Solvent-free synthesis and antifungal activity of ۳-alkenyl oxindole derivatives

A simple, efficient, and environmentally benign green approach was developed for the synthesis of ۳-alkenyl oxindole derivatives with effective antifungal properties. The targeted compounds (۳a-۳g) 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 (۳-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, ۱H-NMR, ۱۳C-NMR, and elemental analysis. The desired products were isolated with ۷۲-۸۸% yields in ۱۲ 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 ۳-alkenyl oxindole derivatives exhibited the selective antifungal properties with the minimum inhibitory concentration (MIC) values ranging from ۲ µg/mL to ۱۲۵ µg/mL against tested Candida species. The findings of this study emphasized that green synthesized ۳-alkenyl oxindole derivatives can be considered as the potential lead compounds to develop the effective antifungals against human pathogenic Candida species.

Keywords:

Microwave , Assisted Solvent , Free ۳ , Alkenyl Oxindole Derivatives Amino Functionalized Silica Antifungal Activity