Assessing product adulteration of Eurycoma longifolia (Tongkat Ali) herbal medicinal product using DNA barcoding and HPLC analysis

Integrating DNA Barcoding Within an Orthogonal Approach for Herbal Product Authentication: A Narrative Review

INTRODUCTION

Existing methods for morphological, organoleptic, and chemical authentication may not adequately ensure the accurate identification of plant species or guarantee safety. Herbal raw material authentication remains a major challenge in herbal medicine. Over the past decade, DNA barcoding, combined with an orthogonal approach integrating various testing methods for quality assurance, has emerged as a new trend in plant authentication.

OBJECTIVE

The review evaluates DNA barcoding and common alternative testing in plant-related sectors to enhance quality assurance and accurate authentication.

METHOD

Studies were selected based on their relevance to the identification, quality assurance, and safety of herbal products. Inclusion criteria were peer-reviewed articles, systematic reviews, and relevant case studies from the last two decades focused on DNA barcoding, identification methods, and their applications. Exclusion criteria involved studies lacking empirical data, those not peer-reviewed, or those unrelated to the main focus. This ensured the inclusion of high-quality, pertinent sources while excluding less relevant studies.

RESULTS

An orthogonal approach refers to the use of multiple, independent methods that provide complementary information for more accurate plant identification and quality assurance. This reduces false positives or negatives by confirming results through different techniques, combining DNA barcoding with morphological analysis or chemical profiling. It enhances confidence in results, particularly in cases of potential adulteration or misidentification of plant materials.

CONCLUSION

This study highlights the persistent challenges in assuring the quality, purity, and safety of plant materials. Additionally, it stresses the importance of incorporating DNA-based authentication alongside traditional methods, to enhance plant material identification.

Trends in the Tissue Culture Techniques and the Synthesis of Bioactive Compounds in Eurycoma longifolia Jack-Current Status and Future Perspectives

Over the last two decades, there has been a concerted effort by researchers to mass propagate Eurycoma longifolia and improve the yield of its very important and sought-after anti-cancer and aphrodisiac bioactive compounds. To achieve this, various techniques have been used to mass propagate and improve the yield of these bioactive compounds in tissue cultures. These techniques include the optimization of media conditions and application of various types and combinations of plant growth regulators (PGRs). In addition, some elicitation techniques have been used to improve the synthesis of these bioactive compounds. However, in comparison with other herbal species with similar economic importance, many techniques have not been applied to E. longifolia. Adopting the most recent methodologies would ensure efficiency and sustainability in the in vitro production of bioactive compounds in E. longifolia. Therefore, in this review, we present an up-to-date record on the success stories in the tissue culture techniques and synthesis of bioactive compounds. In addition, we attempted to identify some of the missing links on the road to the effective and sustainable biotechnological utilization of this super important biological resource.

Authentication, chemical profiles analysis, and quality evaluation of corn silk via DNA barcoding and UPLC-LTQ/Orbitrap MS chemical profiling

Corn silk is commonly consumed in teas, food ingredients, and herbal medicines. Several varieties of corn silk are grown in different habitats in China. However, as information regarding their phytochemistry and genetic diversity is limited, their medicinal potential has not been utilized thoroughly. Thus, we aimed to use a combination of DNA barcoding based on specific primer ITSC sequences and ultra-performance liquid chromatography coupled with linear trap quadrupole-Orbitrap mass spectrometry (UPLC-LTQ/Orbitrap MS) approach for identifying and evaluating corn silk. ITSC barcoding helped us to identify that 52 samples could be classified into 7 groups of corn silk varieties, but the widely used nrITS and psbA-trnH barcodes failed to identify these varieties. UPLC-LTQ/Orbitrap MS was used to study the components in alcohol extracts derived from different corn silk varieties, and the detected chemical components were analyzed via bioinformatics techniques. We proposed 199 components using untargeted UPLC-LTQ/Orbitrap MS-based metabolomics analysis and identified 67 components. PCA and OPLS-DA analysis revealed two distinct chemotypes by selecting 27 components that could act as difference indicators. KEGG analysis showed that the 199 components were enriched in 12 metabolic pathways. The results showed that corn silk is rich in many types of chemicals and DNA barcoding is better than UPLC-LTQ/Orbitrap MS in distinguishing the differences between different varieties of corn silk. Our findings provide new insights into the chemical and molecular characteristics of different varieties of corn silk, which play a crucial role in the utilization of corn silk resources.

