In vitro evaluation of antibacterial, anticollagenase, and antioxidant activities of hop components (Humulus lupulus) addressing acne vulgaris

Antimicrobial Properties of Spent Hops Extracts, Flavonoids Isolated Therefrom, and Their Derivatives

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.

Effect of a botanical cleansing lotion on skin sebum and erythema of the face: A randomized controlled blinded half-side comparison

BACKGROUND

Elevated levels of skin sebum are associated with the growth of Propionibacterium acnes. Intensive degreasing of the skin reduces Propionibacterium acnes but also may cause skin irritation.

AIMS

We assessed the degreasing effect and skin tolerability of a botanical face cleanser with hops and willow bark extract and disodium cocoyl glutamate as mild cleansing agent compared to a standard face cleanser with sodium laureth sulfate (SLES).

MATERIALS AND METHODS

A total of 21 healthy volunteers with normal to oily skin were enrolled in this study. Both cleansers were applied twice a day on the left or right side of the forehead for 15 days in a standardized manner. Bioengineering measurements were performed on day 8 and 15 and on day 17 after an application break of 48 hours. The sebum level was determined using a Sebumeter^® , and skin redness was measured using a Mexameter^® .

RESULTS

The botanical face cleanser significantly reduced the sebum level (P < .01) in the test area on day 17. The SLES containing cleanser showed a statistically relevant degreasing effect already on day 15, but after the application break the sebum level increased again on day 17. None of the cleansers caused skin irritation as determined by skin redness measurements.

CONCLUSIONS

In contrast to the SLES containing cleanser, the botanical skin cleanser with hops and willow bark extract had a continuous degreasing effect without reactive seborrhoe after the treatment break. Skin cleansing without SLES might be advantageous for sensitive skin.

Sequential Elution of Essential Oil Constituents during Steam Distillation of Hops (Humulus lupulus L.) and Influence on Oil Yield and Antimicrobial Activity

The profile and bioactivity of hops (Humulus lupulus L.) essential oil, a complex natural product extracted from cones via steam distillation, depends on genetic and environmental factors, and may also depend on extraction process. We hypothesized that compound mixtures eluted sequentially and captured at different timeframes during the steam distillation process of whole hop cones would have differential chemical and bioactivity profiles. The essential oil was collected sequentially at 8 distillation time (DT) intervals: 0-2, 2-5, 5-10, 10-30, 30-60, 60-120, 120-180, and 180-240 min. The control was a 4-h non-interrupted distillation. Nonlinear regression models described the DT and essential oil compounds relationship. Fractions yielded 0.035 to 0.313% essential oil, while control yielded 1.47%. The oil eluted during the first hour was 83.2%, 9.6% during the second hour, and only 7.2% during the second half of the distillation. Essential oil (EO) fractions had different chemical profile. Monoterpenes were eluted early, while sequiterpenes were eluted late. Myrcene and linalool were the highest in 0-2 min fraction, β-caryophyllene, β-copaene, β-farnesene, and α-humulene were highest in fractions from middle of distillation, whereas α- bergamotene, γ-muurolene, β- and α-selinene, γ- and δ-cadinene, caryophyllene oxide, humulne epoxide II, τ-cadinol, and 6-pentadecen-2-one were highest in 120-180 or 180-240 min fractions. The Gram-negative Escherichia coli was strongly inhibited by essential oil fractions from 2-5 min and 10-30 min, followed by oil fraction from 0-2 min. The strongest inhibition activity against Gram-negative Yersinia enterocolitica, and Gram-positive Clostridium perfringens, Enterococcus faecalis, and Staphylococcus aureus subs. aureus was observed with the control essential oil. This is the first study to describe significant activity of hops essential oils against Trypanosoma brucei, a parasitic protozoan that causes African trypanosomiasis (sleeping sickness in humans and nagana in other animals). Hops essential oil fractions or whole oil may be used as antimicrobial agents or for the development of new drugs.

