28-day Repeated-dose Toxicity Research Articles

Evaluation of acute toxicity, 28-day repeated dose toxicity, and genotoxicity of Moringa oleifera leaves infusion and powder

Ethnopharmacological relevanceMoringa oleifera Lam. leaves infusion and powder are widely used by population due the nutritional and medicinal potentials, however data regarding safety of use are still inconclusive, leading to prohibition of this plant in some countries. Aim of the studyThe present work investigated the nutritional and phytochemical composition, acute and 28-day repeated dose toxicity, and genotoxicity of M. oleifera leaves infusion and powder. Materials and methodsFor nutritional characterization of leaf powder, it was determined: humidity; mineral residue (ash); total lipid, protein, carbohydrate, and crude fiber contents; and total caloric value. Phytochemical composition was determined by high performance liquid chromatography (HPLC). The acute toxicity assay used Swiss female albino mice and oral administration in a single dose at 2000 and 5000 mg/kg of infusion or powder. The 28-day repeated dose toxicity assay employed female and male mice, with oral administration of infusion or powder at the doses 250, 500 and 1000 mg/kg. The animals were evaluated for body weight, water and feed consumption, biochemical and hematological parameters, and histology of the liver, spleen, and kidneys. In vivo genotoxicity and mutagenicity (2000 mg/kg) were evaluated by the comet assay and the micronucleus test, respectively. ResultsNutritional characterization confirmed that M. oleifera leaves are rich in proteins, carbohydrates, lipids, minerals, and fiber. HPLC indicated the presence of flavonoids and cinnamic derivatives as major polyphenols. Acute toxicity did not reveal alterations in weight gain and water and feed consumptions and no change in biochemical, hematological, and histological parameters. Behavior alterations was observed in the first 2 h after administration at 5000 mg/kg in both treatments. Infusion did not present toxicity when administered for 28 days. Conversely, the powder at 500 and 1000 mg/kg promoted liver and kidney damages observed through biochemical parameters and histopathology. Genotoxicity and mutagenicity were not detected at 2000 mg/kg. ConclusionsThe present study reveals that M. oleifera leaves are an important source of polyphenols and nutrients. Indiscriminate use of both infusion and crude leaf powder above 2000 mg/kg and powder at 500 and 1000 mg/kg are not recommended. Chronic toxicological studies and establishment of preparation protocols are suggested aiming to guarantee the safety in the use of M. oleifera leaves as nutraceutical by population.

Acute and 28-day repeated dose toxicity evaluations of cold pressed Pinus halepensis Mill. seed oil in mice and rats

Pinus halepensis Mill. seed (Pinaceae), popularly known as ‘Zgougou’, is widely consumed in the Mediterranean countries and used traditionally in the treatment of some diseases such as bronchitis, rheumatism, infection, and inflammation. The present study aimed to evaluate the oral safety of cold pressed oil of Pinus halepensis Mill. seeds (COPHS) by acute and 28-day repeated dose toxicities studies in Wistar mice and rats, respectively. In the acute toxicity study, oral administration of COPHS to mice did not provoke mortality or any toxic signs at doses up to 5000 mg/kg bw. After administration of COPHS at doses of 250, 500, and 1000 mg/kg bw/day for 28 days, no abnormal changes were observed in body weight, water intake, food consumption, organ weight, blood haematological, serum biochemistry parameters, and histology profile. Furthermore, there was no animal death or any symptom of toxicity in any group during sub-acute toxicity test period. Our findings demonstrate that COPHS is relatively non-toxic and has a large safety margin (>5000 mg/kg). The results of the present research provide basic reference data for food consumption and for future in vivo screening of biological and pharmacological properties of cold pressed oil of Pinus halepensis Mill. seeds.

