Hop Extract Research Articles

Depigmenting effect of Xanthohumol from hop extract in MNT-1 human melanoma cells and normal human melanocytes

Xanthohumol (XH) is the most abundant prenylated flavonoid found in the hop plant (Humulus lupulus L.) and has previously been shown to have depigmenting effects in B16F10 mouse melanoma cells; however, studies of its depigmenting efficacy in human melanocytes are still lacking. In this work, we explored the effects of XH on melanogenesis in MNT-1 human melanoma cells and normal human melanocytes from darkly-pigmented skin (HEM-DP). XH was screened for cytotoxicity over 48 h, and subsequently tested on melanogenesis in MNT-1 cells. XH was further tested in HEM-DP cells for melanin synthesis and melanosome export; dendricity was quantitated to assess effects on melanosome export. Melanosome degradation was studied in human keratinocytes (HaCaT). Our results showed that XH inhibited melanin synthesis in MNT-1 cells at 30 μM but increased intracellular tyrosinase activity without affecting ROS levels. In HEM-DP cells, XH robustly suppressed cellular tyrosinase activity at nontoxic concentrations (2.5–5 μM) without any effect on melanin synthesis. However, XH inhibited melanosome export by reducing dendrite number and total dendrite length. Further testing in HaCaT cells demonstrated that XH induced melanosome degradation at low micromolar concentrations without any cytotoxicity. In summary, our results demonstrate that XH at low micromolar concentrations might hold promise as a potent inhibitor of human pigmentation by primarily targeting melanin export and melanin degradation. Further studies to elucidate the signaling mechanisms of action of melanosome export inhibition by XH and in vivo efficacy are warranted.

Abstract PS8-10: Inhibition of estrogen biosynthesis by hops, licorice species, and their bioactive compounds

Abstract Introduction: Breast cancer risk continues to rise following menopause, despite the cessation of ovarian estrogen synthesis. Pathways involving increased aromatase activity and inflammation in the breast microenvironment are implicated. Their concerted disruption could be protective against breast cancer. Popular botanicals for menopausal health, such as hops (Humulus lupulus), three licorice species (Glycyrrhiza glabra, Glycyrrhiza inflata, Glycyrrhiza uralensis) extracts, and their bioactive compounds have shown estrogenic and chemopreventive properties in vitro and in vivo. Their effects on aromatase expression and activity, and on inflammatory responses in the breast are not well characterized.Methods: Inhibition of aromatase activity by hops extract, its compounds (8-prenylnaringenin, 6-prenylnaringenin, and xanthohumol); three licorice extracts, and their bioactive compounds, (liquiritigenin, isoliquiritigenin, 8-prenylapigenin, and licochalcone A) were evaluated fluorometrically, using aromatase supersomes. Computational docking was performed to assess the binding of the bioactive compounds to the binding pocket of aromatase crystal structure compared to the known aromatase inhibitors, letrozole (non-steroidal) and exemestane (steroidal). Using qPCR, the effect of treatments on aromatase mRNA expression in breast microstructures of menopausal women was evaluated. The effects of hops and licorice on transactivation of NF-kB in MCF-7 breast cancer cells were studied, using a luciferase assay.Results: Among the extracts, one of the licorice species, Glycyrrhiza inflata showed the highest aromatase inhibitory potency (IC50 ≈ 1 µg/mL). Among the compounds, the phytoestrogens 8-prenylnaringenin (IC50 = 50 nM or 17 ng/mL) from hops, liquiritigenin (400 nM or 0.1 µg/mL), and 8-prenylapigenin (IC50 ≈ 590 nM or 0.2 µg/mL) from licorice exhibited the highest potency. Computational docking suggested that these phytoestrogens bind to the aromatase binding pocket like the aromatase inhibitor, letrozole. This effect was not observed with non-estrogenic bioactive compounds including 6-prenylnaringenin and xanthohumol from hops as well as isoliquiritigenin and licochalcone A from licorice. Hops and 8-prenylnaringenin reduced aromatase expression in breast microstructures by 60% (P < 0.05). Moreover, hops and licorice extracts suppressed NF-kB-luciferase activity by 70% in MCF-7 cells (P< 0.01). Conclusions: Hops, licorice species, and their phytoestrogens inhibit aromatase activity and expression. The extracts suppress NF-kB transactivation in MCF-7 cells, suggesting inhibition of inflammatory response. Further studies will better elucidate the potential of these popular botanicals and their bioactive compounds for preventing breast cancer in menopausal women. Citation Format: Atieh Hajirahimkhan, Caitlin Howell, Tareisha Dunlap, Shao-Nong Chen, Susan E. Clare, Guido F. Pauli, Judy L. Bolton, Birgit M. Dietz, Seema A. Khan. Inhibition of estrogen biosynthesis by hops, licorice species, and their bioactive compounds [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS8-10.

