Correlation between cytotoxicity in vitro and LD50-values

In vitro cytotoxic assessment of e-waste-related chemical pollution in impacted soil matrix

The environmental quality and toxicity of soil from some selected informal e-waste sites in West Africa was assessed on PLHC-1 liver cells. In addition, toxicity mechanisms such as apoptosis, necrosis and necroptosis were analysed in order to determine the effect of the actual chemical mixture present in the e-waste soil matrix. The investigation revealed that although e-waste soil extracts (polar and non-polar) and elutriates were significantly cytotoxic at the tested concentration (16 mg soil EQ/ml), PLHC-1 cell viability was not reduced below 50%. The non-polar extracts were more toxic compared to polar extracts and elutriates. The cytotoxic potency of soil from the informal e-waste-recycling sites ranged in this order: Alaba > Godome-Kouhounou > Agbogblosie. The study revealed that all e-waste soil extracts and elutriates induced significant (P < 0.01) PLHC-1 cell death by apoptosis and necrosis; however, cell death by apoptosis was higher compared to that by necrosis. The results indicated that except for non-polar extracts (N4, B4 and G4) from open burning areas that induced significant (P < 0.01) PLHC-1 cell death by necroptosis, other extracts and elutriates could not cause cell death by necroptosis. The study has demonstrated that soils from the Alaba e-waste site in Lagos could be more toxic than soils from Godome-Kouhounou (Cotonou) and Agbogblosie (Accra) e-waste sites and further highlighted open burning as an informal e-waste-handling method with greater negative impact on soil quality in the e-waste sites. The study emphasizes the urgent need for regulatory agencies to introduce regular residue-monitoring programmes in order to forestall the adverse effects of soil pollution episodes in the e-waste sites.

The use of Bayesian methodology in the development and validation of a tiered assessment approach towards prediction of rat acute oral toxicity

There exists consensus that the traditional means by which safety of chemicals is assessed—namely through reliance upon apical outcomes obtained following in vivo testing—is increasingly unfit for purpose. Whilst efforts in development of suitable alternatives continue, few have achieved levels of robustness required for regulatory acceptance. An array of “new approach methodologies” (NAM) for determining toxic effect, spanning in vitro and in silico spheres, have by now emerged. It has been suggested, intuitively, that combining data obtained from across these sources might serve to enhance overall confidence in derived judgment. This concept may be formalised in the “tiered assessment” approach, whereby evidence gathered through a sequential NAM testing strategy is exploited so to infer the properties of a compound of interest. Our intention has been to provide an illustration of how such a scheme might be developed and applied within a practical setting—adopting for this purpose the endpoint of rat acute oral lethality. Bayesian statistical inference is drawn upon to enable quantification of degree of confidence that a substance might ultimately belong to one of five LD50-associated toxicity categories. Informing this is evidence acquired both from existing in silico and in vitro resources, alongside a purposely-constructed random forest model and structural alert set. Results indicate that the combination of in silico methodologies provides moderately conservative estimations of hazard, conducive for application in safety assessment, and for which levels of certainty are defined. Accordingly, scope for potential extension of approach to further toxicological endpoints is demonstrated.

A Review of the Toxicity and Phytochemistry of Medicinal Plant Species Used by Herbalists in Treating People Living With HIV/AIDS in Uganda

Introduction: Despite concerns about toxicity, potentially harmful effects and herb-drug interactions, the use of herbal medicines remains widely practiced by people living with HIV/AIDS (PLHIV) in Uganda. Objective: The objective of the paper was to comprehensively review the literature on the toxicity and chemical composition of commonly used medicinal plant species in treating PLHIV in Uganda. Methods: We reviewed relevant articles and books published over the last sixty years on ethnobotany, antiviral/anti-HIV activity, toxicity, phytochemistry of Vachellia hockii, Albizia coriaria, Bridelia micrantha, Cryptolepis sanguinolenta, Erythrina abyssinica, Gardenia ternifolia, Gymnosporia senegalensis, Psorospermum febrifugium, Securidaca longipendunculata, Warburgia ugandensis and Zanthoxylum chalybeum and their synonyms. We searched PubMed, Web of Science, Scopus, Science Direct and Google Scholar. Discussion: Most of the plant species reviewed apart from P. febrifugium, S. longipedunculata and C. sanguinolenta lacked detailed phytochemical analyses as well as the quantification and characterization of their constituents. Crude plant extracts were the most commonly used. However, purified/single component extracts from different plant parts were also used in some studies. The U87 human glioblastoma was the most commonly used cell line. Water, ethanol, methanol and DMSO were the commonest solvents used. In some instances, isolated purified compounds/extracts such as Cryptolepine and Psorospermin were used. Conclusion: Cytotoxicity varied with cell type, solvent and extract type used making it difficult for direct comparison of the plant species. Five of the eleven plant species namely, A. coriaria, C. sanguinolenta, G. ternifolia, P. febrifugium and Z. chalybeum had no cytotoxicity studies in animal models. For the remaining six plant species, the crude aqueous and ethanol extracts were mainly used in acute oral toxicity studies in mice. Herbalists reported only A. coriaria and W. ugandensis to cause toxic side effects in humans. However, selective cytotoxic plant extracts can potentially be beneficial as anticancer or anti-tumour drugs.

