Evaluation of Subchronic Toxicity and Genotoxicity of Ethanolic Extract of Aster glehni Leaves and Stems

Aster glehni, a traditional plant on Ulleung Island in the Republic of Korea, has been recognized for its multiple medicinal properties. However, potential toxicity and safety analyses of A. glehni have not been previously investigated. Therefore, this study aimed to evaluate the safety profile of ethanolic extract of A. glehni leaves and stems (EAG) in terms of genotoxicity and subchronic oral animal toxicity under OECD guidelines and GLP conditions. Toxicological assessments were performed at doses of 1,250, 2,500, and 5,000 mg/kg/day in a 13-week oral repeated-dose toxicity study of EAG in male and female SD rats. In addition, an Ames test, an in vitro mammalian chromosomal aberration test, and a micronucleus test were performed. No toxicological changes in clinical signs, body weights, water and food consumption, urinalysis, hematology, clinical biochemistry, gross findings, and histopathological examinations were observed in subchronic oral animal toxicity. In addition, EAG gave negative results when evaluated using in vitro and in vivo genotoxicity tests. In conclusion, the no-observed-adverse-effect level (NOAEL) of EAG was considered to be 5,000 mg/kg/day, and no target organs were identified in both sexes of rats. EAG was also classified as nonmutagenic and nonclastogenic in genotoxicity testing. Collectively, these results show a lack of general toxicity and genotoxicity for EAG that supports clinical work for development as a herbal medicine.

Prediction of Human Lethal Doses and Concentrations of MEIC Chemicals from Rodent LD50 Values: An Attempt to Make Some Reparation

The prediction of human toxicities from animal toxicity tests is often poor, and is now discouraged and in some cases banned, especially those involving the LD50 test. However, there is a vast number of historical LD50 data in both public and in-house repositories that are being put to little use. This study examined the correlations between human lethality (doses and concentrations) of 36 MEIC chemicals and the median values of a large number of mouse and rat LD50 values obtained for four different routes of administration. The best correlations were found with mouse and rat intraperitoneal LD50 values (r2 = 0.838 and 0.810 for human lethal dose, and r2 = 0.753 and 0.785 for human lethal concentration). The results show that excellent prediction of human lethal dose and concentration can be made, for this series of chemicals at least, by using uncurated rodent LD50 values, thus offering some reparation for the millions of rodent lives sacrificed in LD50 testing.

Toxicology Paradise: Sorting Out Adverse and Non-adverse Findings in Animal Toxicity Studies

A challenge for all toxicologists is defining what study findings are actually adverse versus non-adverse in animal toxicity studies, and which ones are relevant for generating a no observed adverse effect level (NOAEL) to assess human risk. This article presents views on this challenge presented by toxicologists, toxicologic pathologists, and regulatory reviewers at the 2019 annual meeting of the American College of Toxicology during a workshop entitled “Toxicology Paradise: Sorting Out Adverse and Non-adverse Findings.” The speakers noted that setting a NOAEL is not always straightforward, not only for small molecules but also for biopharmaceuticals, and that a “weight of evidence” approach often is more useful than a rigid threshold-setting algorithm. Regulators from the US Food and Drug Administration and European Union told how assessment of adverse nonclinical findings is undertaken to allow clinical studies to commence and drug marketing approvals to succeed, along with the process that allows successful dialogs with regulators. Nonclinical case studies of findings judged to be adverse versus non-adverse were presented in relation to the many factors that might halt or delay clinical development. The process of defining adverse findings and the NOAEL in final study reports was discussed, as well as who should be involved in the process.

Opinion on Current Use of Non-Blinded Versus Blinded Histopathologic Evaluation in Animal Toxicity Studies

The Society of Toxicologic Pathology (STP) explored current institutional practices for selecting between non-blinded versus blinded histopathologic evaluation during Good Laboratory Practice (GLP)-compliant, regulatory-type animal toxicity studies using a multi-question survey and STP-wide discussion (held at the 2019 STP annual meeting). Survey responses were received from 107 individuals representing 83 institutions that collectively employ 589 toxicologic pathologists. Most responses came from industry (N = 46, mainly biopharmaceutical or contract research organizations) and consultants (N = 24). For GLP-compliant animal toxicity studies, histopathologic evaluation usually involves initial (primary) non-blinded analysis, with post hoc informal blinded re-examination at the study pathologist’s discretion to confirm subtle findings or establish thresholds. Initial blinded histopathologic evaluation sometimes is chosen by study pathologists to test formal hypotheses and/or by sponsors to address non-pathologist expectations about histopathology data objectivity. Current practice is that a blinded histopathologic evaluation is documented only if formal blinding (ie, using slides with coded labels) is employed, using simple statements without detailed methodology in the study protocol (or an amendment) and/or pathology report. Blinding is not an appropriate strategy for the initial histopathologic evaluation performed during pathology peer reviews of GLP-compliant animal toxicity studies. [Box: see text]

The Exposome in Toxicologic Pathology

The “exposome” is an individual’s lifetime spectrum of chemical exposures beginning at conception. An exposome includes general external influences such as pollution and weather; external individual-specific factors (diet, infections, self-selected chemical intake); and internal individual-specific constituents (metabolic byproducts, microbiome derivatives, inflammatory mediators, stress hormones, etc). The exposome paradigm is inherent in animal toxicity testing because laboratory studies are designed so that subjects share a common exposure history encompassing not only exposure(s)/treatment(s) but also other chemical sources (eg, air, bedding, food, water). Toxicologic pathologists should remember that some differences in responsiveness to a test article may reflect subtle differences in individual exposomes of seemingly equivalent test animals. Translation of toxicity data obtained in tests of genetically inbred animals maintained under controlled environmental conditions to produce quasi-identical exposomes at best offers only approximate guidance regarding potential responses in genetically heterogeneous human populations who live in many environmental settings and thus have divergent, complex exposomes.