Dietary iso-α-acids prevent acetaldehyde-induced liver injury through Nrf2-mediated gene expression.

Acetaldehyde is the major toxic metabolite of alcohol (ethanol) and enhances fibrosis of the liver through hepatic stellate cells. Additionally, alcohol administration causes the accumulation of reactive oxygen species (ROS), which induce hepatocyte injury-mediated lipid peroxidation. Iso-α-acids, called isohumulones, are bitter acids in beer. The purpose of this study was to investigate the protective effects of iso-α-acids against alcoholic liver injury in hepatocytes in mice. C57BL/6N mice were fed diets containing isomerized hop extract, which mainly consists of iso-α-acids. After 7 days of feeding, acetaldehyde was administered by a single intraperitoneal injection. The acetaldehyde-induced increases in serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were suppressed by iso-α-acids intake. Hepatic gene expression analyses showed the upregulation of detoxifying enzyme genes, glutathione-S-transferase (GST) and aldehyde dehydrogenase (ALDH). In vitro, iso-α-acids upregulated the enzymatic activities of GST and ALDH and induced the nuclear translocation of nuclear factor-erythroid-2-related factor 2 (Nfe2l2; Nrf2), a master regulator of antioxidant and detoxifying systems. These results suggest that iso-α-acid intake prevents acetaldehyde-induced liver injury by reducing oxidative stress via Nrf2-mediated gene expression.

A new perspective of a well-recognized raw material: Phenolic content, antioxidant and antimicrobial activities and α- and β-acids profile of Brazilian hop (Humulus lupulus L.) extracts

Hop is a plant with several biological properties. Many factors affect both the presence and concentration of hop compounds, such as cultivar, location and growth conditions. Recently, the interest of hop cultivation in Brazil has grown despite the tropical weather and it has been possible to obtain hop completely cultivated in Brazilian soil. This study analyzed the chemical composition and verified the antioxidant and antimicrobial activities of Brazilian hop hydroethanolic extracts in comparison to a commercially available hop cultivar. Brazilian hops were a good source of flavonoids (5.72–12.82 mg CE/g dw), and presented a high content of phenolic compounds, in particular the Canastra cultivar (35.1 mg GAE/g dw). The Brazilian cultivars showed interesting antioxidant and antimicrobial proprieties. Gram-positive and Gram-negative bacteria were susceptible to hop hydroethanolic extracts and Staphylococcus aureus was inhibited by the extracts of all cultivars. The extracts presented antifungal activity against Byssochlamys nivea and significant growth inhibition at the higher concentration tested (20 μl/ml). The hydroethanolic extracts exhibited a high content of α- and β-acids, mainly the Vitoria, Columbus and Canastra cultivars, reaching almost 60% (w/w). These characteristics evidenced the potential application of Brazilian hops as raw materials in both pharmaceutical and food industries.

Effect of hop extracts on rheological properties of wheat dough

The choice of technological equipment and the mode selection in bakery industry is determined by the rheological properties of the processed or transported food masses, pre-ferments, and products. In this aspect, the effect of new ingredients in bakery production such as two types of hop extracts (the hop-water and hop-milk whey systems) and their percentage in the formula on the rheological properties of wheat dough during kneading and fermentation has been investigated. The effect of extracts and their percentage in dough formula on time development and strength of the dough has been studied. It was found, using the Brabender Farinograph, that hop extracts lead to decreasing of the elasticity and degree of softening of wheat dough with hop-water extract by 9—27% compared to the control, and hop-milk whey-by 33—41%. Brabender Extensograph carried out the assessment of changes in physical properties of the dough with hop extracts during fermentation after 45, 90 and 135 min. It was found that hop extracts increase the strength of the dough and resistance to extension, which also indicates strengthening effect of hop extracts on wheat gluten. The changes in the quality characteristics of wheat bread with different dosage of hop extracts have been investigated. It was found that the addition of the extract based on water increases the ability to hold the shape of baked bread, on average, by 2—17% whereas extract based on whey increase this index by 8—25%.

