Search

[Display omitted] • Utilization of brewers' spent grain (BSG), spent hops (SH) and spent yeast (SY). • BSG, SH, and SY applied as fillers for poly(ε-caprolactone) (PCL)-based composites. • The first direct connection between SH or SY and the polymer technology. • Composites' oxidative resistance enhanced by SY incorporation. • Compatibility of PCL-based composites enhanced by SY application. Beer is among the most popular beverages in the world, with the production distributed uniformly between the biggest continents, so the utilization of brewing by-products is essential on a global scale. Among their potential recipients, the plastics industry offers extensive range of potential products. Herein, the presented study investigated the application of currently underutilized solid brewing by-products (brewers' spent grain, spent hops, spent yeast) as fillers for highly-filled poly(ε-caprolactone)-based composites, providing the first direct connection between spent hops or spent yeast and the polymer composites. Comprehensive by-product characterization revealed differences in chemical composition. The elemental C:O ratio, protein content, and Trolox equivalent antioxidant capacity varied from 1.40 to 1.89, 12.9 to 32.4 wt%, and 2.41 to 10.24 mg/g, respectively, which was mirrored in the composites' structure and performance. Morphological analysis pointed to the composition-driven hydrophilicity gap limiting interfacial adhesion for high shares of brewers' spent grain and spent hops, due to high hydrophilicity induced by carbohydrate content. Phytochemicals and other components of applied by-products stimulated composites' oxidative resistance, shifting oxidation onset temperature from 261 °C for matrix over 360 °C for high spent yeast shares. Simultaneously, spent yeast also provided compatibilizing effects for poly(ε-caprolactone)-based composites, reducing complex viscosity compared to other fillers and indicating its highest affinity to poly(ε-caprolactone)due to the lowest hydrophilicity gap. The presented results indicate that the proper selection of brewing by-products and adjustment of their shares creates an exciting possibility of engineering composites' structure and performance, which can be transferred to other polymers differing with hydrophilicity. [ABSTRACT FROM AUTHOR]

Iron oxide nanoparticles (IONPs) have many practical applications, ranging from environmental protection to biomedicine. IONPs are being investigated due to their high potential for antimicrobial activity and lack of toxicity to humans. However, the biological activity of IONPs is not uniform and depends on the synthesis conditions, which affect the shape, size and surface modification. The aim of this work is to synthesise IONPs using a mixed method, i.e., chemical co-precipitation combined with biogenic surface modification, using extracts from spent hops (Humulus lupulus L.) obtained as waste product from supercritical carbon dioxide hop extraction. Different extracts (water, dimethyl sulfoxide (DMSO), 80% ethanol, acetone, water) were further evaluated for antioxidant activity based on the silver nanoparticle antioxidant capacity (SNPAC), total phenolic content (TPC) and total flavonoid content (TFC). The IONPs were characterised via UV-vis spectroscopy, scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS) and Fourier-transform infrared (FT-IR) spectroscopy. Spent hop extracts showed a high number of flavonoid compounds. The efficiency of the solvents used for the extraction can be classified as follows: DMSO > 80% ethanol > acetone > water. FT-IR/ATR spectra revealed the involvement of flavonoids such as xanthohumol and/or isoxanthohumol, bitter acids (i.e., humulones, lupulones) and proteins in the surface modification of the IONPs. SEM images showed a granular, spherical structure of the IONPs with diameters ranging from 81.16 to 142.5 nm. Surface modification with extracts generally weakened the activity of the IONPs against the tested Gram-positive and Gram-negative bacteria and yeasts by half. Only the modification of IONPs with DMSO extract improved their antibacterial properties against Gram-positive bacteria (Staphylococcus epidermidis, Staphylococcus aureus, Micrococcus luteus, Enterococcus faecalis, Bacillus cereus) from a MIC value of 2.5–10 mg/mL to 0.313–1.25 mg/mL. [ABSTRACT FROM AUTHOR]

World beer production generates large volumes of waste discharged with every brew. Recently, new methods of reducing and reusing hops waste: hot trub (HT), and brewer-spent hops (BSH) are being exploited to improve the circular economy processes. This review outlines the current achievements in the management of hops waste. Following an in-depth review of various scientific publications, current strategies are discussed as a sustainable alternative to food waste exploitation and an inexpensive source of valuable compounds. Moreover, key aspects concerning the nutritional value of hops waste and the potential to enhance the functional properties of food and beverages are highlighted. Due to their nutritional composition, hops residues may be used as prospective sources of added-value co-products or additives for food enrichment, especially for products rich in fat, or as a new source of vegetable protein.

