Shyamali Wijekoon - Department of Chemistry, University of Sri Jayewardenepura, Colombo, Sri Lanka
Chinthika Gunasekara - Department of Microbiology, University of Sri Jayewardenepura, Colombo, Sri Lanka
Lalinda Palliyaguru - Department of Chemistry, University of Sri Jayewardenepura, Colombo, Sri Lanka
Neluka Fernando - Department of Microbiology, University of Sri Jayewardenepura, Colombo, Sri Lanka
Pradeep Jayaweera - Department of Chemistry, University of Sri Jayewardenepura, Colombo, Sri Lanka
Upul Kumarasinghe - Department of Chemistry, University of Sri Jayewardenepura, Colombo, Sri Lanka

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.

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