MORPHOLOGICAL EFFICACY EVALUATION OF GEL WITH CARBON DIOXIDE EXTRACT OF HOPS IN CASE OF COMPLICATED WOUND INFECTION ACNE VULGARIS

The aim of the study is to reveal in the experiment the morphological features of the infected skin wounds healing, which are a manifestation of acne vulgaris severe and very severe forms, using a gel with carbon dioxide extract of hops. Materials and methods: An experimental study was carried out on 80 male WAG rats of three months of age. The animals were divided into 9 groups. Group 1 consisted of intact animals (n=6). Group 2 was represented by animals (n=6), which had hair epilation on the dorsal surface of the body in an area of 1 сm2, followed by application of 2 ml of placebo gel to this area. Group 3 included animals (n=6), which were epilated on the dorsal surface of the body in an area of 1 сm2 and applied 2 ml of 1 % gel with carbon dioxide extract of hops. Group 4 included rats (n=6), which were epilated on the dorsal surface of the body in an area of 1 сm2 and simulated thermal damage. Group 5 was represented by 10 rats, who were epilated on the dorsal surface of the body in an area of 1 сm2, simulated thermal damage, followed by applying 2 ml of placebo gel to the wound surface. Group 6 included rats (n=10), who underwent measures similar to group 5, followed by application of 2 ml of 1 % gel with carbon dioxide extract of hops to the wound surface. In group 7, there were 6 rats, which were epilated on the dorsal surface of the body in an area of 1 сm2, thermal damage to the skin with underlying soft tissues was simulated, followed by application to the wound surface the reference strains of Staphylococcus aureus, Streptococcus pyogenes, Proteus vulgaris, Propionibacterium acnes, Escherichia coli, Pseudomonas aeruginosa, Malassezia slooffiae, Malassezia pachydermatis, Candida albicans, Candida parapsilosis. In groups 8 and 9, there were 15 rats each, which underwent measures similar to group 7, followed by applying 2 ml of placebo gel on its surface on the next day after infection of the wound in group 8, and in group 9 - 2 ml of 1 % gel with carbon dioxide extract hops. The material for the study was the skin with underlying soft tissues. It was used histological, histochemical, morphometric and statistical methods. Results: This experimentally created gel with carbon dioxide extract of hops activates separation processes of horny masses from the surface of the epidermis, cleaning the pores of the skin; stimulating the proliferative activity of the epidermis, which is located in the marginal sections of the wound or covers the surface of the regenerate; activating the processes of cleansing the wound from necrotic tissue; activating the growth and maturation of granulation tissue with its subsequent transformation into connective tissue. It has anti-inflammatory, bactericidal and antimycotic effects, normalizing skin microbiocenosis. Conclusions: The complex morphological study has showed that gel with carbon dioxide extract of hops is a highly effective drug in treatment of severe and very severe acne vulgaris, characterized by the development of deep and infected wound defects.

Low temperature preservation: Influence of putative bioactive microalgae and hop extracts on sperm quality and bacterial load in porcine semen

The frequent use of antibiotics in artificial insemination promotes the development of antibiotic resistance. Therefore, alternatives must be considered. In this study, putative bioactive microalgae and hop extracts were examined to estimate their effect on quality and bacterial load of preserved porcine semen when used a low-temperature storage at 5 °C in Androstar® Premium (ASP) extender (Minitüb). Firstly, five algae extracts (Neochloris oleoabundans (NEO), Pseudococcomyxa simplex (PSEY), Phormidium ambiquum (PHA), Schizochlamydella minutissima (SCH), Cyanidioschyzon merolae (CYA)) and one hop extract (Humulus lupulus (HOP)) in four concentrations (0.2, 2, 20 and 200 μg/mL) were tested on their sperm-compatibility at 17 °C. All extracts in the concentrations 0.2 and 2 μg/mL appeared to be sperm compatible. After 72 h of storage at 5 °C, variants showed an increase of total bacterial subcultures from 103 (ASP w/o supplements) to 113/136/135/136/126/118 (ASP w/NEO/PSEY/PHA/HOP/SCH/CYA). Even though bacterial growth was not inhibited in general, all extracts showed an antimicrobial effect on specific bacteria, including Gram-positive (Trueperella pyogenes, Streptococcus porcinus) and Gram-negative bacterial species (Alcaligenes faecalis, Pseudomonas aeruginosa, Ralstonia sp., Pasteurella sp., Proteus sp., Providencia stuartii, and Escherichia coli). While the proportion of these species was 10% in the control (ASP w/o supplements), their proportion in the supplemented variants ranged from 8% (NEO, HOP) to as low as 3% (PSEY). Although the tested extracts are not suitable to replace conventional antibiotics due to their lack of broad-spectrum antimicrobial activity, they nevertheless present promising opportunities for bacteria-specific, customizable usage in boar semen extenders combined with antibiotics or other antimicrobial agents.

