Yoshiki Onji

Direct analysis of several Fusarium mycotoxins in cereals by capillary gas chromatography–mass spectrometry

A method for qualitative and quantitative analysis of Fusarium mycotoxins by gas chromatography-mass spectrometry (GC-MS) using cold on-column injection was improved. Eight typical mycotoxins, including deoxynivalenol (DON), 3-acetyldeoxynivalenol (3ADN), fusarenon-X (FX), diacetoxyscirpenol (DAS), 15-monoacetylscirpenol (15MAS), T-2 toxin (T-2), scirpentriol (SCT), and zearalenone (ZEA) were subjected to GC-MS without chemical derivatization by means of the on-column injection technique. Chromatographic separation of the toxins extracted from barley was achieved as a single peak, and the specific EI mass spectra of each toxin were obtained. The fatty acids in the extract that interfere with measurements of the toxins on the gas chromatogram were removed by precipitation as an insoluble metal soap with zinc acetate. Additional clean-up was accomplished using a Bond Elut Florisil cartridge. The quantitative detection limit in barley ranged from 0.1 to 0.5 micrograms/g. The average recoveries of 93.1% for DON, 3ADN, 15MAS, DAS, T-2 and ZEA, and 46.0% for FX and SCT added to barley at the level of 1 microgram/g were obtained.

Antiviral Activity of Trichothecene Mycotoxins (Deoxynivalenol, Fusarenon-X, and Nivalenol) against Herpes Simplex Virus Types 1 and 2

The effect of trichothecene mycotoxins, deoxynivalenol (DON), fusarenon‐X (FX) and nivalenol (NIV), on plaque formation of herpes simplex virus types 1 and 2 (HSV‐1 and HSV‐2) in HEp‐2 cells was examined. The 50% effective concentrations (EC50) of DON, FX, and NIV for HSV‐1 plaque formation were 160, 56, and 120 ng/ml, respectively. Those for HSV‐2 plaque formation were 94, 26, and 50 ng/ml, respectively. These three mycotoxins showed about 2‐fold higher selectivity to HSV‐2 than to HSV‐1. Plaque formation of HSV‐1 was not inhibited with trichothecenes at concentrations completely inhibiting plaque formation when cells were treated during virus adsorption period or 15 hr before infection. These results indicate that trichothecenes affect replication of HSV‐1 after virus adsorption, but not before or during virus adsorption to the host cells.

Isolation of Nivalenol and Fusarenon-X from Pressed Barley Culture by Centrifugal Partition Chromatography

Abstract A method for the production and isolation of gram quantities of nivalenol and fusarenon-X, trichothecene mycotoxins, is presented. Fusarium graminearum F-1465 was inoculated and cultured on the pressed barley, and the cultured product was extracted with acetonitrile. The crude extracts were subjected to silica gel column chromatography and then to centrifugal partition chromatography (CPC) using two-phase solvent system n-butanol/water and chloroform/methanol/water. The simple procedures were advantageous for the large scale purification of two toxins from cultured pressed barley medium because it was more time and yield effective. Starting from 1 Kg of the pressed barley substrate, 0.34 g of crystalline nivalenol (purity 103%) was obtained by recrystallization of CPC fraction from hot methanol and 0.78 g of fusarenon-X (purity 77%) was obtained directly from CPC fraction by evaporating to dryness.