Abstract
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 ED50 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 ED50 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.
