Green ultrasound-assisted extraction of bioactive compounds from Alternanthera sessilis leaves

Abstract Alternanthera sessilis is a traditional edible and medicinal plant with potential as a source of bioactive compounds. This study provides an initial and innovative assessment of ultrasound‑assisted extraction using green solvents, ethanol and palm olein, for the recovery of phytochemicals and antioxidant activity from its leaves. Extraction conditions were evaluated through a one variable at a time approach under 23 experimental conditions, considering ultrasound intensity, ethanol concentration, solvent composition, particle size, temperature and extraction time. The resulting data were further examined using principal component analysis, multiple linear regression, and partial least squares regression. The best extraction performance was obtained with 70% ethanol, ethanol: palm olein (1:1), 60 mesh particle size, 9.5 W cm⁻², 25 °C and 10 min. Under these conditions, the contents of phenolics (6.42–37.47 mg GAE/g), flavonoids (4.23–40.81 mg CAT/g), tannins (83.85–263.40 mg CAT/g), and saponins (25.89–387.12 mg DIO/g), increased markedly, accompanied by substantial improvements in antioxidant capacity (4.27 to 225.12 µmol TE/g and 25.29 to 232.10 mg GAE/g). All solvents showed environmental performance (AGREE) with scores between 0.63 and 0.54 (palm olein> EtOH: palm olein (1:1)> EtOH). The extracts also showed strong scavenging activity against H₂O₂, NO•, and HO• radicals, as well as antimicrobial activity, especially against Gram positive bacteria. Multivariate analysis indicated that ultrasound intensity was the most influential extraction parameter, while the regression models showed good predictive ability. Taken together, these findings indicate that ultrasound assisted extraction combined with green solvents is a rapid and promising strategy for enhancing the recovery of bioactive compounds from Alternanthera sessilis leaves, providing a useful foundation for future optimization studies.