Effect of butylated hydroxytoluene on bilineage differentiation of the human HL-60 myeloblastic leukemia cell

Butylated hydroxytoluene (BHT), which has both antioxidant and membrane active properties, has been reported to affect cellular differentiation. We studied its effect on the bipotent lineage differentiation of the important HL-60 human myeloblastic leukemia cell line using reduction of nitroblue tetrazolium, cell cycle analysis, population growth rate, monoclonal antibodies, and morphology. BHT markedly accelerated retinoic acid-induced myelocytic differentiation and dihydroxyvitamin D3-induced monocytic differentiation in a concentration and time-dependent manner. Butylated hydroxyanisole (BHA) had a comparable effect. Preincubation with the compounds was not necessary to evoke the acceleration Other antioxidants and inhibitors of eicosanoid synthesis were inactive. We conclude that the important food preservatives BHT and BHA accelerate the kinetics of terminal differentiation of human leukemia and that this effect is likely due at least in part to their membrane active properties.     

Effects of naled and dichlorvos on growth and production of Luteoskyrin byPenicillium islandicum

Two organophosphorus insecticides, 1, 2-dibromo ?2, 2-dichloroethyl dimethyl phosphate (naled) and dimethyl 2, 2 -dichlorovinyl phosphate (dichlorvos) were used for investigation of their effects on growth and production of luteoskyrin mycotoxin byPenicillium islandicum in various cultural media at 25°C for 30 days or 60 days. When the concentration of naled and dichlorvos in Czapek solution broth reached 5mg/50mL, growth and production of luteoskyrin by the fungus was completely inhibited. In unpolished rice medium, 15mg/50g of naled was required to retard fungal growth, while the concentration to inhibit the biosynthesis of luteoskyrin was 10mg/50g. On the other hand, if the medium contained dichlorvos at the level of 30mg/50g, the ability to produce luteoskyrin byP islandicum was significantly reduced. In the unhulled rice case, both naled and dichlorvos at the concentration of 15mg/50g were necessary to retard the fungal growth, and 1 mg/50g of each compound exhibits its ability to inhibit the toxin production. Furthermore, it was also found when the cultural medium contained only small amounts of naled and dichlorvos [0.5mg/50g (mL)] the capability to synthesize luteoskyrin by the fungus was drastically reduced. These data strongly suggest that both naled and dichlorvos have similar ability to inhibit luteoskyrin biosynthesis byP islandicum and are also able to retard the fungal growth.     

Butylated hydroxyanisole, butylated hydroxytoluene and tert.-butylhydroquinone are not mutagenic in the Salmonella/microsome assay using new tester strains

The phenolic antioxidants butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and tert.-butylhydroquinone (TBHQ) were reassessed for mutagenic activity using the recently developed Salmonella tester strains TA97, TA102 and TA104, and in addition TA100. None of the phenolic antioxidants showed mutagenic activity, either with or without metabolic activation. At doses of 100 micrograms/plate and higher all 3 phenolic antioxidants exhibited toxic effects. A modification of the assay using the preincubation procedure with strain TA104 did not affect mutation frequencies. Combinations of BHA and BHT, tested to detect possible synergistic effects, did not exert mutagenic activity.     

Effects of the butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) on the arylamines N-acetyltransferase activity in rat white blood cells

Butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) were used to determine any effects on the N-acetyltransferase (NAT) activity in rat whole blood and white blood cells as measured by high performance liquid chromatography assay for the amounts of N-acetyl-2-aminofluorene (AAF) and 2-aminofluorene (AF). Two assay systems were performed, one with cellular cytosols, the other with intact white blood cells. The NAT activity in the whole blood and white blood cell cytosols was suppressed by BHA and BHT in a dose-dependent manner, i.e. the higher the concentrations of BHA and BHT, the higher the inhibition of NAT activity. Time-course experiments showed that NAT activity measured from the intact white blood cells was inhibited by BHA and BHT up to 24 h. The results suggest that BHA and BHT suppressed AF acetylation in rat blood with intact white blood cells.     

