**2. Overview of major mycotoxin-producing species**

The genus *Fusarium* comprises an outsize cluster that includes animal and plant pathogenic species with great biological properties [5]. Some species are used as biocontrol agents, as industrially applicable enzymes, and some cause diseases in many agronomical crops and are probably the most prevalent toxin-producing fungi [6]. The genera *Aspergillus*, *Penicillium* and *Fusarium* are filamentous fungi and produce mycotoxins that are toxic and/or carcinogenic secondary metabolites produced under appropriate environmental conditions [7]. *Fusarium* produces three of the most important of mycotoxins, such as *fumonisins*, *trichothecenes* or *zearalenone*, and these furthermore produce emerging mycotoxins as well as *fusaproliferin*, *beauvericin*, *enniatins* and *moniliformin* [8].

and humidity (30–33°C, 0.99 water activity) [13]. Aflatoxins showed carcinogenic, teratogenic, hepatotoxic, mutagenic and immunosuppressive effects; specific limits have been set on aver-

*Fusarium* Mycotoxins and Metabolites that Modulate Their Production

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Trichothecenes can be divided into four types: A (T-2 and HT-2 toxins, diacetoxyscirpenol), B (deoxynivalenol, nivalenol), C and D, and these are the main and most diverse chemical groups of the three major classes of *Fusarium* mycotoxins [14, 15]. These are shaped by a set sesquiterpenoids with or without a tricyclic nucleus. Trichothecenes are small, amphipathic molecules that can move passively across cell membranes [16, 17]. The most prevalent contaminants in wheat, barley, oats and maize are trichothecenes of types A and B. Exposure to these toxins can cause immunological problems, vomiting, skin dermatitis, hemorrhagic lesions, acute diseases and gastroenteritis. Trichothecenes in wheat behaves as phytotoxic were causing chlorosis, inhibition of root elongation, and dwarfism [4, 9]. Trichothecenes show several inhibitory effects such as inhibition of proteins, DNA and RNA synthesis on the primary metabolism of eukaryotic cells [18].

Trichothecene of type B (deoxynivalenol) is produced by *Fusarium graminearum* and *Fusarium culmorum*; these mycotoxin-producing species are found in wheat, rye, barley and oats [18]. These are a group of toxins with a keto group at carbon 8 of the parent epoxytrichothecene nucleus [19]. Deoxynivalenol is divided into five types (deoxynivalenol, 15-acetyldeoxynivalenol, 3-acetyldeoxynivalenol, fusarenon-X and nivalenol). "ribotoxic stress response" is produced

age to 50 mg/kg for total aflatoxins.

**Figure 1.** Group of mycotoxin-producing species.

**2.2. Trichothecenes**

**2.3. Deoxynivalenol**

Mycotoxins possess biological activities that represent a problem for both human and animal health (**Figure 1**). The ingestion of these compounds can cause chronic disease, morbidity and death and reduce the resistance to pathogens [9]. Most mycotoxin are stable during food processing, and these are commonly resistant to chemical and thermal changes. Mycotoxins can also come to the human by animal products [10, 11].

#### **2.1. Aflatoxins**

Aflatoxins (B1, B2, G1, G2) are difuranocoumarin synthesized by *Aspergillus flavus* and *Aspergillus parasiticus* present in soil and various organic materials. Aflatoxin-producing species has been reported in a wide variety of food commodities (maize, peanuts, barley oats, rice, cottonseed, spices and figs [12]. Optimal conditions for their propagation are high temperature

**Figure 1.** Group of mycotoxin-producing species.

and humidity (30–33°C, 0.99 water activity) [13]. Aflatoxins showed carcinogenic, teratogenic, hepatotoxic, mutagenic and immunosuppressive effects; specific limits have been set on average to 50 mg/kg for total aflatoxins.
