Antimicrobial Activity of Xanthohumol and Its Selected Structural Analogues

Bio-fabricated zinc oxide nanoparticles mediated by endophytic fungus Aspergillus sp. SA17 with antimicrobial and anticancer activities: in vitro supported by in silico studies

Introduction

In recent years, the world's attention has been drawn to antimicrobial resistance (AMR) because to the frightening prospect of growing death rates. Nanomaterials are being investigated due to their potential in a wide range of technical and biological applications.

Methods

The purpose of this study was to biosynthesis zinc oxide nanoparticles (ZnONPs) using Aspergillus sp. SA17 fungal extract, followed by characterization of the produced nanoparticles (NP) using electron microscopy (TEM and SEM), UV-analysis, X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FT-IR).

Results and Discussion

The HR-TEM revealed spherical nanoparticles with an average size of 7.2 nm, and XRD validated the crystalline nature and crystal structure features of the generated ZnONPs, while the zeta potential was 18.16 mV, indicating that the particles' surfaces are positively charged. The FT-IR was also used to identify the biomolecules involved in the synthesis of ZnONPs. The antibacterial and anticancer properties of both the crude fungal extract and its nano-form against several microbial strains and cancer cell lines were also investigated. Inhibition zone diameters against pathogenic bacteria ranged from 3 to 13 mm, while IC50 values against cancer cell lines ranged from 17.65 to 84.55 M. Additionally, 33 compounds, including flavonoids, phenolic acids, coumarins, organic acids, anthraquinones, and lignans, were discovered through chemical profiling of the extract using UPLC-QTOF-MS/MS. Some molecules, such pomiferin and glabrol, may be useful for antibacterial purposes, according to in silico study, while daidzein 4'-sulfate showed promise as an anti-cancer metabolite.

Nanofibrous ε-Polycaprolactone Matrices Containing Nano-Hydroxyapatite and Humulus lupulus L. Extract: Physicochemical and Biological Characterization for Oral Applications

Oral bone defects occur as a result of trauma, cancer, infections, periodontal diseases, and caries. Autogenic and allogenic grafts are the gold standard used to treat and regenerate damaged or defective bone segments. However, these materials do not possess the antimicrobial properties necessary to inhibit the invasion of the numerous deleterious pathogens present in the oral microbiota. In the present study, poly(ε-caprolactone) (PCL), nano-hydroxyapatite (nHAp), and a commercial extract of Humulus lupulus L. (hops) were electrospun into polymeric matrices to assess their potential for drug delivery and bone regeneration. The fabricated matrices were analyzed using scanning electron microscopy (SEM), tensile analysis, thermogravimetric analysis (TGA), FTIR assay, and in vitro hydrolytic degradation. The antimicrobial properties were evaluated against the oral pathogens Streptococcus mutans, Porphyromonas gingivalis, and Aggregatibacter actinomycetemcomitans. The cytocompatibility was proved using the MTT assay. SEM analysis established the nanostructured matrices present in the three-dimensional interconnected network. The present research provides new information about the interaction of natural compounds with ceramic and polymeric biomaterials. The hop extract and other natural or synthetic medicinal agents can be effectively loaded into PCL fibers and have the potential to be used in oral applications.

Xanthohumol, a prenylated flavonoid from hops (Humulus lupulus L.) exerts multidirectional pro-healing properties towards damaged zebrafish hair cells by regulating the innate immune response

Xanthohumol (XN) is a prominent prenylated flavonoid present in the hop plant (Humulus lupulus L.). Despite undoubted pro-healing properties of hop plant, there is still a need for clinical investigations confirming these effects as well as the underlying molecular mechanisms. The present study was designed to (1) establish the role of XN in non-invasive inflammation induced by chemical damage to zebrafish hair cells, (2) clarify if it influences cell injury severity, neutrophil migration, macrophage activation, cell regeneration, and (3) find out whether it modulates the gene expression profile of chosen immune and stress response markers. All experiments were performed on 3 dpf zebrafish larvae. After fertilization the embryos were transferred to appropriate XN solutions (0.1 μM, 0.3 μM and 0.5 μM). The 40 min 10 μM CuSO4 exposure evoked severe damage to posterior lateral line hair cells triggering a robust acute inflammatory response. Four readouts were selected as the indicators of XN role in the process of inflammation: 1) hair cell death, 2) neutrophil migration towards damaged hair cells, 3) macrophage activation and recruitment to damaged hair cells, 4) hair cell regeneration. The assessments involved in vivo confocal microscopy imaging and qPCR based molecular analysis. It was demonstrated that XN (1) influences death pathway of damaged hair cells by redirecting their severe necrotic phenotype into apoptotic one, (2) impacts the immune response via regulating neutrophil migration, macrophage recruitment and activation (3) modulates gene expression of immune system markers and (4) accelerates hair cell regeneration.