28-day repeated dose toxicological evaluation of Coronil in Sprague Dawley rats: Behavioral, hematological, biochemical and histopathological assessments under GLP compliance

Ayurvedic medicines are widely employed globally for prophylaxis and treatment of a variety of diseases. Coronil is a tri-herbal medicine, constituted with the traditional herbs, Tinospora cordifolia, Withania somnifera and Ocimum sanctum, with known immunomodulatory activities. Based on its proven in-vitro activity and in-vivo efficacy, Coronil has been approved as a ‘Supporting Measure for COVID-19’ by the Ministry of AYUSH, Government of India. The current study was aimed to assess the non-clinical safety of Coronil in a 28-day repeated dose toxicity study along with a 14-day recovery period in Sprague Dawley rats. This toxicity study was conducted in accordance with OECD test guideline 407, under GLP-compliance. Specific-Pathogen-Free animals of either sex, housed in Individually-Ventilated-Cages were particularly used in the study. The tested Coronil dose levels were 0, 100, 300 and 1000 mg/kg/day, orally administered to 5 males and 5 female rats per test group. In the current study, no mortality was observed in any group and in addition, Coronil did not elicit any finding of toxicological relevance with respect to clinical signs, ocular effects, hematology, urinalysis and clinical chemistry parameters, as well as macro- or microscopical changes in any organs, when compared to the control group. Accordingly, the No-Observed-Adverse-Effect-Level (NOAEL) of Coronil was ascertained to be 1000 mg/kg/day, subsequent to its 28-day oral administration to male and female rats. The acceptable safety profile of Coronil paves the way further toxicity assessments in rodents for a longer duration as well as in higher animals, and towards its clinical investigation.

Early detection of urinary bladder carcinogens in rats by immunohistochemistry for γ-H2AX: a review from analyses of 100 chemicals.

In safety evaluations of chemicals, there is an urgent need to develop short-term methods to replace long-term carcinogenicity tests. We have reported that immunohistochemistry for γ-H2AX, a well-established biomarker of DNA damage, can detect bladder carcinogens at an early stage using histopathological specimens from 28-day repeated-dose oral toxicity studies in rats. Given the markedly low level of γ-H2AX formation in the bladder urothelium of untreated rats, an increase in γ-H2AX-positive cells following chemical exposure can be relatively easy to identify. Among the 100 compounds examined to date, bladder carcinogens can be detected with high sensitivity (33/39; 84.6%) and specificity (58/61; 95.1%). As expected, γ-H2AX formation levels tended to be high following exposure to genotoxic bladder carcinogens, whereas nongenotoxic bladder carcinogens also increased the number of γ-H2AX-positive cells, probably through secondary DNA damage associated with sustained proliferative stimulation. γ-H2AX formation in the bladder urothelium reflects species differences in susceptibility to bladder carcinogenesis between rats and mice and shows a clear dose-dependency associated with the intensity of tumor development as well as high reproducibility. Some of the bladder carcinogens that showed false-negative results in the evaluation of γ-H2AX alone could be detected by combined evaluation with immunostaining for bladder stem cell markers, including aldehyde dehydrogenase 1A1. This method may be useful for the early detection of bladder carcinogens, as it can be performed by simple addition of conventional immunostaining using formalin-fixed paraffin-embedded tissues from 28-day repeated-dose toxicity studies in rodents, which are commonly used in safety evaluations of chemical substances.

Long term toxicity study of a Siddha formulation Vetpalai thailam (VT) in Rats

Vetpalai thailam, a Siddha formulation is used topically as well as orally in the treatment of Psoriasis. Vetpalai thailam is prepared from the leaves of Wrightia tinctoria by insolation with coconut oil as the base. The adverse effect profile of VT has not been addressed and hence this study was taken up to assess the long term toxicity of VT in rats. A 90-day repeated dose toxicity study was performed by modifying the protocol described by OECD guideline 408 for testing chemicals. The study constituted of six groups consisting of six rats in each group. There was no mortality among the six study groups. No signs of toxicity and behavioural changes were observed. The histopathological examination of vital organs did not show any change in the architecture. Our study demonstrates that Vetpalai thailam does not cause any toxicity on long term use in rats.

Acute toxicity, 28-day repeated-dose toxicity and toxicokinetic study of timosaponin BII in beagle dogs

The safety evaluation of timosaponin BII (TBII) in beagle dogs with toxicokinetic study was performed. For the acute oral toxicity study, the minimum lethal dose (MLD) of TBII was more than 2000 mg/kg and suggested the characteristics of absorption saturation. For the 28-day repeated dose oral toxicity and toxicokinetic studies, there was no significant effect on all test parameters except for prolonged APTT in the 60 and 180 mg/kg groups, which recovered after withdrawal. The increase of drug exposure of 180 mg/kg group was not proportional to the increase of administration dose, showing the characteristics of absorption saturation.