Iron oxide nanoparticles (IONPs) have many practical applications, ranging from environmental protection to biomedicine. IONPs are being investigated due to their high potential for antimicrobial activity and lack of toxicity to humans. However, the biological activity of IONPs is not uniform and depends on the synthesis conditions, which affect the shape, size and surface modification. The aim of this work is to synthesise IONPs using a mixed method, i.e., chemical co-precipitation combined with biogenic surface modification, using extracts from spent hops (Humulus lupulus L.) obtained as waste product from supercritical carbon dioxide hop extraction. Different extracts (water, dimethyl sulfoxide (DMSO), 80% ethanol, acetone, water) were further evaluated for antioxidant activity based on the silver nanoparticle antioxidant capacity (SNPAC), total phenolic content (TPC) and total flavonoid content (TFC). The IONPs were characterised via UV-vis spectroscopy, scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS) and Fourier-transform infrared (FT-IR) spectroscopy. Spent hop extracts showed a high number of flavonoid compounds. The efficiency of the solvents used for the extraction can be classified as follows: DMSO > 80% ethanol > acetone > water. FT-IR/ATR spectra revealed the involvement of flavonoids such as xanthohumol and/or isoxanthohumol, bitter acids (i.e., humulones, lupulones) and proteins in the surface modification of the IONPs. SEM images showed a granular, spherical structure of the IONPs with diameters ranging from 81.16 to 142.5 nm. Surface modification with extracts generally weakened the activity of the IONPs against the tested Gram-positive and Gram-negative bacteria and yeasts by half. Only the modification of IONPs with DMSO extract improved their antibacterial properties against Gram-positive bacteria (Staphylococcus epidermidis, Staphylococcus aureus, Micrococcus luteus, Enterococcus faecalis, Bacillus cereus) from a MIC value of 2.5–10 mg/mL to 0.313–1.25 mg/mL.

Brewing generates large amounts of residues including barley malt rootlets, spent hops, and spent yeast. These residues are sustainable and rich sources of compounds with valuable nutritional and functional properties such as proteins, polyphenols, and polysaccharides. The growing scarcity of natural resources and the increasing unsustainability of waste management, in the context of a rising global population, stress the need for reusing these wastes. This requires the development of suitable methodologies to recover interesting compounds. This work reviews the characteristics of brewery residues, the methodologies employed for the recovery of their valuable compounds, their functionalities, and their potential applications. A special consideration was focused to those methods employing innovative and sustainable approaches such as the use of deep eutectic solvents, microwave-assisted extraction, pulsed electric fields, high intensity focused ultrasounds, pressurized liquids, and supercritical fluids. Key findings and conclusions : Despite the general use of conventional solid-liquid extraction, works using emerging techniques are becoming more usual. While the benefits of these techniques in relation to sustainability are clear, yields are not always as high as expected. Polyphenols and proteins were mostly extracted from barley malt rootlets, while spent hops are more appreciated for their polyphenols, especially xantohumol and essential oils, and spent yeast is rich in polysaccharides, especially β-glucan, proteins, fatty acids, and flavour enhancers nucleotides. Some of these compounds exert significant antioxidant, antiproliferative, and immunoactivity and are potentially interesting for the food, cosmetic or pharmaceutical industries. [Display omitted] • Malt rootlets, spent hops, and spent yeast from brewery are sources of valuable compounds. • They have been mainly recovered by conventional solid-liquid extraction. • Great efforts are recently performed to use emergent and more sustainable techniques. • Some compounds show antioxidant, antiproliferative, antiinflammatoty or immune activity. • β-glucan, proteins, polyphenols, and nucleotides show potential industrial applicability. [ABSTRACT FROM AUTHOR]

