Comparative evaluation of ultrasound, enzyme, microwave and solvent-assisted extraction of flavonoids in nephrolepis cordifolia (l.) C. Presl

Abstract

Flavonoids are bioactive secondary metabolites with diverse pharmacological properties, including antioxidant, anti-inflammatory, and antimicrobial activities. Their efficient recovery from plant sources is essential for pharmaceutical, cosmetic, and nutraceutical applications. This study compared four extraction techniques, namely, ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE), enzyme-assisted extraction (EAE), and conventional solvent extraction, for the isolation of flavonoids from the bulbils of Nephrolepis cordifolia. Ethanol was used as the extraction solvent, and yields were quantified as quercetin equivalents using UV-VIS spectrophotometry. TLC analysis confirmed flavonoid fractions, while antioxidant activity was assessed using the hydrogen peroxide scavenging assay. The results demonstrated significant differences among the methods: UAE yielded the highest flavonoid concentration (23.5 mg/L) and antioxidant activity (47.5%), followed by EAE (17.0 mg/L) and 36.3% antioxidant activity. MAE had (13.3 mg/L), and 31.3% antioxidant activity, and solvent conventional solvent extraction yielded (8.0 mg/L) and an antioxidant activity of 15%. The UAE, MAE, and EAE reduced solvent consumption by approximately 66.7% and isolated higher yields compared to conventional solvent extraction, underscoring their alignment with green chemistry principles. The null hypothesis was rejected, confirming that the extraction efficiency and bioactivity are method-dependent. This research establishes UAE as the most effective and sustainable technique for recovering flavonoids from N. cordifolia, combining high yield with enhanced antioxidant activity and reduced environmental impact. The findings contribute to the advancement of eco-conscious phytochemical extraction workflows and provide a methodological framework for industrial-scale applications in pharmaceutical and nutraceutical development.