Abstract P39: Pre-clinical evaluation of NEOS-223, an (S)-valine-thiazole derived peptidomimetic N-heterocycle, as an anticancer agent and P-glycoprotein inhibitor

Abstract The ability to control the proliferation and cell death by inhibiting specific target kinase offers the opportunity to apply targeted therapies in the treatment of cancer. It has been found that (S)-valine-thiazole-derived compounds such as NEOS-223 are effective inhibitors of one or more of these kinases. NEOS 223 was developed, synthesized, and tested in the NCI 60 human tumor cell-screening panel demonstrating inhibition of colon (-53%), melanoma (-41%), and breast cancers (-9%). Microsomal clearance was determined in mouse, rat, dog, and human, and analyzed by LC-MS/MS by percent of parent material. IC<sub>50</sub> values for CYP inhibition of >10 μM were calculated for 1A2, 2C19, and 3A4 with IC<sub>50</sub> values of 4.86, 4.31, and 7.84 μM for 2C9 and 2D6. Microsomal clearance was high in all species with clearance rates ranging from 69-136 mL/min/kg. Plasma protein binding was determined by Rapid Equilibrium Dialysis in mice, rats, dogs, and humans. High plasma protein binding (>70%) was observed across all species. Based on the NCI results several cell lines were assayed in an MTT assay (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl- tetrazolium bromide) to determine cell viability in the presence of NEOS-223 resulting in <20% viability in colon, breast, melanoma, pancreatic and prostate human cancer cell lines at a 10 uM concentration. Maximum tolerated dose studies were conducted by both intraperitoneal and oral administration in mice. NEOS-223 delivered up to 80 mg/kg was well tolerated. Minimal or no toxicity was observed in acute and repeat dose animal studies. Pharmacokinetics of oral administration demonstrated adequate systemic exposure at therapeutic levels in mice, rats, and dogs. Preliminary in vivo mouse xenograft studies were performed on colon (COLO 205, HT-29 red FLUC), breast (MDA-MB-468), melanoma (M-14), pancreatic (PANC-1), and prostate (PC3) human cancer cells with significant tumor inhibition observed compared to positive control agent groups with twice daily dosing of NEOS-223. In addition, a five-day pilot oral toxicity study in rats with dose range-finding studies and a 28-day repeat dose toxicity study performed in both rats and dogs provided favorable results. NEOS-223 has demonstrated active in vitro activity along with a favorable safety profile. <i>in vivo efficacy resulted in inhibition of growth of multiple cell line. As a novel effective structure possibly targeting multiple kinases and transporters in one hybrid molecule, NEOS-223 may be a preferred monotherapy or combined therapy for multiple cancers. If upon further development, this drug is effective in humans, it would advance clinical practice and could improve current therapy significantly. Citation Format: Sumathi Chittamuru, Timothy M. Murphy, Sara A. Little, Andrew A. Taylor, Roseanne Wexler, Laxman Desai. Pre-clinical evaluation of NEOS-223, an (S)-valine-thiazole derived peptidomimetic N-heterocycle, as an anticancer agent and P-glycoprotein inhibitor [abstract]. In: Proceedings of the AACR Virtual Meeting: COVID-19 and Cancer; 2021 Feb 3-5. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(6_Suppl):Abstract nr P39.

