MYCOTOXINS
These are substances produced by some fungi which are toxic to humans and animals, mostly through
foodstuffs and feedstuffs. They are secondary metabolites produced on agricultural products before or
after harvest or during transit or storage. It is estimated that not less than 70% of world grains were
contaminated by these toxins. They are secreted on candidate crops like maize, peanuts, guinea corn and
melon, whether in farm, transit, or store and they can incite a variety of morbidities(Table 6.2)
Table 1 Mycotoxin types and effects
TYPE SOURCE EFFECTS
1. Aflatoxin (B1) maize, cotton seed, live damage,
and others groundnut, bread and jaundice, death.
A. flavus baked products.
2. Ochratoxin citrus, coffee, beans kidney disease.
A. spp (25 spp)
3. Patulin mainly bread, sausage, cancer, toxic
P. expansum (18 spp) all wheat products,
apple juice
4. Trichothecene All cereals toxic causes,
Fusarium spp diarrhea,
vomitting
5. Alternariol cereals toxic, damage
Alternariol spp to mucous
Membrane of
Mouth, stomach,
Blockage of
blood Circulation,
death
6. Ergot alkaloid cereals toxic, damage to
Claviceps spp Mucous
Membrane of
mouth, stomach,
blockage of
Blood circulation,
death
7. Mushroom and direct consumption liver and
Toadstool inhalation of spores kidney damage
Usually the level of mycotoxins in samples are in very small quantities and are measured as parts per
million (ppm) or parts per billion (ppb)
(Interpretation = ppm can be equated with one minute in 2 years or one penny in ten thousand dollars,
while ppb is the equivalent of one penny in ten million dollars or one second in 2 years).
Although about 350 mycotoxins are known, the most widely studied are aflatoxins, ochratoxins,
deoxynivalenol, zearalenone, fumonisins, patulin, and citrinin with Aspergillus ,Fusarium and Penicillium
species being regularly implicated in their production .Of recent, mycotoxins are secreted by unusual
genera and species further increasing the scare in human health. They can be classified based on factors
like
, A first original producing fungus e.g Aflatoxin from Aspergillus flavus toxin , ochratoxin from A.
ochraceus toxin
B Effect of mycotoxin e g vomitoxin, from vomiting toxin
C The chemical structure e g trichothecenes from 12, 13 epoxy-trichothecene unit.
D Fluorescence colour e g blue (B), green(G)
E Route of excretion e g Milk for M
F Description of effect e g carcinogenic e g aflatoxin B1( In 1988, the IARC placed aflatoxin B1 on the
list of human carcinogens) OTA, and Fumonisin; estrogenic e g zearalenone; neurotoxin e.g Fumonisin
B1; nephrotoxic e g ochratoxin; dermatotoxic e trichothecenes or immunosuppressive e g aflatoxin B1,
OTA and T-2 toxins
Aflatoxins, the group of secondary metabolites, produced by at least 3 species of Aspergillus--A. flavus,
A parasiticus, and A. nomius, occur in a wide range of food and feed materials in farm or store . On
Czapek agar, conidial heads of A. flavus are gray green whereas those of A. parasiticus are dark green.
There is also a difference in the mycotoxin profile: A. flavus produces B aflatoxins and cyclopiazonic acid
(nontoxigenic strains are not uncommon) and A. parasiticus nearly always produces B and G aflatoxins
(never cyclopiazonic acid). Aflatoxins are crystalline, tasteless, odourless and colourless(to the naked
eye) and stable even at temperatures as high as 1000C. They are soluble in solvents like chloroform,
methanol and acetonitrile. They fluoresce under UV light as green for the G aflatoxins, and blue for the B
aflatoxins.
Their structures and melting points are :
Aflatoxin B1= C17H12O6;MW=312;MP=2680C
Aflatoxin B2= C17H14O6;MW=314; MP=2880C
Aflatoxin G1= C17H12O7; MW 328; MP=2460C
Aflatoxin G2= C17H14O7; MW=330; MP=2380C
Aflatoxin M1= C17H12O7; MW=328;MP=2990C
Aflatoxin M2= C17H14O7;MW=330; MP=2930C
Aflatoxin P1 = C16H10O6; MW=;298.25
Aflatoxin Q1= C17H12O7; MW=328.27
The M1 and M2 are derivatives of B1 and B2 in dairy livestock like cows. Aflatoxin P1 and Q1 are
derivatives of B1, detected in monkeys, mouse and rats, . Aflatoxin Q1 used to be categorized as
mutagenic but lately this is no longer associated with it. The International Agency on Research on
Cancer, an arm of the WHO has placed Aflatoxin B1 on the list of category 1 human carcinogen. AFB1 is
thermostable, colourless, odourless and tasteless. AFM1 is also stable in raw milk and processed milk
products. Pasteurization has little or no effect when being processed into cheese, yoghurt or butter.
Various national or international organizations set maximum permissible limits in each food or feed item.
For example, Codex Commission approved 0.5microgram/kg aflatoxin in milk. The EU set 2ppb for
AFB1 and 4ppb for total aflatoxin in cereals for human consumption. In animal feed, it can between 5 and
30ppb. For Ochratoxin A(OTA), it is 5ppb for unprocessed cereals and 3ppb for products made from
unprocessed cereals. Because pigs are more susceptible, 0.05ppm OTA is set for pig feed while 0.25ppm
is allowed for other feed materials. Of recent, OTA was implicated in Alzheimer’s disease.