The main aim of this review was to check for the applicability of the concept of circular economy to brewing chain. By analyzing the beer brewing process, it was possible to identify the main brewery wastes formed and packaging materials used as well as their range of composition and yields. In order to reduce the contribution of packaging material to the carbon footprint of beer, it would be necessary to replace one-way containers used nowadays with lighter, reusable, or recycled ones. Even if the contribution of beer consumption phase was taken into account, there was no definitive solution about the less environmentally impacting beer packaging format. The direct management of polyethylene terephthalate (PET) packaging for liquid foodstuffs could make available 100% recycled PET flakes to be reconverted into food-grade bottles with minimum downcycling to other non-food usage. The countless potential uses of brewery wastes in nutritional and biotechnological fields were tested in laboratory by disregarding any cost–benefit or market analysis. This was mainly because the estimated market price of dried brewer’s spent grain (BSG) resulted to be about 450% higher than that of conventional lignocellulose residues. All the alternative uses hailed in the literature appeared to be more useful for publishing articles than for defining any economically feasible reusing procedure for all brewery wastes. Owing to their high moisture content, such wastes are so perishable as to prevent their safe usage in the human food chain. Currently, their use as-is in animal feeding is the disposal method not only economically feasible but also able to reduce the greenhouse gas load of beer packed in glass bottles (GB) by about one-third of that associated with packaging materials. Not by chance, it is practiced by most industrial and craft breweries. [ABSTRACT FROM AUTHOR]

Dry-hopping, which is the cold, aqueous extraction of hops into beer, has gained popularity in recent years as a method for achieving intense hop aroma and flavor in beer. With some brewers dry-hopping at rates up to 2 kg/hL (∼5 lb/barrel), considerable waste is generated in terms of both beer loss and spent hops. The retention of valuable volatile and non-volatile hop components within spent hops, as well as their extraction into beer, was investigated on both a pilot and industrial scale. On the pilot scale (80 L), an unhopped pale ale was statically dry-hopped with differing lots of whole cone Amarillo®, Centennial, and Cascade at a rate of 386 g/hL (1 lb/bbl) for 24 h at 13 °C (55 °F). Spent hop material was also collected from a local brewery that dry-hopped ∼60 hL (50 bbl) of beer at a rate of 1,592 g/hL (4.125 lb/bbl). Approximately one-third of the dry-matter composition of hops was lost during dry-hopping regardless of hop variety; however, there was high retention of both α-acids (77% pilot scale, 52% industrial) and hop essential oil (51% pilot scale, 33% industrial). The oil remaining in the spent hops was enriched in hydrocarbon compounds and depleted in oxygenated compounds. These results indicate that spent dry-hops contain considerable brewing value and have the potential for re-use. [ABSTRACT FROM AUTHOR]

Spent hop extract (SHE) is hypothesized to possess multifaceted anticoagulant effect and to reduce platelet reactivity in a direct manner and to improve the antiplatelet action of endothelium. The results demonstrated that SHE, rich in flavanols (50% of total phenolic compounds), hydroxycinnamic acids, proanthocyanidin oligomers, flavan-3-ol monomers, and flavonol glycosides, inhibited ADP-induced platelet aggregation up to 11% for 7.5 µg/ml or up to 23% for 15 µg/ml, P

