Lipid-soluble green tea extract: Genotoxicity and subchronic toxicity studies

To assess the potential safety of lipid soluble green tea extract, also referred to as lipid soluble tea polyphenols (LSTP), a series of genotoxicity tests were conducted, including an Ames, in vivo mouse micronucleus, and in vivo mouse sperm abnormality test. The toxicity of LSTP was evaluated in 90- and 30-day feeding studies. LSTP did not show mutagenic activity in the Ames test and no genotoxic potential in the in vivo assays at doses up to 10 g/kg body weight (bw). In the 90-day feeding study, LSTP was given in the diet at levels providing 0, 0.125, 0.25, or 0.50 g/kg bw/day. No significant effects were noted on body weight, food consumption, hematology, clinical chemistry, organ weights, and histopathological examination. The no-observed-adverse-effect level (NOAEL) was therefore considered to be 0.50 g/kg bw/day, the highest dose tested. Likewise, dosing of SD rats by gavage for 30 days also showed no adverse effects of growth, hematology, clinical chemistry, organ weights, or histopathology at doses of 0.58, 1.17, and 2.33 g/kg bw/day. The NOAEL in the 30-day study was considered to be the highest dose tested. These data provide evidence to support the safe use of LSTP in food.     

A comprehensive study on in vitro and in vivo toxicological evaluation of Artemisia capillaris

Artemisia capillaris (AC) has been used as an alternative therapy in obesity, atopic dermatitis, and liver diseases through several biological activity including anti-steatotic, antioxidant, and anti-inflammatory activities. Despite its ethnomedicinal benefits, no sufficient background information is available about the long-term safety and genotoxicity of the AC extract. Therefore, the present study was carried out to investigate the 13-week subchronic toxicity and genotoxicity of the AC extract according to the test guidelines published by the Organization for Economic Cooperation and Development. In the 13-week toxicity study using doses of 25, 74, 222, 667, and 2000 mg/kg body weight, oral administration of the AC extract in male and female rats did not result in any significant adverse effects in food/water consumption, body weight, mortality, hematology, serum biochemistry, organ weight and histopathology. Accordingly, the no-observed-adverse-effect level in rats of both genders was established for the AC extract at 2000 mg/kg/day, the highest dose level tested. In addition, the AC extract was not genotoxic in a battery of tests including Ames test, in vitro chromosome aberration assay and in vivo micronucleus assay. In conclusion, we demonstrated that the AC extract is considered as a safe traditional medicine for human consumption.     

Assessment of oxidative stress responses and the cytotoxic and genotoxic potential of the herbicide tembotrione in HepG2 cells

Tembotrione is a triketone herbicide, usually used for post-emergence weed control in corn. Currently, there is little or no published data on its genotoxicity to human cells either in vitro or in vivo. This study evaluated the impact of acute (4 and 24 h) exposure to low concentrations of tembotrione [corresponding to the acceptable daily intake (0.17 μg/mL), residential exposure level (0.002 μg/mL) and acceptable operator exposure level (0.0012 μg/mL)] on human hepatocellular carcinoma cell line HepG2, using biomarkers of oxidative stress, CCK-8 colorimetric assay for cell viability, alkaline comet assay, and cytokinesis-block micronucleus “cytome” assay. Tembotrione applied at concentrations likely to be encountered in occupational and residential exposures induced cytogenetic outcomes in non-target cells despite non-significant changes in the values of oxidative stress biomarkers. We assume that the observed effects were mainly the consequence of impaired metabolic pathways in HepG2 cells due to the inhibition of the enzyme 4-hydroxyphenyl-pyruvate-dioxygenase by tembotrione, which possibly caused a depletion of folate levels leading to excess formation of nuclear buds in the affected cells. Regardless of the fact that tembotrione was previously reported negative for mutations and chromosome aberrations in vitro, our findings call for more precaution in its use.     

