A mycological study was carried out on 11 samples of imported green coffee beans. Molds isolated from the green coffee beans have been identified. Mold flora of the green coffee beans consisted mainly of Aspergillus flavus, A. fumigatus, A. niger, A. tamarii, Eurotium herbariorum, Penicillium chrysogenum, and P. citrinum. Nine isolates of A. flavus were examined for aflatoxin production on rice and coffee bean media. Only one strain of A. flavus produced 1.1595 mg/kg and 58.69 μg/kg of aflatoxins on rice and coffee bean media, respectively. Existence of this caffeine-resistant aflatoxigenic strain would indicate that green coffee beans are not always the unfavorable substrate for aflatoxin production.
Deoxyluteoskyrin (DLs) was isolated from crude luteoskyrin in the metabolites of Penicillium islandicum. Pure deoxyluteoskyrin was obtained by using HPLC and characterized with 1H NMR (400 MHz) and mass spectrometry. Cytotoxicity of deoxyluteoskyrin was examined on Yoshida sarcoma culture cells and rat hepatoma cells (H4-II-E).
The effects of sterigmatin and its structural isomer, demethylsterigmatocystin, on mitochondrial respiration were studied in comparison with sterigmatocystin. Both compounds uncoupled the oxidative phosphorylation of rat liver mitochondria, causing marked decreases in RC index and P/O ratio. Sterigmatin, in which the xanthone and dihydrobisfuran moieties are fused in a linear style, was more toxic to mitochondrial function than demethylsterigmatocystin which had an angular shape. In addition, the uncoupling activity of sterigmatocystin was markedly decreased by its demethylation.
Metabolic transformation of ochratoxin A (OA) and emodin (EM) was investigated in the microsomal and reconstituted cytochrome P-450 systems of the rat liver. In the microsomal system, OA was transformed into 4 (R)- and 4 (S)-4-hydroxy-OAs, and 3-methylcholanthrene (3 MC) as well as PCB enhanced the microsomal hydroxylation of OA to 4 (R)-4-hydroxy-OA. In the reconstituted cytochrome P-450 system, cytochrome P-450 II-a (maximal CO-differential spectrum at 448.0 nm and high-spin form), fractionated from PCB-microsomes, selectively catalyzed the hydroxylation of OA and EM into 4 (R)-4-hydroxy-OA and 2-hydroxy-EM, respectively.
Two monoclonal antibodies (7 D 4, 6 E 9) reactive with T-2 toxin (T-2) were prepared. The antibody 7 D 4 was also reactive with T-2 hemisuccinate (T-2 HS) and acetyl T-2 toxin, but less reactive with HT-2, 3'-OH-T-2, and 3'-OH-HT-2 toxins. By using the antibody 7 D 4 in the indirect competitive ELISA method, the least detectable limit for T-2 was about 25 pg per assay.
Two metabolites, tentatively designated as PB-1 and PB-4, were isolated from moldy rice artificially inoculated with Pseudallescheria boydii IFM 4642. PB-1 was identified as pseurotin A (1) isolated from Pseudeurotium ovalis. The structure of PB-4 was determined to be (2) in Fig. 1. These metabolites exhibited inhibitory effect on the activity of monoamine oxidase (MAO).
The productivities of tremorgenic mycotoxins in EtOAc extracts of moldy rice inoculated artificially with 45 strains of 40 species of Eupenicillium were examined. By intraperitoneal injection to mice, extracts of five species were found to be tremorgenic: E. angustiporcatum, E. crustaceum, E. lapidosum, E. tularense and Eupenicillium sp. Verruculogen was detected in the extracts of E. crustaceum, E. tularense and Eupenicillium sp. by TLC analysis.