Acute toxicity in the microbial poisonings plays an important role not only in occurrence of such poisonings in the field but also in detections and purification of the toxins in laboratories. Factors associated with acute toxicities are as toxin solubility, absorption by the body, administration route, potency, interval between intake and onset of poisoning symptoms, and toxin target. Characteristics of the acute toxicities induced by several mycotoxins and phycotoxins areanalyzed and discussed.
Some species of the genus Penicillium (P. palitans, P. expansum and P. farinosum) were examined for the ability to produce nitrogen-containing mycotoxins (alkaloids) on synthetic, complex media, summer wheat and apple juice in the submerged and surface culture. Bioproduction of clavine and benzodiazepine alkaloids was observed in all media tested in surface conditions. However, the essential differences were found in the total amounts of alkaloids as well as in the ratio of separate components and their distribution between the mycelium and culture broth. It was suggested that a correlation exists between the ability of fungi to produce N-containing mycotoxins (alkaloids) on artificial media and that on natural substrates.
Stimulatory effect of dimethyl sulfoxide (DMSO) on trichothecene biosynthesis by Fusarium graminearum KU 1352 [deoxynivalenol (DON) producer] and F. graminearum KU 1383 [nivalenol (NIV) producer)] were investigated in yeast extract-polypepton-sucrose medium. DMSO at concentrations subinhibitory to fungal growth significantly enhanced production of trichothecenes in both strains. Maximum yields of trichothecenes were 162% (660 μg/ml) of control at 5% DMSO in the DON producer and 141% (778 μg/ml) at 2% DMSO in the NIV producer. This is the first report on the enhancement of tricho-thecene production by DMSO without inhibition of biomass formation.
Twenty-seven strains of Aspergillus niger group stored in the Institute for Fermenta-tion, Osaka (IFO) were examined for their ochratoxin A (OTA) producibility. TLC and HPLC analyses revealed the production of OTA by 5 out of the 27 strains, A. awamori var. fumeus IFO 4122, A. usamii IFO 8875, 8876, 8877, and A. usamii mut. shirousamii IFO 6082. The production was also confirmed by its spectral assignment of both nuclear magnetic resonance (NMR) and mass spectra (MS).
Trichothecium roseum causes pink mold rot of muskmelons and tomatoes cultivated in greenhouses, and also produces trichothecin, a 12, 13-epoxytrichothecene. To clarify the pathogenicity and trichothecin production of T. roseum, mycological examination was carried out in 8 greenhouses in Chiba Prefecture. The contamination of muskmelon and tomato fruits with trichothecin was also examined. Trichothecium roseum was isolated from almost all of the moldy or discolored muskmelon and tomato fruits, as well as tomato stem dumped near the greenhouse. The fungus was found in the air of a greenhouse in which many moldy tomato fruits were present, but in none of the soil samples from the greenhouses tested. In an inoculation test, T. roseum isolated from muskmelon and tomato invaded and decayed the flesh of matured muskmelons. Moreover, almost all the isolates of T. roseum tested produced trichothecin on Czapek-Dox broth supplemented with 0.2% corn steep liquor cultured for 21 days at 25°C. Trichothecin was detected in moldy muskmelon and tomato fruits collected in the greenhouses.
Three new components, tentatively named GP-A, -B, and -C, with monoamine oxidase (MAO) inhibitory activity and a known anthraquinone chrysophanol were isolatedfrom Mycelia Sterilia derived from an Ascomycete, Gelasinospora pseudoreticulata.GP-A and -B, the main MAO inhibitory principles of this fungus, were deduced tobe 5-hydroxy-7-methoxy-4, 9-dioxonaphtho[2, 3-c]furan and l, 3-dihydro-5-hydroxy-7-methoxy-4, 9-dioxo-naphtho[2, 3-c]furan, respectively. The IC50 values of GP-A, -B, and -C were evaluated against the MAO from mouse liver.
Natural occurrences of aflatoxin B1, fumonisins and trichothecenes were investigated in 80 corn samples harvested in the low and high risk of primary liver cancer, Penlai (Sandong) and Haimen (Jiangsu), respectively, in China in1993. In Haimen area, the positives were 37 (average levels of 24.0 ppb), 37 (average levels of 5.11 ppm), 25 (average levels of 2.02 ppm), 25 (average levels of 1.12 ppm) and 40 (average levels of 0.89 ppm) for aflatoxin B1, fumonisins B1, B2, B3 and deoxynivalenol, respectively. In Penlai area, 12, 2, and 9 out of 13 kernel samples were positive for aflatoxin B1, fumonisin B1 and deoxynivalenol, respectively. However, no fumonisin B2 and B3 were found in these Penlai's samples. As for other trichothecenes, nivalenol was detected in only one sample from Haimen, but no T-2 toxin was found in all corn samples in this investigation. These results indicate that co-contamination of aflatoxin B1, fumonisins and deoxynivalenol is popular in Chinese corn. Furthermore, the positive rate for natural occurrence of combinated aflatoxin B1 and fumonisins in Haimen was superior to those in Penlai. These results suggest that tumor risk factor in high frequency area of primary liver cancer in China may be associated with co-contamination of aflatoxin B1 and fumonisins.