The Antimicrobial Potential of the Hop (Humulus lupulus L.) Extract against Staphylococcus aureus and Oral Streptococci

Plant extracts are in the focus of the pharmaceutical industry as potential antimicrobials for oral care due to their high antimicrobial activity coupled with low production costs and safety for eukaryotic cells. Here, we show that the extract from Hop (Humulus lupulus L.) exhibits antimicrobial activity against Staphylococcus aureus and Streptococci in both planktonic and biofilm-embedded forms. An extract was prepared by acetone extraction from hop infructescences, followed by purification and solubilization of the remaining fraction in ethanol. The effect of the extract on S. aureus (MSSA and MRSA) was comparable with the reference antibiotics (amikacin, ciprofloxacin, and ceftriaxone) and did not depend on the bacterial resistance to methicillin. The extract also demonstrated synergy with amikacin on six S. aureus clinical isolates, on four of six isolates with ciprofloxacin, and on three of six isolates with ceftriaxone. On various Streptococci, while demonstrating lower antimicrobial activity, an extract exhibited a considerable synergistic effect in combination with two of three of these antibiotics, decreasing their MIC up to 512-fold. Moreover, the extract was able to penetrate S. aureus and S. mutans biofilms, leading to almost complete bacterial death within them. The thin-layer chromatography and LC-MS of the extract revealed the presence of prenylated flavonoids (2',4',6',4-tetrahydroxy-3'-geranylchalcone) and acylphloroglucides (cohumulone, colupulone, humulone, and lupulone), apparently responsible for the observed antimicrobial activity and ability to increase the efficiency of antibiotics. Taken together, these data suggest an extract from H. lupulus as a promising antimicrobial agent for use both as a solely antiseptic and to potentiate conventional antimicrobials.

Gut enterotype-dependent modulation of gut microbiota and their metabolism in response to xanthohumol supplementation in healthy adults

Xanthohumol (XN), a polyphenol found in the hop plant (Humulus lupulus), has antioxidant, anti-inflammatory, prebiotic, and anti-hyperlipidemic activity. Preclinical evidence suggests the gut microbiome is essential in mediating these bioactivities; however, relatively little is known about XN's impact on human gut microbiota in vivo. We conducted a randomized, triple-blinded, placebo-controlled clinical trial (ClinicalTrials.gov NCT03735420) to determine safety and tolerability of XN in healthy adults. Thirty healthy participants were randomized to 24 mg/day XN or placebo for 8 weeks. As secondary outcomes, quantification of bacterial metabolites and 16S rRNA gene sequencing were utilized to explore the relationships between XN supplementation, gut microbiota, and biomarkers of gut health. Although XN did not significantly change gut microbiota composition, it did re-shape individual taxa in an enterotype-dependent manner. High levels of inter-individual variation in metabolic profiles and bioavailability of XN metabolites were observed. Moreover, reductions in microbiota-derived bile acid metabolism were observed, which were specific to Prevotella and Ruminococcus enterotypes. These results suggest interactions between XN and gut microbiota in healthy adults are highly inter-individualized and potentially indicate that XN elicits effects on gut health in an enterotype-dependent manner.

A dual mechanism with H2S inhibition and membrane damage of morusin from Morus alba Linn. against MDR-MRSA

It's urgent to discover new antibiotics along with the increasing emergence and dissemination of multidrug resistant (MDR) bacterial pathogens. In the present investigation, morusin exhibited rapid bactericidal activity against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE) by targeting the phospholipid of bacterial inner membrane, increasing membrane rigidity and disrupting bacterial homeostasis together with the membrane permeability, which caused fundamental metabolic disorders. Furthermore, morusin can also accumulate ROS, suppress H2S production, and aggravate oxidative damage in bacteria. Importantly, morusin also inhibited the spread of wounds and reduced the bacterial burden in the mouse model of skin infection caused by MRSA. It's a chance to meet the challenge of existing antibiotic resistance and avoid the development of bacterial resistance, given the multiple targets of morusin.

Current strategies for the management of valuable compounds from hops waste for a circular economy

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.

Promising Role of the Scutellaria baicalensis Root Hydroxyflavone-Baicalein in the Prevention and Treatment of Human Diseases

Plant roots, due to a high content of natural antioxidants for many years, have been used in herbal medicine. It has been documented that the extract of Baikal skullcap (Scutellaria baicalensis) has hepatoprotective, calming, antiallergic, and anti-inflammatory properties. Flavonoid compounds found in the extract, including baicalein, have strong antiradical activity, which improves overall health and increases feelings of well-being. Plant-derived bioactive compounds with antioxidant activity have for a long time been used as an alternative source of medicines to treat oxidative stress-related diseases. In this review, we summarized the latest reports on one of the most important aglycones with respect to the pharmacological activity and high content in Baikal skullcap, which is 5,6,7-trihydroxyflavone (baicalein).

Antimicrobial Compounds in Food Packaging

This review presents current knowledge on antimicrobial agents that are already used in the food packaging industry. At the beginning, innovative ways of food packaging were discussed, including how smart packaging differs from active packaging, and what functions they perform. Next, the focus was on one of the groups of bioactive components that are used in these packaging, namely antimicrobial agents. Among the antimicrobial agents, we selected those that have already been used in packaging and that promise to be used elsewhere, e.g., in the production of antimicrobial biomaterials. Main groups of antimicrobial agents (i.e., metals and metal oxides, organic acids, antimicrobial peptides and bacteriocins, antimicrobial agents of plant origin, enzymes, lactoferrin, chitosan, allyl isothiocyanate, the reuterin system and bacteriophages) that are incorporated or combined with various types of packaging materials to extend the shelf life of food are described. The further development of perspectives and setting of new research directions were also presented.

