Solvent-dependent efficiency of conventional and ultrasound-assisted extraction methods for antioxidants from Khasia betel leaves

Khasia paan (Piper betle L.), traditionally cultivated by the Khasia community in Sylhet, is renowned for its antioxidant properties; however, studies on solvent-based extraction techniques remain limited. This study compared conventional extraction (CE) and ultrasound-assisted extraction (UAE) methods to evaluate the efficiency of five solvents—ethanol, methanol, acetone, ethyl acetate, and dimethylformamide (DMF)—at 50% and 80% concentrations for extracting antioxidant compounds. UAE was conducted in a sonication bath (40 kHz, 150 W, 60 min), while CE involved maceration in a shaking incubator for 6 h. In most cases, UAE significantly outperformed CE, yielding higher total phenolic content (TPC: 63.33 ± 3.21–164.6 ± 3.01 mg GAE/g), total flavonoid content (TFC: 4.25 ± 0.36–21.62 ± 2.52 mg QE/g), and DPPH radical scavenging activity (35.51 ± 2.25–81.37 ± 2.26%). DMF, acetone, and ethanol were the most effective solvents for TPC, TFC, and DPPH scavenging activity, respectively, while ethyl acetate consistently showed the lowest efficiency. UAE at 80% solvent concentration demonstrated superior extraction performance. Moreover, UAE required less energy and resulted in lower CO2 emissions compared to CE. Spearman’s correlation revealed a strong positive relationship between TPC and DPPH scavenging activity, confirming the contribution of phenolics to antioxidant potential. These findings underscore the efficiency and sustainability of UAE as a promising method for commercial-scale extraction of natural antioxidants and highlight the most effective solvent systems for maximizing antioxidant yield. Additionally, the findings support the potential of Khasia paan as a sustainable source of natural antioxidants suitable for functional foods, nutraceuticals, and clean-label preservative applications.