The study of the composition of the lipophilic hop extract for using in the composition of finished dosage forms

In the industrial production of the hop infructescence dry extract, the non-polar fraction in the form of a lipophilic extract obtained by extraction with heptane or hexane remains as a waste. The lipophilic extract obtained under such conditions is characterized by a significant content of biologically active substances from the groups of terpene alcohols, aldehydes, ketones, epoxides, acids, and esters. In this case, it is promising to use the lipophilic extract in further research on the development of new drugs, and it will also provide a comprehensive treatment of hop infructescences.Aim. To study the chemical composition of the lipophilic hop extract by gas chromatography for further standardization and use as a constituent of finished dosage forms.Materials and methods. The lipophilic hop extract was obtained at the SPC “Borshchagovsky CPP”, Kyiv. The chemical composition of the lipophilic fraction of hop infructescences was studied according to the requirements of the State Pharmacopoeia by gas chromatography with a flame ionization detector using an Agilent 7890 GC gas chromatograph with a 597 Agilent GC/MSD mass spectrometric detector.Results. According to the results of the studies conducted, using library spectra, 47 volatile compounds were identified in the lipophilic hop extract. The main components were (S)-3-ethyl-4-methylpentanol, 1,3,3-trimethyl-bicyclo [2,2,1] heptane-2-one, eicosamethyl-cyclodecasiloxane, 4-pentene-2-ol, Z-7-hexadecanoic acid, phthalic acid esters, 7-tetradecenal, CIS-11-hexadecenal, their content reached 75% of the area of all peaks of substances.Conclusions. In the lipophilic hop extract, the content of volatile substances has been identified and quantified by gas chromatography with a mass spectrometric detector. The major representatives of the substances are (S)-3-ethyl-4-methylpentanol and 1,3,3-trimethyl-bicyclo[2,2,1]heptane-2-one, their content is 49.5 % of the total amount of substances.

Prevention of Fine Dust-Induced Vascular Senescence by Humulus lupulus Extract and Its Major Bioactive Compounds.

Both short- and long-term exposure to fine dust (FD) from air pollution has been linked to various cardiovascular diseases (CVDs). Endothelial cell (EC) senescence is an important risk factor for CVDs, and recent evidence suggests that FD-induced premature EC senescence increases oxidative stress levels. Hop plant (Humulus lupulus) is a very rich source of polyphenols known to have nutritional and therapeutic properties, including antioxidant behavior. The aims of this study were to evaluate whether Humulus lupulus extract prevents FD-induced vascular senescence and dysfunction and, if so, to characterize the underlying mechanisms and active components. Porcine coronary arteries and endothelial cells were treated with FD in the presence or absence of hop extract (HOP), and the senescence-associated-beta galactosidase (SA-β-gal) activity, cell-cycle progression, expression of senescence markers, oxidative stress level, and vascular function were evaluated. Results indicated that HOP inhibited FD-induced SA-β-gal activity, cell-cycle arrest, and oxidative stress, suggesting that HOP prevents premature induction of senescence by FD. HOP also ameliorated FD-induced vascular dysfunction. Additionally, xanthohumol (XN) and isoxanthohumol (IX) were found to produce the protective effects of HOP. Treatment with HOP and its primary active components XN and IX downregulated the expression of p22phox, p53, and angiotensin type 1 receptor, which all are known FD-induced redox-sensitive EC senescence inducers. Taken together, HOP and its active components protect against FD-induced endothelial senescence most likely via antioxidant activity and may be a potential therapeutic agent for preventing and/or treating air-pollution-associated CVDs.

Removal of NO2 from gas stream by activated bio-carbons from physical activation of residue of supercritical extraction of hops

Production of activated bio-carbons from the residue of supercritical extraction of hops has been described. The precursor was first subjected to pyrolysis at 500 and 700 °C in nitrogen atmosphere. The bio-chars were next subjected to physical activation at 700 and 800 °C in carbon dioxide atmosphere. The effects of pyrolysis and activation temperature on the physicochemical properties and sorption capacity toward NO2 were established. The results have shown that by physical activation of residue of supercritical extraction of hops it is possible to produce bio-sorbents with very high capacity towards NO2, reaching maximum 79.2 mg/g. It has been proved that the effectiveness of NO2 removal to large extent depends on the conditions of adsorption. The presence of steam in the stream of gases and preliminary wetting of the adsorbent bed have positive effect on the adsorption of NO2 by the bio-sorbents obtained.

