Research Article: Unexpected formation of N′-phenyl-thiophosphorohydrazidic acid O,S-dimethyl ester from acephate: chemical, biotechnical and computational study

Date Published: December 23, 2015

Publisher: Springer Berlin Heidelberg

Author(s): Vijay Kumar, Sukhmanpreet Kaur, Simranjeet Singh, Niraj Upadhyay.


By the nucleophilic attack of phenylhydrazine on acephate in aqueous medium, a stable product N′-phenyl-thiophosphorohydrazidic acid O,S-dimethyl ester (1) was obtained and characterized by elemental, spectral and thermal analysis. Thermodynamic parameters, Ea, ΔH°, ΔS° and ΔG°, have found to be 62.15, −67.95, −0.068 and −20.05 kJ mol−1 according to the Coats–Redfern equation. Analysis of interaction of 1 with BSA protein was done by using the UV–Vis and FTIR spectroscopic methods. The observed binding constants was 1.12 (±0.09) × 104 M−1. The biological effect of 1 was checked on different plant growth-promoting (PGPR) strains such as Rhizobiumleguminosarum, Pseudomonasfluorescens, Arthrobactercitreus, Bacillusbrevis and Salmonellatyphimurium and compared with parent molecule acephate where 1 has shown less toxicity against PGPRs as compared to acephate. The experimental results for geometric parameters and values of peak position in IR spectra have found to match excellently with the computational studies performed by GAMESS software package. Theoretically, twelve new analogs of 1 were prepared and their comparative reactivity (HOMO–LUMO energy) and biodecomposition (on the basis of polarizability) is discussed.

Partial Text

All the contaminants including insecticides, nematodes and herbicides applied to crops reach to soil and influence the soil fertility by inhibiting the soil’s microorganisms. Moreover, plant protection has become necessary in order to increase the food production, and therefore, multiple and over use of pesticides are called necessary evil (David 1998; Krämer 2007; Prasad et al. 2013; Wasim et al. 2009). Pesticides are considered to be an integral part of modern agriculture. So the topics such as green decomposition, production of less toxic and green pesticides are the prime most requirements of current era.

Phenylhydrazine binds with acephate through nucleophilic attack on it. The obtained product neutralized toxic effect of acephate on plant growth-promoting strains. The binding of 1 to BSA protein and interactions with PGPR strains may not be expected to explain the toxicity directly, but it can serve as a model to study the effect of 1 and other pesticides on proteins and microorganisms. A combined experimental and computational study was developed with the aim of evaluating and understanding the structural, energetic and stability of 1.

Acephate is an organophosphate pesticide that inhibits the activity of cholinesterase. Direct contact with this should be avoided. Work performed with this pesticide in the open should take place in a fume hood using gloves and eye protection.




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