Pyrrolizidine alkaloid-induced transcriptomic changes in rat lungs in a 28-day subacute feeding study

Analysis of potential risks of clinical application of Yi Dian Hong and its proprietary Chinese medicines: A review

Yi Dian Hong, belonging to the Asteraceae family, finds widespread use in traditional Chinese medicine for its effectiveness in clearing heat, detoxifying, promoting blood circulation, reducing swelling, and cooling the blood. Modern medical research has revealed that Yi Dian Hong and its proprietary Chinese medicines possess biological functions such as inhibiting tumor-specific angiogenesis and regulating immune-related molecules. However, studies have identified that the primary component of Yi Dian Hong contains pyrrolizidine alkaloids (PAs), a toxic substance with potential risks to the liver, lungs, genes, and a propensity for carcinogenicity. Many countries impose strict controls on the content of PAs in herbal medicines and products. Unfortunately, China currently lacks relevant content standards, thereby introducing greater clinical application risks. To ensure the safety of clinical use of Yi Dian Hong, this review will analyze the risk associated with Yi Dian Hong and its proprietary Chinese medicines in clinical applications based on the PAs content in these medicines and provide recommendations.

Hepatotoxicity screening and ranking of structurally different pyrrolizidine alkaloids in zebrafish

Pyrrolizidine alkaloids (PAs) are phytotoxins distributed in ∼6000 plant species. PA-contaminated/containing foodstuffs/herbs/supplements pose a potential threat to human health. Various regulatory authorities established different PA margins of exposure assuming an equal hepatotoxic potency of structurally diverse PAs, although they exhibit different toxic potencies. Therefore, understanding hepatotoxic potencies of different PAs would facilitate a more appropriate risk assessment of PA exposure. In this study, a zebrafish model, which mimics physiological processes of absorption, distribution, metabolism, and excretion, was selected to evaluate acute hepatotoxic potency of different PAs (7 PAs and 2 PA N-oxides) and explore possible physiological pathways involved in PA-induced hepatotoxicity. After 6 h oral administration, PAs caused distinct structure-dependent hepatotoxicity with a series of biochemical and histological changes in zebrafish. Based on the measured toxicological endpoints, the relative toxic potency order of different PAs was derived as lasiocarpine ∼ retrorsine > monocrotaline > riddelliine > clivorine > heliotrine > retrorsine N-oxide ∼ riddelliine N-oxide≫>platyphyline. Further, compared to control group, different upregulation/downregulation of mRNA expression in PA-treated groups indicated that inflammation, apoptosis, and steatosis were involved in PA-induced hepatotoxicity in zebrafish. These findings demonstrate that zebrafish model is useful for screening and ranking hepatotoxicity of PAs with diverse structures, which would facilitate the more accurate risk assessment of PA exposure.

Comparative Pharmacokinetic Study of Two Pyrrolizidine Alkaloids Lasiocarpine and Heliotrine in Rats

Lasiocarpine (LAS) and heliotrine (HEL) are two different ester types of toxic pyrrolizidine alkaloids (PAs): open-chain diester and monoester. However, the pharmacokinetics of these two types of PAs in rats have not been reported. In the present study, two LC-MS/MS methods for determining LAS and HEL were established and validated. The methods exhibited good linearity, accuracy, and precision and were then applied to a comparative pharmacokinetic study. After intravenous administration to male rats at 1 mg/kg, the AUC_0-t values of LAS and HEL were 336 ± 26 ng/mL × h and 170 ± 5 ng/mL × h. After oral administration at 10 mg/kg, the AUC_0-t of LAS was much lower than that of HEL (18.2 ± 3.8 ng/mL × h vs. 396 ± 18 ng/mL × h), while the C_max of LAS was lower than that of HEL (51.7 ± 22.5 ng/mL × h vs. 320 ± 26 ng/mL × h). The absolute oral bioavailability of LAS was 0.5%, which was significantly lower than that of HEL (23.3%). The results revealed that the pharmacokinetic behaviors of LAS differed from that of HEL.

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.

Analyses of Transcriptomics Cell Signalling for Pre-Screening Applications in the Integrated Approach for Testing and Assessment of Non-Genotoxic Carcinogens

With recent rapid advancement of methodological tools, mechanistic understanding of biological processes leading to carcinogenesis is expanding. New approach methodologies such as transcriptomics can inform on non-genotoxic mechanisms of chemical carcinogens and can be developed for regulatory applications. The Organisation for the Economic Cooperation and Development (OECD) expert group developing an Integrated Approach to the Testing and Assessment (IATA) of Non-Genotoxic Carcinogens (NGTxC) is reviewing the possible assays to be integrated therein. In this context, we review the application of transcriptomics approaches suitable for pre-screening gene expression changes associated with phenotypic alterations that underlie the carcinogenic processes for subsequent prioritisation of downstream test methods appropriate to specific key events of non-genotoxic carcinogenesis. Using case studies, we evaluate the potential of gene expression analyses especially in relation to breast cancer, to identify the most relevant approaches that could be utilised as (pre-) screening tools, for example Gene Set Enrichment Analysis (GSEA). We also consider how to address the challenges to integrate gene panels and transcriptomic assays into the IATA, highlighting the pivotal omics markers identified for assay measurement in the IATA key events of inflammation, immune response, mitogenic signalling and cell injury.