Mutagenicity studies on thymomodulin

Thymomodulin (Leucotrofina), an orally administrable thymic derivative endowed with interesting immunomodulating and myelomodulating properties, was tested for mutagenicity by means of the following in vitro and in vivo tests: mutagenesis on S. typhimurium with and without metabolic activation system (S-9), gene conversion on S. cerevisiae D 7 with and without metabolic activation, urinary assay in the mouse with and without metabolic activation, urinary assay in the mouse with S. cerevisiae D 7, host mediated assay in the mouse with S. cerevisiae and DNA repair test with and without metabolic activation. On the basis of the results obtained thymomodulin proved to be free of mutagenic activity.     

Mutagenicity studies on tiopronin

alpha-Mercaptopropionylglycine (tiopronin, Mucolysin), a drug endowed with an interesting mucolytic activity, was tested for mutagenicity by means of the following in vitro and in vivo tests: mutagenesis on S. typhimurium with and without metabolic activation, genetic mutation on S. pombe P1 with and without metabolic activation, gene conversion on S. cerevisiae D4 with and without metabolic activation, urinary assay in the mouse with S. cerevisiae D4, host mediated assay in the mouse with S. cerevisiae D4 and micronucleus test in the mouse. On the basis of the results obtained tiopronin proved to be free of mutagenic activity.     

Mutagenicity studies

An antiulcer drug, 4-(2-carboxyethyl) phenyl trans 4-aminomethylcyclohexane carboxylate hydrochloride (DV-1006), was studied for mutagenicity using bacterial systems, in vitro and in vivo cytogenetics, and dominant lethal tests.No mutagenicity of DV-1006 was observed either in the rec-assay on Bacillus subtilis or in the Salmonella/microsome test (Ames test). In in vitro cytogenetics, DV-1006 had no effects on the chromosomes of Chinese hamster cells at cytotoxic doses. Rats were treated singly or on 5 consecutive days orally with dose levels of 16, 160, or 1600 mg DV-1006/kg for detecting cytogenetic effects in vivo. As a result, no increase of the incidence of chromosomal aberrations in bone marrow cells was observed in any group of DV-1006. A single or 5 daily oral administration of DV-1006 (16 or 1600 mg/kg) to male mice and subsequent mating for 8 weeks produced no dominant lethal mutational effects. These results show that DV-1006 has no mutagenic potential.     

Mutagenicity studies of miporamicin

Mutagenic activity of miporamicin (MPM), a new macrolide antibiotic for animal use, was examined using the reversion test with bacteria, the chromosomal aberration test with mammalian cells in culture and the micronucleus test with rodents. In the reversion test, MPM exhibited severe growth inhibition effect on the test bacteria but caused no increase of revertant colonies over the baseline levels, alone or in combination with S 9 mixture. In the chromosome aberration test, MPM induced a medium grade increase of chromosome aberrations at high concentrations, but induced no increase of polyploid cells over the control level. In the micronucleus test, MPM had no effect on induction of micronucleated polychromatic erythrocyte even at the 1/2 LD50 dose. From these results, we concluded that MPM has no effect on the induction of point mutations but has a weak clastogenicity which is detectable only by in vitro tests.     

Mutagenicity studies of FAVOR PAC

A series of in vitro and in vivo assays have been conducted using FAVOR PAC (CAS Registry No. 9003-04-7), a cross-linked sodium polyacrylate polymer, to test its ability to induce mutations. FAVOR PAC is a member of the FAVOR family of superabsorbent polymers (SAPs) developed by Stockhausen GmbH & Co KG (Krefeld, Germany). These SAPs are known for their ability to retain large volumes of fluid, even against pressure. The genotoxic potential of FAVOR PAC and its extracts was examined in the following five standard mutagenicity assays: the Salmonella typhimurium and Escherichia coli reverse mutation assay, the mouse lymphoma fluctuation assay, the mouse lymphoma forward mutation assay, the in vivo mouse micronucleus assay, and an in vitro rat DNA synthesis assay. Based on the results of these assays, it was concluded that FAVOR PAC was clearly not genotoxic under any of the conditions of the mutagenicity assays performed.     

Mutagenicity studies of kojic acid.

Kojic acid, a fungal metabolite produced by some species of Aspergillus and Penicillium, was found to induce sister chromatid exchanges and chromosomal aberrations in Chinese hamster ovary cells in the presence or absence of the rat liver S9 mix. Furthermore, this compound was demonstrated to induce mutations in Salmonella typhimurium strains TA98 and TA100 using both plate-incorporation and preincubation methods.     

Mutagenicity studies on denzimol, a new anticonvulsant drug

N-[beta-[4-(beta-Phenylethyl)phenyl]-beta-hydroxyethyl] imidazole hydrochloride (denzimol, Rec 15-1533), a new anticonvulsant drug, was tested using the Ames procedures with and without metabolic activation, on five strains of Salmonella tythimurium and using the host mediated assay with Schizosaccharomyces pombe as microorganism test. In both tests the drug did not show any mutagenic activity when compared with mutagenic standards.     

