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bioRxiv2026

In vitro EAS-mediated activity of Alternaria toxins

Alternaria mycotoxins represent an emerging concern due to their frequent occurrence in food and feed. However, available toxicological data remain limited. Under the current EU regulatory framework, and in line with the EFSA/ECHA/JRC guidance for the identification of endocrine disruptors (EDs), assessment of endocrine activity relies on standardized assays performed according to OECD Test Guidelines (TGs) for the estrogen-, androgen- and steroidogenesis- (EAS) modalities. Within the framework of the European Partnership for the Assessment of Risks from Chemicals (PARC), standardized in vitro methods of regulatory relevance were performed for six chemically characterized Alternaria toxins, aiming to address current regulatory gaps on EAS-mediated activity. Alternariol (AOH), alternariol monomethyl ether (AME), tenuazonic acid (TeA), altertoxin-I (ATX-I), tentoxin (TEN) and altenuene (ALT) were assessed over a broad concentration range, from 0.001 up to 60 M, depending on cytotoxicity and solubility profile of each compound. Our findings indicate estrogenic activity for AOH (PC50: 3.9 - 4.6 {micro}M) and AME (PC50: 5.2 - 8.5 {micro}M) in the estrogen receptor transactivation assay (OECD TG 455), as well as an anti-estrogenic activity for ATX-I (IC30: 0.27 - 0.37 {micro}M). Minimal positive responses were observed at high concentrations for AOH (from the dose of 3 {micro}M) and for AME (from the dose of 10 {micro}M) in the agonistic part of the androgen receptor transactivation assay (OECD TG 458), which may also reflect glucocorticoid receptor activation. No effects on estradiol or testosterone production were observed for any of the tested Alternaria compounds in the steroidogenesis assay (OECD TG 456).

pharmacology and toxicology↗

bioRxiv2026

From TD50 to Benchmark Dose in Nitrosamine Risk Assessment: Evidence from N-Nitrosotrimetazidine Carcinogenicity and TGR Mutation Data.

The presence of N-nitrosamine drug substance-related impurities (NDSRIs) in pharmaceuticals represents a significant regulatory and safety challenge due to their classification as "cohort of concern" compounds. This paper describes the toxicological evaluation of N-Nitrosotrimetazidine (NTMZ), performed to refine the initial default acceptable intake (AI) limits of 18 to 26.5 ng/day established by regulatory authorities. The evaluation followed a tiered approach: NTMZ was first confirmed as mutagenic in vitro via the standard Ames test. To further investigate its genotoxic potential, two in vivo studies were conducted in Wistar and transgenic rats. Detection of DNA strand breaks in the liver and duodenum (comet assay) together with positive results in the cII mutation assay confirmed an in vivo mutagenic mode of action. Benchmark Dose (BMD) analysis of the transgenic rat data yielded a BMDL50 of 7 mg/kg/day in the male liver. To characterize long-term carcinogenic risk, a GLP-compliant 2-year carcinogenicity study was conducted in Wistar rats. Chronic exposure induced dose-dependent increases in liver tumors (hemangiosarcomas, hepatocellular carcinomas and adenomas) and intestinal tumors (adenomas and adenocarcinomas), leading to a Tumor Dose 50 (TD50) of 23 mg/kg/day in male rats. Benchmark dose analysis of tumor incidence identified a lowest BMDL10 of 2.6 mg/kg/day in females, which served as the basis for deriving an AI of 13 microg/day. This assessment demonstrates a strong predictive correlation between the BMD derived from the in vivo transgenic model, the BMDL10 and the final TD50 values obtained in the 2-year carcinogenicity study. These findings provided the scientific basis for establishing a conservative AI of 13 microg/person/day based on the BMDL10 and further support the regulatory acceptance and use of BMD-derived approaches for the evaluation of nitrosamine impurities.

