**3.2 Detoxification**

130 Health Management – Different Approaches and Solutions

Fig. 8. Biotransformation process of aflatoxin B1 (Parker et al., 1998)

The major metabolites of aflatoxin B1 includes B1-8, 9-dihydro-8-9-diol; the aflatoxins –B2a,- P1, M1, -Q1; aflatoxicol, aflatoxicol H1 and aflatoxicol M1 (Essigmann et al., 1982; Smith et al., 2007). However, not all metabolites have been identified in all species. Aflatoxicol is a major aflatoxin B1 in rat plasma (Wong and Hsieh, 1978; Pestka & Bondy 1990). It is reported as having equivalent carcinogenic potency as aflatoxin B1 (Schoenhard et al., 1981; Pasquali et al 2010), and about 70% the mutagenicity (Coulombe et al., 1982Porbst et al., 2007). Since Many methods have been used in an effort to detoxify contaminated feeds. Physical separation of obviously contaminated materials has proven successful in controlling aflatoxin contamination in peanuts. *Aspergillus flavus* and several other fungi emit a bright yellow-green fluorescence under ultraviolet light (Takayuki and Bjeldanes, 1993; Wilson et al., 2002). This telltale signal of fungal contamination has been useful in the physical separation of contaminated peanuts and corn as well as a few other crop samples.

Heat treatment of contaminated crops has also been used to detoxify food or feed material. Generally, under dry conditions the aflatoxins are quite heat stable. Normal roasting conditions can reduce the aflatoxin B1 content in peanuts by 80% after an hour. Heating under conditions similar to the moist conditions used for autoclaving is much more effective in reducing aflatoxin content than dry heating (Park et al., 1988; Pitt & Miscamble, 1995).

Several chemicals such as hydrogen peroxide, ozone, and chlorine have been used to destroy aflatoxins. These substances react readily with aflatoxins in food as well as with many desired substances, including vitamins. A more useful method of chemical detoxification of contaminated feed is treatment with ammonia.

#### **3.2.1 Ammonia detoxification**

Ammonia was first used for the detoxification of aflatoxin-contaminated cottonseed meal, in the USA in the late 1960s (Park et al., 1988). The use of ammonia to detoxify corn meal and cotton meal increases the nutritional value of the feed.

The detoxified feed supports the growth of trout, cows, and other animals without apparent ill effects. An ammoniation process developed in Arizona involves placing a mixture of aqueous ammonia and cottonseed in large plastic bags used for silage (Cocker, 1999; Wu & Munkvold, 2008). The bags are sealed and allowed to stand in the sun for several weeks. The process has been shown to be effective in reducing the levels of aflatoxin in highly contaminated cottonseed (800ppb) to less than the 100 ppb action levels set by the FDA (Pepplinski et al., 1983).

Detoxication process involves numerous oxidising agents, aldehydes,acids and bases (inorganic and organic) that have been reported as potential chemical detoxification agents (Wild and Hall, 2000).

#### **3.2.2 Chemistry of ammoniazation**

The nature of the reaction products produced by the ammoniation of aflatoxin is still poorly defined. Most studies have focused on the reaction products of aflatoxin B1 produced under a variety of conditions including the treatment in vitro, of pure toxin or of pure toxin on an inert carrier. The ammoniazation process of aflatoxin B1 is illustrated in figure 8. Ammoniation, *in* 

Mycotoxins: Quality Management, Prevention, Metabolism, Toxicity and Biomonitoring 133

administration;much less aflatoxin accumulated in the kidney. The ip administration of radiolabelled aflatoxin B1 to rats resulted in the presence of approximately 17% of the label in the liver within 30 minutes. The kidneys and the eviscerated carcass contained about 5 and 27% respectively; traces (< 0.5%) of labelled material were present in the adrenal glands, brain, heart, pancreas, spleen, thymus and testes (Wogan et al, 1967). The radioactivity

The excretion of aflatoxin B1 occurs mainly through biliary pathway and, to a lesser extent,

Studies show that when radiolabelled aflatoxin B1 was feed to rats, the reported plasma halflife for radioactivity was 91.8 hours. Twenty-three days after dosing, 70% of the radioactivity had been excreted; 55% was present in the faeces compared to 15% in the urine