A Multifaceted Review of Eurycoma longifolia Nutraceutical Bioactives: Production, Extraction, and Analysis in Drugs and Biofluids

Eurycoma longifolia Jack (known as Tongkat Ali) is a popular traditional herbal medicine, native to southeast Asia, that is well-known for its aphrodisiac as well as several other effects. Mostly, the root extract of E. longifolia is used as a folk medicine for sexual dysfunction, aging, anxiety, exercise recovery, fever, increased energy, and osteoporosis. These health effects led to the inclusion of E. longifolia in dietary supplements, particularly for bodybuilding purposes. These effects are mediated by a myriad of bioactive compounds belonging to quassinoids, canthin-6-one alkaloids, tirucallane triterpenes, squalene derivatives, and bioactive steroids. Among these phytoconstituents, quassinoids account for a large portion of E. longifolia root phytochemicals. Of these ingredients, eurycomanone, the major quassinoid in E. longifolia extract, accounts to a large extent for its health effects. This review capitalizes on the novel trends toward the production of E. longifolia bioactives using biotechnology and extraction optimization for best yields and recovery. Alongside, novel extraction methods, i.e., green techniques, of E. longifolia bioactives are described. Further, an overview of the different analytical approaches for the quality control assessment of E. longifolia plant material and nutraceuticals is presented alongside studies in body fluids to determine its pharmacokinetics and efficacy level. Such a compilation of analytical methods will help ensure safety and efficacy of that major drug.

Rapid discrimination of the native medicinal plant Adenostemma lavenia from its adulterants using PCR-RFLP

Background

In Taiwan, the aerial part of Adenostemma lavenia (Al) is used in the form of herbal tea or in a folk remedy primarily to mitigate inflammatory conditions in the lungs and liver. Due to the excellent health benefits of Al against inflammation, it has become increasingly crucial and in great demand during the COVID-19 pandemic. However, Al has been found to be adulterated with Wedelia biflora, Sigesbeckia orientalis, and/or Wedelia chinensis because of similarities in appearance and vernacular names.

Methods

This study aimed to develop a PCR-RFLP DNA molecular method for the authentication of Al. The restriction enzyme BsrI was used according to the sequencing and alignment results of PCR products in the ITS2 regions of Al and its adulterants. Gel electrophoresis resulted in the clear separation of Al and its adulterants into two distinct categories.

Results

In conclusion, the PCR-RFLP authentication method developed herein provides an easy, rapid, and accurate method to distinguish Al from its adulterants to assure user health and safety.

Authentication of Marantodes pumilum (Blume) Kuntze: A Systematic Review

Botanical drug products consist of complex phytochemical constituents that vary based on various factors that substantially produce different pharmacological activities and possible side effects. Marantodes pumilum (Blume) Kuntze (Primulaceae) is one of the most popular Malay traditional botanical drugs and widely recognized for its medicinal use. Many studies have been conducted focusing on the identification of bioactive substances, pharmacological and toxicological activities in its specific varieties but less comprehensive study on M. pumilum authentication. Lack of quality control (QC) measurement assessment may cause different quality issues on M. pumilum containing products like adulteration by pharmaceutical substances, substitution, contamination, misidentification with toxic plant species, which may be detrimental to consumers' health and safety. This systematic literature review aims to provide an overview of the current scenario on the quality control of botanical drug products as determined by pharmacopoeia requirements specifically for M. pumilum authentication or identification. A systematic search for peer-reviewed publications to document literature search for M. pumilum authentication was performed using four electronic databases: Web of Science, PubMed, Scopus and ScienceDirect for related studies from January 2010 to December 2021. The research studies published in English and related articles for identification or authentication of M. pumilum were the main inclusion criteria in this review. A total 122 articles were identified, whereby 33 articles met the inclusion criteria. Macroscopy, microscopy, chemical fingerprinting techniques using chromatography, spectroscopy and hyphenated techniques, and genetic-based fingerprinting using DNA barcoding method have been used to identify M. pumilum and to distinguish between different varieties and plant parts. The study concluded that a combination of approaches is necessary for authenticating botanical drug substances and products containing M. pumilum to assure the quality, safety, and efficacy of marketed botanical drug products, particularly those with therapeutic claims.