Blood prolactin-lowering activity of dihydroergocristine

The prolactin lowering activity of dihydroergocristine, a dihydrogenated ergopeptine derivative, was evaluated in male rats. The drug caused a significant decrease of prolactin levels both in the normoprolactinemic animals and in reserpine-induced hyperprolactinaemia at 5 mg/kg p.o. while 0.2 and 1 mg/kg p.o. were ineffective. In a second experiment the prolactin lowering activity of dihydroergocristine (0.2; 1.5 mg/kg), in reserpine-induced hyperprolactinaemia was compared with bromocryptine (0.1; 0.5; 2.5 mg/kg) administered intraperitoneally. Both dihydroergocristine and bromocryptine caused a significant decrease of prolactin plasma concentrations at all dose levels. Moreover the prolactin lowering effect was independent of the dose administered. Our data suggest prolactin lowering activity of oral or i.p. dihydroergocristine both on normal plasma concentrations and on the experimentally-induced hypersecretion of the hormone.     

Mutagenicity and toxicity studies of p-phenylenediamine and its derivatives

The mutagenicity of p-phenylenediamine and its derivatives was tested using Ames Salmonella strains TA98 and TA100. p-Phenylenediamine was weakly mutagenic to TA98 with metabolic activation. 2-Nitro-p-phenylenediamine was directly mutagenic to both strains, while 2-methyl-p-phenylenediamine required S9 mix. All the test compounds induced a dose-related increase in chromosomal aberrations m Chinese hamster ovary (CHO) cells in the absence of the S9 mix. The mutagenicity and toxicity of these compounds did not correlate with their oxidation potentials, or any other tested physicochemical properties including the energy difference between the lowest unoccupied and the highest occupied molecular orbital, ionization potential, and dipole moment.     

Mutagenicity and toxicity studies with high pressure nitrous oxide

The mutagenic and toxic potential of nitrous oxide were assessed in vitro by microbial assay using two histidine dependent strains of Salmonella typhimurium, TA98 and TA 100. Bacteria on plates and in liquid suspension in the presence or absence of enzymes prepared from rat liver, were exposed in a pressure chamber to partial pressures of nitrous oxide ranging from 0.5 to 6 atmospheres. Nitrous oxide decreased viability of both strains of bacteria at 4 and 6 atmospheres but was not mutagenic at any pressure tested.     

Mutagenicity studies on N-nitrosated products of the Maillard browning reaction: N-nitroso-fructose-amino acids

The N-nitroso derivatives of D-fructose-L-glycine, D-fructose-L-alanine, D-fructose-L-phenylalanine, D-fructose-L-serine, Dfructose-L-aspartic acid and D-fructose-L-tryptophan (a mixture of alpha-N-nitroso-D-fructose-L-tryptophan and 'indolyl-nitrosamine'-D-fructose-L-tryptophan) were tested for mutagenicity in five auxotrophic strains of Salmonella typhimurium with and without metabolic activation (S-9 mix). The alanine, phenylalanine and aspartic acid compounds were not mutagenic. The glycine and serine compounds showed a very low but reproducible increase in the numbers of his+ revertants in strain TA1535 without S-9 mix. The mixture containing both nitrosated D-fructose-L-tryptophan compounds was mutagenic in all five strains, with or without metabolic activation. The alpha-N-nitroso-D-fructose-L-tryptophan component of the mixture, which is nitrosated at the amino group, was isolated and tested without S-9 mix. It was mutagenic in three strains. Unnitrosated D-fructose-L-amino acids, D-fructose, and the individual L-amino acids were non-mutagenic when tested under those conditions for which a positive response had been obtained with the corresponding nitrosated compounds. These results indicate the potential value of developing analytical methods to identify alpha-N-nitroso-D-fructose-L-tryptophan in food or food extracts that are to be screened for mutagenic components.     

Mutagenicity studies on irradiated potatoes and chlorogenic acid; micronucleus test in rats

The micronucleus test was used to study possible mutagenic effects of (1) Irradiated potatoes extracted (a) immediately and (b) after 24-h storage following irradiation; (2) Irradiated and unirradiated chlorogenic acid; and (3) Trenimon. It was observed that irradiated potatoes (groups 1 a, b) and chlorogenic acid (group 2) did not cause mutagenic effects in the bone-marrow cells of rats. The Trenimon group (group 3), which was used as the positive control group, did show significant mutagenic effects.     