pharmacology and toxicology↗

bioRxiv2019

Effects of MCHM on yeast metabolism

On January 2014 approximately 10,000 gallons of crude 4-Methylcyclohexanemethanol (MCHM) and propylene glycol phenol ether (PPH) were accidentally released into the Elk River, West Virginia, contaminating the tap water of around 300,000 residents. Crude MCHM is an industrial chemical used as flotation reagent to clean coal. At the time of the spill, MCHMs toxicological data were limited, an issue that have been addressed by different studies focused on understanding the immediate and long-term effects of MCHM on human health and the environment. Using S. cerevisiae as a model organism we study the effect of acute exposition to crude MCHM on metabolism. Yeasts were treated with MCHM 3.9 mM in YPD for 30 minutes. Polar and lipid metabolites were extracted from cells by a chloroform-methanol-water mixture. The extracts were then analyzed by direct injection ESI-MS and by GC-MS. The metabolomics analysis was complemented with flux balance analysis simulations done with genome-scale metabolic network models (GSMNM) of MCHM treated vs non-treated control. We integrated the effect of MCHM on yeast gene expression from RNA-Seq data within these GSMNM. 181 and 66 metabolites were identified by the ESI-MS and GC-MS procedures, respectively. From these 38 and 34 relevant metabolites were selected from ESI-MS and GC-MS respectively, for 72 unique compounds. MCHM induced amino acid accumulation, via its effects on amino acid metabolism, as well as a potential impairment of ribosome biogenesis. MCHM affects phospholipid biosynthesis and decrease the levels of ergosterol, with a potential impact in the biophysical properties of yeast cellular membranes. The FBA simulations were able to reproduce the deleterious effect of MCHM on cells growth and suggest that the effect of MCHM on ubiquinol:ferricytochrome c reductase reaction, caused by the under-expression of CYT1 gene, could be the driven force behind the observed effect on yeast metabolism and growth.

pharmacology and toxicology↗

bioRxiv2026

Context and exposure history shape insecticide sensitivity in Drosophila melanogaster

Current insecticide toxicology still lacks an integrated understanding of how lethal and sublethal exposure shape organismal performance across biologically and environmentally relevant contexts. In particular, insecticide susceptibility may vary with physiological state, environmental conditions, and recent exposure history, factors that are only partially captured by standardized toxicity assessments. Here, using Drosophila melanogaster, we systematically compared responses to three insecticides with distinct modes of action - acetamiprid, chlorantraniliprole, and deltamethrin - across developmental stages, sexes, adult ages, and ambient temperatures. Insecticide sensitivity varied substantially across these conditions, with temperature modulating toxicity in a compound-dependent manner. Notably, deltamethrin caused substantial lethality at concentrations more than 10,000-fold below approved field application rates. Beyond these context-dependent differences in acute toxicity, sublethal pre-exposure to each insecticide rapidly reduced lethality during a subsequent challenge with the same compound, with increased tolerance already detectable after 24 h. Importantly, these exposure conditions that enhanced insecticide tolerance were associated with reduced resistance to environmental challenges, including heat and nutrient starvation, revealing a potential trade-off in organismal stress resilience. Acetamiprid exposure further altered reproductive performance in a concentration-dependent manner, with higher exposure reducing egg production while increasing developmental success among the resulting offspring, such that the number of offspring reaching adulthood remained largely unchanged. Together, these findings demonstrate that insecticide susceptibility is highly context dependent and can be rapidly modified by recent exposure history. We identify short-term, compound-specific, and potentially costly tolerance as an underappreciated consequence of insecticide exposure and highlight the importance of incorporating biological context, environmental conditions, and sublethal exposure history into pesticide risk assessment.

pharmacology and toxicology↗

bioRxiv2026

Towards Bayesian-based quantitative adverse outcome pathways using in vitro data from open literature and continuous variables: a case example for liver fibrosis.

As toxicology shifts towards non-animal testing, quantitative models are essential to predict adverse health effects from molecular or cellular perturbations. Quantitative Adverse Outcome Pathways (qAOPs) represent such models, building on mechanistic knowledge and quantifying the Key Event Relationships (KERs) described in AOPs. Despite the recognized need, the number of qAOPs remains limited. Bayesian-based approaches are often chosen for developing qAOP for their flexibility, but most use discretized variables, limiting their predictive power. In addition, these models are mainly built from newly generated data, underexploiting the large amount of information available. This study successfully leverages data from public literature and presents an innovative framework based on continuous variables to develop a Bayesian-based quantitative model for a central KER towards liver fibrosis. The model predicts the probability of the expression fold change for two key markers of hepatic stellate cell activation (aSMA and COL1A1), given the effects on tissue injury, using in vitro data from 9 chemicals. We propose a newly developed workflow to assist in knowledge identification, organization, and extraction from scientific literature and chemical databases. Based on in vitro data and in vivo information from the Open TG-GATEs (Toxicogenomics Project-Genomics Assisted Toxicity Evaluation System) database, we estimate a biologically relevant range in COL1A1 fold change that indicates an activated state of stellate cells and high liver fibrosis odds ratios. Our study provides a case example of integrating published data and continuous variables to build a Bayesian-based model, which constitutes an essential step for predicting liver fibrosis from in vitro data.