Hepatocytes in Primary Culture: An Alternative to LD50 Testing? Validation of a Predictive Model by Multivariate Analysis

The cytotoxicity of 30 chemicals was assessed in rat hepatocyte primary cultures using four methods: lactate dehydrogenase release, neutral red uptake, the MTT assay, and measurement of total protein content.

Comparison of the data obtained in vitro (IC50 values) and in vivo (LD50 values) resulted in a significant correlation (p<0.001) between IC50 values and intravenous LD50 values. The validity, as well as the predictability of the model, were determined by multivariate analysis (principal component analysis and correspondence analysis). The predictability area, expressed in IC50 values, was in the range of 0–l,500μg/ml and reached 95%, with a 75–100% confidence interval (p = 0.05).

Assessment of the cytotoxicity of 54 additional chemicals would provide a more accurate predictability limit around l,500μg/ml and the estimated predictability confidence interval could be reduced to 90–100%.

Evaluation of the Cytotoxicity and Apoptotic Induction in Human Liver Cell Lines Exposed to Three Food Additives

BACKGROUND

Rapid lifestyle, especially among people living in urban areas, has led to increasing reliance on the processed food market. Unfortunately, harmful effects caused by the excessive use of food additives in such type of industry are often neglected.

OBJECTIVE

This proposal investigates in vitro cytotoxic and apoptotic effects of three food preservatives commonly consumed in daily meals; sodium sulphite, boric acid, and benzoic acid.

METHODS

The effect of the three preservatives on cell viability was tested on two different cell lines; normal liver cell line THLE2 and human hepatocellular carcinoma cancer cell line HepG2 using MTT assay. Cell cycle arrest was measured using flow cytometry by propidium iodide. Measurement of expression levels of two central genes, p53 and bcl-2 that play key roles in cell cycle and apoptosis was carried out in HepG2 cells using real time-PCR.

RESULTS

Although the effect was more significantly realized in the HepG2 cell line, the viability of both cell lines was decreased by all of the three tested compounds. Flow cytometric analysis of HepG2 cells treated with sodium sulphite, boric acid, and benzoic acid has revealed an increase in G2/M phase cell cycle arrest. In Sodium sulphite and boric acid-treated cells, expression levels of p53 were up-regulated, while that of the Bcl2 was significantly down-regulated. On the other hand, Benzoic acid has shown an anti-apoptotic feature based on the increased expression levels of Bcl-2 in treated cells.

CONCLUSION

In conclusion, all of the tested compounds have decreased the cell line viability and induced both cell cycle arrest and apoptotic events indicating their high potential of being cytotoxic and genotoxic materials.

In silico toxicity as a tool for harm reduction: A study of new psychoactive amphetamines and cathinones in the context of criminal science

The emergence of new psychoactive substances (NPS) has raised many issues in the context of law enforcement and public drug policies. In this scenario, interdisciplinary studies are crucial to the decision-making process in the field of criminal science. Unfortunately, information about how NPS affect people's health is lacking even though knowledge about the toxic potential of these substances is essential: the more information about these drugs, the greater the possibility of avoiding damage within the scope of a harm reduction policy. Traditional analytical methods may be inaccessible in the field of forensic science because they are relatively expensive and time-consuming. In this sense, less costly and faster in silico methodologies can be useful strategies. In this work, we submitted computer-calculated toxicity values of various amphetamines and cathinones to an unsupervised multivariate analysis, namely Principal Component Analysis (PCA), and to the supervised techniques Soft Independent Modeling of Class Analogy and Partial Least Square-Discriminant Analysis (SIMCA and PLS-DA) to evaluate how these two NPS groups behave. We studied how theoretical and experimental values are correlated by PLS regression. Although experimental data was available for a small amount of molecules, correlation values reproduced literature values. The in silico method efficiently provided information about the drugs. On the basis of our findings, the technical information presented here can be used in decision-making regarding harm reduction policies and help to fulfill the objectives of criminal science.

