# Novel green solvent-in situ ultrasound synergistic extraction of phenolic acids from Lonicera japonica thunb

## TL;DR

A new green extraction method using ultrasound and a special solvent efficiently recovers phenolic acids from Lonicera japonica, outperforming traditional techniques.

## Contribution

The study introduces a novel ternary deep eutectic solvent combined with in situ ultrasound for enhanced extraction of bioactive compounds.

## Key findings

- The TDES-ISUSE method achieved a total yield of 90.66 ± 1.46 mg/g of phenolic acids, surpassing conventional methods.
- 19 compounds were identified, including seven phenolic acids, three flavonoids, and others.
- SEM and molecular dynamics confirmed improved cell-wall disruption and solvation in the TDES system.

## Abstract

A novel ternary deep eutectic solvent combined with in situ ultrasound–synergized extraction (TDES–ISUSE) was designed and implemented for the efficient recovery of four phenolic acids from Lonicera japonica Thunb. From twenty synthesized TDES formulations, the ternary system comprising choline dihydrogen citrate, lactic acid, and urea (Chd:Lac:Ure) demonstrated superior extraction performance. Process optimization via an integrated RSM–ANN–GA approach established the following optimal conditions: water content 37%, liquid/solid ratio 28 mL/g, ultrasound time 30 min, vortex time 12 min, and ultrasound power 240 W. The total yield of the four phenolic acids reached 90.66 ± 1.46 mg/g, significantly surpassing conventional extraction techniques. Chemical profiling by UHPLC–Q–TOF–MS in both positive and negative ionization modes led to the identification of 19 compounds, categorized as seven phenolic acids, three flavonoids, one iridoid, one terpenoid, five saponins, and two fatty acids, while a dedicated HPLC method was validated for quantitation of the four target phenolic acids. The characteristic FT–IR signatures corroborated the successful formation of the TDES. The enhanced cell–wall disruption was directly visualized by SEM, while molecular dynamics simulations elucidated the improved solvation of phenolic acids within the TDES system at the molecular level. Antioxidant assays further indicated notable radical–scavenging activity of the extract. Collectively, this study presents an efficient, environmentally benign, and reproducible strategy for the extraction of bioactive phenolic acids from L. japonica.