Azoxystrobin metabolism

The metabolism of azoxystrobin in whole plants results in numerous metabolites (12). Three of die major metabolites generated from the parent molecule in whole plants are shown in Figure 7. Despite the slow rate of azoxystrobin metabolism in the wheat-cell culture (beyond the duration of the experiment), three metabolites were observed in the 48-hour extracts. Two of the metabolites were identified to be the same as metabolites, 1 and 2, observed in whole plants (Figure 7). The third was a benzoic acid metabolite which could be a precursor to metabolite 3. All three are results of Phase 1 metabolism. Metabolite 1 was the result of a ring hydroxylation, metabolite 2 was formed by 0-dealkylation and metabolite 3 by de-esterification. These metabolites were... 

Plants. Metabolism was extensive, but parent azoxystrobin was the only major (>10%) residue... 

Florasulam (II) is a triazolopyrimidine herbicide used for selective broadleaf weed control in wheat, barley, and oats, but is included in this experiment as a positive standard because it is rapidly metabolized in the test system. Azoxystrobin (12) serves as a negative standard because it metabolizes slowly in the test system. These standards provided positive and negative controls for the system, and helped put the metabolism rates of the other compounds into perspective. 

Florasulam and trifloxystrobin are both observed to metabolize rapidly in the wheat cell culture system (Figure 4), with half lives calculated using a nonlinear fit at 1S.4 and 15.S hours, respectively. Azoxystrobin was also observed to be metabolized, but the rate of metabolism was much slower than that of florasulam and trifloxystrobin (84% parent remaining 48 hours after treatment). It was not possible to accurately calculate the half life for azoxystrobin (the half life exceeded the incubation time), but it was extrapolated to be approximately 230 hours. All the other fungicides tested were stable over the 48 hour... 

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