Grouping of chemicals based on the potential mechanisms of hepatotoxicity of naphthalene and structurally similar chemicals using in vitro testing for read-across and its validation

Integrated Approaches to Testing and Assessment provides a framework to improve the reliability of read-across for chemical risk assessment of systemic toxicity without animal testing. However, the availability of only a few case studies hinders the use of this concept for regulatory purposes. Thus, we compared the biological similarity of structurally similar chemicals using in vitro testing to demonstrate the validity of this concept for grouping chemicals and to extract key considerations in read-across. We analyzed the hepatotoxicity of naphthalene and three chemicals structurally similar to naphthalene (2,7-naphthalenediol, 1,5-naphthalenediol, and 1-naphthol) for which 90-day repeated dose toxicity data are available. To elucidate and compare their potential mechanisms, we conducted in vitro microarray analysis using rat primary hepatocytes and validated the results using a biomarker and metabolic activation analysis. We observed that 2,7-naphthalenediol, 1,5-naphthalenediol, and 1-naphthol had similar potential mechanisms, namely, induction of oxidative stress by their metabolic activation. Conversely, naphthalene did not show a similar toxicity effect. The existing in vivo data confirmed our grouping of chemicals based on this potential mechanism. Thus, our findings suggest that in vitro toxicogenomics and related biochemical assays are useful for comparing biological similarities and grouping chemicals based on their toxicodynamics for read-across.

Subacute toxicity study of the ethanolic extract of Mesua ferrea (L.) flowers in rats

Mesua ferrea Linn. is used traditionally in India and South East Asian countries as an antiseptic, antidote and a brain tonic. Recent pharmacological studies on the plant have highlighted M. ferrea to be a rich source of secondary metabolites, with proven therapeutic applications. Since the toxicity of a plant following repeated exposure is of higher clinical significance, the present investigation was conducted to establish the subacute toxicity profile of the ethanolic extract of Mesua ferrea flowers (MFE). The study was conducted in accordance with the OECD Guideline 407, wherein MFE was administered orally to groups of male and female rats (n = 5/group/sex) at the doses of 100, 500 and 1000 mg/kg, over a period of 28 days. Repeated administration of MFE had no adverse effect on the growth rate and hematological parameters of the animals. There were no changes in the biochemical parameters, except for a slight decrease in the CHOL (total cholesterol) levels, and an increase in the levels of AST (aspartate aminotransferase) and ALT (alanine aminotransferase), at the highest dose. The latter corroborated with the histopathological findings exhibiting mild lymphocytic infiltration and hepatocyte degeneration observed in the liver tissues of both sexes. According to the study, the no-observed-adverse-effect level (NOAEL) of M. ferrea in the 28-day repeated dose toxicity study in rats was 500 mg/kg. Though the overall effects of the extract at the highest dose did not translate into any serious complications, its effect on hepatic function needs to be established over a longer period of study.

Safety evaluation of water extract of Gastrodia elata Blume: Genotoxicity and 28-day oral toxicity studies

Water extract of Gastrodia elata Blume (WGE) has great potential as an anti-depressant and could be developed as a functional food. This study aims to assess the safety of WGE using in vitro and in vivo genotoxicity assays and a 28-day oral toxicity study. Results from a bacterial reverse mutation assay (Ames test) using five Salmonella typhimurium strains (TA98, TA100, TA102, TA1535, and TA1537) with or without metabolic activation (S9 system) showed that WGE did not induce mutagenicity. Nor did it induce clastogenic effects in Chinese hamster ovary (CHO–K1) cells with or without S9 activation. Moreover, WGE did not affect the proportion of immature to total erythrocytes or the number of micronuclei in immature erythrocytes of ICR mice. Finally, a dose-dependent 28-day repeated dose toxicity assessment of WGE (2040, 4080, and 8065 mg/kg body weight, p.o.) in mice revealed no adverse effects on behavior, mortality, body weight, haematology, clinical biochemistry, or organ weight. No toxicopathologic lesions were detected following administration of high-dose WGE compared to controls. In conclusion, WGE has no significant mutagenic or toxic properties, and the no-observed-adverse-effect level (NOAEL) of WGE can be defined as at least 8065 mg/kg/day orally for 28 days for male and female mice.

