Quantitative Structure Activity Relationship Study for Antifungal Activity of Aryl Aldehydes

Twenty three differently substituted aryl aldehydes were evaluated in vitro for fungicidal activity against three fungi viz. Rhizoctonia solani, Sclerotium rolfsii and Fusarium oxysporum. Few of these aldehydes exhibited good activity. Among all, the 2-Cl substituted aldehyde (ED₅₀=100 μg ml⁻¹) against R. solani, 2-OH (ED₅₀=143 μg ml⁻¹) against S. rolfsii and 3-NO₂ (ED₅₀=185 μg ml⁻¹) against F. oxysporum exhibited the highest fungicidal activity.The quantitative structure activity relationship (QSAR) study using the in vitro fungicidal activity data and physico-chemical parameters of benzene ring substituents for hydrophobic, electronic and steric properties by means of multiple regression analysis has revealed that the fungicidal activity of aryl aldehydes against R. solani and F. oxysporum was dependent on position dependent steric effect and against S. rolfsii on hydrophobicity and electronic effect of aryl substituents. The fungicidal activity against F. oxysporum besides the position dependent steric effect also depended on the electronic effect of aryl substituents.