PSXII-18 Treatment of composted poultry litter with natural hop extracts, effects on nitrogen accumulations, coliforms and select Gram-positive pathogenic and antimicrobial resistant bacteria

Abstract Poultry litter, produced by intensive poultry production systems, is a potentially valuable crude protein feedstuff for ruminants if effectively treated to kill pathogens before feeding. Composting effectively kills pathogens but risks losses of ammonia during uric acid degradation. To test if hop extracts may help preserve uric acid concentrations during composting, 11-g portions of used wood chip litter (WCL, 88% dry matter) were treated with 6 mL water containing Galena or Chinook hop extracts to achieve 0.06 g of either extract/g WCL. Control WCL was treated with buffer alone. The WCL was distributed to 50-mL tubes (3 tubes/treatment), capped and incubated in Gas Pac jars for 8 days at 30oC, followed by 3 days at 37oC and an additional 2 days at 42oC to simulate a 13-day compost period. A repeated measures analysis of variance revealed a treatment by day interaction on uric acid (P < 0.05), with concentrations being highest upon initiation of composting (41.9 ± 3.6 µmol/g), lowest on day 13 for the untreated compost (17.5 ± 9.2 µmol/g) and intermediate for Galena and Chinook hop-treated compost (28.0 ± 4.7 and 25.8 ± 0.8 µmol/g, respectively). Effects of treatment, day of composting or their interaction, however, were not observed (P > 0.05) on concentrations of ammonia and urea, which averaged 1.2 ± 1.0 and 2.9 ± 0.6 µmol/g, respectively. As expected, an effect of day-of composting on survivability (P < 0.05) of select bacterial populations was confirmed, with counts being decreased more than 3.0 log10 units after 13 days composting than on day 0 for enterococci, staphylococci, lactic acid bacteria, coliforms and total aerobes (6.7 ± 0.09, 9.0 ± 0.01, 5.8 ± 0.16, 5.9 ± 0.09 and 9,9 ± 0.06 log10 CFU/g, respectively). These results indicate that hops-treatment may help preserve crude protein within WCL during composting.

Resistant starch intake alleviates collagen-induced arthritis in mice by modulating gut microbiota and promoting concomitant propionate production

Gut dysbiosis precedes clinic symptoms in rheumatoid arthritis (RA) and has been implicated in the initiation and persistence of RA. The early treatment of RA is critical to better clinical outcome especially for joint destruction. Although dietary interventions have been reported to be beneficial for RA patients, it is unclear to whether diet-induced gut microbiome changes can be a preventive strategy to RA development. Here, we investigated the effect of a high fiber diet (HFD) rich with resistant starch (RS) on collagen-induced arthritis (CIA) and gut microbial composition in mice. RS-HFD significantly reduced arthritis severity and bone erosion in CIA mice. The therapeutic effects of RS-HFD were correlated with splenic regulatory T cell (Treg) expansion and serum interleukin-10 (IL-10) increase. The increased abundance of Lactobacillus and Lachnoclostridium genera concomitant with CIA were eliminated in CIA mice fed the RS-HFD diet. Notably, RS-HFD also led to a predominance of Bacteroidetes, and increased abundances of Lachnospiraceae_NK4A136_group and Bacteroidales_S24-7_group genera in CIA mice. Accompanied with the gut microbiome changes, serum levels of the short-chain fatty acid (SCFA) acetate, propionate and isobutyrate detected by GC-TOFMS were also increased in CIA mice fed RS-HFD. While, addition of β-acids from hops extract to the drinking water of mice fed RS-HFD significantly decreased serum propionate and completely eliminated RS-HFD-induced disease improvement, Treg cell increase and IL-10 production in CIA mice. Moreover, exogenous propionate added to drinking water replicated the protective role of RS-HFD in CIA including reduced bone damage. The direct effect of propionate on T cells in vitro was further explored as at least one mechanistic explanation for the dietary effects of microbial metabolites on immune regulation in experimental RA.Taken together, RS-HFD significantly reduced CIA and bone damage and altered gut microbial composition with concomitant increase in circulating propionate, indicating that RS-rich diet might be a promising therapy especially in the early stage of RA.

