α-Acids and β-acids, two main components of hop resin, are known to be susceptible to oxygen and degraded during hop storage, although the oxidation products in stored hops have not been fully ...identified. In this study, we developed a high-performance liquid chromatography (HPLC) analysis method suitable for separation and quantification of the oxidation products. This HPLC analysis clearly proved, for the first time, that humulinones and hulupones are major products in oxidized hops. We are also the first to identify novel 4′-hydroxy-allohumulinones, suggested to be oxidative products of humulinones, by means of NMR spectroscopy and high-resolution mass spectrometry. Using the developed analytical method, changes in α- and β-acids and their oxidation products during hop storage were clearly revealed for the first time.
Beer is a complex alcoholic beverage made from barley (malt), hop, water and yeast. Phenolic constituents of beer are derived from malt (70–80%) and hop (20–30%). Structural classes include simple ...phenols, benzoic- and cinnamic acid derivatives, coumarins, catechins, di-, tri- and oligomeric proanthocyanidins, (prenylated) chalcones and flavonoids as well as alpha- and
iso-alpha-acids derived from hop. Compounds belonging to different structural classes have distinct profiles of biological activity in
in vitro test systems, and in combination might lead to enhanced effects. Scientific evidence has accumulated over the past 10 years pointing to the cancer preventive potential of selected hop-derived beer constituents,
i.e., prenylflavonoids including xanthohumol and isoxanthohumol, and hop bitter acids. Chemopreventive activities observed with these compounds relevant to inhibition of carcinogenesis at the initiation, promotion and progression phases, as well as results from
in vivo studies on metabolism, bioavailability and efficacy are summarised in this review.
•Degradation mechanisms of xanthohumol in Humulus lupulus L. revealed.•Explored xanthohumol's instability under different storage conditions.•Differentiated xanthohumol, isoxanthohumol, and related ...products.•Established kinetic model aids xanthohumol degradation insights.
Xanthohumol (XN), possessing potent physiological activity, is exclusively derived from hops (Humulus lupulus L.) and exhibits high instability. However, its inherent instability often results in degradation during storage, leading to a decline in its activity due to the formation of various products. This study aimed to explore the stability of XN in beer under different storage conditions, establish or clarify degradation kinetic models, and understand the degradation mechanism. Our findings revealed that XN would degrade rapidly when exposed to high temperature and light. Its degradation followed a first-order kinetic model, involving reactions such as isomerization, hydration and ortho-position cyclization, resulting in the formation of five products. These insights shed light on the factors and mechanisms underlying the instability and degradability of XN, serving as a foundation for the development of a stable beer product enriched with functional XN.
Bioactive compounds extracted from plant are of great value for those enterprises interested in the use of natural products; plant tissue culture techniques guarantee a reliable and constant biomass ...production. Hop (
Humulus lupulus
L.), with its wealth in bioactive compounds, may represent an invaluable resource. The present study focused on the characterization of
vitro
-derived leaves and roots of two hop plant types, Cascade and Gianni. Extracts obtained from the selected hop explants were investigated, determining their polyphenolic content as their antioxidant capacity, applying DPPH, ABTS and FRAP assays; moreover, extract molecular profile was obtained through UHPLC-MS/MS. Results confirm the wealthy in bioactive compounds and the antioxidant properties of the tested
vitro-
derived hop explants. The qualitative characterization of
vitro
-derived hop tissue extracts evidenced the presence of twenty one different compounds, already identified in open field grown hop plants, such as polyphenols,
α
- and
β
-acids, as well as xanthohumol and isoxanthohumol. The obtained outcomes lay the groundwork to further investigate the potential of
vitro
-derived hop plantlets as bioactive compounds source.
Graphical abstract
Key message
Characterizing and recovering secondary metabolites from micropropagated hop plantlets.
In order to screen for the bitter compounds generated from hop-derived precursors during the wort boiling process, an ethanolic hop extract was fractionated; the fractions obtained were thermally ...treated under model wort boiling conditions and, then, sensorially evaluated for their bitterness. Besides the isomerisation of the alpha-acids into the intensely bitter iso- alpha-acids, the bitterness of the fraction containing the beta-acids was also found to be enhanced after wort boiling. To gain first insights into the beta-acid-derived bitter compounds, the beta-acid colupulone was isolated, thermally treated under wort boiling conditions and, then, investigated for bitter tasting degradation products by means of a taste dilution analysis (TDA). Besides the cohulupone, five previously unreported bitter-tasting colupulone degradation products, all of which exhibited a lingering, beta-acid-like bitter taste with low recognition thresholds between 37.9 and 90.3 micromol/l, were isolated and their structures determined as two tricyclocolupone epimers, two dehydrotricyclocolupone epimers, and nortricyclocolupone, respectively, by means of LC-TOF-MS and 1D/2D-NMR spectroscopy.