Butylated hydroxyanisole specifically inhibits tumor necrosis factor-induced cytotoxicity and growth enhancement.

The effect of commonly used food antioxidants on recombinant tumor necrosis factor alpha (rTNF-alpha)-induced cytotoxicity, growth enhancement and adhesion has been evaluated. Butylated hydroxyanisole (BHA) and 4-hydroxymethyl-2,6-di-t-butylphenol (HBP) were the only two of nine antioxidants that completely inhibited rTNF-alpha-induced cytotoxicity in L929 and WEHI 164 fibrosarcoma cells. Ethoxyquin, propyl gallate and butylated hydroquinone only partially inhibited rTNF-alpha-induced cytotoxicity, while the antioxidants butylated hydroxytoluene (BHT), alpha-tocopherol, ascorbic acid and thiodipropionic acid had minimal effects. The only difference between the molecular structure of the efficient HBP and the non-efficient BHT, is a hydroxymethyl group instead of a hydroxyl group on the phenolic ring. Neither BHA nor BHT inhibited the activation of NF kappa B after 10 or 60 min challenge with rTNF-alpha in L929 cells. BHA also inhibited rTNF-alpha-induced, but not rIL-1 beta-induced growth enhancement in FS-4 fibroblasts. Further, BHA blocked both rTNF-alpha-induced and rIL-1 beta-induced prostaglandin E2 synthesis in FS-4 fibroblasts. BHA inhibited the rTNF-alpha-induced release of arachidonic acid in both FS-4 and L929 cells, suggesting that BHA inhibits cellular phospholipase(s). Neither alpha-tocopherol nor BHA inhibited rTNF-alpha-induced adhesiveness of human endothelial cells. The results indicate that BHA is a specific and potent inhibitor of rTNF-alpha- and rTNF-beta-induced cytotoxicity, as well as of rTNF-alpha-induced growth enhancement.     

Control of Aspergillus growth and aflatoxin production using antioxidants at different conditions of water activity and pH

AIMS: The effect of butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), trihydroxybutyrophenone (THB) and propyl paraben (PP) (at concentrations of 1, 10 and 20 mmol l(-1)) on germination, growth and aflatoxin B1 production by Aspergillus section Flavi was evaluated. METHODS AND RESULTS: Studies on the percentage of spore germination, elongation rate, growth rate and aflatoxin B1 production were carried out in vitro in relation to water activity (aw) at 0.982, 0.937, 0.809 and 0.747 values. At 0.809 and 0.747aw values none of the isolates was able to germinate. Overall, PP and BHA were the antioxidants most effective at inhibiting germination of both species. In the presence of the lowest concentration of BHA and PP (1 mmol l(-1)) the conidial germination percentage ranged from 2 to 19% after 15 h of incubation at the highest water activity tested. BHA and PP at 10-20 mmol l(-1) completely inhibited conidial germination. The antioxidants more efficient in controlling Aspergillus elongation rate were PP, BHT and BHA. All strains were much more sensitive to all antioxidants tested on the percentage of spore germination and growth rate at 0.937aw. The antioxidants PP and BHA completely inhibited aflatoxin B1 production by all strains when added at 1 mmol l(-1). Decreased aflatoxin B1 levels in comparison with the control, were observed with BHT at 1, 10 and 20 mmol(-1) with the strain T20 at 0.982aw. In contrast, stimulation was observed with the antioxidant THB at 10 and 20 mmol l(-1) at 0.937aw with the strains T20 and T23. The effect of BHA and PP at 1 mmol l(-1) on lag phase and growth rate was maintained in the pH range between 6 and 8. At all pH values the inhibitory effect of BHA was higher than PP. No aflatoxin B1 was detected at all pH values. CONCLUSIONS: The data show that BHA and PP could be considered as effective fungitoxicants for A. flavus and A. parasiticus. SIGNIFICANCE AND IMPACT OF THE STUDY: The information obtained show promise for controlling growth and aflatoxin B1 in stored maize. Futher studies should be carried out to examine the potential for antioxidants, such as BHA and PP to effectively control both growth and aflatoxin production.     