pharmacology and toxicology↗

bioRxiv2021

Alterations in human gut microbiome composition and metabolism after exposure to glyphosate and Roundup and/or a spore-based formulation using the SHIME(R) technology

Despite extensive research into the toxicology of the herbicide glyphosate, there are still major unknowns regarding its effects on the human gut microbiome. As a step in addressing this knowledge gap, we describe for the first time the effects of glyphosate and a Roundup glyphosate-based herbicide on infant gut microbiota using SHIME technology, which mimics the entire gastrointestinal tract. SHIME(R) microbiota culture was undertaken in the presence of a concentration of 100 mg/L (corresponding to a dose of 1.6 mg/kg/day) glyphosate and the same glyphosate equivalent concentration of Roundup, which is in the range of the US chronic reference dose, and subjected to molecular profiling techniques to assess outcomes. Roundup and to a lesser extent glyphosate caused an increase in fermentation activity, resulting in acidification of the microbial environment. This was also reflected by an increase in lactate and acetate production concomitant to a decrease in the levels of propionate, valerate, caproate and butyrate. Ammonium production reflecting proteolytic activities was increased by Roundup exposure. Global metabolomics revealed large scale disturbances in metabolite profiles, including an increased abundance of long chain polyunsaturated fatty acids (n3 and n6). Although changes in bacterial composition measured by qPCR and 16S rRNA sequencing were less clear, our results suggested that lactobacilli had their growth stimulated as a result of microenvironment acidification. Co-treatment with the spore-based probiotic formulation MegaSporeBiotic reverted some of the changes in short-chain fatty acid levels. Altogether, our results suggest that glyphosate can exert effects on human gut microbiota at permitted regulatory levels of exposure, highlighting the need for epidemiological studies aimed at evaluating the effects of glyphosate herbicides on human gut microbiome function.

pharmacology and toxicology↗

bioRxiv2023

Neurobehavioral effects of fungicides in zebrafish: a systematic review and meta-analysis

With the aim of yielding high productivity levels, pesticides are widely used in global agriculture. Among them, fungicides are compounds intended to inhibit fungal proliferation in crops and seeds. Their application often leads to environmental contamination, with these chemicals persistently being detected in surface waters. This presence may threaten non-target organisms that dwell in the affected ecosystems, including humans. In toxicologic research, the zebrafish (Danio rerio) is the most used fish species to assess the potential effects of fungicide exposure, generating numerous and sometimes conflicting findings. We conducted a systematic review and meta-analysis aiming to synthesize the neurobehavioral effects of fungicides in zebrafish. The search was performed in three databases (PubMed, Scopus, and Web of Science) and the screening was based on a two-stage process guided by pre-defined inclusion/exclusion criteria. Qualitative and quantitative data, as well as reporting quality, were extracted from the included studies (n = 60). Meta-analyses were performed for the outcomes of distance traveled in larvae and adults, and spontaneous movements in embryos. We found an overall significant effect of fungicide exposure on distance, which was lower in exposed versus control groups (SMD -0.44 [-0.74; -0.13], p = 0.0055). No effect was observed for spontaneous movements. The overall heterogeneity for distance and spontaneous movements was considered high (I2 = 80%) and moderate (I2 = 74%), respectively. This can be explained by substantial methodological variation between protocols, whereas a poor reporting practice hinders the proper critical evaluation of the findings. However, a sensitivity analysis did not indicate any study skewing the meta-analyses. This review demonstrates the need for better-designed and reported experiments in this field. Highlights- We systematically reviewed the behavioral effects of fungicides in zebrafish - Fungicides decrease the distance traveled - Fungicide exposure has no significant effects on spontaneous movements - Moderate to high levels of heterogeneity were found - The results showed a need for better-designed studies with clarity of report

pharmacology and toxicology↗

bioRxiv2025

Physiologically Relevant 3D CRISPR Screening Enhances Mechanistic Insight into Chemical Toxicity Compared to 2D Screening