DNA Barcoding Medicinal Plant Species from Indonesia

Over the past decade, plant DNA barcoding has emerged as a scientific breakthrough and is often used to help with species identification or as a taxonomical tool. DNA barcoding is very important in medicinal plant use, not only for identification purposes but also for the authentication of medicinal products. Here, a total of 61 Indonesian medicinal plant species from 30 families and a pair of ITS2, matK, rbcL, and trnL primers were used for a DNA barcoding study consisting of molecular and sequence analyses. This study aimed to analyze how the four identified DNA barcoding regions (ITS2, matK, rbcL, and trnL) aid identification and conservation and to investigate their effectiveness for DNA barcoding for the studied species. This study resulted in 212 DNA barcoding sequences and identified new ones for the studied medicinal plant species. Though there is no ideal or perfect region for DNA barcoding of the target species, we recommend matK as the main region for Indonesian medicinal plant identification, with ITS2 and rbcL as alternative or complementary regions. These findings will be useful for forensic studies that support the conservation of medicinal plants and their national and global use.

Flow cytometry and start codon targeted (SCoT) genetic fidelity assessment of regenerated plantlets in Tylophora indica (Burm.f.) Merrill

Tylophora indica (Burm.f.) Merrill. is a pharmacologically important plant, popular for alkaloidal and non-alkaloidal richness. Large scale propagation of T. indica is difficult in the wild as the seeds are small and the frequency of germination is very poor. In the present study, the genome size estimation of in vitro regenerated (indirect, direct and somatic embryo mediated) T. indica was made by flow cytometric method. Clonal fidelity of the regenerants was assessed using a start codon targeted (SCoT) molecular marker. Initially, the explants were inoculated on Murashige and Skoog basal medium supplemented with various concentrations of plant growth regulators like 2,4-dichlorophenoxy acetic acid (2,4-D), Kinetin, 6-benzyl amino purine (BAP) and 1-naphthalene acetic acid either singly or in combinations. The highest callus induction frequency (87.75%) was obtained in 6.7 µM 2,4-D added MS medium which metamorphosed into progressive stages (globular, heart, torpedo, and cotyledonary) of embryos. Mature and healthy somatic embryos efficiently germinated into plantlets on 8.8 µM BAP + 1.4 µM GA₃ enriched MS medium. Histological and scanning electron microscopic study confirmed the above developing stages. The regenerated shoots were rooted best in 2.45 µM Indole-3-butyric acid supplemented solid MS medium. The plants were hardened and acclimatized with 90% survivability. The flow cytometric 2C DNA content of indirect, direct and somatic embryo derived plants was 1.896 pg, 1.940 pg and 1.926 pg respectively, very similar to the mother plant (1.928 pg). SCoT marker generated a high percentage of monomorphic bands (94%) revealing similarity with the mother plant, thus ensuring genetic fidelity. To the best of our knowledge, this is perhaps the first ever report of 2C DNA content estimation and SCoT marker based genetic homogeneity study in T. indica.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s11240-022-02254-z.

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.

Integrated Approach for Species Identification and Quality Analysis for Labisia pumila Using DNA Barcoding and HPLC

Labisia pumila is a precious herb in Southeast Asia that is traditionally used as a health supplement and has been extensively commercialized due to its claimed therapeutic properties in boosting a healthy female reproductive system. Indigenous people used these plants by boiling the leaves; however, in recent years it has been marketed as powdered or capsuled products. Accordingly, accuracy in determination of the authenticity of these modern herbal products has faced great challenges. Lack of authenticity is a public health risk because incorrectly used herbal species can cause adverse effects. Hence, any measures that may aid product authentication would be beneficial. Given the widespread use of Labisia herbal products, the current study focuses on authenticity testing via an integral approach of DNA barcoding and qualitative analysis using HPLC. This study successfully generated DNA reference barcodes (ITS2 and rbcL) for L. pumila var. alata and pumila. The DNA barcode that was generated was then used to identify species of Labisia pumila in herbal medicinal products, while HPLC was utilized to determine their quality. The findings through the synergistic approach (DNA barcode and HPLC) implemented in this study indicate the importance of both methods in providing the strong evidence required for the identification of true species and to examine the authenticity of such herbal medicinal products.

