Hops (Humulus lupulus) – Bitter Compounds and Prenylflavonoids as Key Markers for Quality Control

Hops are far more than just the classic flavouring agent in beer. Characteristic hop bitter compounds such as lupulone and colupulone, along with bioactive prenylflavonoids like xanthohumol, isoxanthohumol and 8-prenylnaringenin, make Humulus lupulus an analytically demanding and versatile medicinal and industrial plant.

For centuries, hops (Humulus lupulus) have been used both in brewing and as a medicinal plant. While their bitter compounds significantly influence the taste and stability of beer, hop extracts are today increasingly used in food supplements and herbal medicines. Due to its complex phytochemical profile, hops rank among the more analytically challenging plant raw materials.

Among the analytically most relevant hop constituents are bitter compounds from the group of α- and β-acids as well as characteristic prenylflavonoids. These include lupulone and colupulone as well as xanthohumol, isoxanthohumol and 8-prenylnaringenin. In addition, hops contain characteristic prenylflavonoids such as xanthohumol, isoxanthohumol and 8-prenylnaringenin, which are attracting growing scientific interest due to their biological activities. The spectrum of constituents is complemented by characteristic sesquiterpenes such as α-humulene and further components of the essential oil.

The analytical examination of hop raw materials and extracts places high demands on methodology due to the structural diversity and in some cases similar chemical properties of the constituents. In particular, the identification and quantification of bitter compounds and prenylflavonoids by HPLC, UHPLC or LC-MS requires high-purity reference standards to ensure reliable results in identity testing, assay determination and quality control.

Whether for quality control of hop raw materials, standardisation of extracts, method development or stability studies, phyproof reference standards provide the foundation for precise analytical characterisation and reproducible results throughout the entire product lifecycle.