Facile Preparation of WO3-x Dots with Remarkably Low Toxicity and Uncompromised Activity as Coreactants for Clinic Electrochemiluminescent Diagnosis

<p></p><p>The exceptional nature of WO_3-<i>x</i> dots has inspired widespread interests (<i>Science</i>, 2017, 358, 1192; <i>Adv. Mater.</i><i>,</i> 2016, 28, 10518), but it is still a major challenge to synthesize high-quality WO_3-<i>x</i> dots without using unstable reactants, expensive equipment, and complex synthetic processes. Chemical tailoring of nanosheets is an essential way for the synthesis of nanodots, however it is NOT applicable to exfoliate bulk WO₃due to its covalently-bound layers. As such, most of the synthesis rely on a bottom-up method by using WCl₆ as a typical precursor but water-free conditions are usually required due to the highly hydrolytic property of WCl₆ (<i>J. Am. Chem. Soc.</i> 2005, 127, 15595). In addition, to diminish the anisotropic growth during the synthesis, the surface of the WO_3-<i>x</i> dots is usually anchored with aliphatic amines or oleic acid as surfactant/template, which leads to SLOW Faradic electrochemistry (<i>Adv. Mater. </i>2014, 26, 4260). Along these lines, it is of both fundamental and technical importance to overcome these deficiencies in the synthesis of high-quality WO_3-<i>x</i> dots. </p> <p>In this work, we report the synthesis of WO_3-<i>x</i> dots by a facile exfoliation of bulk WS₂ instead of bulk WO₃ followed by a mild chemical conversion. The WO_3-<i>x</i> dots were not only ligand-FREE and highly water-dispersible but also had tunable oxygen-vacancies, ready for a varity of high-demanding applications. As an example, the WO_3-<i>x</i>dots were emerged as a new generation of coreactants for the electrochemiluminescence (ECL) of Ru(bpy)₃²⁺ with a tremendous enhancement factor up to 500-fold, owing to the unique electrochemical and catalytic properties. More importantly, compared to the commonly used tripropylamine (TPA) coreactant in the clinics, the WO_3-<i>x</i> dots displayed a factor of ca. 300 less ANIMAL toxicity. Along these lines, the enormous potential of WO_3-<i>x</i> dots as ECL coreactants in replacing TPA for clinic diagnosis was further exemplified by cytosensing circulating tumor cells with a uncompromised performance. This work would not only open a new way to synthesize WO_3-<i>x</i>dots with superior properties but also stimulate an emerging application in clinic ECL diagnosis as coreactants with uncompromised high performance and unprecedented low toxicity.</p><br><p></p>

Facile Preparation of WO3-x Dots with Remarkably Low Toxicity and Uncompromised Activity as Coreactants for Clinic Electrochemiluminescent Diagnosis

<p></p><p>The exceptional nature of WO_3-<i>x</i> dots has inspired widespread interests (<i>Science</i>, 2017, 358, 1192; <i>Adv. Mater.</i><i>,</i> 2016, 28, 10518), but it is still a major challenge to synthesize high-quality WO_3-<i>x</i> dots without using unstable reactants, expensive equipment, and complex synthetic processes. Chemical tailoring of nanosheets is an essential way for the synthesis of nanodots, however it is NOT applicable to exfoliate bulk WO₃due to its covalently-bound layers. As such, most of the synthesis rely on a bottom-up method by using WCl₆ as a typical precursor but water-free conditions are usually required due to the highly hydrolytic property of WCl₆ (<i>J. Am. Chem. Soc.</i> 2005, 127, 15595). In addition, to diminish the anisotropic growth during the synthesis, the surface of the WO_3-<i>x</i> dots is usually anchored with aliphatic amines or oleic acid as surfactant/template, which leads to SLOW Faradic electrochemistry (<i>Adv. Mater. </i>2014, 26, 4260). Along these lines, it is of both fundamental and technical importance to overcome these deficiencies in the synthesis of high-quality WO_3-<i>x</i> dots. </p> <p>In this work, we report the synthesis of WO_3-<i>x</i> dots by a facile exfoliation of bulk WS₂ instead of bulk WO₃ followed by a mild chemical conversion. The WO_3-<i>x</i> dots were not only ligand-FREE and highly water-dispersible but also had tunable oxygen-vacancies, ready for a varity of high-demanding applications. As an example, the WO_3-<i>x</i>dots were emerged as a new generation of coreactants for the electrochemiluminescence (ECL) of Ru(bpy)₃²⁺ with a tremendous enhancement factor up to 500-fold, owing to the unique electrochemical and catalytic properties. More importantly, compared to the commonly used tripropylamine (TPA) coreactant in the clinics, the WO_3-<i>x</i> dots displayed a factor of ca. 300 less ANIMAL toxicity. Along these lines, the enormous potential of WO_3-<i>x</i> dots as ECL coreactants in replacing TPA for clinic diagnosis was further exemplified by cytosensing circulating tumor cells with a uncompromised performance. This work would not only open a new way to synthesize WO_3-<i>x</i>dots with superior properties but also stimulate an emerging application in clinic ECL diagnosis as coreactants with uncompromised high performance and unprecedented low toxicity.</p><br><p></p>