Radiosensitizing property of butylated hydroxytoluene in Drosophila sperm

Effect of butylated hydroxytoluene (BHT) on the cryopreservation of common carp (Cyprinus carpio) spermatozoa

The aim of the present study was to test the effects of butylated hydroxytoluene (BHT) on the cryopreservation of common carp spermatozoa. BHT is widely used in the cryopreservation of the spermatozoa of different animal species and successfully sustains the characteristics of spermatozoa during freezing and thawing, but it has not previously been used with fish. After sampling, common carp spermatozoa were diluted with an extender composed of modified Kurokura's extender, 10% DMSO, and 10% egg yolk containing 0.0001, 0.001, 0.01, 0.1, 1, 2.5, 5, or 10mM BHT and subsequently frozen in liquid nitrogen. The post-thaw spermatozoa characteristics (i.e., progressive motility percentage (%), duration of progressive motility (s), fertilization rate (%), and eyed-eggs rate (%)) were evaluated and compared with those of the control group. There were significant increases in the percentage of progressive motility and the duration of progressive motility at the concentrations of 0.1 and 0.001mM BHT (P<0.05). The duration of post-thawed spermatozoa progressive motility at 0.001mM BHT was significantly greater than that of the other groups (39.6±0.4s, P<0.05), and the fertilization rates and eyed-eggs rates were also higher following the 0.1 and 1mM BHT treatments. BHT at concentrations of more than 1mM caused sperm immobility during the preparatory stages of the sperm freezing. We concluded that 0.001-0.1mM BHT can be beneficial for the cryopreservation of common spermatozoa.

Safety assessment of butylated hydroxyanisole and butylated hydroxytoluene as antioxidant food additives

Butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) are widely used antioxidant food additives. They have been extensively studied for potential toxicities. This review details experimental studies of genotoxicity and carcinogenicity which bear on cancer hazard assessment of exposure to humans. We conclude that BHA and BHT pose no cancer hazard and, to the contrary, may be anticarcinogenic at current levels of food additive use.

Review of the mutagenicity/genotoxicity of butylated hydroxytoluene

Butylated hydroxytoluene (BHT) is an effective, widely used, low cost antioxidant. A host of studies examining the potential of BHT to cause point mutations have been published. They include in vitro studies on various bacterial species and strains and on various types of mammalian cell lines as well as in vivo studies on Drosophila melanogaster, silk worms and also the mouse specific locus test (involving long-term exposure). Together these studies convincingly show the absence of a potential for BHT to cause point mutations. A great number of studies on many cell types and species have also been carried out to examine the potential of BHT to cause chromosome aberrations. In vitro studies have been published using plant cells and the WI-38, CHL, CHO, and V79 mammalian cell lines. In vivo studies have been carried out on somatic and/or germ cells of Drosophila melanogaster, rats and mice. Nearly all studies, especially those using validated test systems, indicate that BHT lacks clastogenic potential. In vitro studies on bacterial, yeast and various mammalian cell lines including DON, CHO, CHL cells and primary hepatocytes demonstrate the absence of interactions with or damage to DNA. Taking all the existing data into account, the weight of evidence suggests that BHT does not represent a relevant mutagenic/genotoxic risk to man.

Synthetic antioxidants: biochemical actions and interference with radiation, toxic compounds, chemical mutagens and chemical carcinogens

Biological actions of 4 commonly used synthetic antioxidants--butylated hydroxyanisole, butylated hydroxytoluene, ethoxyquin and propyl gallate--on the molecular, cellular and organ level are complied. Such actions may be divided into modulation of growth, macromolecule synthesis and differentiation, modulation of immune response, interference with oxygen activation and miscellaneous. Moreover, an overview of beneficial and adverse interactions of these antioxidants with exogenous noxae is given. Beneficial interactions include radioprotection, protection against acute toxicity of chemicals, antimutagenic activity and antitumorigenic action. Possible mechanisms of the antitumorigenic action of antioxidants are discussed. This discussion is centered around antioxidant properties which may contribute to a modulation of initiation-related events, especially their ability to interfere with carcinogen metabolism. The beneficial interactions of antioxidants with physical and chemical noxae are contrasted to those leading to unfavorable effects. These include radiosensitization, increased toxicity of other chemicals, increased mutagen activity and increased tumor yield from chemical carcinogens. At present, the latter one can most adequately be characterized as tumor promotion at least in the case of butylated hydroxytoluene. It is concluded that current information is insufficient to promote expectations as to the use of antioxidants in the prevention of human cancer.