O ácaro-rajado é uma praga polífaga que ataca diversas culturas, entre elas o lúpulo, cultura para a qual no Brasil ainda não existem defensivos registrados. Como uma alternativa para o manejo dessa ...praga, destaca-se o emprego de óleos essenciais. Diante disso, os objetivos deste trabalho foram identificar a composição química e avaliar os efeitos do óleo essencial de alecrim na mortalidade de ácaro-rajado em lúpulo. Fêmeas adultas do ácaro-rajado foram submetidas a câmaras de fumigação contendo o óleo essencial de alecrim nas concentrações de 5, 10, 15 e 20 μL/L, durante 24, 48 e 72h. Na análise contabilizou-se a mortalidade e a fecundidade das fêmeas de ácaro. Os principais compostos identificados através da caracterização do óleo essencial de alecrim foram a cânfora, 1,8-cineol, α-pineno e β-mirceno. Por meio do teste de fumigação foi verificado que o óleo essencial de alecrim apresentou ação acaricida, sendo que as maiores taxas de mortalidade foram encontradas nas concentrações de 15 e 20 μL/L. Quanto maior a concentração do óleo na câmara, menor era o número médio de ovos nas folhas, devido à mortalidade das fêmeas.
•Humulus lupulus L. extract reduces carrageenan-induced inflammatory hyperalgesia.•Humulus lupulus L. extract modulate inflammation via increases the activity of antioxidant enzymes.•Humulus lupulus ...L. extract reduces the lipid peroxidation.
Hops (Humulus lupulus L.) are widely utilized worldwide as a raw material for various medical applications due to their numerous beneficial health effects. This study aimed to assess the potential neuroprotective effects of hop extract on cerebral oxidative markers and pain using rat models. In the experimental study, rats were divided into five groups and administered varying doses of Humulus lupulus L. extract (HLE) for a period of 15 days prior to the administration of carrageenan. To induce acute inflammation in rats, carrageenan (1 %) was injected into the sub-plantar region of the left paw. Subsequently, analgesic responses, the antioxidant activity and lipid peroxidation in the cerebral cortex were assessed. In the investigation of pain tolerance caused by inflammation in the hot plate test, the HLE treatment groups as exhibited a significant increase (P < 0.001) in delay time for removing the paw from the hot plate compared to the carrageenan group. The results demonstrate that HLE treatment significantly increased the activity of CAT (P < 0.001) and SOD (P < 0.01) enzymes, while decreasing the level of MDA (P < 0.01). It can be concluded that the consumption of hops may alleviate pain caused by inflammation and mitigate cerebral oxidative stress in rats.
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•Xanthohumol has several pharmacological properties of interest for human health.•Female inflorescences of Humulus lupulus (Hops) are the natural source of xanthohumol.•Emerging ...technologies have been investigated to increase xanthohumol extraction yield.•Hot trub and spent hops, by-products from beer brewing, can be sources of xanthohumol.
Xanthohumol, a chalcone unique to hops, has attracted attention from researchers due to its several pharmacological effects on humans. In industry, hops are almost exclusively used in beer production, generating tons of solid waste – hot trub from the boiling step and spent hops from the dry hopping – rich in biocompounds, among them xanthohumol, that could be recovered and used for several nutritional purposes. The literature is extensive on extraction processes of xanthohumol directly from hops, but only a few studies present its recovery from brewery solid waste. We focus on presenting the xanthohumol characteristics and benefits for human consumption, and discuss the main extraction techniques, their advantages and limitations, to prospect strategies to recover this high-value compound from brewing solid waste. Recent extraction processes represent promising approaches to overcome the limitations of conventional methods, but further studies are still needed to understand xanthohumol extraction and purification and induce industrial upscaling.
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•Hop is an important ingredient for brewing mainly due to its bitterness and aromatic flavor features.•Humulones and Lupulones, also known as - and -acids, are some of the most ...valuable hop compounds.•High performance liquid chromatography is the most used separation technique for bitter acids determination.•Capillary electrophoresis has emerged as a faster and greener alternative to chromatography for bitter acids determination.•Analytical methods for hop acids determination, by LC and CE, are summarized and discussed.
Hop plays an essential role in brewing beer and its study and analysis is of paramount importance. - and -acids are considered two of the most important hop components. While -acids are associated with the bitter flavor, -acids have antimicrobial effects. This work aims to critically review the published analytical methods for - and -acids determination in hops employing separation methods in liquid medium: liquid chromatography (LC) and capillary electrophoresis (CE). The types of hop samples, the optimized protocols to extract the hop acids, and the main instrumental conditions for both LC and CE techniques are highlighted and discussed. Specific and critical aspects of the - and β-acids separation by LC and CE and some challenges in this field are raised. Several key aspects discussed in this review may be of practical importance for brewers, whether in the microbrewery or industry and for researchers in the brewing field.
