Abstract:
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 Grampositive 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.
