Optimization of Eugenol Extraction From Piper betle Leaves Using Natural Deep Eutectic Solvents and Ultrasound‐Assisted Extraction

Abstract

Piper betle L. (Piperaceae) is a herbal plant used in Thai traditional medicine for its antifungal and antiallergic properties, particularly through topical application. This study aimed to optimize the extraction of Piper betle leaves using natural deep eutectic solvents to enhance the extraction efficiency of eugenol, the active compound in Piper betle leaves. Various types of hydrogen bond donors—including glycolic acid, lactic acid, malic acid, tartaric acid, ascorbic acid, and citric acid—were combined with a hydrogen bond acceptor, choline chloride, to prepare natural deep eutectic solvents. The results indicated that lactic acid was the most effective hydrogen bond donor for eugenol extraction. Subsequently, the choline chloride:lactic acid molar ratios, the natural deep eutectic solvent:water mass ratios, and ultrasonication times were varied. Results showed that the optimal conditions based on one‐factor‐at‐a‐time approach were a choline chloride:lactic acid molar ratio of 1:5, a natural deep eutectic solvent:water mass ratio of 2:1, and an ultrasonication time of 30 min. Under these conditions, the eugenol concentration reached 457.22 ± 21.68 µg/mL, compared to 224.76 ± 6.99 µg/mL when ethanol was used. In conclusion, this study successfully optimized the extraction of eugenol from Piper betle leaves using natural deep eutectic solvents. These findings suggest that natural deep eutectic solvents could be a more effective solvent for the extraction of eugenol.