Efficacy of Natural Formulations in Bovine Mastitis Pathology: Alternative Solution to Antibiotic Treatment.

IntroductionBovine mastitis is an inflammatory disease of the udder that causes important economic losses in the animal breeding and dairy product industries. Nowadays, the conventional livestock antibiotic treatments are slowly being replaced by alternative treatments. In this context, the main aim of this study was to evaluate the efficacy of natural products in alternative treatment of bovine mastitis.Material and MethodsTwo natural formulations with previously suggested in vitro antimicrobial effect were tested in vivo on mastitic cows. Animals with a positive diagnosis for mastitis (n = 20) were divided into three treatment groups: two groups (n = 8) were administered formulations of propolis, alcoholic extracts of Brewers Gold and Perle hops, plum lichen, common mallow, marigold, absinthe wormwood, black poplar buds, lemon balm, and essential oils of oregano, lavender, and rosemary designated R4 and R7 (differing only in the latter being more concentrated) and one group (n = 4) a conventional antibiotic mixture. In vivo efficacy of treatments was evaluated by somatic cell and standard plate counts, the treatment being considered efficacious when both parameters were under the maximum limit.ResultsR7 was effective in the most cases, being therapeutically bactericidal in six out of eight cows, while R4 gave good results in three out of eight cows, and conventional antibiotics cured one out of four.ConclusionThese results suggest the possible therapeutic potential of these natural products in bovine mastitis.

Hop Polyphenols in Relation to Verticillium Wilt Resistance and Their Antifungal Activity.

(1) Background: Verticillium wilt (VW) of hop is a devastating disease caused by the soil-borne fungi Verticillium nonalfalfae and Verticillium dahliae. As suggested by quantitative trait locus (QTL) mapping and RNA-Seq analyses, the underlying molecular mechanisms of resistance in hop are complex, consisting of preformed and induced defense responses, including the synthesis of various phenolic compounds. (2) Methods: We determined the total polyphenolic content at two phenological stages in roots and stems of 14 hop varieties differing in VW resistance, examined the changes in the total polyphenols of VW resistant variety Wye Target (WT) and susceptible Celeia (CE) on infection with V. nonalfalfae, and assessed the antifungal activity of six commercial phenolic compounds and total polyphenolic extracts from roots and stems of VW resistant WT and susceptible CE on the growth of two different V. nonalfalfae hop pathotypes. (3) Results: Generally, total polyphenols were higher in roots than stems and increased with maturation of the hop. Before flowering, the majority of VW resistant varieties had a significantly higher content of total polyphenols in stems than susceptible varieties. At the symptomatic stage of VW disease, total polyphenols decreased in VW resistant WT and susceptible CE plants in both roots and stems. The antifungal activity of total polyphenolic extracts against V. nonalfalfae was higher in hop extracts from stems than those from roots. Among the tested phenolic compounds, only p-coumaric acid and tyrosol markedly restricted fungal growth. (4) Conclusions: Although the correlation between VW resistance and total polyphenols content is not straightforward, higher levels of total polyphenols in the stems of the majority of VW resistant hop varieties at early phenological stages probably contribute to fast and efficient activation of signaling pathways, leading to successful defense against V. nonalfalfae infection.

The effects of storage and hop extract on aroma and flavour compounds in Balkan-style sausages packed under a CO2-containing anaerobic atmosphere

Changes in the levels of pH, lactic acid, acetic acid, headspace volatile compounds, and spoilage odour intensity during a 35 day refrigerated storage period in two sets of a Balkan-style fresh sausage, a control sausage (CON) and a sausage containing an aqueous hop extract (HOP), packaged under a 20% CO2 and 80% N2 atmosphere were evaluated. Storage resulted in progressive sausage acidification and increased the levels of acetic acid, 1-methylbutanol, ethyl acetate, ethyl hexanoate, and 2-ethylhexanol; all of which are associated with anaerobic microbial metabolism under sugar restricted conditions. Storage decreased the levels of hexanal, heptanal, pentanol, and garlic-derived organosulfur compounds. Hop extract showed oxygen scavenging abilities, and decreased the levels of the volatile compounds derived from lipid auto-oxidation while contributing to the presence of specific terpene compounds. The use of hop extract did not improve the shelf life of sausages packed under anaerobic atmosphere. The spoilage odour appeared in both types of sausages on the 14th day, and it was considered strong from day 21 onwards.