Stimulation of Monensin Biosynthesis in Streptomyces Cinnamonensis by Antioxidants Butylated Hydroxyanisole and Butylated Hydroxytoluene

Phenolic antioxidants butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) at concentration 0.55 mM and 2.25 mM, respectively, added to cultures of Streptomyces cinnamonensis C-100-5 caused up to 380% higher production of polyether antibiotic monensin. S. cinnamonensis exhibits high tolerance to BHT, but it is more sensitive towards BHA. 5.5 mM BHA practically stopped growth, while 45 mM BHT still stimulated antibiotic production. Another antioxidants probucol and tocoferol acetate did not exert such positive effects. BHA was predominantly metabolised to 5-hydroxy-BHA. When BHA and BHT were applied simultaneously, the main transformation metabolite was 3,3,5,5-tetra-tert-butyl-stilbene-4,4-quinone accompanied by 1,2-bis(3,5-di-tert-butyl-4-hydroxyphenyl)ethane.     

Cytotoxicity of butylated hydroxyanisole in Vero cells

Butylated hydroxyanisole (BHA) is perhaps the most extensively used synthetic antioxidant in the food and cosmetic industry, although considerable controversy exists in the literature regarding the safety of this compound. Most in vitro studies describing the effects of BHA have been performed in cancer cells, but it is unclear whether normal cells are equally susceptible to BHA exposure. The present study investigate the toxic potential of BHA in mammalian cells, using biochemical and morphological parameters, which reveal interference with structures essential for cell survival, proliferation and/or function. Cell growth inhibition was assessed by using colorimetric assays, whereas cellular alterations after BHA exposure, were evaluated using conventional light and fluorescence microscopy. Low doses of BHA exerted a significant cytotoxic effect, associated with loss of mitochondrial function. As the concentration of BHA was increased, morphological alterations in critical subcellular targets such as lysosomes, mitochondria and actin cytoskeleton, were observed. In parallel, BHA induced an irreversible loss of cell proliferative capacity, preceding apoptosis induction. Thus, the dose-dependent activity of BHA on Vero cells appears to be cytotoxic as well as cytostatic. Our observations, although simplified with respect to the in vivo situations, allowed the assessment of the specific damage at the cellular level, and provide some clue about the effects of BHA in non-tumoral mammalian cells.     

Effect of different antioxidants and free radical scavengers on aflatoxin production

Different antioxidants and free radical scavengers on aflatoxin production are analysed. The different compounds at different concentration were used: buthylated hydroxyanisole (BHA), buthylated hydroxytoluene (BHT), α-tocopherol (vitamin E), ascorbic acid (vitamin C), reduced glutathione, cysteine, cysteamine. The above compounds were tested in culture ofAspergillus parasiticus supplemented with carbon tetrachloride, a potent stimulating agent of aflatoxin biosynthesis. Cysteamine and BHA highly inhibited the aflatoxin production induced by carbon tetrachloride, the inhibition decreased by lowering the concentration. On the contrary, vitamin E, vitamin C, reduced glutathione and cysteine further enhanced the carbon tetrachloride stimulating effect. The addition of the above compounds did not significantly affect the growth of the fungal mycelia.     