Hop tannin extract (HTE), produced by ethanol extraction of hops, is a material with brewing potential. Fresh and oxidised hop tannin extracts (OHTE) made from spent hop material were tested for their ability to reduce lautering time. The filtration of wort supplemented with HTE took ~20% less time than the control wort. The active dose of HTE was between 0.5 and 1.25 mL/L of brewing water (10–25 mg of gallic acid equivalents/L). HTE accelerated filtration more than the previously used gallotannins. The efficiency of HTE was influenced by oxidation. The filtration rate of worts adjusted with OHTE increased by <15% relative to the control wort. A pilot scale experiment showed the suitability of HTE application at the beginning of mashing and the analysis of sweet worts showed that the use of HTE slightly increased foam stability, but had no effect on wort colour. The mechanism of lautering acceleration was partly revealed by filtration of Congress worts adjusted with antioxidants and haze forming polyphenols. The antioxidant properties of polyphenolic extracts played only a minor role in this effect, which is likely to be influenced by a combination of factors originating from the polyphenol composition of HTE. © 2018 The Institute of Brewing & Distilling [ABSTRACT FROM AUTHOR]

Hop cones (Humulus lupulusL.), very rich source of phenolic compounds, possessing anticancer, antioxidant and anti-inflammatory activities, are considered as beneficial diet ingredients improving human health. In this study, the antiplatelet action of xanthohumol (XN), the principal flavonoid in hop cones, was investigated. XN significantly attenuated ADP-induced blood platelet aggregation (97.2 ± 35.7 AU for 6 μg/ml of XNvs. 120.4 ± 30.1 AU for 0.17% dimethyl sulfoxide (DMSO),p < 0.001) and significantly reduced the expression of fibrinogen receptor (activated form of GPIIbIIIa) on platelets’ surface (47.6 ± 15.8 for 1.5 μg/ml XN, 44.6 ± 17.3% for 3 μg/ml XNvs. 54.5 ± 19.2% for control or 43.3 ± 18.4% for 6 μg/ml XNvs.49.7 ± 19.4% for 0.17% DMSO,p < 0.05 or less). These findings suggest that the phenolic compounds originating from hops (XN) have a novel role as antiplatelet agents and can likely be used as dietary supplements in prophylactic approaches. [ABSTRACT FROM AUTHOR]

Hop cones preparations possess a wide range of biological activities including antimicrobial properties. In this work, we evaluated the effect of various organic extracts obtained from spent hops, as well as six hops flavonoids and their twenty natural and synthetic derivatives on human and plant microbial pathogens. Methylene chloride, acetone, ethyl acetate, and methanol were used as extractants. Seven flavonoids, among them two natural (α,β-dihydroxanthohumol and 8-prenylnaringenin) showed significant activity against methicillin sensitive and resistant Staphylococcus aureus and Staphylococcus epidermidis strains with the lowest MIC80 value of 0.5 µg/mL. The crude ethyl acetate, acetone, and methanol extracts from the spent hops exhibited antifungal activity against Fusarium oxysporum, F. culmorum, and F. semitectum with the lowest MIC50 of 0.5 mg/mL, while the methylene chloride extract exerted antifungal activity against Botrytis cinerea with the MIC50 of 1 mg/mL. The preparation obtained after the removal of xanthohumol from the spent hops crude extracts retained up to 95% of activity. These findings suggest that various spent hops extracts may be effective agents for the control of plant pathogens of economic importance, like Botrytis cinerea and Fusarium oxysporum, while some compounds from spent hops or their derivatives may become useful for staphylococcal infections.

Synthesis of minor prenylflavonoids found in hops and their non-natural derivatives were performed. The antiproliferative activity of the obtained compounds against some human cancer cell lines was investigated. Using xanthohumol isolated from spent hops as a lead compound, a series of minor hop prenylflavonoids and synthetic derivatives were obtained by isomerization, cyclisation, oxidative-cyclisation, oxidation, reduction and demethylation reactions. Three human cancer cell lines—breast (MCF-7), prostate (PC-3) and colon (HT-29)—were used in antiproliferative assays, with cisplatin as a control compound. Five minor hop prenyl flavonoids and nine non-natural derivatives of xanthohumol have been synthetized. Syntheses of xanthohumol K, its dihydro- and tetrahydro-derivatives and 1″,2″,α,β-tetrahydroxanthohumol C were described for the first time. All of the minor hops prenyl flavonoids exhibited strong to moderate antiproliferative activity in vitro. The minor hops flavonoids xanthohumol C and 1″,2″-dihydroxanthohumol K and non-natural 2,3-dehydroisoxanthohumol exhibited the activity comparable to cisplatin. Results described in the article suggest that flavonoids containing chromane- and chromene-like moieties, especially chalcones, are potent antiproliferative agents. The developed new efficient, regioselective cyclisation reaction of the xanthohumol prenyl group to 1″,2″-dihydroxantohumol K may be used in the synthesis of other compounds with the chromane moiety.