Many omics-based approaches in toxicology research primarily rely on correlative data, often lacking functional relationships or causal links between genotypes and phenotypes. CRISPR-based approaches can overcome this limitation by establishing direct causal connections between genes and toxicological phenotypes. Moreover, CRISPR screens enable scalable and systematic interrogation of gene function and associated mechanisms following chemical exposure, predominantly using in vitro models. In line with the paradigm of new approach methodologies (NAMs) in toxicology research, CRISPR screens hold promise to provide an in vitro cell-based functional toxicogenomics approach. One of the main limitations of conventional in vitro assays is their compromised physiological relevance to humans due to their inability to fully recapitulate in vivo physiology. To improve the functional and physiological relevance of the toxicogenomics approach, we developed a 3D CRISPR screening system using HepG2/C3A spheroids generated and cultivated in a continuously rotating bioreactor (ClinoStar). We first performed time-course 3D CRISPR screens to identify genes that confer growth disadvantage or advantage, influencing spheroid development compared to 2D cultures. We then applied this approach to a chemical toxicity study using doxorubicin, comparing the performance of the 3D and 2D systems in identifying chemical-specific mechanisms. The results showed that the 3D system captured more candidate genetic determinants and biological pathways related to DNA damage processes--a known toxicity mechanism of doxorubicin--demonstrating improved performance in identifying chemical-specific pathways over the 2D counterpart. In our screens, we employed custom CRISPR sgRNA libraries representing common human loss-of-function genetic variants (mean allele frequency > 0.1% in all individuals catalogued in the genome aggregation database), which potentially affect toxicity responses. By comparing our CRISPR screen results with previously reported genetic associations for doxorubicin response, we found that the 3D system identified more known associated genes than the 2D system. Together, the 3D CRISPR screening system demonstrated its feasibility and utility for physiologically relevant functional toxicogenomics. This platform enables in vitro NAMs, by providing a scalable and effective approach to identify causal genetic determinants and biological pathways that modulate chemical-induced toxicity.

pharmacology and toxicology↗

bioRxiv2023

Comparative cardiotoxicity assessment of bisphenol chemicals and estradiol using human induced pluripotent stem cell-derived cardiomyocytes

BackgroundBisphenol A (BPA) is commonly used to manufacture consumer and medical-grade plastics. Due to health concerns, BPA substitutes are being incorporated - including bisphenol S (BPS) and bisphenol F (BPF) - without a comprehensive understanding of their toxicological profile. ObjectivePrevious studies suggest that bisphenol chemicals perturb cardiac electrophysiology in a manner that is similar to 17{beta}-estradiol (E2). We aimed to compare the effects of E2 with BPA, BPF, and BPS using human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM). MethodsCardiac parameters were evaluated using microelectrode array (MEA) technology and live-cell fluorescent imaging at baseline and in response to chemical exposure (0.001-100 M). ResultsCardiac metrics remained relatively stable after exposure to nanomolar concentrations (1-1,000 nM) of E2, BPA, BPF, or BPS. At higher micromolar concentrations, chemical exposures resulted in a decrease in the depolarizing spike amplitude, shorter field potential and action potential duration, shorter calcium transient duration, and decrease in hiPSC-CM contractility (E2 > BPA > BPF >> BPS). Cardiomyocyte physiology was largely undisturbed by BPS exposure. BPA-induced effects were exaggerated when co-administered with an L-type calcium channel antagonist (verapamil) or E2 - and reduced when co-administered with an L-type calcium channel agonist (Bay K8644) or an estrogen receptor alpha antagonist (MPP). E2-induced effects generally mirrored those of BPA, but were not exaggerated by co-administration with an L-type calcium channel antagonist. DiscussionCollectively across multiple cardiac endpoints, E2 was the most potent and BPS was the least potent disruptor of hiPSC-CM function. Although the observed cardiac effects of E2 and BPA were similar, a few distinct differences suggest that these chemicals may act (in part) through different mechanisms. hiPSC-CM are a useful model for screening cardiotoxic chemicals, nevertheless, the described in vitro findings should be validated using a more complex ex vivo and/or in vivo model.

pharmacology and toxicology↗

bioRxiv2026

Multi-Modal Toxicological Evaluation of NiO nanoparticles and ionic nickel in a Human Lung-Cardiac Co-Culture System