Toxicology of 3-epi-deoxynivalenol,a deoxynivalenol-transformation product by Devosia mutans 17-2-E-8

Microbial detoxification of deoxynivalenol (DON) represents a new approach to treating DON-contaminated grains. A bacterium Devosia mutans 17-2-E-8 was capable of completely transforming DON into a major product 3-epi-DON and a minor product 3-keto-DON. Evaluation of toxicities of these DON-transformation products is an important part of hazard characterization prior to commercialization of the biotransformation application. Cytotoxicities of the products were demonstrated by two assays: a MTT bioassay assessing cell viability and a BrdU assay assessing DNA synthesis. Compared with DON, the IC₅₀ values of 3-epi-DON and 3-keto-DON were respectively 357 and 3.03 times higher in the MTT bioassay, and were respectively 1181 and 4.54 times higher in the BrdU bioassay. Toxicological effects of 14-day oral exposure of the B6C3F₁ mouse to DON and 3-epi-DON were also investigated. Overall, there were no differences between the control (free of toxin) and the 25 mg/kg bw/day or 100 mg/kg bw/day 3-epi-DON treatments in body and organ weights, hematology and organ histopathology. However, in mice exposed to DON (2 mg/kg bw/day), white blood cell numbers and serum immunoglobulin levels were altered relative to controls, and lesions were observed in adrenals, thymus, stomach, spleen and colon. Taken together, in vitro and in vivo studies indicate that 3-epi-DON is substantially less toxic than DON.     

Parameters and pitfalls to consider in the conduct of food additive research,Carrageenan as a case study

This paper provides guidance on the conduct of new in vivo and in vitro studies on high molecular weight food additives, with carrageenan, the widely used food additive, as a case study. It is important to understand the physical/chemical properties and to verify the identity/purity, molecular weight and homogeneity/stability of the additive in the vehicle for oral delivery. The strong binding of CGN to protein in rodent chow or infant formula results in no gastrointestinal tract exposure to free CGN. It is recommended that doses of high Mw non-caloric, non-nutritive additives not exceed 5% by weight of total solid diet to avoid potential nutritional effects. Addition of some high Mw additives at high concentrations to liquid nutritional supplements increases viscosity and may affect palatability, caloric intake and body weight gain. In in vitro studies, the use of well-characterized, relevant cell types and the appropriate composition of the culture media are necessary for proper conduct and interpretation. CGN is bound to media protein and not freely accessible to cells in vitro. Interpretation of new studies on food additives should consider the interaction of food additives with the vehicle components and the appropriateness of the animal or cell model and dose–response.     

Safety evaluation of oleic-rich triglyceride oil produced by a heterotrophic microalgal fermentation process

Numbers of macro- and microalgae have been used as food sources in various cultures for centuries. Several microalgae are currently being developed as modern food ingredients. The dietary safety of oleic-rich microalgal oil produced using a heterotrophic fermentation process was assessed in a 13-week feeding trial in rats with genotoxic potential evaluated using in vitro and in vivo assays. In the genotoxicity assays, the test oil was not mutagenic in Salmonella typhimurium or Escherichia coli tester strains (⩽5000 μg/plate) with or without metabolic activation. Further, no clastogenic response occurred in chromosome aberration assays in the bone marrow of mice administered a single intraperitoneal dose (2000 mg/kg). In the subchronic study, rats consumed feed containing 0, 25,000, 50,000 or 100,000 ppm oleic-rich oil for 90 days. No treatment-related mortalities or adverse effects occurred in general condition, body weight, food consumption, ophthalmology, urinalysis, hematology, clinical chemistry, gross pathology, organ weights or histopathology. Although several endpoints exhibited statistically significant effects, none were dose-related or considered adverse. Taking all studies into consideration, the NOAEL for the oleic-rich oil was 100,000 ppm, the highest concentration tested and equivalent to dietary NOAELs of 5200 mg/kg bw/day and 6419 mg/kg bw/day in male and female rats, respectively.     