[Display omitted] • 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. [ABSTRACT FROM AUTHOR]

Spent hop extract (SHE) is hypothesized to possess multifaceted anticoagulant effect and to reduce platelet reactivity in a direct manner and to improve the antiplatelet action of endothelium. The results demonstrated that SHE, rich in flavanols (50% of total phenolic compounds), hydroxycinnamic acids, proanthocyanidin oligomers, flavan-3-ol monomers, and flavonol glycosides, inhibited ADP-induced platelet aggregation up to 11% for 7.5 µg/ml or up to 23% for 15 µg/ml, P  <   0.05. Additionally, SHE ameliorated anticoagulant activity of human endothelial cells to significantly reduce platelet reactivity. This effect could be related to the increased expression/activity of the ecto-ADPase (CD39). ADP-induced platelet reactivity was reduced in the case of platelets incubated with the extract-treated endothelial cells compared to the untreated cells. Diabetic rats fed with SHE demonstrated longer survival time than the group treated with placebo. In conclusion, our study provided evidence for a potential beneficial role of SHE in the regulation of platelet and endothelial function. [ABSTRACT FROM AUTHOR]

There is a wide range of information available on by-product disposal methods used by large national breweries. However, little information is available on the methods of by-product disposal used by craft breweries. An investigation was carried out in which 200+ British craft brewers were contacted, of which 90 craft brewers provided basic information about their brewery operations and by-product disposal. Representatives of eleven breweries were interviewed to provide an in-depth case study of their by-product disposal methods. The research found that urban craft brewers use a wider range of disposal methods compared to rural craft brewers; urban brewers dispose of more waste through sewage and landfill, as well as using external companies, such as bio-recycling and anaerobic digester plants, whereas rural brewers have relationships with farmers who dispose of the by-products in various ways. Craft brewers tend to have a direct relationship with the by-product users. Even though they do not have all disposal options available to them which the large industrial breweries have, due to their small scale of by-product production, craft brewers appear to find alternative means of sustainability.

Spent hops is a waste produced in large amount by the brewing industry. Rhyzopertha dominica and Sitophilus granarius are insects that cause important economic losses of stored foods. In this study, for the first time, spent hops has been evaluated as a source of essential oil (EO) and chemicals with repellent activity against R. dominica and S. granarius. Spent hops EO yield was 0.11 %. The terpenes myrcene, α-humulene, and β-caryophyllene were its main components (47 %). Spent hops EO RD values were 0.01 and 0.19 μL cm for R. dominica and S. granarius, respectively. Among the chemicals, myrcene was able to exert the highest repellency against R. dominica (RD = 0.27 µM cm), while limonene was the most effective compound against S. granarius (RD = 0.89 µM cm). These results indicate spent hops as an excellent source of EO and chemicals to be utilized as low-cost, eco-friendly insect pests repellents in the protection of stored food. [ABSTRACT FROM AUTHOR]

Xanthohumol, a prenylated flavonoid from hops, and a supercritical carbon dioxide extract of spent hops were studied for their antifeedant activity against stored product insect pests: Sitophilus granarius L., Tribolium confusum Duv. and Trogoderma granarium Everts. Xanthohumol exhibited medium deterrent activity against the adults of S. granarius L. and larvae of T. confusum Duv. The spent hops extract was more active than xanthohumol towards the adults of T. confusum Duv. The potential application of the crude spent hops extract as a feeding deterrent against the stored product pests is proposed. [ABSTRACT FROM AUTHOR]