Nickel is a widespread environmental and occupational contaminant associated with respiratory and cardiovascular toxicity, yet the mechanisms linking pulmonary exposure to adverse cardiac effects remain poorly understood. This study aimed to establish and evaluate a human in vitro lung-heart co-culture model for investigating cardiovascular responses following pulmonary exposure. Human alveolar epithelial A549 cells were exposed at the air-liquid interface to different concentrations of NiO nanoparticles or NiCl2 for 4- and 24-hours. Following cloud exposure, A549 cells were co-cultured with human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). Cytotoxicity, metabolic activity, cytokine release, DNA damage, epigenetic alterations, and cardiac electrophysiological function were assessed. Nickel translocation across the epithelial barrier was quantified to facilitate interpretation of downstream cardiomyocyte effects. Exposure to both nickel forms induced cytotoxicity and resulted in measurable nickel translocation into the basolateral compartment. NiCl2 exhibited a time-dependent increase in basolateral nickel concentrations, whereas NiO translocation remained relatively stable over time. Cytokine profiling revealed selective induction of IL-8 and IL-18, with no significant changes in IL-1{beta}, IL-6, IL-10, or TNF-. Genotoxicity analyses demonstrated cell type-specific responses, characterized by delayed DNA strand breaks in A549 cells and early but transient DNA damage in hiPSC-CMs. Oxidative DNA damage was particularly pronounced in hiPSC-CMs following NiCl2 exposure. Global DNA methylation was reduced in hiPSC-CMs without corresponding changes in DNA methyltransferase activity. Electrophysiological assessment showed transient increases in conduction velocity, while beating frequency and field potential duration remained largely unaffected. Overall, the lung-heart co-culture model successfully captured both pulmonary and cardiac responses to nickel exposure and provided evidence for direct and indirect mechanisms of cardiotoxicity. Nickel translocation across the epithelial barrier, together with inflammatory and oxidative stress-related signalling, may contribute to downstream cardiac effects. These findings highlight the utility of this human-relevant platform for investigating systemic cardiovascular consequences of inhaled toxicants.

pharmacology and toxicology↗

bioRxiv2020

In vivo Evaluation and in silico Prediction of the Toxicity of Drepanoalpha Hard capsules

GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=95 SRC="FIGDIR/small/411124v3_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@12dbf1aorg.highwire.dtl.DTLVardef@5d6e9forg.highwire.dtl.DTLVardef@9ba26org.highwire.dtl.DTLVardef@9c2017_HPS_FORMAT_FIGEXP M_FIG C_FIG ABSTRACTO_ST_ABSEthnopharmacological relevanceC_ST_ABSDrepanoalpha(R) hard capsules, a dry ethanolic extract (drug-extract ratio, 100/11) of a mixture of Justicia secunda Vahl and Moringa oleifera Lam dried leaves (1: 1, w/w) are used for the management of sickle cell disease in the Democratic Republic of Congo. Aim of the studyThis phytomedicine safety was investigated by acute and sub-acute administration in Guinea pigs. Materials and methodsHealthy, male and nulliparous and non-pregnant female Guinea pigs were obtained from "Laboratory of Animal Experimentation and Toxicology" of the Department of Biology, Faculty of Sciences, University of Kinshasa. The animals were randomly selected, marked and divided into 2 groups of 5 animals each (3 males and 2 females) and 4 groups of 3 animals each for acute and sub-acute toxicity studies, respectively. The contents of hard capsules were dissolved in normal saline solution (NaCl 9 {per thousand}). Animals received by gavage a single dose of 5000 mg/ kg of body weight (B.W.) of Drepanoalpha(R) hard capsules (acute toxicity) and 125 mg/ kg, 250 mg/ kg and 500 mg/ kg of B.W. twice daily for 28 days (sub-acute toxicity). Normal saline solution was used as control. Hematological, biochemical and histopathological analyses were performed and the behavior of the animals was observed after treatment. ResultsThe median lethal dose (LD50) is higher than 5000 mg/ kg of B.W., and the relative weights of vital organs (kidneys, liver and heart) collected from Guinea pigs at the end of treatment on D14 (acute toxicity) and D28 (sub-acute toxicity) has not undergone significant changes (p > 0.05). The results of haematological (red and white blood cells counts, haemoglobin, haematocrit) and biochemical (ALT, AST, albumin, total protein) tests did not show significant differences between control and test groups (=0.05 for acute toxicity), while the histopathological study revealed no damage to the various organs excised. ConclusionThe results indicate the safety of Drepanoalpha(R) hard capsules, confirming previous studies, in rats and Guinea pigs, based on aqueous decoction of its raw herbs mixtures and the corresponding lyophilizate.

pharmacology and toxicology↗

bioRxiv2022

Molecular annotation of AOPs guides the development of the next generation mechanistic chemical safety assessment and new approach methods

