No Adulteration in Garcinia Crude Raw Materials and Dietary Supplements

Reviewed: Seethapathy GS, Tadesse M, Urumarudappa SKJ, Gunaga SV, Vasudeva R, Malterud KE, Shaanker RU, de Boer HJ, Ravikanth G, Wangensteen H. Authentication of Garcinia fruits and food supplements using DNA barcoding and NMR spectroscopy. Sci Rep. 2018;8:10561.

Keywords: Adulteration, DNA barcoding, garcinia, Garcinia gummi-gutta, Garcinia indica, ¹H NMR, ITS, kokum

A number of investigations into the authenticity of crude herbal drugs by genetic test methods have received financial support from the Indian government. In this paper, results were presented from analyzing 24 crude herbal garcinia (Garcinia gummi-gutta, syn. G. cambogia, Clusiaceae, n = 19) or kokum (G. indica, n = 5) materials from markets in the Indian states of Karnataka, Kerala, Maharashtra, and Tamil Nadu. The dried fruit samples were analyzed by DNA barcoding, and contents of hydroxycitric acid quantified by proton nuclear magnetic resonance (¹H NMR) spectroscopy. Also analyzed were 10 dietary supplements labeled to contain garcinia or kokum from pharmacies in India (n = 5) or Romania (n = 1), or purchased online from the United States (n = 2), Norway (n = 1), or Sweden (n = 1).

For the genetic identification, the nrITS, psbA-trnH and rbcL sequences of samples from the Indian markets were compared to sequences obtained from authenticated plant material of 11 Garcinia species, including G. gummi-gutta, and G. indica. The nuclear ribosomal ITS sequence provided the best results with regard to species differentiation and amplification success. All the samples were authentic, with hydroxycitric acid concentrations in the fruit rind between 3.9-10.3% in garcinia, and between 1.7-7.6% in kokum based on the quantitative ¹H NMR data. Hydroxycitric acid lactone, also measured by ¹H NMR, was found at 7.4-19.1% in garcinia, and at 3.5-11.7% in kokum.

The concentrations of hydroxycitric acid in garcinia/kokum dietary supplements ranged from 29-289 mg/capsule, with two products containing less than 10% of the labeled hydroxycitric acid contents. However, only one of the 10 dietary supplements contained measurable amounts of hydroxycitric acid lactone, most likely due to specific processing methods providing good yields in purified hydroxycitric acid from Garcinia fruits at the expense of hydroxycitric acid lactone and other Garcinia metabolites.^1,2

Comment: The combination of DNA barcoding and ¹H NMR provides a robust approach for the identification of crude herbal materials (although the whole dried fruits are readily distinguished by visual inspection), and the qualitative use of NMR allows one to determine the concentrations of important marker compounds, as shown by the example of hydroxycitric acid. Based on the processing steps involved to obtain purified hydroxycitric acid from Garcinia fruit, which may involve extraction with an alcohol (e.g., methanol), followed by precipitation of the hydroxycitric acid in an alkaline environment (e.g., using methanolic potassium hydroxide) to obtain a hydroxycitric acid salt,² it may not be surprising that there was no suitable DNA extracted from the 10 dietary supplements. Such processing also explains the absence of hydroxycitric acid lactone, and other characteristic compounds found in the traditional medicinal preparations (dried fruit, decoction, juice, or syrup)^3,4 of Garcinia fruits.

References

1. Samuel P, Saravanan S, Thangaraj M., inventors; Indfrag Ltd., Bangalore (India), assignee. Hydroxycitric acid complex metal salts, methods, and composition. US Patent No. US 7,214,823. 2007.
2. Majeed M, Badmaev V, Rajendran R., inventors. Sabinsa Corp., Piscataway, NJ, assignee. Potassium hydroxycitrate for the suppression of appetite and induction of weight loss. US Patent No. US 5,783,603. 1998.
3. Rasha RM, Salha A, Thanai A, Zahar A. The biological importance of Garcinia cambogia: a review. J Nutr Food Sci. 2015;S5:004.
4. Chuah LO, Ho WY, Beh BK, Yeap SK. Updates on anti-obesity effect Garcinia origin (-)-HCA. Evid Based Compl Alt Med. 2013;2013:751658.