enzymes are widely used in industries. one of the function of enzyme is detoxification of harmful active ingredients in insecticides .

1. Presented by
Aanchal Joshi
18PBC003
MSc Biochemistry
St. Xavier’s College
(Autonomous) , Ahmedabad
Seminar on

2. •Active ingredients of insecticides
•Mode of usage
•Why to use enzymes?
•Phosphotriesterases
•Carboxylesterases
•Industrial applications

3. •Insecticides are pesticides that are formulated to kill, harm, repel or
mitigate one or more species of insect.
•Nowadays they are heavily produced and consumed in agriculture and
various other industries.
•Its direct or indirect application, such as pesticide drift, secondary
poisoning, runoff into local water bodies, or groundwater contamination
can lead to toxicity.
•They pose different levels of risk to non-target insects, people, pets and
the environment.
•Therefore it is very important to degrade these chemicals so that they do
not accumulate in food chain.

4. • ORGANOPHOSPHATES
• CARBAMATES
• PYRETHROIDS

6. Organophosphorus insecticides
Detoxification:
They are mainly detoxified through oxidation and hydrolysis. The two
main enzymatic groups involved are phosphotriesterases and
carboxylesterases.
Toxicity effect:
It causes non-reversible phosphorylation of esterases in the central
nervous system i.e. inhibition of acetylcholinesterase, which causes
over-stimulation of receptors.
Introduction:
These insecticides are esters or thiols derived from phosphoric,
phosphonic, phosphinic or phosphoramidic acid.

7. Carbamate insecticides
Introduction:
These insecticides are derived from carbamic acid
have the widest range of biocide activities & are very a polar
compounds. E.g. carbofuran and aldicarb.
Detoxification:
The main detoxification routes of carbamate insecticides are
hydrolysis and oxidation by CbEs.
Toxicity effect:
It interferes with the reproductive systems and foetal
development.

8. Pyrethroid insecticides
Introduction:
These are man-made pesticides similar to the natural pesticide
pyrethrum. E.g.. permethrin and cypermethrin
Detoxification:
The hydrolysis and cleavage by esterases of the ester bonds
Toxicity effect:
It has high affinity for Na+ channels and causes a prolonged channel
opening by binding to it thus causes changes in its functioning

9. Enzymes can tolerate environmental extremes better and work at
• Wide ph and temperature range
• High salt and solvent concentration which are often encountered in pesticide
production wastewaters.
• Soluble form
• Have low energy requirements
• Easy to control
• Have minimal environmental impact

10. •PTEs break the bond between the phosphorous atom and the releasing group.
•The presence of divalent cations or chelating agents & metal ion concentrations
affects its activity.
•High detoxification efficiency as one molecule of PTE can hydrolyse multiple
molecules of OP.
• Commonly used PTEs are-
diisopropylphosphorofluoridate (DFPase)
O-hexyl O-2,5- dichlorophenyl phosphoramidate (HDCPase)
paraoxonase

11. •These are members of the serine esterase superfamily.
•Carboxylesterases catalyze the addition of water to an ester group
producing a carboxylic acid and an alcohol
•Low detoxification efficiency then PTE, as it hydrolyses one molecule of
OP.
• They metabolises xenobiotics such as toxins or drugs.

12. Step 1
• Reversible acylation of a serine residue
present in the active centre of the enzyme.
Step 2
• Release of the alcohol moiety of the
carboxyl ester and of the corresponding
covalently acylated enzyme.
Step 3
• Acylated intermediate is hydrolysed by
nucleophilic attack of water that releases
carboxylic acid moiety.

13. •Widely used for indoor and agriculture purposes.
•In pharma industry used as therapeutic drugs in human and veterinary
medicine.
•Food industry.
•Pesticide- insecticide industry for bioremediation of waste materials &
biodegradation of insecticide.
•Detoxification of warfare arsenals by safe methods.
•In biotechnology industry as therapeutic agent e.g. in cancer gene
therapy.

14. •Sogorb, M. A., & Vilanova, E. (2002). Enzymes involved in the
detoxification of organophosphorus, carbamate and pyrethroid
insecticides through hydrolysis. Toxicology letters, 128(1-3), 215-228.
•Morais, S., Dias, E., & Pereira, M. L. (2012). Carbamates: human exposure
and health effects. The impact of pesticides, 21-38.
•www.cdc.gov/nceh/clusters/Fallon/organophosfaq.html
•Wheelock, C. E., Shan, G., & Ottea, J. (2005). Overview of
carboxylesterases and their role in the metabolism of insecticides. Journal
of Pesticide Science, 30(2), 75-83.