Abstract: The biotransformation of xanthohumol (1), a prenylated chalcone isolated from hops by selected fungi, was investigated. Microbial regioselective glycosylation at the C-4′ position led to xanthohumol 4′-O-β-d-glucopyranoside (2) and xanthohumol 4′-O-β-d-(4′′′-O-methyl)-glucopyranoside (3). The subsequent cyclization of 2 resulted in isoxanthohumol 7-O-β-glucopyranoside (4). The structures of the products were identified based on spectroscopic methods. The biological activity of isolated metabolites has been evaluated. Compared to xanthohumol (1), metabolite 2 is a better 2,2′-diphenyl-1-picrylhydrazyl (DPPH) radical scavenger, while 2 and 3 have stronger antiproliferative activity against the human HT-29 colon cancer cell line. [Copyright &y& Elsevier]

Abstract: The effect of enzymatic pretreatment of sugar beet pulp and spent hops prior to methane fermentation was determined in this study. These industrial residues were subjected to enzymatic digestion before anaerobic fermentation because of high fiber content (of 85.1% dry matter (DM) and 57.7% DM in sugar beet pulp and spent hops, respectively). Their 24h hydrolysis with a mix of enzymatic preparations Celustar XL and Agropect pomace (3:1, v/v), with endoglucanase, xylanase and pectinase activities, was most effective. Reducing sugars concentrations in hydrolysates of sugar beet pulp and spent hops were by 88.9% and 59.4% higher compared to undigested materials. The highest yield of biogas was obtained from the enzymatic hydrolysate of sugar beet pulp (183.39mL/d from 1g COD at fermenter loading with organic matter of 5.43g COD/L×d). Fermentation of sugar beet pulp gave 19% less biogas. Methane fermentation of spent hops hydrolysate yielded 121.47mL/d biogas from 1g COD (at 6.02g COD/L×d, 13% more than from spent hops). These results provide evidence that suitable enzymatic pretreatment of lignocellulosic wastes improve biogas yield from anaerobic fermentation. [Copyright &y& Elsevier]

Abstract: The research on degradation of hop bitter acids by Candida parapsilosis culture under various conditions is described. The effects of temperature and age of precultures were investigated. Supernatant of the precultures, growing cells and resting cells of the cultures were used for the tests. The highest levels of degradation were obtained in experiments performed in the light, at 40°C, using a 3-day-old preculture of the yeast. Efficiency of the degradation was determined by concentration of riboflavin in the C. parapsilosis culture. Commercial hop extract and spent hops were used in the experiments. [Copyright &y& Elsevier]

Hop pectins were extracted from spent hops using acid extraction conditions and were characterized chemically. The acid extraction of spent hops resulted in a yield of 2%, containing 59% of polysaccharides. The hop pectins under investigation had a relatively high molecular weight and an intrinsic viscosity comparable to that of commercially available apple and citrus pectins. The low degree of methyl esterification of these pectins implicates that they are mainly suitable for use in calcium gels. The degree of acetylation and the neutral sugar content were relatively high.A high molecular weight fraction which contained arabinogalactan-proteins was shown to be present in the hop pectin extract after preparative size-exclusion chromatography. Additionally, a fraction with a lower molecular weight was present containing mainly homogalacturonans. The arabinogalactans in the high molecular weight population consisted of (1→3)- and (1→3,6)-linked galactans highly branched with arabinose and galactose side-chains. The protein part of the arabinogalactan-protein (13%) was found to be rich in cystein, threonin, serinin, alanin, and hydroxyprolin. The molecular weight distribution of the hop pectin after degradation with the enzymes endopolygalacturonase plus pectin methyl esterase suggested that the arabinogalactan-protein present in the hop pectin extract was linked to the pectin and that the arabinogalactan-protein itself had a fairly low molecular weight. [Copyright &y& Elsevier]

