Chromatographic fingerprinting as a strategy to identify regulated plants in illegal herbal supplements

Overview of industrial food fraud and authentication through chromatography technique and its impact on public health

Food fraud is widespread nowadays in the food products supply chain, from raw materials processing to the final product and during storage and transport. The most frequent fraud is practiced in staple food commodities like cereals. Their origin, variety, genotype, and bioactive compounds are altered to deceive consumers. Similarly, in various food sectors like beverage, baking, and confectionary, items like melamine, flour improver, and food colors are used in the market to temple consumers. To tackle food fraud and authentication, non-destructive techniques are being used. These techniques have limitations like lack of standardization, interference from multiple absorbing species, ambiguous results, and time-consuming to perform, depending on the type, size, and location of the system proved difficult to quantify the samples of adulteration. Chromatography has been introduced as an effective technique. It serves to safeguard public health due to its detection capabilities. Chromatography proved a crucial tool against fraudulent practices to preserve consumer trust.

Multidimensional Chromatographic Fingerprinting Combined with Chemometrics for the Identification of Regulated Plants in Suspicious Plant Food Supplements

The popularity of plant food supplements has seen explosive growth all over the world, making them susceptible to adulteration and fraud. This necessitates a screening approach for the detection of regulated plants in plant food supplements, which are usually composed of complex plant mixtures, thus making the approach not so straightforward. This paper aims to tackle this problem by developing a multidimensional chromatographic fingerprinting method aided by chemometrics. To render more specificity to the chromatogram, a multidimensional fingerprint (absorbance × wavelength × retention time) was considered. This was achieved by selecting several wavelengths through a correlation analysis. The data were recorded using ultra-high-performance liquid chromatography (UHPLC) coupled with diode array detection (DAD). Chemometric modelling was performed by partial least squares-discriminant analysis (PLS-DA) through (a) binary modelling and (b) multiclass modelling. The correct classification rates (ccr%) by cross-validation, modelling, and external test set validation were satisfactory for both approaches, but upon further comparison, binary models were preferred. As a proof of concept, the models were applied to twelve samples for the detection of four regulated plants. Overall, it was revealed that the combination of multidimensional fingerprinting data with chemometrics was feasible for the identification of regulated plants in complex botanical matrices.

Advances in Fingerprint Analysis for Standardization and Quality Control of Herbal Medicines

Herbal drugs or herbal medicines (HMs) have a long-standing history as natural remedies for preventing and curing diseases. HMs have garnered greater interest during the past decades due to their broad, synergistic actions on the physiological systems and relatively lower incidence of adverse events, compared to synthetic drugs. However, assuring reproducible quality, efficacy, and safety from herbal drugs remains a challenging task. HMs typically consist of many constituents whose presence and quantity may vary among different sources of materials. Fingerprint analysis has emerged as a very useful technique to assess the quality of herbal drug materials and formulations for establishing standardized herbal products. Rather than using a single or two marker(s), fingerprinting techniques take great consideration of the complexity of herbal drugs by evaluating the whole chemical profile and extracting a common pattern to be set as a criterion for assessing the individual material or formulation. In this review, we described and assessed various fingerprinting techniques reported to date, which are applicable to the standardization and quality control of HMs. We also evaluated the application of multivariate data analysis or chemometrics in assisting the analysis of the complex datasets from the determination of HMs. To ensure that these methods yield reliable results, we reviewed the validation status of the methods and provided perspectives on those. Finally, we concluded by highlighting major accomplishments and presenting a gap analysis between the existing techniques and what is needed to continue moving forward.