Mechanistic toxicology has emerged as a powerful framework to inform on the safety of chemicals and guide the development of new safe-by-design compounds. Although toxicogenomics provides support towards mechanistic evaluation of chemical exposures, the implementation of toxicogenomics-based evidence in the regulatory setting is still hindered by uncertainties related to the analysis and interpretation of such data. Adverse Outcome Pathways (AOPs) are multi-scale models that link chemical exposures to adverse outcomes through causal cascades of key events (KEs). The use of mechanistic evidence through the AOP framework is actively promoted for the development of new approach methods (NAMs) and to reduce animal experimentation. However, in order to unleash the full potential of AOPs and build confidence into toxicogenomics, robust and unified associations between KEs and patterns of molecular alteration need to be established. Here, we hypothesised that systematic curation of molecular events associated with KEs would enable the modelling of AOPs through gene-level data, creating the much-needed link between toxicogenomics and the systemic mechanisms depicted by the AOPs. This, in turn, introduces novel ways of benefitting from the AOP concept, including predictive models, read-across, and targeted assays, while also reducing the need for multiple testing strategies. Hence, we developed a multi-step strategy to annotate the AOPs relevant to human health risk assessment. We show that our framework successfully highlights relevant adverse outcomes for chemical exposures with strong in vitro and in vivo convergence, supporting chemical grouping and other data-driven approaches. Finally, we defined and experimentally validated a panel of robust AOP-derived in vitro biomarkers for pulmonary fibrosis.

pharmacology and toxicology↗

bioRxiv2022

Acute and chronic toxicity of imidacloprid in the pollinator fly, Eristalis tenax

Imidacloprid is a neonicotinoid neurotoxin that remains the most used insecticide worldwide. It persists in the environment long after the initial application resulting in chronic exposure to non-target insects. To accurately map the dose-dependent effects of these exposures across taxa, toxicological assays need to assess various modes of exposure across relevant indicator species. However, due to the difficulty of these experiments, contact bioassays are frequently used to quantify dose, and dipterans remain underrepresented. Here, we developed a novel naturalistic feeding bioassay to precisely measure imidacloprid ingestion and its toxicity for acute and chronic exposures in a dipteran pollinator, Eristalis tenax. Flies which ingested imidacloprid dosages lower than 12.1 ng/mg all showed consistent intake volumes and learned improved feeding efficiency over successive feeding sessions. In contrast, at doses of 12.1 ng/mg and higher flies had a rapid onset of severe locomotive impairment which prevented them from completing the feeding task. Neither probability of survival nor severe locomotive impairment were significantly higher than the control group until doses of 1.43 ng/mg or higher were reached. We were unable to measure a median lethal dose for acute exposure (72 hours) due to flies possessing a relatively high tolerance for imidacloprid. However, with chronic exposure (18 days), mortality went up and an LD50 of 0.41 ng/mg was estimated. Severe locomotive impairment tended to occur earlier and at lower dosages than lethality, with ED50s of 0.17 ng/mg and 7.82 ng/mg for acute and chronic exposure, respectively. Although the adult Eristalis is a honeybee mimic, it possesses a much higher tolerance to this toxin than its model. The similarity in the LD50 to other dipterans such as the fruitfly and the housefly suggests that there may be a phylogenetic component to pesticide tolerance that needs to be further investigated. The absence of obvious adverse effects at sublethal dosages also underscores a need to develop better tools for quantifying animal behaviour to evaluate the impact of insecticides on foraging efficiency in economically important species.

pharmacology and toxicology↗

bioRxiv2021

Inhibition of Lipopolysaccharide E. coli-induced acute lung injury by extracted Antidesma bunius (L.) Spreng fruits as compared to Fluticasone Propionate, a corticosteroid

The hallmark of Acute Lung Injury/Acute Respiratory Distress Syndrome (ALI/ARDS) is inflammation-induced alveolar-vascular barrier destruction and neutrophilic infiltration that leads to the formation of cytokines and oxygen radicals. The objective of the study is to investigate the protective and toxicological effects of Antidesma bunius (L.) Spreng [Bignay] in murine model of Lipopolysaccharide E. coli (LPS)-induced ALI and compared with Fluticasone Propionate (FP), a synthetic corticosteroid. We showed that extracted Bignay fruits have high amount of phenols, steroids and flavonoids but insignificant amount of heavy metals and aflatoxins. BALB/c mice of either sex were divided into 4 groups in the ALI mouse model; Group 1: vehicle control; Group 2: LPS alone; Group 3: Bignay + LPS; and Group 4: FP + LPS. Bignay and FP were administered via intraperitoneal injection while LPS was given intra-tracheally. Biomarkers of ALI such as total lung inflammatory cell count, total lung protein content, lung edema and interleukin-6 (IL-6) secretion were measured 24 hrs after vehicle control or LPS treatment. Compared to vehicle controls, LPS caused significant increased in all measured biomarkers of ALI in samples collected from bronchoalveolar lavage fluid and were significantly attenuated by Bignay fruit extract or FP. Pulmonary vascular leakage caused by LPS was also evaluated after injection with Evans blue dye, an indication of lung injury. Extracted Bignay fruits or FP when given to mice 2 hrs after LPS administration substantially decreased the pulmonary vascular leak. Our findings are the first evidence demonstrating the preventive and non-toxic effects of extracted Bignay fruits in a murine model of LPS-induced ALI. The results could be attributed to the presence of active secondary metabolites such as flavonoids, phenols and steroids. It is also evident that extracted Bignay fruits are as effective as FP, well-established steroid, in blocking the biomarkers of ALI caused by LPS.