Antibacterial potential of chalcones and its derivatives against Staphylococcus aureus

Chalcones are natural substances found in the metabolism of several botanical families. Their structure consists of 1,3-diphenyl-2-propen-1-one and they are characterized by having in their chains an α, β-unsaturated carbonyl system, two phenol rings and a three-carbon chain that unites them. In plants, Chalcones are mainly involved in the biosynthesis of flavonoids and isoflavonoids through the phenylalanine derivation. This group of substances has been shown to be a viable alternative for the investigation of its antibacterial potential, considering the numerous biological activities reported and the increase of the microbial resistance that concern global health agencies. Staphylococcus aureus is a bacterium that has stood out for its ability to adapt and develop resistance to a wide variety of drugs. This literature review aimed to highlight recent advances in the use of Chalcones and derivatives as antibacterial agents against S. aureus, focusing on research articles available on the Science Direct, Pub Med and Scopus data platforms in the period 2015-2021. It was constructed informative tables that provided an overview of which types of Chalcones are being studied more (Natural or Synthetic); its chemical name and main Synthesis Methodology. From the analysis of the data, it was observed that the compounds based on Chalcones have great potential in medicinal chemistry as antibacterial agents and that the molecular skeletons of these compounds as well as their derivatives can be easily obtained through substitutions in the A and B rings of Chalcones, in order to obtain the desired bioactivity. It was verified that Chalcones and derivatives are promising agents for combating the multidrug resistance of S. aureus to drugs.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03398-7.

Antibacterial effects of biologically active ingredients in hop provide promising options to fight infections by pathogens including multi-drug resistant bacteria

Antibiotic resistance constitutes a global threat to the health care systems. The number of infections due to multidrug-resistant (MDR) bacteria increases progressively resulting in an estimated annual number of 750,000 fatal cases worldwide. Additionally, the lack of novel antibiotic compounds worsens the dilemma. Hence, there is an urgent need for alternative ways to fight antibiotic resistance. One option may be natural compounds with antibacterial properties such as hop and its biologically active ingredients which are used in traditional medicine since ancient times. This prompted us to perform an actual literature survey regarding the antibacterial properties of biologically active ingredients in hop including humulone, lupulone and xanthohumol. The 20 included studies revealed that lupulone and xanthohumol do in fact inhibit the growth of Gram-positive bacteria in vitro. In combination with distinct antibiotic compounds the hop ingredients can even exert synergistic effects resulting in enhanced antibiotic activities against defined Gram-positive and Gram-negative bacteria. In conclusion, biologically active ingredients in hop including lupulone and xanthohumol may be potential antibiotic compounds which either alone or in combination with other antibacterial substances open novel avenues in the combat of infections caused by pathogenic including MDR bacteria.

Herbals and Plants in the Treatment of Pancreatic Cancer: A Systematic Review of Experimental and Clinical Studies

Background: Pancreatic cancer represents the most lethal malignancy among all digestive cancers. Despite the therapeutic advances achieved during recent years, the prognosis of this neoplasm remains disappointing. An enormous amount of experimental (mainly) and clinical research has recently emerged referring to the effectiveness of various plants administered either alone or in combination with chemotherapeutic agents. Apart from Asian countries, the use of these plants and herbals in the treatment of digestive cancer is also increasing in a number of Western countries as well. The aim of this study is to review the available literature regarding the efficacy of plants and herbals in pancreatic cancer. Methods: The authors have reviewed all the experimental and clinical studies published in Medline and Embase, up to June 2021. Results: More than 100 plants and herbals were thoroughly investigated. Favorable effects concerning the inhibition of cancer cell lines in the experimental studies and a favorable clinical outcome after combining various plants with established chemotherapeutic agents were observed. These herbals and plants exerted their activity against pancreatic cancer via a number of mechanisms. The number and severity of side-effects are generally of a mild degree. Conclusion: A quite high number of clinical and experimental studies confirmed the beneficial effect of many plants and herbals in pancreatic cancer. More large, double-blind clinical studies assessing these natural products, either alone or in combination with chemotherapeutic agents should be conducted.

Recent Advances in Biological Activity, New Formulations and Prodrugs of Ferulic Acid

Trans-ferulic acid (FA) is a derivative of 4-hydroxycinnamic acid, which is found in many food products, fruits and beverages. It has scientifically proven antioxidant, anti-inflammatory and antibacterial properties. However, its low ability to permeate through biological barriers (e.g., the blood-brain barrier, BBB), its low bioavailability and its fast elimination from the gastrointestinal tract after oral administration limit its clinical use, e.g., for the treatment of neurodegenerative diseases, such as Alzheimer's disease. Therefore, new nanotechnological approaches are developed in order to regulate intracellular transport of ferulic acid. The objective of this review is to summarize the last decade's research on biological properties of ferulic acid and innovative ways of its delivery, supporting pharmacological therapy.

The Ability of Hop Extracts to Reduce the Methane Production of Methanobrevibacter ruminantium

Background

Methane emissions from agriculture are responsible for over 40% of the world's greenhouse gas emissions. In the past, antibiotics were used to control methane production by animals, but concerns over the emergence and spread of antibiotic-resistant bacteria to humans have prompted a search for alternative approaches. Hops are the flowers of the hop plant Humulus lupulus. They have been used to feed cattle for many years and are known to contain antibacterial compounds, and their extracts have been shown to kill members of the Mycobacterium spp including Mycobacterium bovis, the causative agent of bovine tuberculosis as well as a number of human pathogens. In this study, hop extracts were studied for their ability to inhibit methane production from Methanobrevibacter ruminantium, a major methane-producing archaeon found in the rumen of cattle.

Methods

Methanobrevibacter ruminantium M1^T (DSM 1093) was grown at 37°C for 30 days, and the amount of methane produced at different time points during this period was measured using gas chromatography. The archaeon was exposed to commercial hop extracts (tetra-hydro-iso-alpha acid and beta acid) and to aqueous hop extracts of a range of hop variants, and their effect on methane production was determined.

Results

All of the extracts reduced the level of methane production of M. ruminantium over the 30-day period compared to the negative control (sterile distilled water). The commercial hop extracts were the most effective at inhibiting methane production over the course of the experiment in contrast to the aqueous extracts, which showed a gradual reduction of inhibition with time.