Transcriptomics-driven Evaluation on Liver Toxicity Using Adverse Outcome Pathways (AOP)

Because the liver is the primary target organ for chemicals and pharmaceuticals, evaluation of these substances' liver toxicity is of critical importance. New evaluation methods without animal testing (i.e., in vitro and/or in silico) are eagerly anticipated, both for animal welfare and for decreasing cost. Also, the importance of mechanistic interpretation of the output derived from non-animal testing has been increasing. Accordingly, we investigated the potential for evaluating liver toxicity by applying the adverse outcome pathway (AOP) concept using gene set enrichment analysis (GSEA) from gene expression (GEx) data. A case study targeting hepatocellular fatty degeneration (HFD) is reported and discussed. We first identified the events detectable in an in vitro system by comparing the GEx data from the rat primary hepatocyte (in vitro) and rat liver (in vivo) treated with a chemical with the ability to induce HFD as one of the phenotypes in a 28-day repeated-dose toxicity test. Then, the scores based on GSEA were calculated after establishing the gene sets for each event leading to HFD. As a result, the mechanistic information leading to HFD was obtained from the score calculated based on the GSEA and the usefulness of the transcriptome-driven evaluation using AOP was demonstrated.

Initial hazard assessment of 1,4-dichlorobutane: Genotoxicity tests, 28-day repeated-dose toxicity test, and reproductive/developmental toxicity screening test in rats

1,4-Dichlorobutane (1,4-DCB) is used as raw materials for drugs, pesticides, fragrances, and chemical fibers, and being used as a solvent. Its toxicity data was insufficient for screening assessment under the Japanese Chemical Substances Control Law. We conducted toxicity tests and hazard classification for screening assessment 1,4-DCB showed negative in the Ames test, positive in the in vitro chromosomal aberrations test with metabolic activation, and negative in the in vivo mouse bone-marrow micronucleus test. The 28-day repeated-dose toxicity study, where male and female rats were administered 1,4-DCB by gavage at 0, 12, 60, and 300 mg/kg/day, showed significant effects on the liver and pancreas from 12 mg/kg/day and kidney at 300 mg/kg/day. Based on periportal hepatocellular hypertrophy and decreased zymogen granules in pancreas, the lowest observed adverse effect level (LOAEL) of 12 mg/kg/day was obtained. The reproductive/developmental toxicity screening study, in which male and female rats were administered 1,4-DCB by gavage at dose of 0, 2.4, 12, and 60 mg/kg/day for 42–46 days, showed that the delivery index was decreased at 60 mg/kg/day without maternal toxicity. Based on the general toxicity, we classified this chemical as hazard class 2, with a D-value (Derived No Effect Level) of 0.002 mg/kg/day.

Toxicopathological effects of siddha drug thamira kattu chendooram in Wistar rats

A 28-day repeated dose toxicity study was conducted to evaluate the toxicity of thamira kattu chendooram (TKC) in Wistar rats. Thirty two male rats were randomly distributed eight each into four groups of control, low, mid and high dose. Rats were treated with different doses of TKC for 28 days. Reduced body weight and feed consumption were noticed in the mid and high dose groups. Blood samples were collected for haemato-biochemical analysis at the end of the study. Haematological parameters revealed decreased total erythrocyte count, haemoglobin and packed cell volume in high dose group. Alterations of serum biochemical values were noticed in glucose, total protein, albumin and magnesium. Gross and histopathological examinations did not reveal any treatment related changes.

The safety evaluation of phycocyanin-enrichedGaldieria sulphurariaextract using 90-day toxicity study in rats and in vitro genotoxicity studies

The microalgae Galdieria sulphuraria, which belong to the class of cyanidiophyceae, are thermostable at temperatures up to 55°C and have successfully been cultivated under controlled fermentation conditions to produce a protein-rich biomass from which a natural blue proteinaceous pigment, C-phycocyanin can be isolated. The C-phycocyanin has potential use as a colour additive and as a dietary supplement. This C-phycocyanin is resistant to acidic pH down to 2.75, in contrast to the one from Spirulina, which is already used as a colouring agent in agri-food applications. To further promote its use for industrial applications, we report, here, the results of a safety evaluation on a G. sulphuraria extract enriched to 33% C-phycocyanin. This was conducted in a 90-day repeated dose toxicity study in rats at doses from 250 to 4000 mg/kg body weight/day, in bacterial reversal mutation test at doses from 312.5 to 5000 µg/plate and in micronucleus assay at doses from 500 to 2000 µg/mL. Overall, our results indicated that the C-phycocyanin extract from G. sulphuraria did not exert any noteworthy adverse effect of toxicological significance in any of the system used for its safety evaluation, even if some minor changes were observed. According to the 90-day repeated dose toxicity study, no observed adverse effect level of 4000 mg/kg/day could be estimated. In conclusion, this study supports the safety of soluble fraction enriched with C-phycocyanin from G. sulphuraria for its use as food ingredient or supplement.