Addition of butylated hydroxytoluene (BHT) in tris-based extender improves post-thaw quality and motion dynamics of dog spermatozoa

The aim of this study was to evaluate the interaction of different concentrations of butylated hydroxytoluene (BHT) in a tris-based extender on semen quality parameters in post-thawed dog semen. Twenty-four ejaculates were collected from eight male Beagle dogs using an artificial vagina. Pooled semen was diluted with a tris-based extender supplemented with 0 (control), 0.5, 1.0, 1.5, and 2.0 mM BHT, at a final concentration of 200 × 10⁶ spermatozoa/mL. After thawing, sperm samples were assessed for motility parameters (CASA), membrane integrity (SYBR-14/PI), acrosome integrity (FITC-PNA), mitochondrial activity (JC-1/PI), malondialdehyde (MDA) concentration, and glutathione peroxidase (GPx) activity. The total motility, progressive motility, and average path velocity of the frozen-thawed sperm were significantly higher in the BHT1.5 group than in the control and the other sample groups (P < 0.05). Higher values of straight-line velocity, curvilinear velocity, amplitude of the lateral head displacement, and linearity were observed in the BHT1.0, BHT1.5, and BHT2.0 groups than in the control (P < 0.05). The BHT1.0 and BHT1.5 groups had higher percentages of straightness and acrosome integrity than the other groups (P < 0.05). Beat cross frequency, plasma membrane integrity, and GPx activity of the BHT1.5 and BHT2.0 groups were higher than those of the control (P < 0.05). A lower concentration of MDA was observed in the BHT1.0, BHT1.5, and BHT2.0 groups than in the control (BHT0) (P < 0.05).Our results indicate that 1.5 mM BHT is the optimal concentration for improving the post-thaw quality of canine spermatozoa.     

The peroxidase-dependent activation of butylated hydroxyanisole and butylated hydroxytoluene (BHT) to reactive intermediates. Formation of BHT-quinone methide via a chemical-chemical interaction

The food antioxidants butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) are shown to be metabolized to covalent binding intermediates and various other metabolites by prostaglandin H synthase and horseradish peroxidase. BHA was extensively metabolized by horseradish peroxidase (80% conversion of parent BHA into metabolites) resulting in the formation of three dimeric products. Only two of these dimers were observed in prostaglandin H synthase-catalyzed reactions. In contrast to BHA, BHT proved to be a relatively poor substrate for prostaglandin synthase and horseradish peroxidase, resulting in the formation of a small amount of polar and aqueous metabolites (23% conversion of parent BHT into metabolites). With arachidonic acid as the substrate, prostaglandin H synthase catalyzed the covalent binding of [14C]BHA and [14C]BHT to microsomal protein which was significantly inhibited by indomethacin and glutathione. The covalent binding of BHA and its metabolism to dimeric products were also inhibited by BHT. In contrast, the addition of BHA enhanced the covalent binding of BHT by 400%. Moreover, in the presence of BHA, the formation of the polar and aqueous metabolites of BHT was increased and two additional metabolites, BHT-quinone methide and stilbenequinone, were detected. The increased peroxidase-dependent oxidation of BHT in the presence of BHA is proposed to occur via the direct chemical interaction of BHA phenoxyl radical with BHT or BHT phenoxyl radical. These results suggest a potential role for phenoxyl radicals in the activation of xenobiotic chemicals to toxic metabolites.     

In vitro effect of phenolic antioxidants on germination, growth and aflatoxin B accumulation by peanut Aspergillus section Flavi

AIMS: The effectiveness of the food-grade antioxidants butylated hydroxytoluene (BHT), trihydroxybutyrophenone (THB), propyl paraben (PP) and butylated hydroxyanisole (BHA) at 1, 10 and 20 mmol l(-1) concentrations on germination, growth, and aflatoxin B(1) (AFB(1)) production by Aspergillus section Flavi strains was determined. METHODS AND RESULTS: Assays on the lag phase of germination, germination percentage, germ tube elongation rate, lag phase, growth rate and AFB(1) production by three strains of Aspergillus flavus and three of Aspergillus parasiticus were carried out in vitro on peanut extract meal agar conditioned at different water activities (a(w): 0.982, 0.971, 0.955, 0.937). The antioxidants PP and BHA efficiently inhibited the germination of the two species tested at the doses 10 and 20 mmol(-1). The antioxidants PP and BHA at 1 mmol l(-1) and THB at 20 mmol l(-1) reduced the germ tube elongation rate most effectively, regardless of a(w) levels. An increase in the lag time and a reduction in the growth rate of 100% of the strains was observed, this was due to the action of BHT at the doses 10 and 20 mmol(-1) at 0.982, 0.971 and 0.955 a(w), although these treatments stimulated the AFB(1) accumulation in most of the fungi tested. The more effective antioxidants were PP and BHA, which increased the lag phase, reduced the growth rate and AFB(1) production in all of the strains at the four a(w) assayed. At concentrations 10 and 20 mmol l(-1), these antioxidants totally inhibited fungal development. CONCLUSIONS: The study shows that the antioxidants BHA and PP are effective fungal inhibitors to peanut Aspergillus section Flavi in wide range of water activity. SIGNIFICANCE AND IMPACT OF THE STUDY: The results suggest that phenolic antioxidants, BHA and PP, can be effective fungitoxicants on aflatoxigenic strains in peanut at industrial level.     