Conclusions

Hops contain compounds which inhibit methane production. Given that hops can be safely fed to cattle, this raises the possibility of rationally designing a feed strategy which could reduce greenhouse gas emissions and protect against bovine tuberculosis. This study recommends that further research be undertaken to further identifying bioactive components from hops and their efficacy against a range of archaea.

Preparation of Hop Estrogen-Active Material for Production of Food Supplements

In recent years, the interest in the health-promoting effects of hop prenylflavonoids, especially its estrogenic effects, has grown. Unfortunately, one of the most potent phytoestrogens identified so far, 8-prenylnaringenin, is only a minor component of hops, so its isolation from hop materials for the production of estrogenically active food supplements has proved to be problematic. The aim of this study was to optimize the conditions (e.g., temperature, the length of the process and the amount of the catalyst) to produce 8-prenylnaringenin-rich material by the magnesium oxide-catalyzed thermal isomerization of desmethylxanthohumol. Under these optimized conditions, the yield of 8-prenylnaringenin was 29 mg per 100 gDW of product, corresponding to a >70% increase in its content relative to the starting material. This process may be applied in the production of functional foods or food supplements rich in 8-prenylnaringenin, which may then be utilized in therapeutic agents to help alleviate the symptoms of menopausal disorders.

Preliminary Insight of Pyrrolylated-Chalcones as New Anti-Methicillin-Resistant Staphylococcus aureus (Anti-MRSA) Agents

Bacterial infections are regarded as one of the leading causes of fatal morbidity and death in patients infected with diseases. The ability of microorganisms, particularly methicillin-resistant Staphylococcus aureus (MRSA), to develop resistance to current drugs has evoked the need for a continuous search for new drugs with better efficacies. Hence, a series of non-PAINS associated pyrrolylated-chalcones (1–15) were synthesized and evaluated for their potency against MRSA. The hydroxyl-containing compounds (8, 9, and 10) showed the most significant anti-MRSA efficiency, with the MIC and MBC values ranging from 0.08 to 0.70 mg/mL and 0.16 to 1.88 mg/mL, respectively. The time-kill curve and SEM analyses exhibited bacterial cell death within four hours after exposure to 9, suggesting its bactericidal properties. Furthermore, the docking simulation between 9 and penicillin-binding protein 2a (PBP2a, PDB ID: 6Q9N) suggests a relatively similar bonding interaction to the standard drug with a binding affinity score of −7.0 kcal/mol. Moreover, the zebrafish model showed no toxic effects in the normal embryonic development, blood vessel formation, and apoptosis when exposed to up to 40 µM of compound 9. The overall results suggest that the pyrrolylated-chalcones may be considered as a potential inhibitor in the design of new anti-MRSA agents.

The Pro-Health Benefits of Morusin Administration-An Update Review

Prenylflavonoids are widespread in nature. Plants are valuable sources of natural polyphenolic compounds with isoprenyl groups, which include flavones, flavanones, chalcones and aurones. They can be found in flowers, bark and stems. One of the most important compounds found in the bark of white mulberry (Morus alba) is morusin, a prenylated flavone with interesting pro-health properties. The research carried out so far revealed that morusin has antioxidant, antitumor, anti-inflammatory and anti-allergic activity. Moreover, its neuroprotective and antihyperglycemic properties have also been confirmed. Morusin suppresses the growth of different types of tumors, including breast cancer, glioblastoma, pancreatic cancer, hepatocarcinoma, prostate cancer, and gastric cancer. It also inhibits the inflammatory response by suppressing COX activity and iNOS expression. Moreover, an antimicrobial effect against Gram-positive bacteria was observed after treatment with morusin. The objective of this review is to summarize the current knowledge about the positive effects of morusin on human health in order to facilitate future study on the development of plant polyphenolic drugs and nutraceutics in the group of prenylflavones.

Xanthohumol from Hop: Hope for cancer prevention and treatment

Cancer is a major public health concern due to high mortality and poor quality of life of patients. Despite the availability of advanced therapeutic interventions, most treatment modalities are not efficacious, very expensive, and cause several adverse side effects. The factors such as drug resistance, lack of specificity, and low efficacy of the cancer drugs necessitate developing alternative strategies for the prevention and treatment of this disease. Xanthohumol (XN), a prenylated chalcone present in Hop (Humulus lupulus), has been found to possess prominent activities against aging, diabetes, inflammation, microbial infection, and cancer. Thus, this manuscript thoroughly reviews the literature on the anti-cancer properties of XN and its various molecular targets. XN was found to exert its inhibitory effect on the growth and proliferation of cancer cells via modulation of multiple signaling pathways such as Akt, AMPK, ERK, IGFBP2, NF-κB, and STAT3, and also modulates various proteins such as Notch1, caspases, MMPs, Bcl-2, cyclin D1, oxidative stress markers, tumor-suppressor proteins, and miRNAs. Thus, these reports suggest that XN possesses enormous therapeutic potential against various cancers and could be potentially used as a multi-targeted anti-cancer agent with minimal adverse effects.