Residue analysis of gibberellic acid isomer (iso-GA3) in brewing process and its toxicity evaluation in mice

Gibberellic acid (GA3) is an efficient plant growth regulator, which could speed up barley germination in the brewing industry. However, the residue of GA3 in malt gets denatured into an isomer, termed iso-GA3. In this study, the concentration of iso-GA3 and the conversion rate of GA3 to iso-GA3 during the brewing process was studied by high performance liquid chromatography and the potential toxicity of iso-GA3 was evaluated in ICR mice. The concentration of iso-GA3 increased in the saccharification and wort boiling processes while its concentration was stable during fermentation. The maximum conversion rates of GA3 to iso-GA3 in Canadian malt, Australian malt SCO and Australian malt FAQ were 88%, 87% and 87%, respectively. In the acute oral toxicity study, the median lethal dose (LD50) of iso-GA3 was 2.82 g/kg body weight (BW). In the 28-day repeated dose toxicity study, the iso-GA3 could cause weight loss in mice. And the mice of high-dose group showed a slight decrease in food consumption. Moreover, inflammation and cell necrosis were found in kidney and liver tissue, which were alleviated during the recovery phase. These results establish a practical reference for food safety in products, in which GA3 is added as a food additive.

Safety assessment of EPA+DHA canola oil by fatty acid profile comparison to various edible oils and fat-containing foods and a 28-day repeated dose toxicity study in rats

The omega-3 long-chain polyunsaturated fatty acids (LC-PUFAs) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are recognized for their health-promoting qualities. Marine fish and fish oil currently provide the main sources of EPA and DHA for human consumption. An alternative plant-based source of EPA and DHA is provided by EPA + DHA canola event LBFLFK (LBFLFK). A comparative analysis and a 28-day toxicity study assessed the safety of LBFLFK refined, bleached, and deodorized (RBD) oil. Thirty-one different commercially-obtained fat and oil samples were tested, and principal component analysis showed that the overall fatty acid profile of LBFLFK RBD oil was most similar to Mortierella alpina oil and salmon flesh. Samples with the fewest differences in the presence or absence of individual fatty acids compared to LBFLFK RBD oil were menhaden oil and some other fish oils. In a 28-day toxicity study, LBFLFK RBD oil was administered by oral gavage to male and female Wistar rats. No signs of toxicity were evident and no adverse effects were noted in clinical observations, clinical pathology, or histopathology. Overall, these studies support the safety of LBFLFK RBD oil as a source of EPA and DHA for human consumption.

Repeated injection of KMRC011, a medical countermeasure for radiation, can cause adverse health effects in cynomolgus monkeys.

High-dose radiation-induced tissue damage is a major limiting factor in the medical application of nuclear technology. Herein, we tested 28-day repeated-dose toxicity of KMRC011, an agonist of toll-like receptor (TLR) 5, which is being developed as a medical countermeasure for radiation, using cynomolgus monkeys. KMRC011 (0.01, 0.02 or 0.04mg/kg/day) was intramuscularly injected once daily for 4weeks, and each two monkeys in both control and 0.04mg/kg/day group were observed for an additional 2-week recovery period. There were no dose-related toxicological changes in mortality, clinical observations, body weight, food consumption, ophthalmological findings, electrocardiographs, coagulation, serum chemistry, organ weights, or urinalysis and urine chemistry. Although treatment-related changes, such as increased white blood cells, increased absolute and relative neutrophils, decreased relative lymphocytes and inflammatory lesions, were noted in the maximum dose group, these findings were not observed after the 2-week recovery period. Further, we considered that the kidneys and heart may be target organs of TLR5 agonists, as well as the spleen, and that autophagic signals can be triggered in tissue damage and the repair process. Importantly, accumulation of p62 protein, an indicator of autophagy, and a decrease of caveolin-1 protein, a regulator of TLR5 protein half-life, were found in both tissues from the highest dose group. Therefore, we conclude that the no-observed-adverse-effect level for KMRC011 may be greater than 0.04mg/kg/day in male and female monkeys. Additionally, we propose that further studies are needed to identify the molecular signals, which are related to KMRC011-induced adverse effects.

