title: Effects of cysteine and structurally related compounds on ochratoxin production by Aspergillus ochraceus.
abstract: Addition of 10(-2) M L-cysteine, L-cystine, or S-ethyl-L-cysteine to a synthetic medium containing xylose as the sole carbon source did not decrease ochratoxin production by Aspergillus ochraceus. At that concentration, DL-homocysteine thiolactone HC1, DL-cysteine HC1, L-ethionine, S-methyl-L-cysteine, and glutathione (reduced) strongly inhibited ochratoxin production. DL-Homocysteine thiolactone HC1, DL-cysteine HC1, and L-ethionine also strongly inhibited fungal growth. At lower concentrations (10(-3) and 10(-4) M) only L-ethionine decreased the toxin production. Ochratoxin inhibition caused by DL-homocysteine thiolactone HC1, DL-cysteine HC1, and glutathione was observed only in cases where the pH of the media was below 5.0. The inhibition caused by 10(-3) M ethionine was partially prevented by the addition of 10(-3) M methionine but this was not the case after the addition of S-methyl-L-cysteine to the medium.
mesh_terms: D001230:Aspergillus / Q000378:metabolism*; D001235:Aspergillus ochraceus / Q000187:drug effects / Q000378:metabolism*; D003545:Cysteine / Q000031:analogs & derivatives / Q000494:pharmacology*; D003553:Cystine / Q000494:pharmacology; D005001:Ethionine / Q000494:pharmacology; D005978:Glutathione / Q000494:pharmacology; D006710:Homocysteine / Q000031:analogs & derivatives / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D008715:Methionine / Q000494:pharmacology; D009793:Ochratoxins / Q000096:biosynthesis*
chemical_list: D009793:Ochratoxins; D006710:Homocysteine; D003553:Cystine; D008715:Methionine; C026826:S-ethylcysteine; C007957:homocysteine thiolactone; D005978:Glutathione; D003545:Cysteine; C017507:mecysteine; D005001:Ethionine