Discriminating modes of toxic action in mice using toxicity in BALB/c mouse fibroblast (3T3) cells

The objective of this study was to determine whether toxicity in mouse fibroblast cells (3T3 cells) could predict toxicity in mice. Synthesized data on toxicity was subjected to regression analysis and it was observed that relationship of toxicities between mice and 3T3 cells was not strong (R² = 0.41). Inclusion of molecular descriptors (e.g. ionization, pKa) improved the regression to R² = 0.56, indicating that this relationship is influenced by kinetic processes of chemicals or specific toxic mechanisms associated to the compounds. However, to determine if we were able to discriminate modes of action (MOAs) in mice using the toxicities generated from 3T3 cells, compounds were first classified into "baseline" and "reactive" guided by the toxic ratio (TR) for each compound in mice. Sequence, binomial and recursive partitioning analyses provided strong predictions of MOAs in mice based upon toxicities in 3T3 cells. The correct classification of MOAs based on these methods was 86%. Nearly all the baseline compounds predicted from toxicities in 3T3 cells were identified as baseline compounds from the TR in mice. The incorrect assignment of MOAs for some compounds is hypothesized to be due to experimental uncertainty that exists in toxicity assays for both mice and 3T3 cells. Conversely, lack of assignment can also arise because some reactive compounds have MOAs that are different in mice compared to 3T3 cells. The methods developed here are novel and contribute to efforts to reduce animal numbers in toxicity tests that are used to evaluate risks associated with organic pollutants in the environment.

Toxicity of Nine (Doped) Rare Earth Metal Oxides and Respective Individual Metals to Aquatic Microorganisms Vibrio fischeri and Tetrahymena thermophila

Despite the increasing use of rare earth elements (REEs) and oxides (REOs) in various technologies, the information on their ecotoxicological hazard is scarce. Here, the effects of La3+, Ce3+, Pr3+, Nd3+, Gd3+, CeO₂, and eight doped REOs to marine bacteria Vibrio fischeri and freshwater protozoa Tetrahymena thermophila were studied in parallel with REO dopant metals (Co2+, Fe3+, Mn2+, Ni2+, Sr2+). The highest concentrations of REOs tested were 100 mg/L with protozoa in deionized water and 500 mg/L with bacteria in 2% NaCl. Although (i) most REOs produced reactive oxygen species; (ii) all studied soluble REEs were toxic to bacteria (half-effective concentration, EC50 3.5-21 mg metal/L; minimal bactericidal concentration, MBC 6.3-63 mg/L) and to protozoa (EC50 28-42 mg/L); and (iii) also some dopant metals (Ni2+, Fe3+) proved toxic (EC50 ≤ 3 mg/L), no toxicity of REOs to protozoa (EC50 > 100 mg/L) and bacteria (EC50 > 500 mg/L; MBC > 500 mg/L) was observed except for La₂NiO₄ (MBC 25 mg/L). According to kinetics of V. fischeri bioluminescence, the toxicity of REEs was triggered by disturbing cellular membrane integrity. Fortunately, as REEs and REOs are currently produced in moderate amounts and form in the environment insoluble salts and/or oxides, they apparently present no harm to aquatic bacteria and protozoa.

Cytotoxicity of Resorcinol Under Short- and Long-Term Exposure in Vitro

Cytotoxicity of resorcinol to 3T3 fibroblast in short- (3 hrs) and long-term (72 hrs or 6 weeks) exposure was investigated. The effects of resorcinol on cell viability (neutral red uptake, NRU assay), mitochondrial function (MTT assay) and total cell protein (Kenacid Blue assay) were estimated. As a model for long-term exposure an INTEGRA CL 6-WELL bioreactor was used. The concentrations of resorcinol producing 20, 50 and 80% inhibition of cell growth in the NRU test were lower than in the MTT test after 3 hrs of exposure. The use of an INTEGRA CL 6-WELL bioreactor allows continuous culturing and exposure to test chemical of cells for several weeks, but the strong adhesiveness of fibroblast and forming aggregates make it difficult to remove them from chambers. Resorcinol in concentration of 1 microg/cm(3) did not decrease the viability of cells to 50% of control in long-term exposure in the bioreactor.

A novel chitosan–collagen-based hydrogel for use as a dermal filler: initial in vitro and in vivo investigations

The biodegradability, histocompatibility and biocompatibility of injectable HCD hydrogels were determined throughin vitroandin vivotests.