Acute and 28-day repeated dose toxicity evaluations of 2-hydroxybenzylamine acetate in mice and rats

2-hydroxybenzylamine (2-HOBA), a compound naturally found in buckwheat, has been shown to protect cells and tissues from the damaging effects of oxidative stress. The purpose of this report was to evaluate 2-HOBA in preclinical oral rodent toxicity studies. This report includes the results from three oral toxicity studies in rodents: a preliminary 28-day feeding study in mice, a 14-day acute oral toxicity study in rats, and a 28-day repeated dose oral toxicity study in rats. The preliminary mouse feeding study showed no adverse effects of 2-HOBA at concentrations up to 0.456% by weight in feed, but decreased food intake and weight loss were observed at 1.56% 2-HOBA in the diet, likely due to poor palatability. In the acute dosing study, 2000 mg/kg BW 2-HOBA resulted in mortality in one of the six tested female rats, indicating a median lethal dose of 2500 mg/kg BW. In the 28-day repeated oral dose study, small differences were observed between 2-HOBA treated and control group rats, but none of these differences were determined to be of toxicological significance. Together, these studies support the lack of toxicity of oral administration of 2-HOBA acetate at doses up to 1000 mg/kg BW d−1 in rodents.

Safety assessment of the Cistanche tubulosa health food product Memoregain®: Genotoxicity and 28-day repeated dose toxicity test

The pharmacological effects of Cistanches Herba, known as "Ginseng of the desert", have been extensively studied. In this study, we aimed to assess the genotoxic and oral toxic effects of the Cistanche tubulosa health food product Memoregain® using in vitro and in vivo tests. Ames tests using five strains of Salmonella typhimurium showed no signs of increased reverse mutation upon exposure to Memoregain® up to a concentration of 5 mg/plate. Exposure of Chinese hamster ovary (CHO-K1) cells to Memoregain® did not increase the frequency of chromosomal aberrations in vitro. Moreover, Memoregain® treatment did not affect the proportions of immature to total erythrocytes or the number of micronuclei in the immature erythrocytes of ICR mice. Additionally, after 28-day repeated oral dose toxicity tests (0, 0.15, 0.3, and 0.5g/kg body weight) in rats, no observable adverse effects were found. These toxicological assessments supported the safety of Memoregain® for human consumption.

Initial hazard assessment of 4-benzylphenol, a structural analog of bisphenol F: Genotoxicity tests in vitro and a 28-day repeated-dose toxicity study in rats

4-Benzylphenol (CAS No. 101-53-1), a structural analog of bisphenol F, has estrogenic activity in vitro and in vivo, as is the case with bisphenol F. 4-Benzylphenol is used in plastics and during organic synthesis. Since its safety is largely unknown, we conducted toxicity tests as part of screening risk assessment in an existing chemical safety survey program. Based on results of the Ames test and the chromosomal aberration test using Chinese hamster lung cells (OECD TG 471 and 473), 4-benzylphenol was determined to be non-genotoxic in vitro. In a 28-day repeated-dose toxicity study, Crl:CD (SD) rats were administrated 4-benzylphenol by gavage at 0, 30, 150, or 750 mg/kg/day (OECD TG 407). Consequently, body weight was lower in males at 750 mg/kg/day. In the liver, relative organ weights were increased in both sexes at 750 mg/kg/day, and centrilobular hepatocellular hypertrophy was observed in males at 150 and 750 mg/kg/day. In the forestomach, hyperkeratosis and hyperplasia of squamous cells were observed in males at 150 and 750 mg/kg/day, and in females at 750 mg/kg/day. Based on these results, we identified the NOAEL for 4-benzylphenol as 30 mg/kg/day, with a hazard assessment value (D-value) of 0.05 mg/kg/day corresponding to hazard class 3.