European fingerprint study on omeprazole drug substances using a multi analytical approach and chemometrics as a tool for the discrimination of manufacturing sources

Like drug products, Active Pharmaceutical Ingredients (APIs) are subject to substandard and falsification issues, which represent a threat to patient health. In order to monitor the quality of drug substances and prevent the use of non-compliant APIs, Official Medicine Control Laboratories work together in a European network developing coordinated strategies and programmes. The API working group proposed a market surveillance study on omeprazole and omeprazole magnesium with the objectives of controlling the pharmaceutical quality of samples, checking compliance with the monographs of the European Pharmacopoeia, and collecting analytical fingerprints that could be further used to differentiate manufacturing sources for future authenticity investigations. The study described in this article reports the analysis carried out by 7 European laboratories on 28 samples from 11 manufacturers with 5 analytical techniques (related substances with HPLC, residual solvents with GC-MS, near infrared spectroscopy, proton nuclear magnetic resonance spectroscopy and X-ray powder diffractometry). The large amount of resulting analytical data were centralized and treated with two chemometric methods: Principal Component Analysis and Hierarchical Clustering Analysis. Data were analyzed separately and in combination (data fusion), allowing us to conclude that NMR and XRPD were suitable to differentiate samples originating from 9 out of 11 manufacturers. Analytical fingerprints associated with chemometrics were demonstrated to be a valuable methodology to discriminate manufacturers of omeprazole and omeprazole magnesium APIs and detect future substandard and falsified APIs.

Chemical Authentication of Botanical Ingredients: A Review of Commercial Herbal Products

Chemical methods are the most important and widely used traditional plant identification techniques recommended by national and international pharmacopoeias. We have reviewed the successful use of different chemical methods for the botanical authentication of 2,386 commercial herbal products, sold in 37 countries spread over six continents. The majority of the analyzed products were reported to be authentic (73%) but more than a quarter proved to be adulterated (27%). At a national level, the number of products and the adulteration proportions varied very widely. Yet, the adulteration reported for the four countries, from which more than 100 commercial products were purchased and their botanical ingredients chemically authenticated, was 37% (United Kingdom), 31% (Italy), 27% (United States), and 21% (China). Simple or hyphenated chemical analytical techniques have identified the total absence of labeled botanical ingredients, substitution with closely related or unrelated species, the use of biological filler material, and the hidden presence of regulated, forbidden or allergenic species. Additionally, affecting the safety and efficacy of the commercial herbal products, other low quality aspects were reported: considerable variability of the labeled metabolic profile and/or phytochemical content, significant product-to-product variation of botanical ingredients or even between batches by the same manufacturer, and misleading quality and quantity label claims. Choosing an appropriate chemical technique can be the only possibility for assessing the botanical authenticity of samples which have lost their diagnostic microscopic characteristics or were processed so that DNA cannot be adequately recovered.

HPLC-DAD fingerprints combined with chemometric techniques for the authentication of plucking seasons of Laoshan green tea

Laoshan green teas plucked in summer and autumn were measured by high performance liquid chromatography-diode array detector (HPLC-DAD). After baseline correction, the fingerprints data were resolved by multivariate curve resolution-alternating least squares (MCR-ALS) and a total of 57 components were acquired. Relative concentrations of these components were afterwards applied to distinguish plucking seasons using principal component analysis (PCA), support vector machines (SVM) and partial least squares-discriminant analysis (PLS-DA). For both SVM and PLS-DA models, the total recognition rates of training set, cross-validation and testing set were 100%, 91.3% and 100%, respectively. Besides, three variable selection methods were employed to determine characteristic components for the authentication of summer and autumn teas. Results showed that PLS-DA model based on three characteristic components selected by VIP possesses identical predictive ability as the original model. This study demonstrated that our proposed strategy is competent for the authentication of plucking seasons of Laoshan green tea.

Microwave-assisted extraction followed by salting-out phase separation for hierarchical screening of illegal adulterants in aphrodisiac health products by multi-dimensional fingerprint profiling analysis

