Roridin D

Chromatographic separation of extracts from the fungal biomass of a plant pathogenic fungus, Myrothecium roridum, yielded 8 trichothecene toxins including 6 type D trichothecenes (1: -6: ) and 2 type A trichothecenes (7: -8: ). 6',12'-Epoxymyrotoxin A (1: ) and 7'-hydroxymytoxin B (2: ) were new macrocyclic trichothecenes, while the other trichothecenes were identified as myrotoxin B (3: ), myrotoxin D hydrate (4: ), 2',3'-epoxymyrothecine A (5: ), miotoxin A (6: ), and 2 trichothecenes lacking the macrocyclic lactone system, roridin L-2 (7: ) and trichoverritone (8: ). The structures of these mycotoxins were characterized using spectroscopic methods. The absolute configurations of 1: and 2: were determined by NOESY and a comparison of their experimental and calculated ECD spectra. Most of these mycotoxins (1: -4: and 6: ) exhibited highly potent antimalarial activity against Plasmodium falciparum. They also showed strong cytotoxicity towards KB and NCI-H187 cell lines (IC50 0.60 - 112.28 nM), as well as the Vero cell line (IC50 1.50 - 46.51 nM).

Straw is the main by-product of grain production, used as bedding material and animal feed. If produced or stored under adverse hygienic conditions, straw is prone to the growth of filamentous fungi. Some of them, e.g. Aspergillus, Fusarium and Stachybotrys spp. are well-known mycotoxin producers. Since studies on mycotoxins in straw are scarce, 192 straw samples (wheat n = 80; barley n = 79; triticale n = 12; oat n = 11; rye n = 12) were collected across Germany within the German official feed surveillance and screened for the presence of 21 mycotoxins. The following mycotoxins (positive samples for at least one mycotoxin n = 184) were detected: zearalenone (n = 86, 6.0-785 μg/kg), nivalenol (n = 51, 30-2,600 μg/kg), deoxynivalenol (n = 156, 20-24,000 μg/kg), 15-acetyl-deoxynivalenol (n = 34, 20-2,400 μg/kg), 3-acetyl-deoxynivalenol (n = 16, 40-340 μg/kg), scirpentriol (n = 14, 40-680 μg/kg), T-2 toxin (n = 67, 10-250 μg/kg), HT-2 toxin (n = 92, 20-800 μg/kg), T-2 tetraol (n = 13, 70-480 μg/kg). 15-monoacetoxyscirpenol (30 μg/kg) and T-2 triol (60 μg/kg) were only detected in one barley sample. Macrocyclic trichothecenes (satratoxin G, F, roridin E, and verrucarin J) were also found in only one barley sample (quantified as roridin A equivalent: total 183 μg/kg). The occurrence of stachybotrylactam was monitored for the first time in four samples (n = 4, 0.96-7.4 μg/kg). Fusarenon-X, 4,15-diacetoxyscirpenol, neosolaniol, satratoxin H and roridin-L2 were not detectable in the samples. The results indicate a non-negligible contribution of straw to oral and possibly inhalation exposure to mycotoxins of animals or humans handling contaminated straw.

Trichothecenes (TCNs) are the mycotoxins produced by many fungal species such as Fusarium, Myrothecium, and Stachybotrys and pose a considerable health risk. Based on their characteristic functional moieties, they are divided into four categories: Type A (T-2, HT-2, diacetoxyscirpenol (DAS), harzianum A, neosolaniol (NEO) and trichodermin), Type B (deoxynivalenol (DON), nivalenol (NIV), trichothecin and fusarenon X), Type C (crotocin) and Type D (satratoxin G & H, roridin A and verrucarin A) with types A and B being the most substantial. TCNs cause growth retardation in eukaryotes, suppress seedling growth or regeneration in plants and could be a reason for animal reproductive failure. Due to the increased frequency of occurrence and widespread distribution of TCNs in food and feed, knowledge of their sources of occurrence is essential to strategise their control and management. Hence, this review provides an overview of various types and sources of TCNs, the associated biosynthetic pathways and genes responsible for production in food and feed. Further, various processing and environmental effects on TCNs production, detection techniques and management strategies are also briefly outlined.