Antioxidants and iron chelators inhibit oxygen radical generation in fungal cultures of plant pathogenic fungi

Eutypa dieback and Esca are serious fungal grapevine trunk diseases (GTDs). Eutypa dieback is caused by Eutypa lata (Elata), and is often associated Phaeoacremonium minimum (Pmin), and Phaeomoniella chlamydospora (Pch) which are also important contributors to Esca disease.Understanding the complex pathogenesis mechanisms used by these causative fungi may potentially lead targeted treatments for GTDs in the future. Elata has been reported as a wood decay “soft rot” fungus and understanding of Elata’s pathogenesis chemistries can aid in controlling GTDs. Recent work that suggests that Pmin and Pch may contribute to pathogenesis by stimulating hydroxyl radical generation via secretion of low molecular weight phenolic metabolites. Building on these findings, we tested a hypothesis that antioxidants and chelators, and biocontrol agents that have been reported to secrete antioxidants and low molecular weight chelators, may inhibit the growth and activity of these fungi. Butylated hydroxy anisole (BHA) and butylated hydroxytoluene (BHT) were tested as antioxidant/chelators. BHA was found to be a highly effective control measure for the three pathogenic fungi tested at concentrations >0.5 mM. The biocontrol species Bacillus subtilis and Hypocrea (Trichoderma) atroviride were also tested, with both H. atroviride and B. subtilis effectively inhibiting growth of the three GTD fungi.     

Measurement of synthetic phenolic antioxidants in human tissues by high-performance liquid chromatography with coulometric electrochemical detection

The antioxidants, 2-tert.-butyl-4-methoxyphenol (BHA) and its oxidative peroxidation product 2,2′-dihydroxy-3,3′-di-tert.-butyl-5,5′-dimethoxybiphenyl (di-BHA), 3,5-di-tert.-butyl-4-hydroxytoluene (BHT) and propyl gallate, were measured in plasma and tissue homogenates by HPLC and electrochemical detection, with a sensitivity down to 0.2 (BHA), 0.1 (di-BHA), 0.4 (BHT) and 1 (propyl gallate) ng ml⁻¹ of plasma or tissue homogenate. The data demonstrate that in man, at the current level of exposure to dietary antioxidants, significant amounts of BHA, BHT and propyl gallate are accumulated in the omentum. Furthermore, they provide the first evidence that the peroxidase-catalysed oxidation of BHA is operative in man.     

Positive effect of butylated hydroxytoluene (BHT) on the quality of cryopreserved cat spermatozoa