Novel cytotoxicity test based on menadione-catalyzed H2O2 productivity for food safety evaluation

Menadione-catalyzed H(2)O(2) production by viable cells was proportional to viable cell number, and the assay of this H(2)O(2) production was applied to the cytotoxicity test of 17 substances which were used for international validation of fixed-dose procedure as an alternative to the classical LD(50) test. The cytotoxicity of substances tested was observed 4 h after the incubation with animal cells, and the viability was determined in 10 min according to menadione-catalyzed H(2)O(2) production assay. IC(50) of each substance required for 50% inhibition of menadione-catalyzed H(2)O(2) production was similar among HepG2, HuH-6KK, HUVE, Vero, Intestine407, NIH/3T3 and Neuro-2a cells. Twelve substances, 3 substances and 2 substances showed the difference of one, two and three orders in the magnitude between LD(50) and IC(50), respectively. These results show that menadione-catalyzed H(2)O(2) production assay is useful for the rapid detection of toxic compounds having the basal cytotoxicity common to various cells, but is unfit for the detection of organ-specific toxic compounds.

The value of acute toxicity testing of pharmaceuticals for estimation of human response

The determination of single high doses of active pharmaceutical ingredients (API) is used mostly to fulfill regulatory demands. Oral LD(50) values in animals for over 300 API were compared to the minimal effective therapeutic doses (METD) in humans in order to find a correlation between animal and human data. The highest correlation between human METD and animal LD(50) was found for the dog (R=0.323), the lowest for the rat (0.287). It was determined that acute oral LD(50) of rats have poor correlation with the METD, and cannot be used as a classification criteria into official acute toxic categories. Only 13% of API has been classified as fatal if swallowed according to the EU CLP regulation, none of the substances with very low therapeutic dose have been identified as EU CLP acute toxicity category 1. Substances with very low therapeutic doses, which could potentially have toxic effects in humans, are not identified with the use of oral LD(50) and current classification system. We propose that the acute toxicity based on rat LD(50) dose is not used as a basis for classification of pharmaceuticals, and that the METD is applied as basis for classification.

Effect of cyclosporin A in Lewis rats in vivo and HeLa cells in vitro

The aim of this study was to compare the effect of cyclosporin A (CsA) in inbred Lewis rats with published assessment of immunotoxicity in 'classical' outbred Wistar rats. A second purpose was to consider the contribution of a panel of in vitro assays in cell cultures when added to an immunotoxicity study in vivo. The in vivo effect of CsA was investigated in a 28-day subacute immunotoxicity study in male Lewis rats at three different concentrations: 1.25, 5 and 20 mg kg(-1). The highest dose of CsA exceeded the maximum tolerated dose. A drop in body, spleen and popliteal lymph node weight of exposed animals displayed symptoms of toxicity. At a high toxic dose, haematological changes showed a decrease in the leucocyte count and in the percentage of lymphocytes, and an increase in the percentage of polymorphonuclear leucocytes. The haematocrit was significantly dose-dependently suppressed in all rats exposed to CsA. A similar dose-dependent depression of the mean cell volume of erythrocytes was found in rats given high and middle doses of CsA. The phagocytic activity of polymorphonuclear leucocytes and monocytes also was significantly dose-dependently suppressed. No significant changes in primary antibody response to sheep erythrocytes or in vitro proliferative response of spleen lymphocytes to mitogens were found in those rats.A battery of in vitro cytotoxicity methods was selected for the evaluation of metabolic and functional activity of subcellular organelles (mitochondria, lysosomes) and for the detection of drug-induced superoxide-mediated damage in HeLa cells. This cell line was chosen because it has a lower activity of superoxide dismutase (SOD) than normal cells and is sufficiently sensitive for the detection of the induction of oxygen radicals. The in vitro results indicated a direct relationship between CsA cytotoxicity and a change in the mitochondrial enzyme activity, as well as an induction of superoxide production. The results of the study indicated that a combination of selected in vivo and in vitro methods is an inexpensive way to obtain more complex information on cell status affected by xenobiotics.

