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Quantitative structure-activity relationships for phosphoramidothioate toxicity in housefly
1Department of Veterinary Diagnostic Medicine and Minnesota Veterinary Diagnostic Laboratory, College of Veterinary Medicine, University of Minnesota, St Paul 55108, USA.
Summary
The spatial configuration and 3D structure of phosphoramidothioate (Ace) analogs significantly influence their inhibition of fly-head acetylcholinesterase (AChE). Molecular properties like steric and electronic factors are key determinants of Ace analog toxicity in houseflies.
Area of Science:
- Biochemistry
- Toxicology
- Medicinal Chemistry
Background:
- Acetylcholinesterase (AChE) is a crucial enzyme in the nervous system.
- Phosphoramidothioate (Ace) analogs are known inhibitors of AChE.
- Understanding structure-activity relationships is vital for developing targeted inhibitors.
Purpose of the Study:
- To establish quantitative structure-activity relationships (QSAR) for phosphoramidothioate (Ace) analogs.
- To investigate the influence of molecular structure on Ace analog inhibition of fly-head AChE.
- To determine the factors governing the toxicity of Ace analogs in houseflies.
Main Methods:
- Formulation of quantitative structure-activity relationships (QSAR).
- Analysis of inhibition kinetics (k(i)) for Ace analogs against fly-head AChE.
- Correlation of inhibition constants with steric (e.g., sterimol indices L1, B1, B3, Ebend) and electronic parameters.
- Assessment of LD50 values and their correlation with electronic, topological, and steric properties.
Main Results:
- The spatial configuration of Ace analogs dictates their inhibitory potency against fly-head AChE.
- Specific 3D interactions, including the P-O(-) group with the oxy-anion hole and NH2+ group with the H-bonding site, are crucial for potent inhibition.
- Inhibition constants (k(i)) for Ace II and Ace IV correlated with various sterimol indices, dispersion, H-bond donor capacity, and dihedral angles.
- The LD50 of Ace analogs in houseflies was primarily governed by electronic, topological, and steric properties, with hydrophobic interactions having minimal or negative effects.
Conclusions:
- The 3D characteristics of substituents and molecular charge are critical determinants of fly-head AChE inhibition by phosphoramidothioates.
- Toxicity of Ace analogs in houseflies is significantly influenced by their physicochemical properties.
- QSAR provides a valuable framework for predicting and designing novel Ace analogs with specific inhibitory and toxicological profiles.