The metabolism in the rat of the herbicidally active isomer (R)-flamprop-methyl in comparison with the racemic form
1991
Hutson, D.H. | Logan, C.J. | Taylor, B.
A single dose (4 mg kg-1) of 14C-labelled (R)-flamprop-methyl to rat was rapidly metabolised and 90% of the dose was eliminated in urine and faeces within 48 h. Four days after dosing, tissue residues were 0.1 microgram equivalents g-1 tissue or much less, with the exception of kidney (0.22 microgram g-1). There was a statistically significant sex difference in the routes of elimination; this may be attributed to differences in the biliary elimination of the major metabolite, flamprop acid, or its glucuronide conjugate. The fate of racemic flamprop-methyl was very similar to that of the (R)-isomer. The major metabolic routes were hydrolysis of the esters to the corresponding acids, hydroxylation of the benzoyl aromatic rings and conjugation. The flamprop acid derived from the (R)-flamprop-methyl was found to be partially converted to the (S)-form (R:S ratio, 87:13). This reaction is discussed in the context of other such biological racemisations recently reported.
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