The effects of naturally occurring bisdihydrofuran ring-containing mycotoxins on cultured chick embryonal hepatocytes.

The cytotoxicity of 16 naturally occurring mycotoxins which contain the bisdihydrofuran ring was evaluated by electron-microscopy and radioautography in a primary culture of chick embryonal hepatocytes. A series of nucleolar changes occurred, including the appearance of microsegregation (stage I), concentration of nucleolar structure (stage II), formation of macrosegregation, fragmentation of nucleoli, and the appearance of homogeneously granular nucleoli (stage III). These nucleolar changes correlate well with the inhibition of RNA synthesis calculated from the results of radioautography. The compounds containing a 2,3-double bond in the bisdihydrofuran ring were most toxic. However, it was clear that there was a remarkable difference between mycotoxins of angular type (group A) and those of linear type (group C). Therefore, not only the active site in the molecule but also the shape of the molecule may play an important role in the cytotoxicity of these mycotoxins.