A novel method for hierarchical screening of illegal adulterants in Fur seal ginseng pills (FSGP) products was developed by microwave-assisted extraction (MAE) coupled to salting-out assisted liquid-liquid extraction (SALLE) with multi-dimensional fingerprint profiling analysis. Using a homogeneous system formed by dimethyl carbonate (DMC) and water as the extractant, the MAE conditions were investigated to maximize extraction recoveries, followed by addition of ammonium sulfate to induce DMC phase separation for SALLE enrichment of 16 potentially illegal adulterants such as phosphodiesterase type-5 inhibitors, androgens, α receptor antagonists and yohimbine etc. By means of high-performance liquid chromatography (HPLC) with diode array detection (DAD) and fluorescence detection (FLD), multi-dimensional fingerprints were acquired by multi-wavelength detection to highlight the signals of the potentially illegal adulterants and reduce or remove interferences from the sample matrix. For high accuracy and reliability, a hierarchical screening strategy was designed by multi-dimensional fingerprinting profiling analysis (MDFPA). The method exhibited proper identification and quantification performance, and it was successfully applied to screening of illegal adulterants in 18 batches of the samples through the step-by-step MDFPA. Also, the results were further confirmed by ultra high-performance liquid chromatography-quadrupole-orbitrap mass spectrometry (UHPLC-Q-Orbitrap/MS). The proposed method was proved to be a green, efficient and reliable alternative to monitoring aphrodisiac health products.

Development of Electrochemical Oscillation Method for Identification of Prunus persica, Prunus davidiana, and Prunus armeniaca Nuts

In this work, an electrochemical oscillation system has been developed using the Belousov-Zhabotinsky reaction. The effect of the combination of each reagent, reaction temperature, and stirring speed on the induction period, oscillating period, and oscillating life were optimized. The nuts of Prunus persica, Prunus davidiana, and Prunus armeniaca have been widely used for medical purposes. The proposed electrochemical oscillation system was then used for the identification of P. persica, P. davidiana, and P. armeniaca. Three nuts exhibited very different electrochemical oscillation profiles. The dendrogram was divided into three main principal infrageneric clades. Each cluster only contains one species, suggesting that no outlier was observed in this study. Based on the discussed results, we proposed a simple method for herbal medicine identification.

The contribution ratio of various characteristic tea compounds in antioxidant capacity by DPPH assay

Tea is a worldwide health beneficial beverage for its antioxidant ability. 1,1-diphenyl-2-picryl-hydrazyl (DPPH) assay is a common method to measure the antioxidant capacity of tea compounds, yet the contribution ratio of various characteristic tea compounds is still unclear. high-performance liquid chromatography (HPLC) was used to examine the content of polyphenol compounds in 24 tea samples from four tea categories (green tea, white tea, oolong tea, and black tea). Based on the results of DPPH and HPLC, contribution ratio of each tea compound was analyzed by the Pearson correlation analysis and the partial least squares regression (PLSR). The Pearson correlation analysis showed that the order of correlation between the area of 13 peaks and the antioxidant ability of tea samples was x8 > x6 > x3 > x13 > x10 > x7 > x2 > x5 > x11 > x9 > x4 > x12 > x1; the regression equation fit by PLSR was Y = 47.258 - 0.760x1 + 0.287x2 - 1.484x3 - 0.569x4 + 0.674x5 + 2.257x6 + 1.698x7 + 1.389x8 - 0.188x9 + 0.467x10 + 0.297x11 + 1.314x12 + 0.963x13. We identified nine common peaks by reference standard substances: the x3 was gallic acid (GA), x4 was theobromine, x5 was catechuic acid (CA), x6 was epigallocatechin (EGC), x8 was epigallocatechin gallate (EGCG), x9 was caffeine, x10 was epicatechin (EC), x12 was epicatechin gallate (ECG), and x13 was gallocatechin gallate (GCG). Based on the study of spectrum-effect correlation, we obtain a better understanding of the antioxidant activity of complex tea polyphenols component. PRACTICAL APPLICATIONS: Identify the contribution of specific chemical compound to antioxidant activity by the coefficients in PLSR equation and provide a deeper insight into the joint effect of multiple ingredients of tea. Further, we can infer the DPPH free radical scavenging ability of a new kind of tea by the PLSR equation without chemical detection.

