Compositional Phenolic Signatures of Antioxidant-Relevant Compounds in Hop (Humulus lupulus L.) Varieties and Local...

Hop (Humulus lupulus L.) cones are increasingly recognized as sources of phenolic compounds relevant to antioxidant-oriented applications beyond their traditional brewing role; however, genotype-dependent chemical diversity remains poorly characterized under South American cultivation. This study evaluated phenolic composition and antioxidant-related chemical signatures in 22 hop accessions, including commercial varieties and Chilean local ecotypes, cultivated under homogeneous conditions in southern Chile. Total phenolic content (TPC), total flavonoid content (TFC), and condensed tannins were determined using spectrophotometric assays, while phenolic acids, catechin, and prenylated flavonoids were quantified by HPLC. Antioxidant capacity was evaluated using the ORAC assay, and principal component analysis (PCA) was applied to integrate chemical variables. TPC ranged from 4051 to 8124 mg gallic acid equivalents/100 g dry weight, TFC from 655 to 3011 mg quercetin equivalents/100 g, and condensed tannins from 11.0 to 60.1 mg catechin equivalents/g. ORAC values ranged from 96,405 to 161,815 µmol Trolox equivalents/100 g dry weight, indicating substantial genotype-dependent variation. PCA explained 69.5% of total variance and revealed distinct phenolic composition patterns among genotypes. Pearson correlation analysis showed that antioxidant capacity was strongly associated with condensed tannins and total phenolic content, whereas total flavonoids were not significantly related to ORAC values. Prenylated flavonoids were negatively associated with antioxidant capacity, suggesting a limited contribution to peroxyl radical scavenging activity. These findings highlight the importance of phenolic subclass composition, particularly condensed tannins, in determining antioxidant capacity and support the selection of hop genotypes based on specific phenolic profiles for functional applications.