# Optimal Extraction of Antioxidants, Flavonoids, and Phenolic Acids from the Leaves of Apocynum venetum L. by Response Surface Methodology with Integrated Chemical Profiles and Bioactivity Evaluation

## TL;DR

This study optimizes the extraction of antioxidants from Apocynum venetum leaves using advanced methods to maximize flavonoid and phenolic acid yields and antioxidant activity.

## Contribution

A novel extraction optimization using RSM and advanced analytical techniques to enhance antioxidant compound recovery from A. venetum leaves.

## Key findings

- Optimal extraction conditions: 64% ethanol, 20 min, 16:1 mL/g liquid-to-solid ratio.
- Yields of phenolic acids and flavonoids matched predicted values within 95% confidence.
- Optimized extracts showed stronger antioxidant activity than conventional methods.

## Abstract

The leaves of Apocynum venetum L. (A. venetum L.) are a functional food that plays an important role in antioxidation due to its high content of flavonoids and phenolic acids. Therefore, the extraction process of leaves of A. venetum L. is closely related to their activity. In this study, ultra-high-performance liquid chromatography (UHPLC) coupled with diode array detector (DAD), electrospray ionization (ESI), and quadrupole time-of-flight mass spectrometry (QTOF/MS) techniques has been established for qualitative and quantitative analysis of three phenolic acids and six flavonoids in the leaves of A. venetum L. Ultrasonic-assisted extraction conditions for the maximum recovery of phenolic and flavonoid compounds with a high antioxidation effect were optimized by response surface methodology (RSM). The optimum extraction conditions were as follows: ethanol concentration 64%, extraction time 20 min, and liquid-to-solid ratio 16:1 mL/g. The yields of three phenolic acids and six flavonoids under the optimal process were found to be 8.932 ± 0.091 and 20.530 ± 0.198 mg/g, respectively, which matched with those predicted (8.751 and 20.411 mg/g) within a 95% confidence level. Antioxidant activities based on ABTS and DPPH assays showed that the optimal extracts had strong activities compared with those of conventional reflux extraction methods. Moreover, the contribution of total and individual phenolic acids and flavonoids to antioxidant activity was also estimated by Pearson correlation analysis.