Toxicity of aflatoxin: effects on spermatozoa, oocytes, and in vitro fertilization.

Aflatoxin B1 has been reported to have a deleterious effect on the reproductive capacity of laboratory and domestic animals. We wanted to elucidate the mechanistic aspect of this phenomenon by determining the toxic potential of aflatoxin B1 on the in vitro fertilizing ability of oocytes and epididymal sperm in albino rats. In vitro fertilization medium (IVFM) containing aflatoxin B1 at concentrations of 2.0, 4.0, 8.0, and 16.0 ppb was cultured with oocytes obtained from superovulated healthy fertile female rats and exposed to sperm cells. Epididymal sperm capacitated in IVFM, with or without aflatoxin B1, were exposed to oocytes, and the rates of fertilization in the two experiments were assessed. Aflatoxin B1 significantly reduced the mean number of ova fertilized, even at the lowest concentration. Exposure to aflatoxin caused a significant reduction in the motility of sperm cells. These results demonstrate the adverse effects of aflatoxin B1 on oocytes, spermatozoa, and in vitro fertilization.

Dietary exposure to aflatoxin in human male infertility in Benin City, Nigeria.

OBJECTIVE: To discover the relationship between aflatoxin levels, if any, in serum of infertile men in comparison with random controls from the community. In a parallel experiment, adult male rats were given an aflatoxin-contaminated diet. SUBJECTS: 100 adult males, yielding 50 semen samples, from men attending Infertility Clinics at a university teaching hospital and 50 normal men in the same community. METHODS: The staple foods of the men were assayed for aflatoxin content. The rats were given the aflatoxin-rich diet, and their spermatozoa were examined and their ability to reproduce assessed. RESULTS: A random sampling of semen from 100 adult males comprising 50 samples drawn from infertile men and 50 drawn from normal individuals within the same community revealed the presence of aflatoxins in 20 semen samples from the infertile group (40.0%) and four samples from the fertile group (8.0%). The mean aflatoxin concentrations were 1.660 +/- 0.04 micrograms/mL (infertile men) and 1.041 +/- 0.01 micrograms/mL (fertile men). Infertile men with aflatoxin in their semen showed a higher percentage of spermatozoal abnormality (50.0%) than the fertile men (10.0-15.0%). Dietary exposure of adult male Albino rats to aflatoxin (8.5 micrograms AF1/g of Guinea growers feed for 14 days) produced deleterious effects on the spermatozoa of the affected rats, producing features that resemble those seen in semen of infertile men exposed to aflatoxin.

HIV-1 seroepidemiological profile in age groups and sexes in Benin City, Nigeria.

A pilot survey of 2,206 collected sera were screened for HIV-Ab by ELISA in the age groups 10-60 years. The age group 20-29 years recorded the highest HIV-1 Ab with 9/239 (3.77%). The age group 10-19, 30-39 and 40-49 recorded 3/192 (1.56%); 4/725 (0.55%) and 2/671 (0.3%), respectively. The age group > 50 years had 1/379 (0.26%). The relative rate was 3.29 between females and male with 95% confidence intervals of 1.33-8.14, p = 0.0125 by Fisher's Exact test. Conditioned on marital status, there was no significant difference in HIV-1 Ab distribution for the various age groups using modified Chi-square, G2 = 18.08 at [symbol: see text] = 0.01.

PIP: HIV infection in Nigeria has not yet been manifested in major clinical terms, but the steady rate of increase in some African countries gives cause for concern. The authors assessed the prevalence of HIV-1 infection among 2206 male and female blood donors in Benin City, Nigeria. Benin City is located between HIV-1 and HIV-2 endemic zones, and is one of the five largest cities in Nigeria. Positive ELISA HIV-antibody test results were obtained for 19 donors, a seroprevalence of 0.9%; 11/1807 (0.6%) of the males and 8/399 (3.3%) of the females. The relative rate of infection between females and males was 3.29 with 95% confidence intervals of 1.33-8.14 by Fisher's Exact test. 9/239 (3.77%) of individuals aged 20-29 were HIV-seropositive, the highest prevalence of HIV infection among the age groups. Otherwise, the age groups 10-19 years, 30-39, 40-49, and 50 and over were infected as follows: 3/192 (1.56%), 4/725 (0.55%), 2/671 (0.3%), and 1/179 (0.26%), respectively. The marital status of the population studied made no difference with regard to the distribution of antibody to HIV.

Dietary exposure to aflatoxin in Benin City, Nigeria: a possible public health concern.

A total of 100 samples of various foods comprising of 10 samples each of garri (Manihot utilis Pohl), beans (Phaseolus lunatus), yam flour (Dioscorea rotundata), cassava flour (Manihot esculentum), melon (Citrulus lunatus), onion (Allium cepa), rice (Oryza sativa), plantain (Musa paradisiaca), red pepper (Capsicum annuum L., Solanaceae) and eggs were screened for the presence of aflatoxins. Fifty percent of yam flour; 40% of cassava flour; 30% of garri; 20% of beans and melon and 10% of rice yielded aflatoxin. The implications of this incidence of aflatoxin in common foodstuff found in this community is discussed.