Mutagenicity tests of the antithyroid agent thiamazole. Cytogenetic studies on male mice

The mutagenic potential of thiamazole, an antithyroid agent, was investigated by an in vivo cytogenetic test and was compared with those of mitomycin C and vincristine. These drugs were subcutaneously injected into slc-ICR male mice either as a single dose or as multiple doses for 5 successive days. Thiamazole (90 or 180 mg/kg) did not increase the number of micronuclei in bone marrow cells. This drug also did not induce chromosomal aberrations in spermatogonium, spermatocyte, or bone marrow cells. On the other hand, mitomycin C (3.0 mg/kg) increased the appearance of chromosomal aberrations and micronuclei. Vincristine (0.2 mg/kg) induced bone marrow cells with a so called large micronucleus (d greater than or equal to D/4). These results suggest that thiamazole may not have significant effects on the genetic systems of mice.     

Mutagenicity studies on two triphenylmethane dyes, bromophenol blue and tetrabromophenol blue.

Bromophenol blue and tetrabromophenol blue are two triphenylmethane dyes. Triphenylmethane derivatives and their structurally related compounds, such as fluoresceins and xathenes, are widely used as industrial dyes for foods, drugs, cosmetics, textiles, printing inks or laboratory indicators. Since a number of these types of dyes have been reported to be genotoxic, safety concerns on these two dyes of interest have been raised. Consequently, a battery of genetic toxicology assays, including the Ames Salmonella/microsome assay, L5178Y TK+/- mouse lymphoma assay, mouse micronucleus test and mitotic recombination assay with yeast Saccharomyces cerevisiae strain D5, has been performed on each of the two dyes. The results of the evaluations indicate that both bromophenol blue and tetrabromophenol blue were not active and can be considered non-genotoxic for the three genetic endpoints assessed (gene mutation, chromosome aberrations and primary DNA damage). Genetic activities in some structurally related compounds of these dyes have been reported but may be attributed to the presence of mutagenic impurities rather than the compound itself.     

Inhibition of norepinephrine- and 5-hydroxytryptamine-induced contraction on rat aorta by dihydroergocristine

Norepinephrine (NE), 5-hydroxytryptamine (5-HT) and tyramine (Tyr) elicited concentration-related contractile responses on rat aorta strips. The maximum contractile responses evoked by 5-HT and NE were comparable; on the contrary the maximum response induced by Tyr was only 50% that of NE. Pretreatment with reserpine failed to modify the concentration-response curve for both Tyr and 5-HT. 5-HT concentration-response curves antagonized competitively by methysergide, 5-HT may be assumed to act directly on 5-HT receptors. The concentration-response curve for NE was shifted to the right by dihydroergocristine (DHEC) and, at least in a certain dose range, the observed agonist-antagonist interaction fulfilled the condition for competitive antagonism. With higher doses a decrease of the maximum response was obtained. DHEC antagonized 5-HT in a non competitive manner, shifting to the right and flattening the dose-response curves of this agonist. The doses needed to obtain such anti-5-HT effect are not too far from those giving alpha-adrenolytic effects.     

Mutagenicity studies on urine concentrates from female users of dark hair color products.

Urines from women, collected before and after hair dyeing, were evaluated for mutagenic activity in the Ames Salmonella-Microsome Test. Thirty (30) sets of samples were tested as concentrates following removal of histidine on an XAD-2 resin column. None of the samples taken following the use of various Clairol products containing high levels of dyes gave any indication of increased mutagenic activity when compared to samples taken before hair dyeing. These results indicate that the use of hair dyes does not result in exposure of the urinary system to mutagens detectable in a sensitive microbial system, and thus suggest the absence of significant biological effects among users of hair dyes and persons occupationally exposed.     

Mutagenicity studies of benzidine and its analogs: structure-activity relationships.

The Ames SALMONELLA:/microsome assay was employed to test the mutagenicity of benzidine and its analogs using strains TA98 and TA100 in the presence and absence of Aroclor 1254-induced rat S9 mix. 3,3'-Dichlorobenzidine-2HCl and 4,4'-dinitro-2-biphenylamine were directly mutagenic to TA98, while 4,4'-dinitro-2-biphenylamine was directly mutagenic to both TA98 and TA100 in the absence of S9 mix. 2-Aminobiphenyl, 3-aminobiphenyl, and 3,3'-5,5'-tetramethylbenzidine were not mutagenic in either strains in the presence or absence of S9. In the presence of S9 mix, 4-aminobiphenyl, benzidine, 3, 3'-dichlorobenzidine-2HCl, 3,3'-dimethoxybenzidine, 3,3'-4, 4'-tetraaminobiphenyl, o-tolidine, N, N-N', N'-tetramethylbenzidine, and 4,4'-dinitro-2-biphenylamine were mutagenic to TA98; 4-aminobiphenyl, 3,3'-dichlorobenzidine-2HCl, 3, 3'-dimethoxybenzidine, and 4,4'-dinitro-2-biphenylamine were mutagenic to TA100. Physicochemical parameters of these compounds including oxidation potentials, the energy difference between the lowest unoccupied molecular orbital and the highest occupied molecular orbital, ionization potentials, dipole moment, relative partition coefficient, and basicity did not correlate with their bacterial mutagenic activities.