Background

Rhodiola rosea L. Crassulaceae, root (Golden Root, Arctic Root) is a high-value herbal medicinal product, registered in the UK for the treatment of stress-induced fatigue, exhaustion and anxiety based on traditional use and used throughout Europe as a herbal medicinal product for similar indications. Numerous unregistered supplements are also available. There are several Chinese species used in traditional Chinese medicine (TCM), including Rhodiola crenulata (Hook.f. & Thomoson) that is believed to be a common adulterant in the R. rosea value chain.

Aims

The project is embedded in a larger study aiming to investigate the diverse value chains that lead to the production of R. rosea as an herbal medicinal product or supplement. Here we focus on a comparison of the quality of the finished products and assess any phytochemical variation between products registered under the Traditional Herbal Medicine Products Directive (THMPD) and products obtained from the market without any registration (i.e. generally unlicensed supplements). Our key aim is to establish the extent of the problem in terms of adulteration of consumer products claiming to contain R. rosea(or R. crenulata).

Methods

Approximately 40 commercial products (granulated powders and extracts) were sourced from different suppliers. We analysed these samples using high performance thin layer chromatography (HPTLC), mass spectrometry (MS) and (1)H NMR spectroscopy coupled with multi-variate analysis software following a method previously developed by our group for the analysis of turmeric products.

Results

We investigate the phytochemistry of the different species and assess the potential of R. crenulata as an adulterant at the end of the R. rosea value chains. The consistency of the products varies significantly. Approximately one fifth of commercial products that claimed to be R. rosea did not contain rosavin (the key reference markers used to distinguish R. rosea from related species). Moreover some products appeared not to contain salidroside, another marker compound found in other Rhodiola species. Approximately 80% of the remaining commercial products were lower in rosavin content than the registered products and appeared to be adulterated with other Rhodiola species.

Conclusions

The variation in phytochemical constituents present in Rhodiola products available to European buyers via the internet and other sources is a major cause for concern. Adulteration with different species, and other sometimes unknown adulterants, appears to be commonplace. Good quality systems and manufacturing practices, including those required under the THMPD, enable consumers to have confidence that products are authentic and meet a high specification for quality and safety.

In Valencia Region (Spain), some wild and cultivated sages are used for medicinal purposes. Among them, Salvia officinalis subsp. lavandulifolia (SL) is widely employed and known for production of Spanish sage oil and herbal products. Nevertheless, it shares the market with S. blancoana subsp. mariolensis (SB) and, to a lesser extent, with their hybrid S. x hegelmaieri (SH). The knowledge on these two species is far low and confusion between them is possible. The aim of the present paper is to improve the ethnopharmacological, morphological and chemical knowledge of these sages, and to contribute to setting up quality specifications for improving identification and distinction from other Salvia species, such as, S. officinalis subsp. officinalis, S. x auriculata and S. microphylla var. microphylla. Samples were collected in Valencia Region and surrounding mountain areas during the ethnopharmacological field work. Twenty-nine medicinal uses were reported for SL, 13 of them being also recorded for SB. Of particular interest is a homemade liquor, used as digestive and known as “salvieta,” which is mainly prepared with SB. The macro- and microscopic characters are insufficient for identification of cut, crushed or powdered material. The study of the essential oil and a HPTLC (High Performance Thin Layer Chromatography) fingerprint of their extracts could help to distinguish SB from the other sages. The essential oil from dried aerial parts of SB (content: 1.8–4.5%) was characterized by GC-FID (Gas Chromatography with Flame Ionization Detector) and GC-MS (Gas Chromatography coupled to Mass Spectrometry) showing a composition close to that currently accepted for Spanish sage essential oil in the European Pharmacopoeia, ISO (International Standard Organization) and UNE (Una Norma Española) standards, with 1,8-cineole (13.7–45.7%) and camphor (12.1–28.6%) as major constituents. HPTLC methods, based on the analysis of hydroalcoholic and dichloromethane extracts, allowed to distinguish SB from other Salvia taxa currently found in Valencia region, except from its hybrid SH. This interdisciplinary study, that combines popular knowledge with botany and chemistry, allows to identify the raw herbal material from SB and to distinguish it from other Salvia species, ensuring a proper commercialization as herbal teas or for the preparation of spirits.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5524814/

