Golden Yellow Continuous

Endpoint summary

Additional information

Toxicokinetic parameters such as uptake, distribution, metabolism and excretion form the essential toxicological profile of a substance. An approximate indication of the toxicokinetic pattern can be gained from the physico-chemical properties taking into account the molecular weight, the number of atoms (hydrogen bond donors and acceptors), the solubility in solvents, log K_OW, etc. and the results of basic toxicity testing of the test article. The assessment of the toxicokinetic properties of Golden Yellow Continuous given below is based on the results obtained for, the following toxicological endpoints:

 

·        Acute oral toxicity in rats

·        Acute dermal toxicity in rats

·        In vivo skin irritation in rabbits

·        In vivo eye irritation in rabbits

·        Skin sensitization (Local lymphnode assay in mice)

·        Bacterial reverse mutation test

·       In vitro mammalian cell gene mutation test (HPRT-assay)

·        In vivo micronucleus test in rats

·        Subacute (28-day) oral toxicity in rats

Allstudieswere carried out according to the principles of Good Laboratory Practice and met the requirements of the OECD and EU-Guideline for the Testing of Chemicals.

Physico-chemical properties

Name:                                    Golden Yellow Continuous

CAS number:                         1184176-83-7

CAS name:                              Butyric acid, 4-[3-cyano-6-hydroxy-5-[2-(4-methoxy-2-nitrophenyl)diazenyl]-4-methyl-2-oxo-2H-pyridin-1-yl]-, 2-oxo-2-phenylethyl ester

Physical state:                         solid, orange powder

Empirical formula:               C₂₆H₂₃N₅O₈

Molecular weight:                 533.5g/mol                             (>500 daltons = bad absorption)

Water solubility:                    <22 µg/L                                 (= insoluble in water)

Partition coefficient:             log Kow = 3.8                        (<-0.4 or >5.6 = bad absorption)

Surface tension:                     NA                                         (>60 = no activity)

Vapor pressure:                     3.6E-6 Pa                               (= not volatile)

Atom count (natoms):        39                                            (>70 = bad bioavailability)

H-bond acceptor (nON):   13                                            (>10 = bad bioavailability)

H-bond donor (nOHNH):        1           (>5 = bad bioavailability)

Toxicological Profile

After single oral administration of Golden Yellow Continuous at a dose level of 2000 mg/kg body weight to female rats neither deaths nor significant adverse symptoms occurred. Similarly, single dermal application of 2000 mg/kg body weight onto male and female rats produced no deaths or symptoms of systemic toxicity. Test item related red staining of the treated area was observed up to and including Day 8. The median lethal dose (LD₅₀) of Golden Yellow Continuous after oral and dermal administration to rats is greater than 2000 mg/kg body weight.

Testing for skin irritating properties of Golden Yellow Continuous in rabbits led to a minimal erythema (score 1) up to 48 hours after test item administration.

The administration of Golden Yellow Continuous into the conjunctival sac of rabbit eyes did not result in significant irritation of the conjunctiva. Based on the system of evaluation defined by the EEC, the following group mean scores after 24, 48 and 72 hours were calculated: conjunctiva redness: 0.77, chemosis: 0.0, discharge: 0.0; cornea opacity: 0.0, iris: 0.0. Consequently, Golden Yellow Continuous is not irritating to skin or eyes according to the classification criteria of Directive 2001/59/EC or Regulation (EC) No 1272/2008.

Testing for sensitizing properties of Golden Yellow Continuous was performed in the Local Lymphnode Assay (LLNA) in female mice. Dose levels tested were 2.5%, 5%, and 10% in DMSO. No evidence of skin sensitizing properties was found.

To assess the toxicity of Golden Yellow Continuous after repeated administration, male and female rats received the test substance at dose levels of 62.5, 250, or 1000 mg/kg body weight per day for a period of 28 days by oral gavage. 14-day recovery groups (controls and high dose animals) were included in the study. Golden Yellow Continuous caused neither test item related mortality, nor systemic adverse effects following administration by oral gavage, daily for at least 28 days, at up to and including 1000 mg/kg bw/day in CRL:(WI)BR rats. Red discoloration of the faeces was noted at all the dose levels tested from Day 1 (250 and 1000 mg/kg bw/day dose level, males and females) or Day 3 onwards (62.5 mg/kg bw/day dose level, males and females) and is an expected staining effect of the test item. The discoloration persisted in the 1000 mg/kg bw/day recovery animals for 2 days after the last dose administration; all the recovery animals showed afterwards no clinical changes for the next 12 days, until completion of the 14-day recovery period. In addition, red urine was noted during the treatment period at 250 and 1000 mg/kg bw/day after Day 1 and up to and/or including Day 28. These changes were ascribed to elimination of Golden Yellow Continuous or its metabolites through faeces and/or urine (cage side observations) and an expected staining effect. In the absence of any clinical pathology alterations or pathology findings, they were not considered to be adverse effects. The behaviour and the general condition of the test animals were normal during the study. There was no treatment-related effect on motor activity or in the functional observation battery tests across groups of treated male or female animals and no findings indicative of neurotoxicity were observed. Evaluation of the vaginal smears prior to necropsy showed the expected distribution of the oestrus cycle phases within the normal population of female Wistar rats. There were no toxicologically significant changes in body weight, body weight gain or animal food consumption between the control and test item treated groups. Minor variations, on occasion attaining statistical significance, were noted in the clinical pathology parameters (haematology, coagulation, or clinical chemistry) in both main and recovery animals. However, no dose- or gender-response was observed, and/or the results were within the historical range. These changes were neither considered toxicologically significant, nor indicated a Golden Yellow Continuous-related etiology. There were no macroscopic or microscopic findings, or changes in the absolute or relative organ weights that could be ascribed to Golden Yellow Continuous-administration.

