Three toxic substances related to nivalenol were tested for their growth inhibiting activity and suppressive effects on DNA, RNA and protein syntheses of HeLa S3 cells in comparison with those of nivalenol.
Fusarenon-X, isolated from culture filtrate of
Fusarium nivale, showed a complete inhibition of growth of HeLa S3 cells at a concentration of 0.5 μg/ml. The ED
50 for
3H-thymidine incorporation into DNA and
3H-leucine into protein were 0.1 and 0.13 μg/ml (2.8 and 3.6×10
-7M), respectively, thus indicating about a 4 times potent activity as compared with that of nivalenol. No inhibi-tion of
3H-uridine incorporation into RNA occurred.
Dihydronivalenol and dihydrof usarenon-X, -9-ene reduced substances of nivalenol and fusarenon-X, respectively, showed similar toxic effects on HeLa cells but with a six to ten times lower toxicity. The complete growth inhibition doses for the cells by both samples were around 3.0 μg/ml and the ED
50 for
3H-thymidine and leucine incorporation were around 2.0 μg/ml.
3H-uridine incorporation was not remarkably inhibited.
Biological effects of some other Fusaria metabolites having closely related chemical structures are discussed in association with nivalenol and f usarenon-X.
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