Pitfalls and promises of raw drug identification techniques in the ayurvedic industry: an overview

India, with a rich heritage of floral diversity, is well-known for its medicinal plant wealth and is the largest producer of medicinal herbs in the world. Ethnobiological Survey of Ministry of Environment and Forests (MOEF) could identify 8000 plant species utilized in various systems of medicine with approximately 25,000 effective herbal formulations. The extensive consumption to meet demand-supply ratio exerts a heavy strain on the existing resources. This subsequently led to the adulteration and substitution of medicinal plants with look-alike species. The consumer's faith on herbal medicine is in the phase of decline due to the extremities in adulteration/substitution and ensuing consequences. It is imperative to bring forth universally acceptable standard tools to authenticate raw drugs before being processed further into formulations. A vast array of techniques such as physical, chemical (analytical), biochemical, anatomical, organoleptic, and recently emerged DNA based molecular methods are widely used for plant species authentication. In recent years, DNA barcoding has made remarkable progress in the field of medicinal plants research. DNA metabarcoding is the latest development for qualitative evaluation of the herbal formulations, whereas for quantitative analysis, combination of pharmacognostic, pharmacovigilance and analytical methods are inevitable for authentication. This review addresses the overall strengths and shortcomings of the existing as well as recently emerged techniques in authenticating ayurvedic raw drugs.

Investigating the authenticity of Ophiopogonis Radix and its Chinese patent medicines by using a nucleotide signature

ETHNOPHARMACOLOGICAL RELEVANCE

Ophiopogonis Radix (Maidong), derived from the dried root tuber of Ophiopogon japonicus (Thunb.) Ker Gawl., has been widely used in the treatment of chronic inflammatory and cardiovascular diseases. However, Ophiopogonis Radix is often adulterated with some species because of morphological similarities. Adulterants circulating in herbal markets are a latent threat to the clinical safety and consumers' interest.

AIM OF THE STUDY

We aimed to develop a nucleotide signature for identification of Ophiopogonis Radix and its Chinese patent medicines.

MATERIALS AND METHODS

A total of 255 ITS2 sequences representing 39 species and 4 varieties were used to develop a nucleotide signature of Ophiopogonis Radix. The nucleotide signature was used to investigate 17 commercial crude drugs and eight batches of Chinese patent medicines.

RESULTS

A 69 bp nucleotide signature unique to Ophiopogonis Radix was found. The survey revealed that 2 of 17 crude drug samples were adulterants detected as Liriopes Radix (Shanmaidong). Fortunately, no adulterants were detected in the eight batches of Chinese patent medicines.

CONCLUSIONS

The newly developed nucleotide signature could be efficiently applied to identify Ophiopogonis Radix and its Chinese patent medicines, aiding in the authentication, quality control, and supervision of processed products in herbal markets.

Mitigating the Impact of Admixtures in Thai Herbal Products

Medicinal plants and their products are extensively used within indigenous healthcare systems in Thailand and several other nations. The international trade of herbal products has a noteworthy impact on the worldwide economy, and the interest in herbal products is expanding in both developing and developed countries. There has been rapid growth in the medicinal plant product market and a broadening consumer base interested in herbal products from Thailand. However, in herbal industries, ingredient substitution and admixture are typical issues wherein species of lower market value are admixed with those of a higher value. The adverse consequences of consuming adulterated drugs are invariably due to the presence of an unintended herb rather than the presence of an intended herb. It has also been argued that admixtures are intentional because of the lack of regulatory policies or centralized tests for product authentication. The consequences of species admixtures can extend from the reduced efficacy of a drug to decreased trade value. This study aims to clarify the nature and extent of species admixtures reported in the Thai herbal trade market and discuss the potential reasons for such adulteration. In the broader context of species admixtures, we strongly propose the establishment of multiple herbal crude drug repositories that can be developed to facilitate the use of comparative identity tests by industry, traders, and researchers to maintain authentic natural health product (NHP) standards and to certify the authenticity of NHPs. The proposition of the establishment of centralized testing (CT) could be a promising initiative in Thailand for the development of science and technology, and the herbal medicines produced as a result of CT could be dispensed as prescription drugs based on disease consideration instead of as health foods or nutraceuticals.