Extraction Behavior and Quantitative Profiling of Prenylated Flavonoids from Hops (Humulus lupulus L.) Under Varying Solvent Polarity, Temperature, and Cryogenic Pretreatment

Abstract

Prenylated flavonoids from hops (Humulus lupulus L.) represent a distinctive class of bioactive compounds with notable antioxidant and health-promoting properties. This study investigated the extraction behavior and quantitative profiles of three major prenylflavonoids—xanthohumol (XN), isoxanthohumol (IXN), and 8-prenylnaringenin (8-PN)—under varying solvent polarity (ethanol vs. methanol), extraction temperature (50–200 °C), and sample pretreatment (mechanical vs. cryogenic homogenization). Extractions were performed using accelerated solvent extraction (ASE), and compounds were quantified by HPLC-DAD. Ethanol exhibited higher extraction efficiency than methanol, while cryogenic pretreatment markedly enhanced the release of all target analytes. The maximum recovery was achieved at 150 °C for XN, 200 °C for IXN, and 100 °C for 8-PN. Multifactor statistical analysis (MANCOVA, ANOVA) confirmed significant effects of solvent, temperature, and pretreatment, as well as their interactions (p < 0.001). The combination of ASE and cryogenic homogenization enables efficient isolation and precise quantification of prenylated flavonoids from hops, providing a valuable analytical framework for the development of standardized hop extracts and bioactive formulations.