Xanthohumol for Human Malignancies: Chemistry, Pharmacokinetics and Molecular Targets

Xanthohumol (XH) is an important prenylated flavonoid that is found within the inflorescence of Humulus lupulus L. (Hop plant). XH is an important ingredient in beer and is considered a significant bioactive agent due to its diverse medicinal applications, which include anti-inflammatory, antimicrobial, antioxidant, immunomodulatory, antiviral, antifungal, antigenotoxic, antiangiogenic, and antimalarial effects as well as strong anticancer activity towards various types of cancer cells. XH acts as a wide ranging chemopreventive and anticancer agent, and its isomer, 8-prenylnaringenin, is a phytoestrogen with strong estrogenic activity. The present review focuses on the bioactivity of XH on various types of cancers and its pharmacokinetics. In this paper, we first highlight, in brief, the history and use of hops and then the chemistry and structure–activity relationship of XH. Lastly, we focus on its prominent effects and mechanisms of action on various cancers and its possible use in cancer prevention and treatment. Considering the limited number of available reviews on this subject, our goal is to provide a complete and detailed understanding of the anticancer effects of XH against different cancers.

The Interactions between Polyphenols and Microorganisms, Especially Gut Microbiota

This review presents the comprehensive knowledge about the bidirectional relationship between polyphenols and the gut microbiome. The first part is related to polyphenols' impacts on various microorganisms, especially bacteria, and their influence on intestinal pathogens. The research data on the mechanisms of polyphenol action were collected together and organized. The impact of various polyphenols groups on intestinal bacteria both on the whole "microbiota" and on particular species, including probiotics, are presented. Moreover, the impact of polyphenols present in food (bound to the matrix) was compared with the purified polyphenols (such as in dietary supplements) as well as polyphenols in the form of derivatives (such as glycosides) with those in the form of aglycones. The second part of the paper discusses in detail the mechanisms (pathways) and the role of bacterial biotransformation of the most important groups of polyphenols, including the production of bioactive metabolites with a significant impact on the human organism (both positive and negative).

Discovery of natural products capable of inducing porcine host defense peptide gene expression using cell-based high throughput screening

Background

In-feed antibiotics are being phased out in livestock production worldwide. Alternatives to antibiotics are urgently needed to maintain animal health and production performance. Host defense peptides (HDPs) are known for their broad-spectrum antimicrobial and immunomodulatory capabilities. Enhancing the synthesis of endogenous HDPs represents a promising antibiotic alternative strategy to disease control and prevention.

Methods

To identify natural products with an ability to stimulate the synthesis of endogenous HDPs, we performed a high-throughput screening of 1261 natural products using a newly-established stable luciferase reporter cell line known as IPEC-J2/pBD3-luc. The ability of the hit compounds to induce HDP genes in porcine IPEC-J2 intestinal epithelial cells, 3D4/31 macrophages, and jejunal explants were verified using RT-qPCR. Augmentation of the antibacterial activity of porcine 3D4/31 macrophages against a Gram-negative bacterium (enterotoxigenic E. coli) and a Gram-positive bacterium (Staphylococcus aureus) were further confirmed with four selected HDP-inducing compounds.

Results

A total of 48 natural products with a minimum Z-score of 2.0 were identified after high-throughput screening, with 21 compounds giving at least 2-fold increase in luciferase activity in a follow-up dose-response experiment. Xanthohumol and deoxyshikonin were further found to be the most potent in inducing pBD3 mRNA expression, showing a minimum 10-fold increase in IPEC-J2, 3D4/31 cells, and jejunal explants. Other compounds such as isorhapontigenin and calycosin also enhanced pBD3 mRNA expression by at least 10-fold in both IPEC-J2 cells and jejunal explants, but not 3D4/31 cells. In addition to pBD3, other porcine HDP genes such as pBD2, PG1-5, and pEP2C were induced to different magnitudes by xanthohumol, deoxyshikonin, isorhapontigenin, and calycosin, although clear gene- and cell type-specific patterns of regulation were observed. Desirably, these four compounds had a minimum effect on the expression of several representative inflammatory cytokine genes. Furthermore, when used at HDP-inducing concentrations, these compounds showed no obvious direct antibacterial activity, but significantly augmented the antibacterial activity of 3D4/31 macrophages (P < 0.05) against both Gram-negative and Gram-positive bacteria.

Conclusions

Our results indicate that these newly-identified natural HDP-inducing compounds have the potential to be developed as novel alternatives to antibiotics for prophylactic and therapeutic treatment of infectious diseases in livestock production.

Biological Activity of Humulus Lupulus (L.) Essential Oil and Its Main Components Against Sitophilus granarius (L.)

Besides its use in the brewing industry, hop cones appear as a powerful source of biologically active compounds, already checked for their putative anticancer, antimicrobial, and other bioactivities. Conversely, hop use in pest control remains to date under-investigated. Therefore, the biological activity of hop essential oil (EO) and its main constituents was investigated here against Sitophilus granarius. Adult contact toxicity was found 24 h after treatment with hop EO (LD50/LD90 13.30/40.23 µg/adult), and its three most abundant components, α-humulene, β-myrcene, and β-caryophyllene (LD50/LD90 41.87/73.51, 75.91/126.05, and 138.51/241.27 µg/adult, respectively); negligible variations at 48 h, except for α-humulene (LD50/LD90 26.83/49.49 µg/adult), were found. The fumigant toxicity of the EO and terpenes was also checked: in the absence of wheat grains, β-myrcene showed the highest inhalation toxicity (LC50/LC90 72.78/116.92 mg/L air), whereas α-humulene, β-caryophyllene, and the EO induced similar values (LC50/LC90 about 130/200 mg/L air); with the exception for EO, the wheat presence increased (30-50%) LC50/LC90 values. Moreover, EO and terpenes were perceived by insect antennae and elicited repellent activity. Only β-caryophyllene showed an anticholinesterase effect, this suggesting that different mechanisms of action should be responsible for hop EO toxicity. Therefore, hop EO appears suitable for developing control means against this pest.