Inhibition of aflatoxin production in groundnut with benzoic acid derivatives and possible toxic effect of their aromatic residues.

Benzoic acid, sodium benzoate, ethyl-rho-aminobenzoate and omicron-hydroxybenzoic acid (salicylic acid) have been found to inhibit mycelial growth and aflatoxin production by A. flavus in groundnut. Benzoic acid (10 mg/g) completely inhibited both mycelial growth and aflatoxin production while sodium benzoate achieved the same result at 24 mg/g of medium. Salicylic acid (20 mg/g) completely inhibited both mycelial growth and aflatoxin in production but ethyl-rho-aminobenzoate inhibited both mycelial growth and aflatoxin production at lower concentrations--3 mg/g of medium for total aflatoxin inhibition and 10 mg/g for complete inhibition of mycelial growth. The results of the possible toxic effects of these aromatic compounds showed that at their effective concentrations they were non-toxic to 1-day-old chicks. Their effects on body and liver weights yielded results similar to the controls. The chicks that were fed aflatoxin-contaminated diets experienced depressed body and liver weights and their livers manifested various pathological changes. Groundnut samples which were supplemented with various concentrations of these aromatic compounds did not give any foul odour. These benzoic acid derivatives could be used, therefore, as fungicides especially against toxigenic A. flavus.

Inhibition of Aspergillus growth and aflatoxin release by derivatives of benzoic acid.

A study was conducted to determine the effects of o-nitrobenzoate, p-aminobenzoate, benzocaine (ethyl aminobenzoate), ethyl benzoate, methyl benzoate, salicylic acid (o-hydroxybenzoate), trans-cinnamic acid (beta-phenylacrylic acid), trans-cinnamaldehyde (3-phenylpropenal), ferulic acid (p-hydroxy-3-methoxycinnamic acid), aspirin (o-acetoxy benzoic acid), and anthranilic acid (o-aminobenzoic acid) upon growth and aflatoxin release in Aspergillus flavus NRRL 3145 and A. parasiticus NRRL 3240. A chemically defined medium was supplemented with various concentrations of these compounds and inoculated with spores, and the developing cultures were incubated for 4, 6, and 8 days at 27 degree C in a mechanical shaker. At the beginning of day 8 of incubation, aflatoxins were extracted from cell-free filtrates, separated by thin-layer chromatography, and quantitated by ultraviolet spectrophotometry. The structure of these aromatic compounds appeared to be critically related to their effects on mycelial growth and aflatoxin release. At concentrations of 2.5 and 5.0 mg per 25 ml of medium, methyl benzoate and ethyl benzoate were the most effective in reducing both mycelial growth and aflatoxin release by A. flavus and A. parasiticus. Inhibition of mycelial growth and aflatoxin release by various concentrations of the above-named aromatic compounds may indicate the possibility of their use as fungicides.

Partial characterization of the mode of action of benzoic acid on aflatoxin biosynthesis.

Aflatoxin production by a toxigenic strain of Aspergillus flavus was greatly reduced by benzoic acid and sodium benzoate in synthetic media. The reduction was accompanied by the appearance of a yellow pigment. Spectral analyses partially characterized this pigment as closely related to an acetyl derivative of a versiconal-type compound. A cell-free extract prepared from A. flavus grown in synthetic media was active in converting this yellow compound into aflatoxin B1 in the presence of reduced nicotinamide adenine dinucleotide phosphate at 25 degrees C (pH 7.4). In the presence of benzoic acid and its salt or autoclaved cell-free extract, conversion of yellow compound to aflatoxin B1 was prevented. These results suggest that the yellow compound is an intermediate in the secondary metabolic cycle involved in aflatoxin B1 production. Benzoic acid, sodium benzoate, or autoclaving the cell-free extract appear to have respectively blocked or denatured an enzymatic step late in the biosynthetic pathway of aflatoxin B1.

Effects of various acids and salts on growth and aflatoxin production by Aspergillus flavus NRRL 3145.

The effects of sodium chloride, sodium acetate, benzoic acid, sodium benzoate, malonic acid, and sodium malonate on growth and aflatoxin production by Aspergillus flavus were investigated in synthetic media. Sodium chloride at concentrations equivalent to or greater than 12 g/100 ml inhibited growth and aflatoxin production, while at 8 g or less/100 ml, growth and aflatoxin production were stimulated. At 2 g or less/100 ml, sodium acetate also stimulated growth and aflatoxin production, but reduction occurred with 4 g or more/100 ml. Malonic acid at 10, 20, 40, and 50 mM reduced growth and aflatoxin production (over 50%) while sodium malonate at similar concentrations but different pH values had the opposite effect. Benzoic acid (pH 3.9) and sodium benzoate (pH 5.0) at 0.4 g/100 ml completely inhibited growth and aflatoxin production. Examination of the effect of initial pH indicated that the extent of inhibitory action of malonic acid and sodium acetate was a function of initial pH. The inhibitory action of benzoic acid and sodium benzoate appeared to be a function of undissociated benzoic acid molecules. Aflatoxin reduction was usually accompanied by an unidentified orange pigment, while aflatoxin stimulation was accompanied by unidentified blue and green fluorescent spots but with lower Rf values that aflatoxins B1, G1, B2, and G2 standards.