Integrative approaches for unmasking hidden species in herbal dietary supplement products: What is in the capsule?

Current Trends in Toxicity Assessment of Herbal Medicines: A Narrative Review

Even in modern times, the popularity level of medicinal plants and herbal medicines in therapy is still high. The World Health Organization estimates that 80% of the population in developing countries uses these types of remedies. Even though herbal medicine products are usually perceived as low risk, their potential health risks should be carefully assessed. Several factors can cause the toxicity of herbal medicine products: plant components or metabolites with a toxic potential, adulteration, environmental pollutants (heavy metals, pesticides), or contamination of microorganisms (toxigenic fungi). Their correct evaluation is essential for the patient’s safety. The toxicity assessment of herbal medicine combines in vitro and in vivo methods, but in the past decades, several new techniques emerged besides conventional methods. The use of omics has become a valuable research tool for prediction and toxicity evaluation, while DNA sequencing can be used successfully to detect contaminants and adulteration. The use of invertebrate models (Danio renio or Galleria mellonella) became popular due to the ethical issues associated with vertebrate models. The aim of the present article is to provide an overview of the current trends and methods used to investigate the toxic potential of herbal medicinal products and the challenges in this research field.

A PCR-lateral flow immunochromatographic assay (PCR-LFA) for detecting Aristolochia species, the plants responsible for aristolochic acid nephropathy

Aristolochic acids (AAs), which are strong carcinogens, have caused dietary supplements with Aristolochia plants to be discontinued worldwide. Therefore, the development of a method to identify these herbs is critical for customer safety. To support the regulation of Aristolochia-free products, a PCR coupled with lateral flow immunochromatographic assay (PCR-LFA) that is specific to the nucleotide signature in plastid rbcL gene region of Aristolochia species was developed to detect Aristolochia plants and related herbal products. Triplex primers (A397F, C357F and R502) were designed based on specific nucleotides observed exclusively in the rbcL sequences of Aristolochia. Positive results for Aristolochia occur when the three pink lines are clearly developed on the developed lateral flow strip and can be seen by the naked eye. In this study, the lateral flow strip has sensitivity for detecting amplicons amplified from genomic DNA at the concentrations as low as 0.01 ng. Various kinds of samples, including purchased crude drugs and polyherbal samples, have been investigated, and the results showed that Aristolochia crude drugs and Aristolochia-containing products are still present in dispensaries. In conclusion, with the goal of protecting consumers from the health risks associated with Aristolochia contamination, PCR-LFA was developed and demonstrated to be efficient for detecting plants belonging to Aristolochia in various kinds of samples.

Combining DNA and HPTLC profiles to differentiate a pain relief herb, Mallotus repandus, from plants sharing the same common name, “Kho-Khlan”

The pain relief formula “Ya Pa Som Kho-Khlan (YPSKK)” or “ยาผสมโคคลาน” in Thai is officially recorded in the Natural List of Essential Medicines (NLEM) of Thailand. The main component is Mallotus repandus (Willd.) Müll. Arg.; however, Anamirta cocculus (L.) Wight & Arn and Croton caudatus Gleiseler share the same common name: “Kho-Khlan”. Confused usage of A. cocculus or C. caudatus can have effects via toxicity or unsuccessful treatment. This study aimed to combine a high-performance thin-layer chromatography (HPTLC) technique and DNA barcoding coupled with high-resolution melting (Bar-HRM) to differentiate M. repandus from the other two species. The M. repandus extract exhibited a distinct HPTLC profile that could be used to differentiate it from the others. DNA barcodes of the rbcL, matK, ITS and psbA-trnH intergenic spacer regions of all the plants were established to assist HPTLC analysis. The rbcL region was selected for Bar-HRM analysis. PCR amplification was performed to obtain 102 bp amplicons encompassing nine polymorphic nucleotides. The amplicons were subjected to HRM analysis to obtain melting curve profiles. The melting temperatures (T_m) of authentic A. cocculus (A), C. caudatus (C) and M. repandus (M) were separated at 82.03±0.09°C, 80.93±0.04°C and 80.05±0.07°C, respectively. The protocol was applied to test crude drugs (CD1-6). The HPTLC profiles of CD2-6 showed distinct bands of M. repandus, while CD1 showed unclear band results. The Bar-HRM method was applied to assist the HPTLC and indicated that CD1 was C. caudatus. While ambiguous melting curves from the laboratory-made formulae were obtained, HPTLC analysis helped reveal distinct patterns for the identification of the plant species. The combination of HPTLC and Bar-HRM analysis could be a tool for confirming the identities of plant species sharing the same name, especially for those whose sources are multiple and difficult to identify by either chemical or DNA techniques.