6-Prenylnaringenin from Hops Disrupts ERα-Mediated Downregulation of CYP1A1 to Facilitate Estrogen Detoxification.

Botanical dietary supplements (BDS) containing hops are sold as women's health supplements due to the potent hop phytoestrogen, 8-prenylnaringenin (8-PN), and the cytoprotective chalcone, xanthohumol. Previous studies have shown a standardized hop extract to beneficially influence chemical estrogen carcinogenesis in vitro by fostering detoxified 2-hydroxylation over genotoxic 4-hydroxylation estrogen metabolism. In this study, hop extract and its bioactive compounds were investigated for its mechanism of action within the chemical estrogen carcinogenesis pathway, which is mainly mediated through the 4-hydroxylation pathway catalyzed by CYP1B1 that can form gentoxic quinones. Aryl hydrocarbon receptor (AhR) agonists induce CYP1A1 and CYP1B1, while estrogen receptor alpha (ERα) inhibits transcription of CYP1A1, the enzyme responsible for 2-hydroxylated estrogens and the estrogen detoxification pathway. An In-Cell Western MCF-7 cell assay revealed hop extract and 6-prenylnaringenin (6-PN) degraded ERα via an AhR-dependent mechanism. Reverse transcription PCR and xenobiotic response element luciferase assays showed hop extract and 6-PN-mediated activation of AhR and induction of CYP1A1. A reduction in estrogen-mediated DNA (cytosine-5)-methyltransferase 1 (DNMT1) downregulation of CYP1A1 accompanied this activity in a chromatin immunoprecipitation assay. Ultimately, hop extract and 6-PN induced preferential metabolism of estrogens to their detoxified form in vitro. These results suggest that the standardized hop extract and 6-PN activate AhR to attenuate epigenetic inhibition of CYP1A1 through degradation of ERα, ultimately increasing 2-hydroxylated estrogens. A new mechanism of action rationalizes the positive influence of hop BDS and 6-PN on oxidative estrogen metabolism in vitro and, thus, potentially on chemical estrogen carcinogenesis. The findings underscore the importance of elucidating various biological mechanisms of action and standardizing BDS to multiple phytoconstituents for optimal resilience promoting properties.

Valorization of hop leaves for development of eco-friendly bee pesticides

The bacterium Paenibacillus larvae and the mite Varroa destructor are two of the most severe biotic stressors affecting honeybees and are responsible for American foulbrood and varroosis respectively. To control these pathogens, beekeepers regularly apply synthetic acaricides or antibiotics to parasitized hives. However, antibiotic and acaricide overuse over time leads to resistance in bacteria strains and mite populations respectively, not to mention the residual contamination of bee products with these chemicals. The development of alternative and effective control methods of bee diseases is therefore crucial. In recent years, natural substances from plant extracts have emerged as the basis of suitable control methods to treat bee colonies parasitized by both P. larvae and V. destructor. Our aim was to evaluate the bioactivity of ethanolic and methanolic hop leaf extract (species: Humulus lupulus L, varieties: Victoria, Spalt, and Cascade) against P. larvae, V. destructor, and A. mellifera. The bactericidal activity against P. larvae was evaluated by the broth microdilution method. Topical administration protocols were used to determine the bioactivity of hop extracts on V. destructor and A. mellifera. Total polyphenols, flavonoids, saponins, and antioxidant capacity were determined for each hop leaf extract tested. The Victoria extract had the highest concentration of phenolic compounds, whereas Cascade and Victoria extracts had higher concentrations of the glycoside saponin. All hop extracts presented low toxicity against A. mellifera bees after 48 h of topical administration (except for Cascade ethanolic extract which reached a maximum of 36% of bee mortality). Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values ranged from 0.69 to 2.75 mg/kg for the Cascade variety, 1.38 to 5.5 mg/kg for the Spalt variety, and 5.5 to 11 mg/kg for the Victoria variety. After 48 h, the acaricidal activity for the ethanolic extract of the Victoria variety reached a value close to 80%, while the methanolic extract of Cascade showed an acaricidal activity close to 70%. The results reported in this study support the potential use of methanolic and ethanolic extracts of hop leaves from Argentina as promising natural alternatives for varroosis and American foulbrood control.