Urinary excretion shows that approximately 15% of radiolabelled aflatoxin B1 was excreted in rats' urine 20-24 hours after ip administration. The major metabolites were the aflatoxin M1 (45% radioactivity) and P1 (<10%), and aflatoxin B1 -N7-guanine (16%). The later is the major degradation product of hepatic B1-DNA adducts (Groopman, 1994).Eighty percent of the excreted B1 -guanine occurred in the urine during the 48-hour period after dosing (Essigmann et al,1982); a dose-dependent correlation between B1 and B1 -guanine has been

Aflatoxin B1 in dairy feed can be metabolised and transferred to cow's milk in the form of aflatoxin M1. The percentage carry-over rate typically lies within the range of 1-5% depending upon, for example, the level of aflatoxin within the feed and the productivity of the cow. Generally, the carry-over rate increases as the feed contamination level decreases and as the productivity increases. However, the carry over rate varies significantly from cow

The aflatoxins have also been reported in human breast milk. In Africa (Sudan, Ghana, Kenya and Nigeria), for example, the aflatoxin M1, B1, B2, G1 and G2 have all been found in breast milk (Maxwell et al 1989). Aflatoxin M1 was the major metabolite, occurring at

The introduction of methods for biomonitoring individual members of the population is a major development which will make a significant contribution towards confirming the perceived linkage between mycotoxin exposure and human diseases. Biomarkers for the

reduces rapidly, only 10% remaining in the liver after 2 hours.

(Coulombe and Sharma, 1985; Herwaarden et al., 2006).

observed in male rats (Bennett et al., 1981; Baerschi et al., 1989).

by the urinary pathway, and by excretion into milk of lactating animals.

**3.4 Excretion** 

**3.4.1 Biliary excretion** 

**3.4.2 Urinary excretion** 

**3.4.3 Excretion through cow milk** 

to cow and on an individual cow basis.

**3.4.4 Excretion through human milk** 

**4. Biomonitoring of mycotoxins** 

**4.1 Biomonitoring of aflatoxins** 

concentrations ranging from 20 to 1800ng/L, in Ghana.

*vitro*, of pure aflatoxin B1 has afforded four compounds of molecular weights (MW) 286, 256, 236 and 206, together with many unidentified compounds of MW less than 200. The compound of MW 286 has been characterized as the decarboxylated derivative (aflatoxin D1) of aflatoxin B1, whereas the compound of MW 206 lacks the cyclopentenone ring of aflatoxin D1. The loss of the methoxy group from aflatoxin D1 affords the compound of MW 256. The reaction product of molecular weight 236 is still to be identified

Fig. 9. Ammoniazation process of aflatoxin B1 (Parker et al., 1998)

#### **3.2.3 Ammoniation and feed toxicity**

The interaction of ammonia with both aflatoxin and nutritional components of feedstuffs has been. The resultant composition of these reaction products will determine the effect of ammoniation on both the nutritional and toxicological properties of treated commodity. These properties in turn, will determine the productivity of animals fed ammoniated feeds, together with the acceptability of animal products (milk, meat and eggs) used as human food.

#### **3.2.4 Toxicity of ammonization reaction products**

The toxicity of the reaction product, aflatoxin D1, has been compared to that of the aflatoxin B1 using a) the Ames test (Salmonella mutagenicity), b) the DNA covalent binding index CBI and c) the chick embryo bioassay as indicators of toxicity. Aflatoxin B1 was reported (Lee et al., 1981; Yunus et al., 2010), as representing a 450-fold decrease in mutagenic potential, a 300-fold decrease, at least, in the DNA CBI (46), and (c ) a 20-fold decrease, in toxicity to check the embryo (Lee et al., 1981; Kisoh et al., 2004). The reaction product MW 206, was over 600 times less mutagenic than aflatoxin B1 (Hawarth et al., 1989; Faisal et al., 2008).

#### **3.3 Distribution**

After absorption from the intestine, aflatoxin B1 rapidly enters the liver through the hepatic portal vein. The toxin is heavily concentrated in the liver after orla, ip and iv administration;much less aflatoxin accumulated in the kidney. The ip administration of radiolabelled aflatoxin B1 to rats resulted in the presence of approximately 17% of the label in the liver within 30 minutes. The kidneys and the eviscerated carcass contained about 5 and 27% respectively; traces (< 0.5%) of labelled material were present in the adrenal glands, brain, heart, pancreas, spleen, thymus and testes (Wogan et al, 1967). The radioactivity reduces rapidly, only 10% remaining in the liver after 2 hours.