Hypericum perforatum L. is the most commonly used herb for treating depression. Due to the popularity of this botanical, there is a potential for economically driven adulteration of St. John’s wort (SJW) products. The goal of this study was to investigate SJW ingredients suspected to be adulterated based on simple preliminary HPTLC tests. Commercial samples were analyzed by HPTLC following the United States Pharmacopeia (USP) monograph methodology, with additional visualization under white light. A number of these samples presented odd methanolic solution colors and unconventional HPTLC fingerprints, suggesting the presence of other species and/or extraneous polar additives. To achieve identification and separation of the polar additives, a new reversed-phase HPTLC method was developed. The adulterants were identified as synthetic dyes in the amounts of 0.51 to 1.36% by weight. Identities of the dyes were confirmed by scanning densitometry and HPTLC-MS. A modified USP method with additional detection mode permitted the identification of eight SJW samples adulterated with dyes and six others with flavonoid fingerprints different from those specified by USP from a total of 37 samples of dry extracts, finished products, and bulk raw herb. A decision flowchart is proposed to guide the detection of adulteration of SJW in a systematic fashion.

The required conditions for an efficient purification (ca. 75% use silica gel at Oril Industrie) are determined by TLC. Then, the purification progress is checked by preparative column chromatography via HPTLC. Twenty fractions were analyzable within 1 hour. TLC/HPTLC is the method of choice due to its simplicity, rapidness and the successful scale up from TLC to preparative separations. HPTLC-MS helped to quickly resolve the composition of a mixture.

TLC plate silica gel 60 F₂₅₄ (Merck), 20 x 5 cm HPTLC plate silica gel 60 F_254s (Merck), 20 x 10 cm

The aim of this study was to obtain a batch with a purity >99% of the isomer Z, containing <1% of isomer E and < 0.15% of other impurities. By RP-HPLC the isomers were not separated satisfyingly, and TLC was selected for method development to separate the two isomers. Ethyl acetate – methylcyclohexane 9:1 was the best option to separate all compounds at reasonable hRF values allowing a fast purification.

Mass spectra were recorded to characterize the different compounds. The same sodium adduct [M+Na]+ and respective dimer [2M+Na]+ were obtained for both Z/E isomeres. For NMR, the crude product solution was concentrated by a factor of 10, applied (15 μL) on the HPTLC plate, separated, and four zones of each target zone were eluted and combined.

The purification of the crude product (2 kg dissolved in toluene) on a 45-cm column (packed at 40 bars with 40 kg silica gel 60, 15–40 μm, Merck) at a flow rate of 10 L/min with ethyl acetate – methylcyclohexane 9:1 led to a productivity of 20 kg per day. The elution process was monitored online by UV 254 nm detection and in parallel offline by HPTLC.

The different fractions of the target isomer Z were collected and the combined fractions analyzed by NMR. The purity was not sufficient, as the NMR spectrum showed several impurities. Thus, the purification was optimized. The new eluent of dichloromethane – ethanol 19:1 together with a crude product load of 0.5 kg also led to a productivity of 20 kg per day. The purity obtained for the Z isomer was 99.8% with a yield of 88%.

TLC is the best method for development and optimization of purification processes using silica gel. It is simple and allows a rapid upscaling to preparative columns. HPTLC is an efficient tool for offline monitoring of the eluted fractions. Up to 20 fractions can be analyzed in parallel and compared in the HPTLC chromatogram at UV 254 nm, achieving a good overview on the purity and amount of the target compound per fraction.

Contact: Amélie Havard, Daniel Dron, Oril Industrie (Servier), Industrial Research Centre, Department of Analytical Innovative Technologies R&D, 13 rue Auguste Desgenétais, CS 60125, 76210 Bolbec, France amelie.havard@servier.com, daniel.dron@servier.com

Adulteration of Ginkgo products sold as unregistered supplements within the very large market of Ginkgo products (reputedly £650 million annually) through the post-extraction addition of cheaper (e.g. buckwheat derived) rutin is suspected to allow sub-standard products to appear satisfactory to third parties, e.g. secondary buyers along the value chain or any regulatory authorities. This study was therefore carried out to identify products that did not conform to their label specification and may have been actively adulterated to enable access to the global markets.