A Review of Nigerian Potential Hop Substitutes in Beer Brewing: 1983-2020

The Nigerian economy depended mainly on crude oil during the era of oil boom of 1973 which lasted up till1983. Agriculture was grossly neglected by successive governments. Following the economic recession that occurred years after and due to fall in crude oil price, the Nigerian government began to advocate for economic diversification. Consequently, agriculture became the area of interest and priority for industrial raw material sources. Unfortunately, Nigeria had imbibed the tradition of importing raw materials for all her industrial productions thereby creating unfavourable balance of trade between Nigeria and her foreign trading partners thus resulting in increase in the prices of finished products. Beer production is not exempted from the price increase since its raw materials are equally imported with their attendant problems on Nigeria’s foreign exchange. One of such raw materials is hops. The hop (Humulus lupulus L.) is a perennial dioecious climbing plant of hemp (cannabis) family and belonging to the order (urticales) which are grown in the temperate regions of the world, solely to meet the demand of the brewing industry. Hop extracts give beer its bitter taste, improve foam stability and act as antiseptics towards microorganisms. The quest to substitute hops with some tropical bitter vegetables in Nigeria’s brewing industry dates back to 1983 and since that time, many have compared hop extracts with those of Nigerian bitter plants such as Garcinia kola, Azadirachta indica, Vernonia amygdalina and Gongronema latifolium. This review takes a critical look on the efforts made so far since 1983 in investigating the potentiality of using Nigerian bitter plant extracts as suitable substitute for those of hop in the Nigerian brewing industry with special emphasis on Gas Chromatography Mass–Spectrometry (GC–MS) and Gas Chromatography–Flame Ionization Detector (GC–FID) techniques. It was concluded that none of the Nigerian plants has perfect potential as suitable substitute for hops in the Nigerian brewing industry. Consequently, further research efforts in the area of mixtures/blends of extract of plant species which mimic hop taste is strongly recommended.

Semi-Synthetic Approach Leading to 8-Prenylnaringenin and 6-Prenylnaringenin: Optimization of the Microwave-Assisted Demethylation of Xanthohumol Using Design of Experiments.

The isomers 8-prenylnaringenin and 6-prenylnaringenin, both secondary metabolites occurring in hops, show interesting biological effects, like estrogen-like, cytotoxic, or neuro regenerative activities. Accordingly, abundant sources for this special flavonoids are needed. Extraction is not recommended due to the very low amounts present in plants and different synthesis approaches are characterized by modest yields, multiple steps, the use of expensive chemicals, or an elaborate synthesis. An easy synthesis strategy is the demethylation of xanthohumol, which is available due to hop extraction industry, using lithium chloride and dimethylformamide, but byproducts and low yield did not make this feasible until now. In this study, the demethylation of xanthohumol to 8-prenylnaringenin and 6-prenylnaringenin is described the first time and this reaction was optimized using Design of Experiment and microwave irradiation. With the optimized conditions—temperature 198 °C, 55 eq. lithium chloride, and a reaction time of 9 min, a final yield of 76% of both prenylated flavonoids is reached.

Brazilian Grown Cascade Hop (Humulus lupulus L.): LC-ESI-MS-MS and GC-MS Analysis of Chemical Composition and Antioxidant Activity of Extracts and Essential Oils

The first harvest of Humulus lupulus (var. Cascade) in Brazil in 2016 originated as an aromatic hop that nowadays is gaining attention from the brewery industry. However, the chemical composition and the properties of this hop have not been well documented to date. In this study, the chemical profile of the phenolic compounds and essential oils of Cascade hops produced in Brazil (BH) and the USA (UH) was determined. The major phenolic compounds identified by LC-ESI-MS-MS in BH and UH were protocatechuic acid, isoquercitrin, and ferulic acid (4.18–11.39; 2.44–4.90; and 1.45–4.48 mg 100 g−1, respectively). The profile of essential oils was shown to differ between the two samples. The compounds trans-β-farnesene (20.60%), β-selinene (18.78%), myrcene (16.57%), and α-selinene (16.22%) were the main compounds in the BH essential oil, while the essential oil of UH showed a high content of α-humulene (35.35%), myrcene (22.35%), β-caryophyllene (12.81%), and trans-β-farnesene (10.59%). A higher antioxidant activity (by DPPH and ABTS) was observed for hop extracts when compared to the essential oils. The results indicated that the Brazilian hop sample analyzed had higher radical scavenging when compared to an American hop sample (associated with its bioactive compound composition). The Cascade hop from Brazil appears to be a high-quality raw material showing significant potential for future industrial applications.