Evaluation of the Cytotoxic Effects of MEIC Chemicals 31–50 on Primary Culture of Rat Hepatocytes and Hepatic and Non-hepatic Cell Lines

The cytotoxicities of 20 chemicals (numbers 31–50) from the Multicenter Evaluation of In Vitro Cytotoxicity (MEIC) programme were assessed with a primary culture of rat hepatocytes and with two hepatic cell lines (Hep G2 and FaO) and one non-hepatic cell line (3T3). The cytotoxicities of the chemicals were evaluated by using the MTT test after the cells had been exposed to the chemicals for 24 hours. For a better evaluation of results, dose–response curves were mathematically linearised and cytotoxicity was expressed as IC50 values and IC10 values (the concentration causing 50% and 10% loss of cell viability, respectively). We found that all the compounds showed similar acute basal cytotoxicity in all four cellular systems (regardless of whether the cells were, or were not, metabolically competent or were or were not of human origin). When these results were used to predicit human toxicity in terms of a mathematical parameter (prediction error [PE]), we found that all four systems gave similar predictions of human toxicity. The best cytotoxicity parameter included in the PE calculation was the IC50/10, because of an underestimation of human toxicity by in vitro systems. However, when PEs were calculated for rodent toxicity, better results were obtained. Data from the literature obtained by using other experimental models for predicting human toxicity were analysed according to the same criteria. We conclude that cellular systems are better predictive tools for human toxicity than are prokaryotic cells or whole-organism models.

Acute cytotoxicities of polynuclear aromatic hydrocarbons determined in vitro with the human liver tumor cell line, HepG2

The neutral red in vitro cytotoxicity assay was adapted for use with the human hepatocellular tumor cell line HepG2 to detect the cytotoxic potencies of polynuclear aromatic hydrocarbons (PAHs). Using benzo[a]pyrene (B[a]P) as the representative PAH, it was determined that a 3-day exposure was the most suitable for detecting cytotoxic potency and that preexposure to 5 micrograms/ml Arochlor enhanced the sensitivity of the HepG2 cells to the toxicant. Such enhanced sensitivity probably reflected increased metabolic conversion of the B[a]P to active metabolites after culturing the cells in the presence of Arochlor. This was shown by a 3-fold increase in the activity of 7-ethoxycoumarin deethylase, an indicator of mixed-function oxygenase activity. Furthermore, a reduction in sensitivity to B[a]P occurred when the cells were cultured in the presence of alpha-napthoflavone, an inhibitor of aryl hydrocarbon hydroxylase activity. When Arochlor-induced cells were transferred to medium lacking Arochlor, the level of 7-ethoxycoumarin deethylase quickly declined to basal levels. Arochlor-induced cells were also able to detect the cytotoxic potencies of benzo[k]fluoranthene, benzo[b]-fluoranthene, chrysene, benzo[a]anthracene pyrene, phenanthrene, and fluoranthene, whereas fluorene, anthracene, acenaphthene, and acenaphthylene were not cytotoxic.

Effects of benorylate and impacina on the metabolism of cultured hepatocytes

To directly evaluate the effects of benorylate and impacina on liver metabolism, we have adapted the use of cultured adult rat hepatocytes as a biological model. Cells were exposed to sub-toxic levels of the xenobiotic which were incorporated into the culture media. This was followed by the evaluation in treated cultures of some biochemical functions typical of the liver, namely, gluconeogenesis, glycogen metabolism, synthesis of plasma proteins and ureogenesis, and a comparison made with non-treated controls. Benorylate impaired glucose release by hepatocytes to the medium and net accumulation of glycogen was detected. Urea production also diminished (20%) in benorylate-treated cells. Impacina significantly increased the synthesis of albumin and tranferrin when added at therapeutic levels into the culture medium and did not alter other biochemical functions of the hepatocytes.

Trends in Scandinavian Cell Toxicology

Over a period of two years the Scandinavian Society for Cell Toxicology* has met three times (on 21 October 1983 and 6–7 June 1984 in Uppsala, Sweden, and on 6–7 September 1985 in Roskilde, Denmark), to present research advances in cell toxicology and to discuss the effects of xenobiotics in isolated and cultured cells. The first part of this report represents a summary of these discussions. In the second part, some of the individual research reports presented by the participating members are summarised. The purpose is to give a review of problems currently dealt with in Scandinavian laboratories associated with the Society for Cell Toxicology.

On the application of cultured neuroblastoma cells in chemical toxicity screening

The acute toxic action of a number of common chemicals was tested by their ability to cause detachment of cultured mouse neuroblastoma C1300 cells. A TD25 value was obtained by graphic estimation of the concentration needed to cause 25% of the total cell number to detach. These TD25 values were compared with LD50 values obtained from the literature, and they were found to correlate with a coefficient of 0.86. For six of the tested substances-diuron, butylated hydroxytoluene, benzidine, cyclophosphamide, Na2SeO3, and KCN-a very poor correlation was obtained. These diverging results could be ascribed to deficiencies in the neuroblastoma cell detachment test and emphasize the necessity for combined in vitro test procedures.