Absence of subchronic oral toxicity and genotoxicity of rice koji with Aspergillus terreus

Koji products have been considered as an effective fermented food consumed in East Asia with many health benefits. Particularly, rice koji with Aspergillus terreus (RAT) has been reported to be able to prevent hyperlipidemia and hepatic steatosis through regulating cholesterol synthesis. Despite its biological activities, there is a lack of comprehensive information to give an assurance of its safety. Therefore, the objective of this study was to perform a series of toxicological studies (repeated dose oral toxicity and genotoxicity) according to test guidelines published by the Organization for Economic Cooperation and Development. Along with acute toxicity study using rats and beagle dogs, a 13-week toxicity study revealed no clear RAT-related toxic changes, including body weight, mortality, hematology, serum biochemistry, organ weight, and histopathology after oral administration at doses of 500, 1000, and 2000 mg/kg BW. The no-observed-adverse-effect level of RAT was considered to be more than 2000 mg/kg BW/day in rats of both genders. In addition, potential genotoxicity was evaluated using a standard battery of tests (Ames test, chromosome aberration assay, and micronucleus assay) which revealed that RAT showed no genotoxicity. Accordingly, these results suggest that RAT is a safe and non-toxic functional food for human consumption at proper dose.     

FEMA expert panel review of p-mentha-1,8-dien-7-al genotoxicity testing results

p-Mentha-1,8-dien-7-al is a naturally occurring cyclic alpha,beta-unsaturated aldehyde that is used as a flavoring substance throughout the world. Due to the chemical structure and the potential DNA reactivity of the alpha,beta-unsaturated carbonyl moiety, a battery of genotoxicity assays was requested by the European Food Safety Authority. Previous genotoxicity studies on the substance gave mixed results, but both positive and negative results were hampered by not always being performed to any standard guideline. The new test battery data indicated some evidence of mutagenicity in vitro, but an in vivo comet/micronucleus combination assay performed in rats was concluded by the study directors to not result in any biologically relevant positive responses. However, EFSA concluded that the in vivo assay gave evidence that p-mentha-1,8-dien-7-al was of potential genotoxic concern. The Expert Panel of the Flavor and Extract Manufacturers Association (FEMA) has reviewed the newly available data and considered its interpretation relative to standard guidelines such as that established by the Organization for Economic Cooperation and Development, and has concluded that the results in the comet/micronucleus combination assay are consistent with the interpretation by the study directors; namely, that p-mentha-1,8-dien-7-al does not appear to have any in vivo genotoxic potential.     

Delamanid is not metabolized by Salmonella or human nitroreductases: A possible mechanism for the lack of mutagenicity

Nitro-containing compounds such as nitrofuran and nitroimidazole are drugs used for the treatment of infectious diseases. However, many of these nitro-containing drugs are positive in the bacterial reverse mutation assay (Ames test). The recently approved anti-multidrug-resistant tuberculosis (MDR-TB) drug, delamanid (Deltyba™; OPC-67683), a derivative of 4-nitroimidazole, was negative for mutagenicity in the Ames assay. In Salmonella typhimurium, mutagenicity of nitro compounds has been closely associated with the ability of nitroreductase to metabolize (degradation)these compounds. To explore the lack of mutagenicity for delamanid, we examined the initial metabolic rate and mutagenic-specific activity of a series of nitro compounds in S. typhimurium TA100. The order of maximum mutagenic-activity was nitrofuran > 2-nitroimidazole > 5-nitroimidazole ≥ 4-nitroimidazole, which is very similar to the order of initial metabolic rate, i.e., the Pearson's correlation coefficient (r = 0.85) showed a correlation between metabolic rate and mutagenic-activity. No metabolism of delamanid was detected even after 60 h of treatment. In addition, delamanid was not reduced by two human nitroreductases. These facts may explain the absence of genotoxicity of delamanid in both in vitro and in vivo tests.     