The semen cryopreservation processes are associated with state of oxidative stress induced by high levels of reactive oxygen species (ROS), causing damage to functional spermatozoa. Whereby, antioxidants have been utilized to scavenge or neutralize the elevated levels of ROS. The aim of at the present study was to evaluate the effect of adding BHT to the freezing extenders on post-thaw characteristics of domestic cat spermatozoa. Semen samples were frozen in Tris-fructose-citric acid-based extender, supplemented with different concentrations of BHT (0.5 mM, 1.0 mM and 2.0 mM) and a control sample without antioxidant. After thawing, sperm samples were assessed for motility by computer‐assisted sperm analysis and viability, acrosome integrity, superoxide anion production and membrane lipid peroxidation status by flow cytometry. In the study, the parameters of sperm motility and acrosome integrity were significantly higher in 2.0 mM BHT compared to sperm frozen in the extender with other concentrations and control (P < 0.05), in addition, this concentration reduced significantly the superoxide anion production and lipid peroxidation of the sperm. The results demonstrated that the supplementation of BHT to the freezing extender could protect the function and cellular structure of domestic cat sperm from cryoinjuries.     

A reappraisal of the proposed metabolic and antioxidant actions of butylated hydroxytoluene (BHT) in the liver

Butylated hydroxytoluene (BHT) was investigated for its metabolic actions in the perfused rat liver. Contrary to what is expected from an uncoupler, BHT up to 500 μM did not stimulate oxygen uptake nor did it inhibit gluconeogenesis from lactate. Transformation of fructose into glucose was also not affected by BHT; only lactate production was slightly increased at the concentration of 100 μM. The uncoupling effect of BHT in isolated mitochondria was confirmed, but only at concentrations above 10 μM; uncoupling at lower concentrations, 10^?9 to 10^?6 M, could not be confirmed. BHT, however, increased reactive oxygen species (ROS) production in isolated mitochondria, starting at the concentration of 10^?8 M. This is the opposite of what can be expected from a compound with proven ex vivo antioxidant action. One cannot exclude the possibility that, in mitochondria, stimulation of ROS production rather than uncoupling could be the most significant effect of BHT.     

Supplementing rabbit diets with butylated hydroxyanisole affects oxidative stress,growth performance,and meat quality

Butylated hydroxyanisole (BHA) is a synthetic antioxidant analogous of vitamin E. It is used as a preservative to prevent free radical-mediated oxidation in high-fat foods, and this study's objective was to investigate the effects of BHA on oxidative stress and apoptosis in addition to delineating its efficacy as a growth-promoting feed additive. 60 weaned male rabbits (V-line) were randomly divided into four equal groups: BHA0.0 (control), BHA50, BHA100, and BHA150, administered basal diets with 0.0, 50, 100, and 150 mg BHA/kg of feed for 60 days. Animals were examined for growth performance, markers of oxidative stress and apoptosis, and meat characteristics. Compared to the control group, rabbits receiving BHA-supplemented diets exhibited increases in BW and average daily gain (P < 0.01), where BHA50 and BHA100 groups showed increased muscle content of methionine aspartic acid, serine, and glutamine (P < 0.05). These two groups also exhibited elevated catalase and superoxide dismutase activities and diminished malondialdehyde levels in the liver. Butylated hydroxyanisole upregulated fatty acid synthase gene (FASN), especially in BHA100 animals. Bcl-2-associated X/B-cell lymphoma-2 (Bax/Bcl-2) ratio significantly increased in animals receiving higher doses of BHA, and the weight of the liver significantly increased following BHA treatment. Supplementing growing rabbits with lower doses of dietary BHA may promote growth performance and meat quality via maintaining the redox balance. Hence, the 50–100 mg/kg may be recommended as a safe and still effective feed additive as well as an oxidative stress attenuator.     

Visible-light promoted degradation of the commercial antioxidants butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT): a kinetic study