500 MHz Bruker NMR spectroscopy instrumentation combined with Topspin version 3.2 and a CAMAG HPTLC system (HPTLC Association for the analysis of Ginkgo biloba leaf) were used to generate NMR spectra (focusing on the 6–8 ppm region for analysis) and chromatograms, respectively.

Out of the 35 samples of Ginkgo biloba analysed, 33 were found to contain elevated levels of rutin and/or quercetin, or low levels of Ginkgo metabolites when compared with the reference samples. Samples with disproportional levels of rutin or quercetin compared with other gingko metabolites are likely to be adulterated, either by accident or intentionally, and those samples with low or non-existent gingko metabolite content may have been produced using poor extraction techniques. Only two of the investigated samples were found to match with the High-Performance Thin-Layer Chromatography (HPTLC) fingerprint of the selected reference material. All others deviated significantly. One product contained a 5-hydroxytryptophan derivative, which is not a natural constituent of Ginkgo biloba.

Overall, these examples either suggest a poor extraction technique or deliberate adulteration along the value chain. Investigating the ratio of different flavonoids e.g. quercetin and kaempferol using NMR spectroscopy and HPTLC will provide further evidence as to the degree and kind of adulteration of Gingko supplements. From a consumer perspective the equivalence in identity and overall quality of the products needs to be guaranteed for supplements too and not only for products produced according to a quality standard or pharmacopoeial monograph.

https://www.sciencedirect.com/science/article/pii/S2210803316300239

Ethnopharmacological relevance

Herbal medicinal products based on ginkgo leaf refined dry extract (GBE) are an European development from the Eastern Asia traditionally used species Ginkgo biloba L. Nowadays, ginkgo products have increased the presence in the market, mainly as dietary supplements. Its adulteration with rutin and quercetin or herbal extracts rich in these compounds is a common practice. Tests featuring assays and detection of adulterants need to be performed on top of other existent methods (e.g. identification test). This may increase the costs of evaluating the quality of ginkgo products.

Aim of the study

To prove that comprehensive HPTLC fingerprinting can provide information beyond identification of ginkgo products, avoiding additional chromatographic tests for detection of adulterations.

Materials and methods

The information contained in the fingerprint obtained by HPTLC analysis of flavonoids was used for identification and for detection of adulterants, as well as to verify the limits of rutin and quercetin, which are normally determined by HPLC and used for detection of adulterants. For this purpose, peak profiles were generated from HPTLC chromatogram images. USP-HPLC methods were used for quantification of total flavonoids and testing the limits of rutin and quercetin. HPLC data were used to support the validity of the HPTLC method. An additional reversed phase HPTLC method was developed as a possible confirmatory method for the quercetin limit test.

Results

The proposed HPTLC method uses a particular sequence of detections, resulting in a number of images, which are later interpreted in a certain order. It is able to identify ginkgo products, to detect adulterants (rutin, quercetin, sophora fruit and flower bud, and buckwheat), and, using peak profiles generated from the chromatogram images prior to and after derivatisation, to evaluate the limits of rutin and quercetin. Forty-eight out of fifty-nine ginkgo dietary supplements analysed contained one or more adulterants. Furthermore, results of the HPTLC and HPLC limit tests for rutin and quercetin were in agreement in 98% of the cases. Finally, a decision tree showing the sequence of interpretation of the fingerprints obtained with the different detections after a single HPTLC analysis is included to help the analyst to evaluate whether samples have the correct identity and whether they contain or not adulterants.

Conclusion

A single HPTLC analysis is able to provide information on identity and purity of the products. This simplifies the analytical workflow and reduces the number of analyses prescribed in the USP powdered ginkgo extract monograph.

https://www.sciencedirect.com/science/article/pii/S0378874118345410