Allethrin, Barthrin, Dimethrin, Phthalthrin and Pyrethrin 
Studies have suggested that metabolic pathways for pyrethrins and 
allethrins differ and also that detoxification mechanisms in houseflies 
and roaches differ. 
Metabolism of Giieehrinecs. by a housefly enzyme system gave rise 
to 13 metabolites and each had the ester group intact. One compound repre- 
sented over half the total radioactivity. Saponification of the major 
metabolite yielded a compound identified as chrysanthemumdicarboxylic 
acid. Chemical, I.R., and chromatographic analyses identified the major 
metabolite as O-demethyl allethrin [3-(3-allyl-2-methy1-4-oxo-2-cyclopentenyl) 
chrysanthemumdicarboxylate] (1525). Dimethrin and Phthalthrin were also 
oxidized to their respective O-demethyl pyrethrin II analogs. 
Initially, it was suggested that decomposition of pyrethrins was 
caused by hydrolytic enzymes. Subsequent studies have shown that lipases 
of roaches and houseflies readily hydrolyze pyrethrin esters to keto 
alcohols, chrysanthemum acids, and several unidentified compounds (260, 
1510, 1520, 1540). Some 8-12% of labeled pyrethrin applied to roaches 
was excreted as Cl O5. When applied to houseflies, no cl4q, was detected 
(268, 690, 1515). Chrysanthemum acid and five unknown metabolites were 
detected. Three of the unknown metabolites had intact chrysanthemum acid 
moiety and an ester linkage. Cinerin I (268) behaved similarly but 
differed quantitatively. Thus, it appears that initial degradation 
occurred on the pyrethrolone or cinerolone moiety. 
In other studies, pyrethrin t-cl4 was converted in vitro by the 
housefly abdomen-NADPH, system to at least 10 metabolites. Saponification 
of the major metabolite gave rise to chrysanthemumdicarboxylic acid. Acid 
labeled dimethrin and phthalthrin gave 11 and 12 metabolites, respectively, 
and phthalthrin-N-methylene-C~" yielded 10 metabolites identical with those 
from acid labeling. Two compounds were detected only with acid labeling- 
hydrolyses products. The major metabolites were in each case identical 
with that from pyrethrin and allethrin and chemical studies indicated that 
the major metabolite of pyrethrin I, dimethrin, and phthalthrin were formed 
by oxidation of the analogous methyl group for allethrin (1525, 1526). 

Metabolism of allethrin by Musca domestica L. was demonstrated. 
Metabolites were resolved chromatographically but not identified (174). 

When pyrethrin I was administered as an anthelmintic, color tests on 
urine of humans indicated the presence of chrysanthemum monocarboxylic 
acid (43). 
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