Development and validation of RP-HPLC method for the determination of stigmasterol in the botanical extract of Ficus deltoidea

A simple, rapid, accurate and precise RP-HPLC method was developed for the determination of stigmasterol in botanical extract of Ficus deltoidea. Separation was achieved with acetonitrile and acetic acid in water (75:25% v/v) in isocratic mode at 210 nm. Single sharp peak of standard stigmasterol was detected at retention time 3.17 min which overlay with the peak of plant extract at 3.14 min. The calibration curve was found to be linear in a concentration range of 2-10 μg/ml with correlation coefficient of 0.998. The LOD and LOQ were found to be 1.50 μg/ml and 4.55 μg/ml respectively. Accuracy and precision was determined with overall recovery of 99.6-100.1% for stigmasterol and RSD values in both intra-day and inter-day repeatability assay lesser than 0.340%, respectively. The robustness study also indicated that there is no influence of minor changes in detecting wavelength and flow rate of mobile phase on the response.

A strategy based on fingerprinting and chemometrics for the detection of regulated plants in plant food supplements from the Belgian market: Two case studies

The sale and consumption of plant food supplements is increasing, especially in the western world. A lot of these supplements can be bought through internet, where a lot of illegal trade is going on. Every year seized dietary supplements are send to laboratories in order to screen for the presence of chemical adulterants or illegally added active pharmaceutical ingredients, though also herbal adulteration occurs and is given less attention. In this paper a two-step approach is presented based on fingerprints recorded by both infrared spectroscopy as liquid chromatography with UV-detection for the screening of five regulated plants used in respectively dietary supplements for slimming and potency enhancement. Both types of fingerprints are combined with chemometric techniques in order to obtain classification models. A first classification model is calculated based on the infrared data and gives a first idea about the plant suspected to be present. This suspicion is then confirmed based on binary classification models calculated with the chromatographic data obtained for the suspected plant. In general, good classification models were obtained for each of the targeted plants. The approach was applied in a small market study comprising 35 dietary supplements for slimming and 34 for male potency enhancement. In total 21 samples were found to contain one of the five targeted plants.

The Traditional Medicinal Plants Cuphea calophylla, Tibouchina kingii, and Pseudelephantopus spiralis Attenuate Inflammatory and Oxidative Mediators

Aerial parts of Cuphea calophylla, Tibouchina kingii, and Pseudelephantopus spiralis have been used in Colombian traditional medicine for inflammation. However, the underlying mechanisms that could explain the anti-inflammatory actions remain unknown. This study aimed to elucidate the anti-inflammatory and cytoprotective effects of hydroalcoholic extracts from C. calophylla (HECC), T. kingii (HETK), and P. spiralis (HEPS) in LPS-stimulated THP-1 macrophages. Reactive oxygen species (ROS), nitric oxide (NO), and malondialdehyde (MDA) were monitored as inflammatory and oxidative markers. The inhibition of lipoxygenase (LOX) and cyclooxygenase (COX) activities in a cell-free system were also investigated. Antioxidant activities were determined using standard in vitro methods. All extracts inhibited the NO, ROS, and MDA levels. HETK showed the highest ROS production inhibition and the highest antioxidant values, whereas HETK and HEPS significantly decreased the cytotoxicity mediated by LPS. The release of MDA was reduced significantly by all extracts. Moreover, the catalytic activity of LOX was inhibited by HECC and HETK. HECC was a more potent reducer of COX-2 activity. All extracts effectively suppressed COX-1 activity. In summary, these results suggest that HECC, HEPS, and HETK possess anti-inflammatory properties. Therefore, these plants could provide a valuable source of natural bioactive compounds for the treatment of inflammatory-related diseases.

Development of Global Chemical Profiling for Quality Assessment of Ganoderma Species by ChemPattern Software

Triterpenoids are the major secondary metabolites and active substances in Ganoderma, considered as the "marker compounds" for the chemical evaluation or standardization of Ganoderma. A response surface methodology was used to optimize the ultrasonic-assisted extraction of triterpenoids. The extraction rate was 7.338 ± 0.150 mg/g under the optimum conditions: 87% ethanol, ratio of solid to liquid (w : v) 1 : 28, and ultrasound extraction time 36 min. Based on the high sensitivity and selectivity of HPLC-LTQ-Orbitrap-MS ⁿ , 24 components of triterpenoids were tentatively identified in the negative mode. Then, the global chemical profiling consisting of HPLC and TLC fingerprints generated by ChemPattern™ software was developed for evaluation of Ganoderma species. For fingerprint analysis, 11 peaks of triterpenoids were selected as the characteristic peaks to evaluate the similarities of different samples. The correlation coefficients of similarity were greater than 0.830. The cluster analysis showed a clear separation of three groups, and 11 peaks played key roles in differentiating these samples. The developed global chemical profiling method could be applied for rapid evaluation, quality control, and authenticity identification of Ganoderma and other herbal medicines.