Abstract

Visible-light photo-irradiation of the commercial phenolic antioxidants (PhAs) butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT), in the presence of vitamin B₂ (riboflavin, Rf), in methanolic solutions and under aerobic conditions, results in the photo-oxidation of the PhAs. The synthetic dye photosensitiser Rose Bengal was also employed for auxiliary experiments. With concentrations of riboflavin and PhAs of ca. 0.02 mM and < 1 mM, respectively, the excited triplet state of the vitamin (³Rf*) is quenched by BHT in a competitive fashion with dissolved ground state triplet oxygen. From the quenching of ³Rf*, the semireduced form of the pigment is generated through an electron transfer process from BHT, with the subsequent production of superoxide anion radical (O₂^??) by reaction with dissolved molecular oxygen. In parallel, the species singlet molecular oxygen, O₂(¹Δ_g), is also generated. Both reactive oxygen species produce the photodegradation of BHT. In the case of BHA, the lack of any effect exerted by superoxide dismutase drives out a significant participation of a O₂^??-mediated mechanism. BHA mainly interacts with O₂(¹Δ_g) and exhibits a desirable property as an antioxidant – a relatively high capacity for O₂(1Δ_g) de-activation and a low photodegradation efficiency by the oxidative species. Electrochemical determinations support the proposed photodegradative mechanism.     

Visible-light promoted degradation of the commercial antioxidants butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT): a kinetic study

Visible-light photo-irradiation of the commercial phenolic antioxidants (PhAs) butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT), in the presence of vitamin B2 (riboflavin, Rf), in methanolic solutions and under aerobic conditions, results in the photo-oxidation of the PhAs. The synthetic dye photosensitiser Rose Bengal was also employed for auxiliary experiments. With concentrations of riboflavin and PhAs of ca. 0.02 mM and < 1 mM, respectively, the excited triplet state of the vitamin (3Rf*) is quenched by BHT in a competitive fashion with dissolved ground state triplet oxygen. From the quenching of 3Rf*, the semireduced form of the pigment is generated through an electron transfer process from BHT, with the subsequent production of superoxide anion radical (O2*-) by reaction with dissolved molecular oxygen. In parallel, the species singlet molecular oxygen, O2(1delta(g)), is also generated. Both reactive oxygen species produce the photodegradation of BHT. In the case of BHA, the lack of any effect exerted by superoxide dismutase drives out a significant participation of a O2(*-)-mediated mechanism. BHA mainly interacts with O2(1delta(g)) and exhibits a desirable property as an antioxidant--a relatively high capacity for O2(1delta(g)) de-activation and a low photodegradation efficiency by the oxidative species. Electrochemical determinations support the proposed photodegradative mechanism.     

In vitro control of growth and fumonisin production by Fusarium verticillioides and F. proliferatum using antioxidants under different water availability and temperature regimes

AIMS: To examine the effect of butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), trihydroxybutyrophenone and propylparaben (PP) (at concentrations of 1-20 mmol l(-1)) on growth of and fumonisin production by Argentinian strains of Fusarium verticillioides and F. proliferatum. METHODS AND RESULTS: Studies on lag phases prior to growth, relative growth rates and fumonisin concentrations were carried out in vitro in relation to water activity (0.995-0.93 a(w)) and temperature (18 and 25 degrees C) on a maize meal agar. Overall, PP was the antioxidant which was most effective at inhibiting strains of both species. The lag phase prior to growth and growth rates were significantly decreased by PP and BHA at 10 and 20 mmol l(-1), regardless of the temperature or aw level tested. Total fumonisin production was higher at 0.98 a(w) and decreased by about 45-50% at 0.995 and 0.95 a(w). Overall, BHT only inhibited fumonisin production at 0.95 aw at 10 and 20 mmol l(-1), while BHA was effective at most a(w) levels tested at 10 and 20 mmol l(-1). Propylparaben completely inhibited fumonisin production by both F. verticillioides and F. proliferatum at > 1 mmol l(-1), regardless of the temperature or a(w) level. Small interstrain differences in the levels of inhibition by the antioxidants were observed for three F. verticillioides and four F. proliferatum strains at 0.995, 0.98 and 0.95 a(w). Propylparaben and BHA completely inhibited the growth of both species at the concentrations evaluated, regardless of the a(w) level. CONCLUSIONS: Two antioxidants show promise for the control of growth of and fumonisin production by these species over a wide range of environmental conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: Potential exists for using such food-grade preservatives for prevention of mycotoxigenic fungi and their toxins entering the food chain.