. zeyheri is not legal as an herbal supplement in the United States.

Purpose of the Study:

• To identify reliable DNA markers for distinguishing H. procumbens from H. zeyheri.
• To develop a DNA mini-barcode assay for quality control of devil's claw supplements.
• To estimate the mislabeling frequency in commercially available devil's claw supplements.

Main Methods:

• Tested four DNA markers (rbcL, matK, nrITS2, psbA-trnH) for species discrimination.
• Developed a novel DNA mini-barcode assay targeting the psbA-trnH region.
• Analyzed 23 devil's claw supplements using the developed assay to assess labeling accuracy.

Main Results:

• The psbA-trnH marker successfully distinguished between H. procumbens and H. zeyheri.
• The novel mini-barcode assay demonstrated high specificity and sensitivity.
• PCR amplification failed in 13% of supplement samples.
• Of 20 analyzable supplements, 75% did not contain H. procumbens, 25% contained both species, and none contained only H. procumbens.

Conclusions:

• The psbA-trnH mini-barcode is a reliable method for differentiating Devil's claw species.
• Significant mislabeling of Devil's claw supplements was detected in the US market.
• Recommended the novel mini-barcode assay for routine quality control in Devil's claw supplement manufacturing.