الفهرس 
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Abstract
The present study aimed to evaluate the insecticidal
activity of fottr or·ganophosphortiS insectjcides to cotton
leafwor.m Spodoptera. li ttoralis to select the most
effect.ive one to study its acute toxicity against rats.
The interactions of this insecticide with rat brain and
S.littoralis larval AChE in the presence and absence of
different drugs were studied in 1n v.i tro and in vivo.
This was a try to regenerate or protec·t the rat brain
enzyme from the inhibition and consequently to protect
the experimental animal against death by organophosphorus
poisoning. Therefore the following studies were done:
1- The toxicity of four organophosphorus insecticides,
which recommended for control of more than one of
agricultural insect pests, was determined against the
4th instar larval of S. littoralis Boisd. According to
their LDso, values results show that profenofos was the
most toxic compound with LDs o value of 0. 1 llg/larvae
followed by chlorpyrifos, chlorpyrifos-methyl and pirimifos-
methyl. Therefore, the toxicological studies was
done on the most potent insecticide, profenofos.
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l’he acutJ” t,oxiciLy o[ profenofos was Jetcrm_ined _tn
albino mFtl.e rats h:vr oral adm_inist,raLJon. The L]):;o \. .; as
fot1nd to be 566.7 mg/kg body weight.
3- The AChE specific activity ( J., 412 nm/mg protein/min)
in rat brain and S. litt,oralis larval homogenates was
determined 1 the results show that rat, brain homogenate
contained t-he highest AChE activity than S. littoralis
homogenate.
4- The AChE activity of rat brain and S. littoralis
larval homogenates ~as determined in the presence of 10-
4M of atropine, 2-P:-\~i, toxogonin, eserine of profenofos.
The druge, (antidotes) atropine, 2-PAM and toxogonin,
increased the activity of rat brain AChE and decreased
the activity of larval AChE. On the other hand, eserine
and profenofos significantly inhibited both enzymes.
However, AChE of rat brain was more sensitive to
inhibition than that of S. littoralis larval homogenate.
5- The in vitro inhibitory effect of profenofos and
eserine on rat brain and S. littoralis larval AChE was
studied. Results show that eserine, the specific
inhibitor of AChE, was more effective as an inhibitor to
rat brain AChE ( ICs o 4 pM) than that of S. littoralis
larvae (ICso 660 pM) On the other hand, profenofos was
more potent inhibitor to AChE of both rat brain and
larvA.l homogenates ( lcs o
respect.lvt~ly than eserine.
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1~xLO ll and ’1 x LO 11 prt),
6- In vitro effect of profenofos on rat brain and S.
littoralis larval AChE in presence of different. drugs
(antidotes) was studied. Results show that at. rapine, 2-
PAtvl and toxogonin reactivate Profenofos (10-9 ~I)-
inhibited enzyme v.:ith a rat1o of 82.4%, 71% and 45%
respectively. On the other hand, a very good
reactivation of profenofos-inhibited enzyme was achieved
by the mixture of atropine plus 2-PAM. The reactivation
power of these drugs decreases by increasing the
concentration of profenofos. On the other hand, these
antidotes increase the inhibitory effect of profenofos on
8. littoralis larval AChE. Based on the ICso values, the
inhibitory effect of the mixture of profenofos with 2-PAM
or with atropine was 2000 or 1250 times potent than
profenofos alone, respectively.
7- The protection offered by atrobine, 2-PAM, toxogonin,
or their mixtures by the oral route, in presence of
profenofos, to rats was also studied. On the basis of
LD50 values, atropine was superior as protectant to rat
from profenofos poisoning to either 2-PAM or toxogonin.
Atropine plus 2-PAM or toxogonin raised LDso value of
profenofos 2.8 and 2.4 fold (exerted 140% and 120% of
atropine’s protective value).
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8- Tho zn vy·vo effr:ct-,s of pt’ofenofos LIJso ctose ( 5tJi) ,’(
m~/kg) h·ith and withouL Ftt~ropi_ne \lb,Ll mg/kg}, 2-P..\;.1 (30
mg/kgl toxog’onin ( L’/ mg/kg) and their mlxtures on rat
brain AChE was investigated. Results show that profenofos
(565.7 mg/kgJ inhibited AChE activit,y in rat brain to
about 51. 7%. The mixture of atropine plus 2-PAI’! or
toxogonin almost produced total reactivation of
profenofos-inhibited er1zyme. Ho~ever, 2-PAM, toxogonirl
and atropine resulted in reactivation of approximately
83.8%, 47.8% and 18.1% of profenofos inhibited AChE,
respectively,
profenofos or
rats.
when they given in conjunction with
hr. after profenofos administrat1on to
9- The joint action of antidotes, atropine, 2-PA~i,
toxogonin and their mixtures on the toxicity of
profenofos to the 4th instar larvae of S. littoralis was
determined. According to the LDs o values for profenofos
with and without antidotes, all of the tested antidotes
increased the toxicity of profenofos to the cotton
leafworm. High degree of synergism was obtained from the
mixtures of atropine plus 2-PAM or toxogonin when
combined with profenofos with a synergistic ratio of 4.3
and 4.0, respectively. The lowest degree of synergism was
obtained in the case of 2-PAM when combined with
profenofos. In all cases the concentration of each drug
(antidote) was 10-4M).
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In conclusi..on, results of this 14ork ~3uggesL that
addition of 2-PAM; toxo~Sonin, atrop1ne or t,helr mixtures
to the spray formulation of profenofos 1ncreased its
toxicity to cotton leafworm and decreased its toxicity to
rats as a result of their protective effect to rat braJn
AChE. How·ever, more extra work is needed to make these
findings practically acceptable.