Dermal absorption for pesticide health risk assessment: Harmonization of study design and data reporting for North American Regulatory submissions

Although an internationally-adopted in vitro dermal absorption test guideline is available (OECD Test Guideline 428), the replacement of the in vivo approach in North America for pesticide formulations has not occurred due to concern over the reliability and consistency of the in vitro results. A 2012 workshop convened a panel of experts in the conduct of in vitro studies used for pesticide risk assessment, together with North American regulators, to examine techniques for in vitro dermal absorption testing. Discussions led to the recommended “best practices” for the conduct of in vitro dermal absorption studies provided herein. The workshop participants also developed recommendations for reporting study results in order to improve the quality and consistency of the data submitted to regulatory agencies in North America. Finally, a case study is presented that illustrates the use of the “triple-pack” approach; the studies, conducted for the registration of sulfoxaflor, follow the standardized recommendations provided at the workshop. In addressing the concerns of these regulators and of the regulated community, and providing harmonized recommendations to facilitate comparative data analyses, it is anticipated that wider acceptance of in vitro dermal absorption studies alone can be achieved for pesticide risk assessment.     

Genotoxicity,acute and subchronic toxicity evaluation of savory food ingredients

The potential toxicity of two savory food ingredients produced by fermentation of enzymatically hydrolyzed corn starch (Savory Base 100 and Savory Base 200) was evaluated individually in a bacterial reverse mutation assay, an in vitro mammalian cell gene mutation assay, an acute oral study and as a mixture in a 90-day dietary study. In the bacterial reverse mutation and in vitro mammalian cell gene mutation assays, neither ingredient was mutagenic at concentrations up to 5000 μg/plate and 5000 μg/mL, respectively in the presence and absence of metabolic activation. In the acute study, the no-observed-adverse-effect level (NOAEL) for each Savory Base 100 and Savory Base 200 in male and female rats was 2000 mg/kg body weight. In the 90-day study, the hematology and clinical chemistry findings and histopathological changes noted in the liver, heart and kidneys were deemed to be of no toxicological significance, as the mean values were within the historical control range, were not dose-dependent, occurred at a similar frequency in control groups, or only occurred in the control group. Considering these findings, the NOAEL for Savory Base 100 and Savory Base 200 was 2333 and 1167 mg/kg body weight, respectively, the highest dose tested in each case.     

CSAHi study-2: Validation of multi-electrode array systems (MEA60/2100) for prediction of drug-induced proarrhythmia using human iPS cell-derived cardiomyocytes: Assessment of reference compounds and comparison with non-clinical studies and clinical information

With the aim of reconsidering ICH S7B and E14 guidelines, a new in vitro assay system has been subjected to worldwide validation to establish a better prediction platform for potential drug-induced QT prolongation and the consequent TdP in clinical practice. In Japan, CSAHi HEART team has been working on hiPS-CMs in the MEA (hiPS-CMs/MEA) under a standardized protocol and found no inter-facility or lot-to-lot variability for proarrhythmic risk assessment of 7 reference compounds. In this study, we evaluated the responses of hiPS-CMs/MEA to another 31 reference compounds associated with cardiac toxicities, and gene expression to further clarify the electrophysiological characteristics over the course of culture period.The hiPS-CMs/MEA assay accurately predicted reference compounds potential for arrhythmogenesis, and yielded results that showed better correlation with target concentrations of QTc prolongation or TdP in clinical setting than other current in vitro and in vivo assays. Gene expression analyses revealed consistent profiles in all samples within and among the testing facilities.This report would provide CiPA with informative guidance on the use of the hiPS-CMs/MEA assay, and promote the establishment of a new paradigm, beyond conventional in vitro and in vivo assays for cardiac safety assessment of new drugs.     

Cyto-genotoxicity and oxidative stress induced by zinc oxide nanoparticle in human lymphocyte cells in vitro and Swiss albino male mice in vivo

ZnO-np has immense potential and application in cosmetic and health care sectors. Hence it was imperative to assess the toxicity/safety of these nanoparticles. In this study, we have evaluated the effects of ZnO-np in human peripheral blood mononuclear cells (PBMCs) in vitro and in Swiss albino male mice in vivo for cyto-genotoxicity and oxidative damage. In vitro results showed that ZnO-nps were weakly genotoxic, induced significant decrease in mitochondrial membrane potential and was capable of ROS generation, leading to apoptosis. In bone marrow cells in vivo, reduction of mitochondrial membrane potential (MMP), increased oxidative stress and G0/G1 cell cycle arrest was observed along with chromosome aberrations and micronuclei formation. In liver cells DNA damage and induction of oxidative stress with concurrent decrease in inhibition of antioxidant enzymes were noted. These in vitro and in vivo results demonstrated that ZnO-np induced genotoxic response and ROS production leading to apoptotic cell death and established a good co-relation between the two biological systems. More importantly, the results stress on the need of multiple endpoint assay-approaches, with an in vitro-in vivo study design to assess nanoparticle toxicology.     

