The survey of 22 commercial samples of imported green coffee beans for aflatoxins and ochratoxin has been conducted in 1982-1983. Ochratoxin A was detected in 4 samples at a level of 9.9-46μg/kg but all samples analyzed were negative for aflatoxins. Major contaminants of the samples were Aspergillus glaucus group, A, niger group, A. flavus group, A. ochraceus group and members of the Mucorales. Among the contaminants, the ability of A, flavus and A, ochraceus isolates to produce the mycotoxins was examined. Particularly, 9 isolates of A. ochraceus group produced high levels of ochratoxin A on artificial polished rice and ground coffee media (yields of ochratoxin A: 48.3-750μg/g on rice and 8.06-130μg/g on coffee, respectively). Addition of caffeine (0.1-1.0%) on MY-20 agar medium in a Petri dish resulted the delayed growth of A. ochraceus strain S-235-100, a representative isolate from the green coffee beans, but had little effect on its ochratoxin production. On the basis of the results obtained in this study, it is apparent that green coffee beans might be susceptible to A, ochraceus infection and subsequent ochratoxin production.
The effects of dechlorinated dyclochlorotine (deCl-CC) on murine liver cells were compared with those of Cyclochlorotine (CC). The deCl-CC were prepared by treating CC with 25% ammonia water-methanol (1:5). Compared with the morphological changes induced by CC in hepatocytes such as vacuole-formation, a marked reduction in cytotoxicity was observed in the rat as well as mouse hepatocytes treated with deCl-CC in in vivo and in vitro systems.
The anthrapuinone mycotoxyins, emodin and skyrin from Penicillium islandicum Sopp, were investigated for their interactions with bovine serum albumin (BSA) using a technique of spectrophotometry in search for their differences in physical properties by which the differences in their in vitro biological activities could be interpreted. BSA produced characteristic spectral alterations of emodin and skyrin in the visible light region, accompanying marked red shift of their absorption maxima. Spectrophotometric titrations of emodin and skyrin with increasing concentrations of BSA gave molar ratios of 2.5 and 5, respectivery, for their binding to BSA. The absorption spectra of emodin and skyrin were affected by pH changes of the system. The pK were significantly shifted to lower pHs in the presence of BSA. The amplitude in the BSA-induced pK shift of skyrin was significantly larger than that of emodin. Sodium dodecylsulfate (SDS) abolished the BSA-induced spectral alterations of emodin and skyrin.
Violaceol-I, -II, and violaceic acid from a toxigenic fungus Ernericella violacea were examined for their uncoupling effect on oxidative phosphorylation of isolated rat liver mitochondria. It was found that toxic metabolites violaceol-I and -II were uncouplers to mitochondrial respiration and non-toxic metabolite violaceic acid was not. Violaceol-I and -II induced large amplitude swelling of mitochondria in isotonic alkali salt solutions and violaceic acid again did not. The uncoupling activities of violaceols were found to be gradually diminished and were finally completely lost when violaceols solution was kept at room temperature due to their chemical instabilities. However instead of uncoupling effect, an inhibitory effect on state 3 respiration was increased, causing a prominent decrease in RC index of mitochondrial respiration.
A simple and sensitive method for chemical analyses of three trichothecene mycotoxins (deoxynivalenol, nivalenol and fusarenon-X) has been developed. Extraction of the toxins from sample with 200 ml of aqueous acetonitrile (acetonitrile: water=150:50) was followed by clean-up using a Florisil column and a Sep-pak silica cartridge, and then determination of the toxins were carried out with GC (ECD) and GC-MS (mass fragmentography). The detection limits of deoxynivalenol, nivalenol and fusarenon-X were 2, 2 and 4 ppb respectively, when the method was applied to rice, wheat, corn and soybean.