Fingerprint analysis of Resina Draconis by ultra-performance liquid chromatography

BACKGROUND

Resina Draconis, a bright red resin derived from Dracaena cochinchinensis, is a traditional medicine used in China. To improve its quality control approach, an ultra-performance liquid chromatography (UPLC) fingerprint method was developed for rapidly evaluating the quality of Resina Draconis.

METHODS

The precision, repeatability and stability of the proposed UPLC method were validated in the study. Twelve batches of Resina Draconis samples from various sources were analyzed by the present UPLC method. Common peaks in the chromatograms were adopted to calculate their relative retention time and relative peak area. The chromatographic data were processed by Similarity Evaluation System for Chromatographic Fingerprint of Traditional Chinese Medicine software (Version 2004 A) for similarity analysis.

RESULTS

The present UPLC method demonstrated a satisfactory precision, repeatability and stability. The analysis time of the present UPLC method was shortened to 30 min, compared with that of the conventional HPLC method was 50 min. The similarities of the 12 Resina Draconis samples were 0.976, 0.993, 0.955, 0.789, 0.989, 0.995, 0.794, 0.994, 0.847, 0.987, 0.997, 0.986, respectively, which indicated that the samples were certainly regionally different. The similarities of the 12 samples showed more similar pattern except for samples 4, 7 and 9. Such variation in similarity may presumably be attributed to differences in source.

CONCLUSIONS

Compared with the conventional HPLC method, the present UPLC method showed several advantages including shorter analysis time, higher resolution and better separation performance. The UPLC fingerprinting established in the present paper provides a valuable reference for the quality control of Resina Draconis.

A review of traditional pharmacological uses, phytochemistry, and pharmacological activities of Tribulus terrestris

Tribulus terrestris L. (TT) is an annual plant of the family Zygophyllaceae that has been used for generations to energize, vitalize, and improve sexual function and physical performance in men. The fruits and roots of TT have been used as a folk medicine for thousands of years in China, India, Sudan, and Pakistan. Numerous bioactive phytochemicals, such as saponins and flavonoids, have been isolated and identified from TT that are responsible alone or in combination for various pharmacological activities. This review provides a comprehensive overview of the traditional applications, phytochemistry, pharmacology and overuse of TT and provides evidence for better medicinal usage of TT.

Chemometrics and chromatographic fingerprints to classify plant food supplements according to the content of regulated plants

Plant food supplements are gaining popularity, resulting in a broader spectrum of available products and an increased consumption. Next to the problem of adulteration of these products with synthetic drugs the presence of regulated or toxic plants is an important issue, especially when the products are purchased from irregular sources. This paper focusses on this problem by using specific chromatographic fingerprints for five targeted plants and chemometric classification techniques in order to extract the important information from the fingerprints and determine the presence of the targeted plants in plant food supplements in an objective way. Two approaches were followed: (1) a multiclass model, (2) 2-class model for each of the targeted plants separately. For both approaches good classification models were obtained, especially when using SIMCA and PLS-DA. For each model, misclassification rates for the external test set of maximum one sample could be obtained. The models were applied to five real samples resulting in the identification of the correct plants, confirmed by mass spectrometry. Therefore chromatographic fingerprinting combined with chemometric modelling can be considered interesting to make a more objective decision on whether a regulated plant is present in a plant food supplement or not, especially when no mass spectrometry equipment is available. The results suggest also that the use of a battery of 2-class models to screen for several plants is the approach to be preferred.