# Linking Global Antioxidant Assays with Targeted HPLC Profiling of Prenylated Flavonoids in Humulus lupulus L. Extracts Obtained by Accelerated Solvent Extraction

## TL;DR

This study explores how global antioxidant tests relate to specific flavonoid compounds in hop extracts, showing that extraction temperature strongly affects results.

## Contribution

The study reveals that global antioxidant assays only partially reflect changes in specific prenylated flavonoids, emphasizing the need for combined analytical approaches.

## Key findings

- Global antioxidant parameters are strongly correlated but only moderately linked to specific flavonoids.
- Extraction temperature significantly influences compound-specific responses not captured by global assays.
- Combining global and targeted analysis improves understanding of hop extract quality and extraction optimization.

## Abstract

Accelerated solvent extraction (ASE) is widely used for recovering bioactive compounds from hops; however, the extent to which global antioxidant assays reflect changes in molecular composition remains unclear. This study evaluated the relationship between global antioxidant parameters and targeted profiling of prenylated flavonoids in hop extracts obtained under different ASE conditions. Total antioxidant capacity (TAC), total phenolic content (TPC), and concentrations of xanthohumol, isoxanthohumol, and 8-prenylnaringenin were determined in extracts prepared using different solvents, extraction temperatures, and homogenization approaches. Global antioxidant parameters responded consistently to technological factors and exhibited a strong mutual correlation. In contrast, their correlations with individual prenylated flavonoids were moderate, indicating that global assays capture only part of the variability associated with specific bioactive compounds. Extraction temperature emerged as a key modulating factor, inducing compound-specific and partly non-linear responses that were not fully reflected by global antioxidant methods. Principal component analysis confirmed a shared chemical trend linking global and targeted parameters while separating extraction temperature as an independent technological driver. Overall, global antioxidant assays provide a robust but simplified assessment of hop extract quality. Their combination with targeted chromatographic analysis enables more accurate interpretation of extraction behavior and supports informed process optimization aimed at preserving and recovering bioactive compounds.