Under the conditions of this study, the no observed adverse effect level (NOAEL) for Golden Yellow Continuous is considered to be 1000 mg/kg bw/day.

Golden Yellow Continuous was tested for bacterial mutagenicity. The experiments were carried out using histidine-requiring auxotroph strains ofSalmonella typhimurium(TA98, TA100, TA1535 and TA1537), and the tryptophan-requiring auxotroph strain ofEscherichia coli(WP2 uvrA) in the presence and absence of a metabolic activation system, which is a cofactor-supplemented post-mitochondrial S9 fraction prepared from rat liver. Biologically relevant increases in the number of revertant colonies compared to the solvent control plates were observed in all Salmonella strains with and without metabolic activation. No mutagenic activity of the test item was observed inEscherichia colitester strain. Usually, stronger effects of the test item were observed in the experiments with metabolic activation system. Furthermore, higher mutation factors were observed in the Salmonella typhimurium tester strains susceptible to frameshift mutations (TA98 and TA1537).

The potential of Golden Yellow Continuous to induce gene mutations in mammalian cells was tested at the HPRT locus in Chinese hamster ovary (CHO KI) cells in vitro using concentrations up to 1000 µg/mL. The test substance proved to be non-mutagenic in this test system in the presence and in the absence of a metabolic activation system (S9-mix).

Golden Yellow Continuous has been assessed for its clastogenic and aneugenic potential in an in vivo Micronucleus Assay in the rat. This assessment was included in the 28-day repeat dose study. No induction of micronuclei in bone marrow erythrocytes was observed, thus, there was no evidence of any genotoxic activity of the test item.

Evaluation and Assessment

Based on all available data, Golden Yellow Continuous does not exhibit a conspicuous toxicokinetic behavior. The data of the acute dermal toxicity, dermal irritation test and skin sensitization testing indicate low dermal permeability, owing to the fact that neither systemic nor irritating or sensitizing effects were observed. This is in accordance with the extremely low solubility of the test substance in water and with the molecular weight and number of H-bond acceptors, giving evidence of a poor systemic bioavailability.

In the subacute oral toxicity study, Golden Yellow Continuous was dissolved in an organic solvent (PEG400); hence, the low water solubility should not play a major role for the bioavailability in this study. According to its log Kow, atom count and H-bond donors, Golden Yellow Continuous should be absorbed from the gastrointestinal tract to some extent, whereas the molecular weight and number of H-bond acceptors indicate a low absorption of the test substance. This assumption is confirmed by the red urine staining, which was a good indication of the bioelimination of absorbed Golden Yellow Continuous. According to the molecular weight, excretion of Golden Yellow Continuous is most likely predominantly eliminated via intestine, as substances with a molecular weight above 300 g/mol are preferentially excreted via the feces in rats. However, the test results showed that the test compound is at least partly eliminated via kidneys/urine, too. The fact that elimination of the test item via urine ceased with the last day of treatment, and excretion via feces stopped 2 days after the last treatment, is a good indicator that the test item has no bioaccumulative properties. This is confirmed by the results of the bioaccumulation modeling, excluding a significant bioaccumulation potential of Golden Yellow Continuous. Additionally, Golden Yellow Continuous was also not genotoxic in a mammalian in-vitro cell mutagenicity test and an in-vivo MNT test. Therefore, a metabolisation towards genotoxic structures by mammalian species can most probably be excluded.

Summary

The results of basic toxicity testing give no reason to anticipate unusual characteristics with regards to the toxicokinetics of Golden Yellow Continuous. The data indicate that there is little or no dermal absorption. No signs of a significant systemic toxicity associated with absorption potential have been observed. Bioaccumulation of Golden Yellow Continuous can most probably be excluded due to the available data. Based on the results of genotoxicity assays, a metabolisation towards genotoxic metabolites can also be excluded for mammalian species.

On the basis of the results, it is anticipated that the substance does not undergo significant metabolic activity; rather it is metabolized for excretion with little subsequent toxicity. The substance is therefore not considered to be of concern for ADME related effects.