Metabolism of cymoxanil and analogs in strains of the fungus Botrytis cinerea using high-performance liquid chromatography and ion-pair high-performance thin-layer chromatography

The metabolism of cyano-oxime fungicide 1-(2-cyano-2-methoxyiminoacetyl)-3-ethylurea (cymoxanil) and analogs was studied on several strains of the fungus Botrytis cinerea owing to their difference in sensitivity towards cymoxanil. Chromatographic analysis of the unextracted culture medium was simpler and more accurate, particularly for ionizable metabolites because it avoids problems associated with extraction. Reversed-phase high-performance liquid chromatography was applied to compare the decrease of cymoxanil and analogs caused by different strains of B. cinerea, by periodic injections of incubated culture medium aliquots, directly on a C 4 wide-pore column. Furthermore, a thin-layer chromatographic monitoring on C 18 bonded silica gel with ion-pairing allowed the monitoring of the ionizable metabolites for substrates that were demonstrated to decompose most rapidly. These complementary analyses showed that the sensitivity of the highly sensitive strain towards cymoxanil was related to the disappearance of cyano-oximes studied from culture medium, namely to the ability of the strain B. cinerea to metabolize them.