Pharmacological activation of Nrf2 promotes wound healing

Wound repair and regeneration is a complex orchestrated process, comprising several phases interconnecting various cellular events and triggering multiple intracellular molecular pathways in damaged cells and tissues. In several metabolic disorders including diabetes mellitus, delay in wound healing due to elevated levels of cellular stress poses a key challenge. Several therapeutic wound dressing materials and strategies including hyperbaric oxygen therapy and negative pressure wound therapy have been developed to accelerate repair and restore cellular homeostasis at the wound site. Further, tremendous progress has been made in identification of transcriptional regulators involved in the process of wound healing. Nuclear factor erythroid 2-related factor 2 (Nrf2), a redox sensitive transcription factor, is the key regulator of intracellular redox homeostasis which induces the expression of cytoprotective genes and increases the production of antioxidants that scavenge free radicals. Activators of Nrf2 have been reported to combat oxidative stress and enhance the process of wound healing in several pathophysiological conditions, including diabetes and its complications such as diabetic foot ulcer, and chronic kidney disease, and diabetic nephropathy. Several bioactive compounds have been reported to reduce cellular stress, and thus accelerate cell proliferation, neovascularization results in repairing damaged tissues by the activation of the transcription factor, Nrf2. This review is focused on the strategies for diabetic wound healing and the highlights the role of bioactive compounds that activate the Nrf2 signaling and revitalize the cellular and molecular mechanism in the chronic wound niche, regulate and restore redox homeostasis thereby promoting wound repair and regeneration.

Anti-obesity effect of a hop-derived prenylflavonoid isoxanthohumol in a high-fat diet-induced obese mouse model

We examined whether oral administration of a hop-derived prenylflavonoid isoxanthohumol (IX) would show anti-obesity activity and the underlying mechanism of the potential activity using a high-fat diet (HFD)-induced obese mouse model. Oral administration of 180 mg/kg IX for 8 weeks suppressed HFD-induced accumulation of visceral fat and body weight gain in mice. Simultaneously, IX changed the composition of the microbiome, as determined by a significant increase in the relative abundances of Akkermansia muciniphila, Blautia, and Escherichia coli. A. muciniphila accounted for 23% and 24% of the total microbiome in the HFD+60 mg/kg and 180 mg/kg IX groups, respectively, while it was undetectable in the normal diet (ND) and HFD groups. Similarly, Blautia accounted for 8% and 10% of the total microbiome in the HFD+60 mg/kg and 180 mg/kg IX groups, respectively, while it accounted for less than 1% in the ND and HFD groups. In contrast, a significant decrease in the relative abundance of Oscillospira was observed in the HFD+60 mg/kg and 180 mg/kg IX groups compared with the HFD group. We further examined the anti-obesity effect of IX using a germ-free (GF) mouse model to clarify the relationship between the microbiome and the effect of IX. IX showed no significant anti-obesity effect on fat accumulation and weight gain in GF mice. These results suggest that the anti-obesity effect of IX may involve microbial changes.

A Review on Sources and Pharmacological Aspects of Sakuranetin

Sakuranetin belongs to the group of methoxylated flavanones. It is widely distributed in Polyomnia fruticosa and rice, where it acts as a phytoalexin. Other natural sources of this compound are, among others, grass trees, shrubs, flowering plants, cheery, and some herbal drugs, where it has been found in the form of glycosides (mainly sakuranin). Sakuranetin has antiproliferative activity against human cell lines typical for B16BL6 melanoma, esophageal squamous cell carcinoma (ESCC) and colon cancer (Colo 320). Moreover, sakuranetin shows antiviral activity towards human rhinovirus 3 and influenza B virus and was reported to have antioxidant, antimicrobial, antiinflammatory, antiparasitic, antimutagenic, and antiallergic properties. The aim of this review is to present the current status of knowledge of pro-health properties of sakuranetin.

Improvements in Metabolic Syndrome by Xanthohumol Derivatives Are Linked to Altered Gut Microbiota and Bile Acid Metabolism

SCOPE

Two hydrogenated xanthohumol (XN) derivatives, α,β-dihydro-XN (DXN) and tetrahydro-XN (TXN), improved parameters of metabolic syndrome (MetS), a critical risk factor of cardiovascular disease (CVD) and type 2 diabetes, in a diet-induced obese murine model. It is hypothesized that improvements in obesity and MetS are linked to changes in composition of the gut microbiota, bile acid metabolism, intestinal barrier function, and inflammation.

METHODS AND RESULTS

To test this hypothesis, 16S rRNA genes were sequenced and bile acids were measured in fecal samples from C57BL/6J mice fed a high-fat diet (HFD) or HFD containing XN, DXN or TXN. Expression of genes associated with epithelial barrier function, inflammation, and bile acid metabolism were measured in the colon, white adipose tissue (WAT), and liver, respectively. Administration of XN derivatives decreases intestinal microbiota diversity and abundance-specifically Bacteroidetes and Tenericutes-alters bile acid metabolism, and reduces inflammation. In WAT, TXN supplementation decreases pro-inflammatory gene expression by suppressing macrophage infiltration. Transkingdom network analysis connects changes in the microbiota to improvements in MetS in the host.

CONCLUSION

Changes in the gut microbiota and bile acid metabolism may explain, in part, the improvements in obesity and MetS associated with administration of XN and its derivatives.