pharmacology and toxicology↗

bioRxiv2019

Widespread dysregulation of long non-coding genes associated with fatty acid metabolism, cell division, and immune response gene networks in xenobiotic-exposed rat liver

Xenobiotic exposure activates or inhibits transcription of hundreds of protein-coding genes in mammalian liver, impacting many physiological processes and inducing diverse toxicological responses. Little is known about the effects of xenobiotic exposure on long noncoding RNAs (lncRNAs), many of which play critical roles in regulating gene expression. Objective: to develop a computational framework to discover liver-expressed, xenobiotic-responsive lncRNAs (xeno-lncs) with strong functional, gene regulatory potential and elucidate the impact of xenobiotic exposure on their gene regulatory networks. We analyzed 115 liver RNA-seq data sets from male rats treated with 27 individual chemicals representing seven mechanisms of action (MOAs) to assemble the long non-coding transcriptome of xenobiotic-exposed rat liver. Ortholog analysis was combined with co-expression data and causal inference methods to infer lncRNA function and deduce gene regulatory networks, including causal effects of lncRNAs on protein-coding gene expression and biological pathways. We discovered >1,400 liver-expressed xeno-lncs, many with human and/or mouse orthologs. Xenobiotics representing different MOAs were often regulated common xeno-lnc targets: 123 xeno-lncs were dysregulated by at least 10 chemicals, and 5 xeno-lncs responded to at least 20 of the 27 chemicals investigated. 81 other xeno-lncs served as MOA-selective markers of xenobiotic exposure. Xeno-lnc-protein-coding gene co-expression regulatory network analysis identified xeno-lncs closely associated with exposure-induced perturbations of hepatic fatty acid metabolism, cell division, and immune response pathways. We also identified hub and bottleneck lncRNAs, which are expected to be key regulators of gene expression in cis or in trans. This work elucidates extensive networks of xeno-lnc-protein-coding gene interactions and provides a framework for understanding the extensive transcriptome-altering actions of diverse foreign chemicals in a key responsive mammalian tissue.

pharmacology and toxicology↗

bioRxiv2019

Induction via Functional Protein Stabilization of Hepatic Cytochromes P450 upon gp78/ Autocrine Motility Factor Receptor (AMFR) Ubiquitin E3-ligase Genetic Ablation in Mice: Therapeutic and Toxicological Relevance.

3.The hepatic endoplasmic reticulum (ER)-anchored monotopic proteins, cytochromes P450 (P450s) are enzymes that metabolize endobiotics (physiologically active steroids and fatty acids) as well as xenobiotics including therapeutic/chemotherapeutic drugs, nutrients, carcinogens and toxins. Alterations of hepatic P450 content through synthesis, inactivation or proteolytic turnover influence their metabolic function. P450 proteolytic turnover occurs via ER-associated degradation (ERAD) involving ubiquitin (Ub)-dependent proteasomal degradation (UPD) as a major pathway. UPD critically involves P450 protein ubiquitination by E2/E3 Ub-ligase complexes. We have previously identified the ER-polytopic gp78/AMFR (autocrine motility factor receptor) as a relevant E3 in CYP3A4, CYP3A23 and CYP2E1 UPD. We now document that liver-conditional genetic ablation of gp78/AMFR in mice disrupts P450 ERAD, resulting in significant stabilization of Cyp2a5 and Cyps 2c, in addition to that of Cyps 3a and Cyp2e1. More importantly, we establish that such stabilization is of the functionally active P450 proteins, leading to corresponding significant enhancement of their drug metabolizing capacities. Our findings with clinically relevant therapeutic drugs (nicotine, coumarin, chlorzoxazone, and acetaminophen) and the prodrug (tamoxifen) as P450 substrates, reveal that P450 ERAD disruption could influence therapeutic drug response and/or toxicity, warranting serious consideration as a potential source of clinically significant drug-drug interactions (DDIs). Because gp78/AMFR is not only an E3 Ub-ligase, but also a cell-surface prometastatic oncogene that is upregulated in various malignant cancers, our finding that hepatic gp78/AMFR-knockout can enhance P450-dependent bioactivation of relevant cancer chemotherapeutic prodrugs is of therapeutic relevance and noteworthy in prospective drug design and development.\n\n4. Significance StatementThe cell surface and ER transmembrane protein gp78/AMFR, a receptor for the prometastatic autocrine motility factor (AMF), as well as an E3 ubiquitin-ligase involved in the ERAD of not only the tumor metastatic suppressor KAI1, but also of hepatic cytochromes P450, is upregulated in various human cancers, enhancing their invasiveness, metastatic potential and poor prognosis. Liver specific gp78/AMFR genetic ablation results in functional protein stabilization of several hepatic P450s and consequently enhanced drug and prodrug metabolism, a feature that could be therapeutically exploited in the bioactivation of chemotherapeutic prodrugs, through design and development of novel short-term gp78/AMFR chemical inhibitors.