• The use of choline chloride-based DESs allows extraction of xanthohumol from spent hops. • Xanthohumol–rich precipitates are obtained by adding water (antisolvent) to the DES extract. • The highest xanthohumol extraction yield was obtained using a DES composed of choline chloride and propylene glycol. • Optimization of the extraction conditions improved the xanthohumol extraction efficiency 3-fold. • DES could be recovered and reused at least three times without compromising the xanthohumol extraction yield. Spent hops (SH) are a rich source of the prenylated chalcone, xanthohumol (XN), which has a broad spectrum of biological activity. In this study, four choline chloride-based deep eutectic solvents (DESs), which contained glycerol, ethylene glycol, propylene glycol, or lactic acid as a hydrogen bond donor, were tested for the extraction of XN from SH. XN-rich precipitates were obtained by the addition of water (as an antisolvent) to the DES extracts. To determine the XN contents, the precipitates were extracted with methanol and then analyzed by HPLC. The highest XN extraction yield (2.30 mg/g SH) was obtained using a DES composed of choline chloride and propylene glycol (1:2 mol/mol) with 5 wt% water, 1:50 SH/DES (w/w), and 3:1 antisolvent/DES (v/w) at 60 °C for 1 h. This DES could be recovered and reused at least three times without significantly decreasing the XN extraction yield. Our results therefore demonstrated that DESs can be considered green, efficient, and promising solvents for the extraction of XN from SH. Moreover, the proposed simple DES-based method appears to be an effective alternative to conventional XN extraction methods. [ABSTRACT FROM AUTHOR]

Hop cones preparations possess a wide range of biological activities including antimicrobial properties. In this work, we evaluated the effect of various organic extracts obtained from spent hops, as well as six hops flavonoids and their twenty natural and synthetic derivatives on human and plant microbial pathogens. Methylene chloride, acetone, ethyl acetate, and methanol were used as extractants. Seven flavonoids, among them two natural (α,β-dihydroxanthohumol and 8-prenylnaringenin) showed significant activity against methicillin sensitive and resistant Staphylococcus aureus and Staphylococcus epidermidis strains with the lowest MIC80 value of 0.5 µg/mL. The crude ethyl acetate, acetone, and methanol extracts from the spent hops exhibited antifungal activity against Fusarium oxysporum, F. culmorum, and F. semitectum with the lowest MIC50 of 0.5 mg/mL, while the methylene chloride extract exerted antifungal activity against Botrytis cinerea with the MIC50 of 1 mg/mL. The preparation obtained after the removal of xanthohumol from the spent hops crude extracts retained up to 95% of activity. These findings suggest that various spent hops extracts may be effective agents for the control of plant pathogens of economic importance, like Botrytis cinerea and Fusarium oxysporum, while some compounds from spent hops or their derivatives may become useful for staphylococcal infections. [ABSTRACT FROM AUTHOR]

Synthesis of minor prenylflavonoids found in hops and their non-natural derivatives were performed. The antiproliferative activity of the obtained compounds against some human cancer cell lines was investigated. Using xanthohumol isolated from spent hops as a lead compound, a series of minor hop prenylflavonoids and synthetic derivatives were obtained by isomerization, cyclisation, oxidative-cyclisation, oxidation, reduction and demethylation reactions. Three human cancer cell lines—breast (MCF-7), prostate (PC-3) and colon (HT-29)—were used in antiproliferative assays, with cisplatin as a control compound. Five minor hop prenyl flavonoids and nine non-natural derivatives of xanthohumol have been synthetized. Syntheses of xanthohumol K, its dihydro- and tetrahydro-derivatives and 1″,2″,α,β-tetrahydroxanthohumol C were described for the first time. All of the minor hops prenyl flavonoids exhibited strong to moderate antiproliferative activity in vitro. The minor hops flavonoids xanthohumol C and 1″,2″-dihydroxanthohumol K and non-natural 2,3-dehydroisoxanthohumol exhibited the activity comparable to cisplatin. Results described in the article suggest that flavonoids containing chromane- and chromene-like moieties, especially chalcones, are potent antiproliferative agents. The developed new efficient, regioselective cyclisation reaction of the xanthohumol prenyl group to 1″,2″-dihydroxantohumol K may be used in the synthesis of other compounds with the chromane moiety. [ABSTRACT FROM AUTHOR]