Xanthohumol Analogues as Potent Nrf2 Activators against Oxidative Stress Mediated Damages of PC12 Cells

The nuclear factor erythroid 2-related factor 2 (Nrf2), a master transcription factor controlling a series of cytoprotective genes, is closely associated with scavenging the reactive oxygen species and maintaining the intracellular redox balance. Accumulating evidence has indicated that activation of Nrf2 is efficient to block or retard oxidative stress mediated neurodegenerative disorders. Small molecules that contribute directly or indirectly to the Nrf2 activation thus are promising therapeutic agents. Herein, we screened xanthohumol and its analogues, and two analogues (11 and 12) were disclosed to possess low cytotoxicity and rescue PC12 cells from the hydrogen peroxide or 6-hydroxydopamine induced injuries. Molecular mechanism studies demonstrated that compounds 11 and 12 are potent Nrf2 activators by promoting the nuclear accumulation of Nrf2 and enhancing the cellular antioxidant defense system. More importantly, genetically silencing the Nrf2 expression shuts down the observed cytoprotection conferred by both compounds, supporting the critical involvement of Nrf2 for the cellular actions of compounds 11 and 12.

Analyzing bioactive effects of the minor hop compound xanthohumol C on human breast cancer cells using quantitative proteomics

Minor prenylated hop compounds have been attracting increasing attention due to their promising anticarcinogenic properties. Even after intensive purification from natural raw extracts, allocating certain activities to single compounds or complex interactions of the main compound with remaining impurities in very low concentration is difficult. In this study, dose-dependent antiproliferative and cytotoxic effects of the promising xanthohumol (XN) analogue xanthohumol C (XNC) were evaluated and compared to XN and a XN-enriched hop extract (XF). It was demonstrated that the cell growth inhibition of human breast cancer cell line (MCF-7) significantly increases after being treated with XNC compared to XN and XF. Based on label-free data-dependent acquisition proteomics, physiological influences on the proteome of MCF-7 cells were analyzed. Different modes of action between XNC and XN treated MCF-7 cells could be postulated. XNC causes ER stress and seems to be involved in cell-cell adhesion, whereas XN influences cell cycles and DNA replication as well as type I interferon signaling pathway. The results demonstrate the utility of using quantitative proteomics for bioactivity screenings of minor hop compounds and underscore the importance of isolating highly pure compounds into their distinct forms to analyze their different and possibly synergistic activities and modes of action.

Antibacterial activity of flavonoids and their structure-activity relationship: An update review

Based on World Health Organization reports, resistance of bacteria to well-known antibiotics is a major global health challenge now and in the future. Different strategies have been proposed to tackle this problem including inhibition of multidrug resistance pumps and biofilm formation in bacteria and development of new antibiotics with novel mechanism of action. Flavonoids are a large class of natural compounds, have been extensively studied for their antibacterial activity, and more than 150 articles have been published on this topic since 2005. Over the past decade, some promising results were obtained with the antibacterial activity of flavonoids. In some cases, flavonoids (especially chalcones) showed up to sixfold stronger antibacterial activities than standard drugs in the market. Some synthetic derivatives of flavonoids also exhibited remarkable antibacterial activities with 20- to 80-fold more potent activity than the standard drug against multidrug-resistant Gram-negative and Gram-positive bacteria (including Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus). This review summarizes the ever changing information on antibacterial activity of flavonoids since 2005, with a special focus on the structure-activity relationship and mechanisms of actions of this broad class of natural compounds.

Antibacterial hop extracts encapsulated in nanochitosan matrices

Hops and the components extracted from them are well known antibacterial agents used in beers and as food preservatives, in formulations for topical applications on their own or together with other antimicrobial agents, in hormone replacement therapy, as antioxidants, tumor development antagonists, and angiogenesis inhibitors. Their shortcomings: very low bioavailability, bitter taste, and susceptibility to oxidative decomposition have limited their applications. We propose nanosized chitosan, an inexpensive, readily available biopolymer with a broad spectrum of antibacterial activity, as carrier for lupulone (L) and xanthohumol (X), two components of hops. Chitosan nanoparticles (CNP) and chitosan-based nanocomposites encapsulating lupulone (CNL) and xanthohumol (CNX) were prepared by ionotropic gelation using sodium tripolyphosphate (TPP) as crosslinker. Different preparative ratios and conditions were investigated and the nanoparticles obtained were characterized by FTIR, colloidal titration, size, zeta potential, and antimicrobial activity. The kinetics of the release of L/X from composites was studied in vitro. All the nanoparticles were active against several Gram-positive, Gram-negative, and Candida strains. Synergistic interactions were observed in all cases, although hops are known mainly for their activity against Gram-positive bacteria. All nanoparticles showed good stability over several months.

Microbial transformations of 4'-methylchalcones as an efficient method of obtaining novel alcohol and dihydrochalcone derivatives with antimicrobial activity

Biotransformations are an alternative method of receiving dihydrochalcones as a result of the reduction of α,β-unsaturated ketones - chalcones. In presented research, two strains of bacteria - Gordonia sp. DSM44456 and Rhodococcus sp. DSM364 - were selected as effective biocatalysts that are able to transform chalcones in a short period of time. As a result of our investigation 3 new dihydrochalcones and one novel alcohol were obtained with high isolated yields. All 4'-methylchalcone derivatives and biotransformations products were tested for antimicrobial activity against Escherichia coli ATCC10536, Staphylococcus aureus DSM799, Candida albicans DSM1386, Alternaria alternata CBS1526, Fusarium linii KB-F1, and Aspergillus niger DSM1957. The best inhibitory effect was observed for all chalcones against E. coli ATCC10536 - compounds 1-6 and 8 prevented thorough growth of this strain (ΔOD = 0). Moreover, dihydrochalcones showed about 2-3 times stronger inhibitory effect against S. aureus DSM799 in comparison to their chalcones. Excluding the E. coli ATCC10536 strain, 3-(4-carboxyphenyl)-1-(4-methylphenyl)propan-1-ol (8b) had weaker biological activity than 4-carboxy-4'-methyl-α,β-dihydrochalcone (8a).

