Synthesis and Antifungal Activity of Citral Oxime Esters against Two Phytopathogenic Fungi Rhizoctonia Solani and Sclerotium Rolfsii

Citral, the major bioactive constituent of citrus essential oil has been converted to its oxime and oxime ester derivatives following reaction of citral oxime with different acid chlorides. The structures of the resultant oxime esters were established by NMR and ESI-mass Spectroscopy. Citral, citral oxime and citral oxime esters were evaluated for their antifungal activity against two phytopathogenic fungi Rhizoctonia solani and Sclerotium rolfsii by poisoned food technique. Most of the esters in general were more active than the parent citral or citral oxime. Among the various compounds citral oxime N-O-propanoyl ester and citral oxime N-O-nonanoyl ester with respective EC₅₀ of 292 mg mL⁻¹ and 257 mg mL⁻¹ against S. rolfsii and R. solani, respectively, were found to be most effective.