Pressurized liquid extraction and characterization of yacon leaf extracts under different solvent and temperature conditions

This study aimed to evaluate extracts obtained from yacon (Smallanthus sonchifolius) leaves using Pressurized Liquid Extraction (PLE) and Subcritical Water Extraction, two emerging green technologies for the sustainable production of bioactive extracts. Dried and ground yacon leaves were used as raw material. Extractions were performed using different solvents (water, 25 %, 50 %, 75 %, and 100 % ethanol) and temperatures (60, 90, and 120 °C), with additional water-only conditions at 110, 130, and 150 °C. The extracts were evaluated for global yield, total phenolic content, phenolic profile, antioxidant capacity (ORAC and FRAP assays), protein content, in vitro anti-inflammatory activity, and antimicrobial activity. PLE was compared with the conventional Soxhlet extraction, which operates at the boiling point of the solvent, whereas PLE allows higher temperatures while maintaining the solvent in a liquid state under pressure. Higher temperatures and ethanol fractions up to 50 % resulted in greater yields, higher recovery of phenolic compounds, and enhanced antioxidant activity, with a strong positive correlation between total phenolics and antioxidant capacity. Major phenolics identified included caffeic acid, glucaric acid, quercetin-O-hexoside, and kaempferol derivatives. Five extracts showed anti-inflammatory activity. Regarding antimicrobial activity, inhibition of Lactococcus lactis ATCC 19435 was observed, with evidence of minimum inhibitory concentrations. Additionally, an anti-quorum sensing effect was noted Against Chromobacterium violaceum LS01. These findings suggest that yacon leaves are a promising source of bioactive compounds for potential applications in the food, pharmaceutical, and cosmetic industries, and that PLE is an efficient method for their recovery.