Demeton (Systox, Bayer 19639) 
(1) 0,0-Diethyl S-ethyl-2-thioethyl phosphorothiolate (also known 
as Isosystox or Demeton S) 
(IL) 0,0-Diethyl O-ethyl-2-thioethyl phosphorothioate (also known 
as systox thiono isomer or Demeton 0) 
I (c,1,0),-B-S-cH, cH, -S-CH,-CH, 
II (C,H.0) 0-H CH, -S-CH, —-CH 
D5 2 a De ma 8 
Investigations of the two isomers have been carried out by use of Bs 
radiotracers, by chromatography, and by infrared spectrophotometry. The 
data obtained showed that these isomers were metabolized in the same manner 
in fruits, beans, and cotton. Seven days after application of demeton 0, 
only traces of the isomer were present. All radioactivity on the chroma~ 
tograms corresponded to the sulfoxide and sulfone (506, 746, 999, 1000, 1084). 
Demeton O also underwent isomerization in plants and gave rise to three 
unidentified compounds (620, 646, 1050). Up to 14 days after the topical 
application of demeton S to cotton, this isomer accumulated rapidly in the 
leaves. Subsequently, the sulfoxide analog appeared in greater quantity. 
Some sulfone was also observed (994). 
With mice, the administered dose was rapidly absorbed, metabolized, 
and eliminated. Only 64 or less was found in the stomach after 1 to 2 
hours; and, after 4 hours, it had almost entirely disappeared from these 
tissues. Small amounts passed through the intestines but most was eliminated 
in the urine rather than the feces. The major site of degradation was the 
liver and degradation continued until elimination in the urine (924). 
In gross aspects, the biochemical mechanisms in mice, cockroaches, 
and plants were similar. Major differences were concerned with rates of 
metabolism and degradation; and, as expected, rates were greater in the 
mammal than in the insect and greater in the insect than in plants. The 
routes of metabolism and the metabolites, however, were the same in each 
case. The principal metabolic path for both isomers was the oxidation of 
the 2-ethylthio ether to the sulfoxide and sulfone. In the case of demeton 
0, a secondary path involved oxidation of P=S to P=0 with subsequent 
oxidation to the sulfoxide and sulfone (924). 
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