Comparative analysis of Polygonum hydropiper L. leaf extracts enhanced by ultrasound-thermal processing and its essential oil: Improvements in physicochemical and antifungal properties

• Extract and essential oil (EO) of Polygonum hydropiper were extracted and characterized. • GC-FID and GC-MS identified β-caryophyllene as main compound in the EO. • Ultrasound-induced heating enhanced extraction yield, total phenolics, flavonoid content, antioxidant, and antimicrobial properties. • FTIR peaks of ultrasound-treated extracts indicated preservation of functional groups. • SEM images illustrated irregular holes in microstructure of the ultrasound-treated extracts. Natural antioxidants originated from medicinal plants have garnered significant attention as potential substitutes for synthetic counterparts. This study aimed to extract essential oil (EO) and methanolic extracts from Polygonum hydropiper L. leaves using three distinct methods: maceration, ultrasound, and combined ultrasound with heating technique. GC-MS analysis of the EO identified 50 compounds, with β-caryophyllene (22.75 %) and drimenol (15.72 %) being the most prominent. The application of ultrasound combined with heating at 50 °C significantly enhanced extraction efficiency (13.50 % yield), total phenolic content (105.43 mg GAE/g DW), flavonoid compounds (9.67 mg QE/g DW), antioxidant activity (IC₅₀ = 7648.79 μg/mL for DPPH and 7833.88 μg/mL for ABTS), and antimicrobial efficacy (MIC = 11.7 μg/mL; MBC = 23.4 μg/mL against C. albicans ), surpassing the other methods. Ultrasound treatments, both independently and in conjunction with heating, increased the FTIR signal intensities of hydroxyl group-associated compounds, particularly phenolics, and led to irregular cavities within the cellular microstructure of the extracts, as observed via scanning electron microscopy. The findings of this study suggest that ultrasound, especially when combined with heating, offers a favorable procedure for efficiently extracting bioactive compounds from plants.