S. E. Megalla

Detoxification of aflatoxin B1 by acidogenous yoghurt

Serial concentrations of aflatoxin B1 ranged from 200 to 1000 p.p.b. were assayed for detoxification by acidogenous yoghurt. Thin-layer chromatography analysis revealed a complete transformation of 800 p.p.b. of aflatoxin B1 to a new fluorescing compound corresponding to aflatoxin B2a which is referred as hydroxydihydroaflatoxin B1. Partial conversion was present in yoghurt sample containing 1000 p.p.b. Toxicity test on chickens, confirmed Ciegler findings.

Aflatoxin and aflatoxicosis

A wide range of fungi, amounting to fifty-six species belonging to twenty-two genera, have been recovered from animal feeds and foodstuffs.The most frequent fungi were Aspergillus niger, and A. flavus, followed by Mucor racemosus, Alternaria alternata, Rhizopus stolonifer, Penicillium corylophilum and P. notatum. Three genera were found to be of moderate occurrence, namely, Mucor, Rhizopus and Alternaria. The three following genera were of low occurrence: Cladosporium, Fusarium, and Neurospora.The fluorescence method of detecting aflatoxin-producing strains demonstrated that only one isolate of A. flavus possesses this property. Certain species of Penicillium and Aspergillus produced fluorescent substances (metabolites) similar in color to B and G aflatoxin. These substances were subsequently proved not to be aflatoxin by (TLC) chromatography.The animal and public health significance from such toxins was also discussed.

Fate of aflatoxin B-1 in fermented dairy products

Polyacrylamide gel electropheresis and thin layer chromatography (TLC) were applied to detect the fate of aflatoxin B-1 in milk fermented with an active culture of Streptococcus lactis (ATCC-11454).TLC analysis revealed the formation of two fluorescent metabolites (B2a and R0) in fermented milk.Electropheretic analysis of both casein and whey protein showed fluorescent bands in the region of Kappa-casien and immunoglobulin which are glycoproteins in nature. The transformation of B-1 to the nontoxic metabolite B2a and the less toxic compound aflatoxicol (R0) reflects the preference for fermented dairy products in consumption in order to reduce chances of toxicity.

Mutagenic effects of aflatoxin B-1 and G-1 on the Egyptian cotton leaf-worm, Spodoptera littoralis (Boisd.).

The aim of this study was to test infertility of the Egyptian cotton leaf-worm, Spodoptera littoralis. Three concentrations, 0.8, 1.6 and 2.0 μg/ larva of aflatoxin B-1 and G-1 were applied to the final instar of the larval period. Both B-1 and G-1 induced mutagenic effects on spermatogenesis and morphogenesis which consequently reflected in infertility of Spodoptera littoralis. The phenomenon of mutagenicity was more obvious in larvae treated with G-1 rather than in those treated with B-1. The two analogues were also capable of inducing malformations in sperms. These abnormalities were transmitted to and inherited by the progeny.

Fungal flora of Egyptian baladi bread with special reference to the mutagenic effects of their toxic metabolites.

The fungal flora of wheat flour and baladi bread in upper Egypt were investigated. Most of the isolated fungal species belong to the genus Aspergillus. The presence of non heat resistant fungi of the both flat surfaces of baladi bread, came from contamination after baking and from improper handling at homes. Among the heat resistant fungi, A. fumigatus and A. niger, were recorded to inhabit the spongy crumb although the high temperature of baking process which reached approximately 100 ° C in the center of the bread.The mutagenic effects of the fungal metabolites of the extract of mouldy bread was investigated. Several kinds of aberrations were observed in all stages of mitotic division. The most interesting effect of these fungal metabolites were the induction of tripolar and quadripolar spindle. Multinucleate and polyploid cells were also observed under relatively high concentrations. It was noticed that at either higher concentrations or lower concentrations with long exposure, damaged cells were observed. The hazards involved through the consumption of individuals to such mouldy bread, is accumulation of possible deleterious effects from both long and short term exposure to these toxic metabolites.