A subchronic toxicity study of Radix Dipsaci water extract by oral administration in F344 rats

Radix Dipsaci, the dried root of Dipsacus asperoides C.Y. Cheng & T.M.Ai, has therapeutic effects on various disorders, and in particular, bone and joint disease. Despite such ethnomedicinal benefits, there is very little information regarding its in vivo toxicity or adverse effects. This study was conducted to evaluate the potential toxicity of the Radix Dipsaci water Extract (RD-wE) by using F344 rats. The RD-wE was administered orally to rats at doses of 0, 125, 250, 500, 1000, and 2000 mg/kg body weight (bw)/day for 13 weeks. During the treatment period there were no mortalities attributed to RD-wE. Moreover, no toxic effects were observed with regard to body weight, clinical pathology (hematology, clinical biochemistry, and urinalysis), and anatomic pathology (gross findings, organ weight, and microscopic examination). The changes related to the treatment were excessive salivation at the mouth and soft feces, observed in male and female rats at 1000 or 2000 mg/kg bw/day, but these were not accompanied by any microscopic correlate or other pathophysiological changes. Based on these results, the oral no-observed-adverse-effect level of the RD-wE was considered to be 2000 mg/kg bw/day in both genders, although the target organs were not determined under the current experimental conditions.     

In vitro and in vivo safety evaluation of Nephure™

Nephure™ is a proprietary oxalate decarboxylase (OxDC) enzyme being developed as a food ingredient. In this study, the safety of Nephure™ was evaluated in a bacterial mutagenicity assay and in a sub-chronic (13-week) oral toxicity study in rats. Nephure™ did not show any mutagenic properties in the mutagenicity assay. In the 13-week sub-chronic oral toxicity study in which 10 Sprague Dawley rats per sex were administered 0, 118, 235 and 475 mg/kg bw/day (8260, 16450 and 33,250 Units/kg bw/day, respectively) of Nephure™ by gavage, male and female rats did not show any test article-related clinical observations or effects on body weight, body weight gain, food consumption, food efficiency, ophthalmology, functional observational battery parameters or motor activity. Furthermore, there were no changes in coagulation, clinical chemistry, urinalysis or hematology parameters, macroscopic/microscopic findings or organ weights that could be attributed to the test article. Based on these results, Nephure™ was not mutagenic and the no-adverse-effect level (NOAEL) in the 13-week study was determined to be 475 mg/kg bw/day (33,250 Units/kg bw/day). Evaluation of the estimated consumption of Nephure™, generation of the metabolite formate, and the current safety studies resulted in a conclusion of a tolerable upper limit of 3450 Units of OxDC activity/day (57.5 Units activity/kg bw/day), when Nephure™ is added to food to decrease dietary oxalate.     

Evaluation of food-relevant chemicals in the ToxCast high-throughput screening program

Thousands of chemicals are directly added to or come in contact with food, many of which have undergone little to no toxicological evaluation. The landscape of the food-relevant chemical universe was evaluated using cheminformatics, and subsequently the bioactivity of food-relevant chemicals across the publicly available ToxCast highthroughput screening program was assessed. In total, 8659 food-relevant chemicals were compiled including direct food additives, food contact substances, and pesticides. Of these food-relevant chemicals, 4719 had curated structure definition files amenable to defining chemical fingerprints, which were used to cluster chemicals using a selforganizing map approach. Pesticides, and direct food additives clustered apart from one another with food contact substances generally in between, supporting that these categories not only reflect different uses but also distinct chemistries. Subsequently, 1530 food-relevant chemicals were identified in ToxCast comprising 616 direct food additives, 371 food contact substances, and 543 pesticides. Bioactivity across ToxCast was filtered for cytotoxicity to identify selective chemical effects. Initiating analyses from strictly chemical-based methodology or bioactivity/cytotoxicity-driven evaluation presents unbiased approaches for prioritizing chemicals. Although bioactivity in vitro is not necessarily predictive of adverse effects in vivo, these data provide insight into chemical properties and cellular targets through which foodrelevant chemicals elicit bioactivity.     