By comparative geographic occurrence, aflatoxins, fumonisins , ochratoxins and zearalenone are
common in Africa. The candidate items for contamination which also serve as dietary items, on repeated
These are substances produced by some fungi which are toxic to humans and animals, mostly through
foodstuffs and feedstuffs. They are secondary metabolites produced on agricultural products before or
after harvest or during transit or storage. It is estimated that not less than 70% of world grains were
contaminated by these toxins. They are secreted on candidate crops like maize, peanuts, guinea corn and
melon, whether in farm, transit, or store and they can incite a variety of morbidities(Table 6.2)
Table 1 Mycotoxin types and effects
TYPE SOURCE EFFECTS
1. Aflatoxin (B1) maize, cotton seed, live damage,
and others groundnut, bread and jaundice, death.
A. flavus baked products.
2. Ochratoxin citrus, coffee, beans kidney disease.
A. spp (25 spp)
3. Patulin mainly bread, sausage, cancer, toxic
P. expansum (18 spp) all wheat products,
apple juice
4. Trichothecene All cereals toxic causes,
Fusarium spp diarrhea,
vomitting
5. Alternariol cereals toxic, damage
Alternariol spp to mucous
Membrane of
Mouth, stomach,
Blockage of
blood Circulation,
death
6. Ergot alkaloid cereals toxic, damage to
Claviceps spp Mucous
Membrane of
mouth, stomach,
blockage of
Blood circulation,
death
7. Mushroom and direct consumption liver and
Toadstool inhalation of spores kidney damage
Usually the level of mycotoxins in samples are in very small quantities and are measured as parts per
million (ppm) or parts per billion (ppb)
(Interpretation = ppm can be equated with one minute in 2 years or one penny in ten thousand dollars,
while ppb is the equivalent of one penny in ten million dollars or one second in 2 years).
Although about 350 mycotoxins are known, the most widely studied are aflatoxins, ochratoxins,
deoxynivalenol, zearalenone, fumonisins, patulin, and citrinin with Aspergillus ,Fusarium and Penicillium
species being regularly implicated in their production .Of recent, mycotoxins are secreted by unusual
genera and species further increasing the scare in human health. They can be classified based on factors
like
, A first original producing fungus e.g Aflatoxin from Aspergillus flavus toxin , ochratoxin from A.
ochraceus toxin
B Effect of mycotoxin e g vomitoxin, from vomiting toxin
C The chemical structure e g trichothecenes from 12, 13 epoxy-trichothecene unit.
D Fluorescence colour e g blue (B), green(G)
E Route of excretion e g Milk for M
F Description of effect e g carcinogenic e g aflatoxin B1( In 1988, the IARC placed aflatoxin B1 on the
list of human carcinogens) OTA, and Fumonisin; estrogenic e g zearalenone; neurotoxin e.g Fumonisin
B1; nephrotoxic e g ochratoxin; dermatotoxic e trichothecenes or immunosuppressive e g aflatoxin B1,
OTA and T-2 toxins
Aflatoxins, the group of secondary metabolites, produced by at least 3 species of Aspergillus--A. flavus,
A parasiticus, and A. nomius, occur in a wide range of food and feed materials in farm or store . On
Czapek agar, conidial heads of A. flavus are gray green whereas those of A. parasiticus are dark green.
There is also a difference in the mycotoxin profile: A. flavus produces B aflatoxins and cyclopiazonic acid
(nontoxigenic strains are not uncommon) and A. parasiticus nearly always produces B and G aflatoxins
(never cyclopiazonic acid). Aflatoxins are crystalline, tasteless, odourless and colourless(to the naked
eye) and stable even at temperatures as high as 1000C. They are soluble in solvents like chloroform,
methanol and acetonitrile. They fluoresce under UV light as green for the G aflatoxins, and blue for the B
aflatoxins.
Their structures and melting points are :
Aflatoxin B1= C17H12O6;MW=312;MP=2680C
Aflatoxin B2= C17H14O6;MW=314; MP=2880C
Aflatoxin G1= C17H12O7; MW 328; MP=2460C
Aflatoxin G2= C17H14O7; MW=330; MP=2380C
Aflatoxin M1= C17H12O7; MW=328;MP=2990C
Aflatoxin M2= C17H14O7;MW=330; MP=2930C
Aflatoxin P1 = C16H10O6; MW=;298.25
Aflatoxin Q1= C17H12O7; MW=328.27
The M1 and M2 are derivatives of B1 and B2 in dairy livestock like cows. Aflatoxin P1 and Q1 are
derivatives of B1, detected in monkeys, mouse and rats, . Aflatoxin Q1 used to be categorized as
mutagenic but lately this is no longer associated with it. The International Agency on Research on
Cancer, an arm of the WHO has placed Aflatoxin B1 on the list of category 1 human carcinogen. AFB1 is
thermostable, colourless, odourless and tasteless. AFM1 is also stable in raw milk and processed milk
products. Pasteurization has little or no effect when being processed into cheese, yoghurt or butter.
Various national or international organizations set maximum permissible limits in each food or feed item.
For example, Codex Commission approved 0.5microgram/kg aflatoxin in milk. The EU set 2ppb for
AFB1 and 4ppb for total aflatoxin in cereals for human consumption. In animal feed, it can between 5 and
30ppb. For Ochratoxin A(OTA), it is 5ppb for unprocessed cereals and 3ppb for products made from
unprocessed cereals. Because pigs are more susceptible, 0.05ppm OTA is set for pig feed while 0.25ppm
is allowed for other feed materials. Of recent, OTA was implicated in Alzheimer’s disease.
By comparative geographic occurrence, aflatoxins, fumonisins , ochratoxins and zearalenone are
common in Africa. The candidate items for contamination which also serve as dietary items, on repeated