Aflatoxin and aflatoxicosis. IV. The effect of dietary aflatoxins on adult fertile male and female rabbits at various reproductive conditions

In this study, adult fertile female and male rabbits were divided into groups of 5. Several experiments were performed at various possible reproductive conditions as follows: one of the female groups received the toxins before mating, and another group of females was treated in the first week after mating, while a third group of females was treated in the fourth week after mating. All these experimental groups as well as control groups of females were mated by untreated fertile males. Moreover, another experiment included a group of treated males used to mate untreated females.Semen was collected from each male rabbit before and after treatment, and evaluated for its gross and microscopical characteristics. Moreover, the electrophoretic pattern of the proteins in the seminal plasma was examined to investigate the protein fraction with which the aflatoxin was conjugated.Animals were weighed twice weekly before and after treatment and all the animals including the litters were kept under observation throughout the study.The results revealed an injurious effect on the reproductive performance in both sexes that received dietary aflatoxins (7.8 ppm aflatoxin B and 4.92 ppm aflatoxin G were received daily for a period of 7 days). It was found that the aflatoxin was secreted in the semen and conjugated with the gamma-globulin fraction of plasma proteins. The results are discussed.

Rapid, economical qualitative method for separation of aflatoxins B-1, B-2 & G-1, G-2 by dry column chromatography

A good resolution of four components of aflatoxins was accomplished by using the dry column chromatography method. The decolorization process of interfering substances, by 0.01 N KOH and defatting the extract with petroleum ether yields a clean residue for DCC separation. It is clear that the dry column chromatography is a very simple and time-saving procedure for separation of aflatoxins. DCC columns are more economical than precoated ‘thick layer’ preparative plates and, in DCC, no large developing tanks need to be used. Hazards associated with the use of large volumes of flammable solvents are greatly reduced.

Binding of aflatoxin B1, G1 and M to plasma albumin

The aflatoxins B1, G1 and their metabolites exist in the systemic blood as protein conjugate. This conjugation is specific to plasma albumin and proceeds enzymatically by liver and kidney cells. The aflatoxin-albumin conjugate is permanent and the conjugation is an irreversible one. This may interpret the acute liver damage of animal ingested a single dose of aflatoxin (3, 4). The existence of bound aflatoxin-albumin in the systematic blood could be considered as one factor of low excretions of aflatoxins and their metabolites in urine (5, 6, 7).

The potential value of silage in detoxifying aflatoxin B1.

Serial concentrations of aflatoxin B1 ranging from 200 to 1500 p.p.b. in 2% lactic acid solution (which is the aimed concentration of lactic acid in fresh silage) were assayed for detoxification. Thin-layer chromatography analysis, revealed a complete transformation of 1 000 p.p.b. of aflatoxin B1 to a new fluorescing compount corresponding to aflatoxin B2a which is referred to as hydroxydihydro-aflatoxin B1 toxicity test on chickens confirmed Cieglers findings (4). The results confirm that the chemical changes taken place in the silo can detoxify aflatoxin B1 to aflatoxin B2a.

Aflatoxin and aflatoxicosis: V. The kinetic behaviour of dietary aflatoxins in colostrum drawn from cows postpartum

This work was conducted in order to study the kinetic behaviour of dietary aflatoxins in the colostrum of a pregnant cow exposed to contaminated feeds for a short period.In this study, two pregnant cows received a single dose of dietary aflatoxins in the form of rice powder contained 31.20 ppm aflatoxin B and 19.68 ppm aflatoxin G during the last stage of pregnancy, at about two weeks before parturition.Samples of colostrum were collected from dams and assayed for the presence of toxic metabolites as well as its conjugations by electrophoretic analysis.The results revealed that the intake of aflatoxins appeared in the colostrum pospartum as AFM1 and also AFB2a which is a non toxic metabolite. Moreover, it was found that the excreted metabolites including AFB2a were conjugated to the immunoglobulin protein fraction of the colostrum.The significance of the obtained results to the newborn calf are discussed.