Estimation of in vivo and in vitro exposure to bisphenol A as food contaminant

The goal of this cross-sectional study was to examine the occurrence of bisphenol A (BPA) in the morning spot urine taken from 145 female volunteers of various ages. Total urine BPA concentration was detected in 38.6% samples in the 0.92–70.96 μg/g Cr range. The majority of BPA + women belonged to the 25 + body mass index (BMI) group (54.5% were overweight and 43.4% were obese women). Occurrence of BPA in the urine samples was higher at 40 + ages. The maximum BPA concentration of 70.96 μg/g Cr was detected in the urine sample of an obese woman. It is known that BPA is highly toxic in vitro. In this study BPA impaired significantly the growth of all investigated cell lines, i.e. the EC₅₀ values were reached at very low concentrations, in the range from 3.24 to 34.85 μg/mL. The obtained in vivo results suggest that a higher exposure to BPA could contribute to weight problems in women and the absence of the BPA in vitro selective toxicity studies indicates to its general toxic mode of action and raises awareness of the health risks associated with its ubiquitous presence in the environment.     

Genotoxicity and subchronic toxicity evaluation of dried Euglena gracilis ATCC PTA-123017

Euglena gracilis is a microalga capable of synthesizing various nutrients of interest in human and animal nutrition. When cultivated aerobically in the dark, Euglena synthesize paramylon, a storage polysaccharide comprised of high molecular weight beta-1,3-D-glucose polymers organized in cytoplasmic granules. Beta-glucans have been shown to have immune modulation effects, including anti-microbial, anti-tumor, and anti-oxidant properties, and metabolic effects, such as regulation of cholesterol and blood sugar levels. Preparations of E. gracilis and paramylon may therefore have potential utility as functional food ingredients for human and animal nutrition. A battery of toxicological studies was conducted on a dried preparation of E. gracilis and paramylon to support their safe food use. The dried alga was not genotoxic in a bacterial reverse mutation test and mammalian micronucleus test. In the subchronic toxicity study, rats were provided E. gracilis in the diet at levels of 0, 12,500, 25,000 or 50,000 ppm. Paramylon was provided at a concentration of 50,000 ppm. No effects that could be attributable to treatment were observed in clinical observations, body weight, food consumption, ophthalmology, hematology and clinical chemistry, urinalysis, and macroscopic and microscopic findings. A NOAEL of 50,000 ppm in the diet was determined for both ingredients.     

Genotoxicity of monosodium glutamate

Monosodium glutamate (MSG) is one of the most widely used flavor enhancers throughout the world. The aim of this study is to investigate the genotoxic potential of MSG by using chromosome aberrations (CAs), sister-chromatid exchanges (SCEs), cytokinesis-blocked micronucleus (CBMN), and random amplified polymorphic DNA-polimerase chain reaction (RAPD-PCR) in cultured human lymphocytes and alkaline comet assays in isolated human lymphocytes, which were incubated with six concentrations (250, 500, 1000, 2000, 4000 and 8000 μg/mL) of MSG. The result of this study indicated that MSG significantly and dose dependently increased the frequencies of CAs, SCE and MN in all treatments and times, compared with control. However, the replication (RI) and nuclear division indices (NDI) were not affected. In this paper, in vitro genotoxic effects of the MSG was also investigated on human peripheral lymphocytes by analysing the RAPD-PCR with arbitrary 10-mer primers. The changes occurring in RAPD profiles after MSG treatment include increase or decrease in band intensity and gain or loss of bands. In the comet assay, this additive caused DNA damage at all concentrations in isolated human lymphocytes after 1-h in vitro exposure. Our results demonstrate that MSG is genotoxic to the human peripheral blood lymphocytes in vitro.