Agriculture Reference
In-Depth Information
I NTRODUCTION
Food safety continues to be an important issue in the whole world. Each year, a large
number of crops are affected by fungal invasion, leading to considerable financial losses and
impaired health in animals and humans. Toxicity is mainly caused by secondary metabolites
of fungi, which are appropriately called mycotoxins [1]. Mycotoxin production can occur
when fungi grow on crops in the field, at harvest, in storage or during the processing of feed,
when conditions are favorable. No region of the word escapes these silent killers, and their
negative impact on animal productivity and human health is enormous [2]. Mycotoxins are
highly undesired substances that must not be present in food, a zero tolerance being an ideal.
However, even the best agricultural, storage and processing practices cannot completely
eliminate these contaminants, and hence it is impossible to achieve a truly mycotoxin-free
food chain. Despite low consumer awareness of the problem, health risk related to mycotoxin
ingestion has been quantified as exceeding risk from other food-related contaminants such as
pesticides, additives, heavy metals, and microbial agents. For this reason mycotoxins have
been called the 'hidden killers' [3]. According to the United Nation's Food and Agriculture
Organization (FAO), approximately 25% of the world's grain supply is contaminated with
mycotoxins. The economic loss due to mycotoxin contamination has been estimated to run
into millions of dollars annually [4]. Fusarium fungi are among the most important
agriculturally toxigenic fungi occurring in the moderate climatic zones of North America and
Europe [5]. These species play an important role as plant pathogens, causing a wide range of
diseases in a diversity of host plants such as vascular wilt, root and stem rots, cereal ear rot,
head and pad blight, fruit rot, etc. Three of the most prevalent mycotoxins that occur in grain
are deoxynivalenol (DON), fumonisins and zearalenone (ZEA) [6].
DON is a member of the trichothecene family of mycotoxins. Structurally, it is a polar
organic compound which belongs to type B trichothecenes, and its chemical name is 12,13-
epoxy-3α,7α,15-trihydroxytrichothec-9-ene-8-one (Figure 1). The occurrence of DON is
associated primarily with Fusarium graminearum (teleomorph Gibberella zeae ) and
Fusarium culmorum (teleomorph unknown), both of which are important plant pathogens
commonly found in cereals and other crops [7]. Although DON is among the least toxic of the
trichothecenes, it is the most frequently detected one throughout the world, and its occurrence
is considered to be an indicator of the possible presence of other, more toxic trichothecenes
[8]. Consumption of contaminated feeds by livestock has been associated with a variety of
adverse health effects including feed refusal (mainly by swine), reduced weight gain, diarrhea
and emesis [9,10].
Figure 1. Chemical structure of deoxynivalenol (DON).
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