Quantitative structure-activity relationship of organophosphate compounds based on molecular interaction fields...

Area of Science:

• Computational chemistry
• Toxicology
• Structure-activity relationship studies

Background:

• Organophosphate compounds (OP) are widely used pesticides.
• Understanding the toxicity mechanisms of OP is crucial for risk assessment.
• Quantitative structure-activity relationship (QSAR) studies can predict compound toxicity based on molecular structure.

Purpose of the Study:

• To develop a QSAR model for predicting the 24-hour acute toxicity of 35 organophosphate compounds against the housefly (Musca nebulo L.).
• To identify key molecular descriptors influencing OP toxicity.
• To elucidate the interaction mechanisms between OP compounds and acetylcholinesterase (AChE).

Main Methods:

• Multi-block partial least-squares (MBPLS) regression was employed.
• Molecular Interaction Fields (MIF) descriptors were generated using O, N, and DRY probes.
• Block Unscaled Weights (BUW) normalization technique was applied.
• Leave-one-out cross-validation was used to assess model performance.

Main Results:

• A robust QSAR model was developed with R(2)=0.995 and Q(2)=0.965.
• The model identified hydrogen bonding (O and N probes) and hydrophobicity (DRY probe) as significant contributors to toxicity.
• Block Importance in Prediction (BIP) values indicated high importance for all probes.

Conclusions:

• QSAR modeling using MIF descriptors provides valuable insights into OP toxicity mechanisms.
• Hydrogen bonding interactions between OP and AChE, along with hydrophobicity, are critical for toxicity.
• This approach can aid in designing safer OP compounds and understanding ligand-receptor interactions.