Strain-differences and inducibility of microsomal oxidative enzymes in Drosophila melanogaster flies

Some basic characteristics of the enzyme system involved in the oxidative metabolism of xenobiotic compounds were investigated in Drosophila melanogaster flies. Attention was focussed on (1) the normal levels of these enzymes and their activities in whole flies, in different parts of the fly's body and in different sexes, (2) the changes in levels and activities of the enzymes elicited by pretreatment of the flies with known enzyme inducers and (3) differences between strains. Four commonly used wild-type (WT) strains, three insecticide resistant strains (IR) and one white-eyed mutant strain were employed. Except in those experiments on sex differences and in spatial distribution in the fly's body of the enzymatic activities, microsomes were isolated from whole-body homogenates of mixtures of female and male flies. Microsomal cytochrome P-450, benzo[a]pyrene (BP) hydroxylation, p-nitroanisole (pNA) demethylation and aminopyrine (AP) demethylation were measured in control flies and in flies pretreated with Aroclor 1254 (AC), phenobarbital (PB) or butylated hydroxytoluene (BHT). In flies of the WT strain Berlin-K, there were no significant differences in BP hydroxylation activity and its inducibility between the two sexes. In males, inducibility of BP hydroxylation activity was similar in the head, thorax and abdomen, but significantly lower in testis. Considerable differences in some enzyme activities were found between the strains. pNA demethylation and AP demethylation were substantially higher in all IR strains, while no correlation could be found between their increased insecticide resistance and BP hydroxylating capacity or cytochrome P-450 content of the microsomes. Response to enzyme inducing compounds was found to be strain-dependent. PB proved to be a more efficient inducer of BP hydroxylation than AC, which does induce pNA demethylation. BHT has inducing properties that are intermediate between PB and AC. IR strain Hikone-R turned out to be an exception, possessing very low BP hydroxylating capacity and a low degree of inducibility of mixed-function oxidase activities. Differential temperature dependence was found for BP hydroxylation as compared with pNA demethylation. While BP hydroxylation was doubled when raising the temperature from 25 degrees C to 35 degrees C, pNA demethylation was reduced by 50%.

The sex-linked recessive lethal test for mutagenesis in Drosophila melanogaster. A report of the U.S. Environmental Protection Agency Gene-Tox Program

The test for sex-linked recessive lethals (SLRL) in Drosophila melanogaster has been used to detect induced mutations since 1927. The advantage of the test for both screening and hazard evaluation is its objectivity in testing for transmissible mutations in the germ cells of a eukaryote. Statistical criteria for both positive and negative mutagenicity at the highest concentration tested under a particular exposure condition were developed by the Work Group, and a recommended protocol for future testing was agreed upon. For 421 compounds there were sufficient data available in the literature for analysis; 198 compounds were found to be positive and 46 negative at the highest concentration tested. Most experiments had been done for objectives of pure research rather than for deliberately screening for mutagenicity, although many of the 421 chemicals were selected for testing because of suspected mutagenicity. Therefore, the statement of 198 positive and 46 negative should not be taken as an example of the proportion of mutagens in the environment. In three sets of experiments with D. melanogaster that were done specifically for screening, one involving 40 compounds for the Environmental Protection Agency (EPA), the others involving 13 for the Food and Drug Administration (FDA), only 6 mutagens were discovered. After completion of the classification of compounds according to their response in the SLRL test, the compounds were classified as to their carcinogenic response according to the list of Griesemer and Cueto (1980). There were 62 compounds that could be classified as positive or negative for both carcinogenesis and mutagenesis. Of the 62 compounds, there was agreement between the carcinogenesis and mutagenesis classification in 56 (50 positive and 6 negative), or 90% would have been correctly classified as to carcinogenesis from only the SLRL test. Because of inadequate sample size, 177 compounds could not be classified as positive or negative according to the statistical criteria established by the Work Group. This large number of inadequately tested compounds reflects the fact that many of the experiments were not done for screening. Further work is needed on the compounds with inadequate sample size.(ABSTRACT TRUNCATED AT 400 WORDS)

Combined mutagenic action of chemicals and radiation in diploid yeast

The interaction between the mutagenic action of chemicals and radiation was studied by using a diploid yeast strain Saccharomyces cerevisiae BZ 34 with mitotic gene conversion as the end-point. The cells were treated with EMS, MMS or 4-NQO alone or in combination with gamma-radiation. The 2 alkylating agents EMS and MMS produced an additive mutagenic response, whereas 4-NQO exhibited an antagonistic effect in the combined treatment with gamma-radiation.

Modification of the mutagenic activity of propane sultone by some phenolic antioxidants

The effects of three phenolic antioxidants, butylated hydroxyanisole, butylated hydroxytoluene and propyl gallate on the mutagenic activity of propane sultone were studied using barley as the test system. The antioxidants produced seedling injury marginally but did not produce any chromosomal aberrations. When administered either prior to propane sultone treatment or in a mixture with it, the seedling injury, chromosomal aberrations, mutations per 100 M1 spikes as well as M2 chlorophyll mutation frequency, were enhanced. On the other hand, however, posttreatments reduced M1 spike sterility, mutations per 100 M1 spikes and M2 chlorophyll mutation frequency. The spectrum of chlorophyll mutations was also broadened in the presence of these antioxidants.

Cytogenetic activity of some common antioxidants and their interaction with x-rays

Experiments were designed to investigate the cytogenetic activity of some commonly used phenolic antioxidants, namely BHA, BHT, BMP and PG, all used widely to preserve and stablize food products rich in fats and oils. Barley and onion were used as test systems. The treatments reduced seed germination and induced a significant amount of seedling injury. Only PMP treatments produced a moderate amount of chromosomal aberrations while others failed to do so. Being strong antioxidants it was expected that these compounds would reduce the cytogenetic damage caused by the radiations. Contrary to expectations, however, a significant increase was observed in the radiation damage measured as seed and seedling lethality and chromosomal aberrations. Chemical post-treatments also increased the radiation damage. The damage was, however, reduced with ATP post-irradiation treatment.