Homogeneous Synthesis of Cationic Chitosan via New Avenue

Using a solvent formed of alkali and urea, chitosan was successfully dissolved in a new solvent via the freezing⁻thawing process. Subsequently, quaternized chitosan (QC) was synthesized using 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHPTAC) as the cationic reagent under different incubation times and temperatures in a homogeneous system. QCs cannot be synthesized at temperatures above 60 °C, as gel formation will occur. The structure and properties of the prepared QC were characterized and quaternary groups were comfirmed to be successfully incorporated onto chitosan backbones. The degree of substitution (DS) ranged from 16.5% to 46.8% and the yields ranged from 32.6% to 89.7%, which can be adjusted by changing the molar ratio of the chitosan unit to CHPTAC and the reaction time. QCs inhibits the growth of Alicyclobacillus acidoterrestris effectively. Thus, this work offers a simple and green method of functionalizing chitosan and producing quaternized chitosan with an antibacterial effect for potential applications in the food industry.

Xanthohumol C, a minor bioactive hop compound: Production, purification strategies and antimicrobial test

Hop has been attracting scientific attention due to its favorable bioactivity properties. It is thus desirable to relate these properties to the specific hop compounds and extract these compounds in highly purified form in order to enhance the effect. The aim of the present study is the isolation of a sufficient amount of the highly purified prenylated minor hop compound xanthohumol C (XNC) for characterizing its bioactivity. Two strategies for the production of XNC were evaluated. The first strategy involved a capture of natural XNC from a xanthohumol (XN)-enriched hop extract (XF) by countercurrent chromatography. In the second approach, a one-step semi-synthesis of XNC was performed starting from XN, which had previously been separated from a natural XN-enriched hop extract. Both methods delivered XNC in sufficient amount and purity (>95%, HPLC), whereas the second strategy was preferable in terms of purity (>99%, HPLC) as well as productivity and solvent consumption. The methods were validated by identifying and quantifying XNC using LC-MS, LC-MS/MS and ¹H NMR analysis. The XNC obtained in this way was supplied to several bacterial, yeast and fungal cultures in order to evaluate its antimicrobial effects. For comparison, microorganisms were also treated with the natural XN-enriched hop extract, as well as the prenylated hop compound XN. While still reducing cell proliferation, XNC was found to be less effective than both XF and XN for all studied bacteria and yeasts. Furthermore, for Bacillus subtilis, a strongly pH-dependent minimal inhibition concentration was observed for all three bioactive compounds, lowest at a pH of 5 and highest at a pH of 7.

In Vitro Effect of 8-Prenylnaringenin and Naringenin on Fibroblasts and Glioblastoma Cells-Cellular Accumulation and Cytotoxicity

Gliomas are one of the most aggressive and treatment-resistant types of human brain cancer. Identification and evaluation of anticancer properties of compounds found in plants, such as naringenin (N) and 8-prenylnaringenin (8PN), are among the most promising applications in glioma therapy. The prenyl group seems to be crucial to the anticancer activity of flavones, since it may lead to enhanced cell membrane targeting and thus increased intracellular activity. It should be noted that 8PN content in hop cones is 10 to 100 times lower compared to other flavonoids, such as xanthohumol. In the study presented, we used a simple method for the synthesis of 8PN from isoxanthohumol—O-demethylation, with a high yield of 97%. Cellular accumulation and cytotoxicity of naringenin and 8-prenylnaringenin in normal (BJ) and cancer cells (U-118 MG) was also examined. Obtained data indicated that 8-prenylnaringenin exhibited higher cytotoxicity against used cell lines than naringenin, and the effect of both flavones was stronger in U-118 MG cells than in normal fibroblasts. The anticancer properties of 8PN correlated with its significantly greater (37%) accumulation in glioblastoma cells than in normal fibroblasts. Additionally, naringenin demonstrated higher selectivity for glioblastoma cells, as it was over six times more toxic for cancer than normal cells. Our results provide evidence that examined prenylated and non-prenylated flavanones have different biological activities against normal and cancer cell lines, and this property may be useful in designing new anticancer drugs for glioblastoma therapy.

Natural Prenylchalconaringenins and Prenylnaringenins as Antidiabetic Agents: α-Glucosidase and α-Amylase Inhibition and in Vivo Antihyperglycemic and Antihyperlipidemic Effects

Inhibition of α-glucosidase and α-amylase decreases postprandial blood glucose levels and delays glucose absorption, making it a treatment strategy for type 2 diabetes. This study examined in vivo and in vitro antidiabetic activities of natural prenylchalconaringenins 1 and 2 and prenylnaringenins 3 and 4, found in hops and beer. 3'-Geranylchalconaringenin (2) competitively and irreversibly inhibited α-glucosidase (IC₅₀ = 1.08 μM) with activity 50-fold higher than that of acarbose (IC₅₀ = 51.30 μM) and showed moderate inhibitory activity against α-amylase (IC₅₀ = 20.46 μM). Docking analysis substantiated these findings. In addition, compound 2 suppressed the increase in postprandial blood glucose levels and serum levels of total cholesterol and triglycerides in streptozotocin-induced diabetic mice. Taken together, these results suggest that 2 has dual inhibitory activity against α-glucosidase and α-amylase and alleviates diabetic hyperglycemia and hyperlipidemia, making it a potential functional food ingredient and drug candidate for management of type 2 diabetes.