pharmacology and toxicology↗

bioRxiv2026

A Human Next Generation PBK Model for PFOA

The human toxicological risk assessment of per- and polyfluoroalkyl substances (PFAS) is challenging, due to their sheer number and structural diversity, but also the paucity of the toxicity data required to characterize them. The development of Next Generation Physiologically Based Kinetic (NG-PBK) models may assist in overcoming this challenge. The mechanistic nature of NG-PBK models allows for their extrapolation from data-rich PFAS, such as perfluorooctanoic acid (PFOA), to data-poor ones, facilitating their application in Next Generation Risk Assessment (NGRA). The present study proposes a NG-PBK model for PFOA in humans, parametrized exclusively using in vitro-, and in silico-derived data. The model describes the toxicokinetic processes of 1) partitioning to plasma and tissue proteins, 2) partitioning to cell membrane lipids, 3a) transporter-mediated entero-hepatic circulation and 3b) renal elimination and reabsorption, and 4) elimination via menstruation. Global sensitivity analysis indicated that the model was most sensitive to the fraction unbound in plasma, active-transport parameters, and tissue-plasma partition coefficients. The model was equivalent to already available validated human PFOA-PBK models, while compared to those, it is not calibrated to observed animal, nor human data, illustrating its strength in being mechanistic. The serum concentrations and half-lives predicted by the NG-PBK model were within the ranges of those reported in human volunteer and biomonitoring (HBM) studies, demonstrating the models capacity to accurately predict PFOA toxicokinetics on exposure estimates. Extrapolation of the NG-PBK model to other PFAS, in conjunction with its integration with HBM data, will facilitate the NGRA of PFAS. This is particularly relevant given the paucity of in vivo data for most PFAS, ensuring compliance with the 3R principles.

pharmacology and toxicology↗

bioRxiv2025

Open-science discovery of DNDI-6510, a compound that addresses genotoxic and metabolic liabilities of the COVID Moonshot SARS-CoV-2 Mpro lead inhibitor

The 2020 SARS-CoV-2 coronavirus pandemic highlighted the urgent need for novel small molecule antiviral drugs. (S)-x38 DNDI-6510 is a non-covalent SARS-CoV-2 main protease inhibitor developed by the open science collaboration COVID Moonshot. Here, we report on the metabolic and toxicologic optimization of the lead series previously disclosed by the COVID Moonshot Initiative, leading up to the selection of (S)-x38 DNDI-6510 as the preclinical candidate. We describe the thorough profiling of the series, identifying key risks such as formation of genotoxic metabolites and high clearance, which were successfully addressed during lead optimization. In addition, we disclose the in vitro and in vivo evaluation of (S)-x38 DNDI-6510 in pharmacokinetic and pharmacodynamic models, exploring multiple approaches to ameliorate rodent-specific metabolic clearance, and show that both co-dosing of (S)-x38 DNDI-6510 with an ABT inhibitor and utilizing a metabolically humanized mouse model (8HUM) achieve significant improvements in exposure. Through comparisons of ABT co-dosing and humanized mouse models in efficacy experiments, we demonstrate that continuous exposure over cellular EC90 is required for SARS-CoV-2 antiviral efficacy in vivo in an antiviral model using a mouse-adapted SARS-CoV-2 strain. Finally, (S)-x38 DNDI-6510 was assessed in maximum tolerated dose experiments in two species, demonstrating significant in vivo PXR-linked auto-induction of metabolism, leading to the discontinuation of this compound. In summary, we report the successful effort to overcome series-specific AMES liabilities in a lead development program. Downstream optimization of existing series will require in-depth optimization of rodent-specific liabilities and metabolic induction profile.

pharmacology and toxicology↗