solvent-free synthesis and antifungal activity of 3-alkenyl oxindole derivatives

A simple, efficient, and environmentally benign green approach was developed for the synthesis of 3-alkenyl oxindole derivatives with effective antifungal properties. the targeted compounds (3a-3g) were synthesized by using knoevenagel condensation with oxindole and substituted aromatic aldehydes in the solvent-free, microwave-assisted reaction conditions. silica extracted from rice husk waste was functionalized with (3-aminopropyl) triethoxysilane (aptes) to use as an eco-friendly, reusable, and solvent-free reaction medium. the structures of the final products were confirmed by their melting points, ir, 1h-nmr, 13c-nmr, and elemental analysis. the desired products were isolated with 72-88% yields in 12 minutes. the in vitro antimicrobial activity against atcc standard cultures of human pathogenic candida species, clinical isolates of candida albicans, and several gram-positive and gram-negative bacteria were investigated and reported. all the synthesized 3-alkenyl oxindole derivatives exhibited the selective antifungal properties with the minimum inhibitory concentration (mic) values ranging from 2 μg/ml to 125 μg/ml against tested candida species. the findings of this study emphasized that green synthesized 3-alkenyl oxindole derivatives can be considered as the potential lead compounds to develop the effective antifungals against human pathogenic candida species.