Inhibitory effect of hop fractions against Gram-positive multi-resistant bacteria. A pilot study

AIM

Our research focused on the antimicrobial effects of purified hop (Humulus lupulus L.) fractions including α-bitter acids (humulones), β-bitter acids (lupulones) and xanthohumol, and a commercial CO2 hop extract of bitter acids against reference and multi-resistant strains of Gram-positive and Gram-negative bacteria and against selected yeast strains.

METHODS

In vitro testing of antimicrobial activity was performed according to standard testing protocols (EUCAST). The effects of hop extracts on bacterial/yeast strains at concentrations below MICs were also determined and the antimicrobial potential of hop extracts was compared with selected antibiotics using optical density measurement.

RESULTS

The fractions were effective not only against reference strains of Gram-positive bacteria but, more importantly, against their methicillin- and vancomycin-resistant variants. No antimicrobial effect was detected against Gram-negative bacterial strains. Among the tested substances, xanthohumol was identified as the hop fraction with the most potent antimicrobial properties. It was also found that hop substances exerted their antimicrobial effects at concentrations considerably lower than the determined MICs, with the strongest effect in case of α-bitter acids in enterococci.

CONCLUSION

The search for and research of new compounds with antimicrobial properties represents a possible solution to the current global problem of bacterial resistance. Our data suggest a desirable activity of hop fractions against some multi-resistant bacterial strains. Thus, hops might find use as a source of potential antimicrobial agents applicable in both human and veterinary medicine.

The Prenylflavonoid Xanthohumol Reduces Alzheimer-Like Changes and Modulates Multiple Pathogenic Molecular Pathways in the Neuro2a/APPswe Cell Model of AD

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder that has proved refractory to drug treatment. Given evidence of neuroprotection in animal models of ischemic stroke, we assessed the prenylflavonoid xanthohumol from the Common Hop (Humulus lupulus L.) for therapeutic potential in murine neuroblastoma N2a cells stably expressing human Swedish mutant amyloid precursor protein (N2a/APP), a well-characterized cellular model of AD. The ELISA and Western-blot analysis revealed that xanthohumol (Xn) inhibited Aβ accumulation and APP processing, and that Xn ameliorated tau hyperphosphorylation via PP2A, GSK3β pathways in N2a/APP cells. The amelioration of tau hyperphosphorylation by Xn was also validated on HEK293/Tau cells, another cell line with tau hyperphosphorylation. Proteomic analysis (2D-DIGE-coupled MS) revealed a total of 30 differentially expressed lysate proteins in N2a/APP vs. wild-type (WT) N2a cells (N2a/WT), and a total of 21 differentially expressed proteins in lysates of N2a/APP cells in the presence or absence of Xn. Generally, these 51 differential proteins could be classified into seven main categories according to their functions, including: endoplasmic reticulum (ER) stress-associated proteins; oxidative stress-associated proteins; proteasome-associated proteins; ATPase and metabolism-associated proteins; cytoskeleton-associated proteins; molecular chaperones-associated proteins, and others. We used Western-blot analysis to validate Xn-associated changes of some key proteins in several biological/pathogenic processes. Taken together, we show that Xn reduces AD-related changes in stably transfected N2a/APP cells. The underlying mechanisms involve modulation of multiple pathogenic pathways, including those involved in ER stress, oxidative stress, proteasome molecular systems, and the neuronal cytoskeleton. These results suggest Xn may have potential for the treatment of AD and/or neuropathologically related neurodegenerative diseases.

Effects of dietary hop (Humulus lupulus L.) β-acids on quality attributes, composition and oxidative stability of pork meat

BACKGROUND

The effects of dietary levels of hop β-acids on physical attributes, lipid oxidation and chemical composition of pork meat were evaluated. Thirty-two castrated male pigs obtained from a complete block design feeding experiment (6.23 ± 0.42 kg initial body weight (BW) to 20.45 ± 0.95 kg final BW) and fed diets supplemented with 0, 120, 240 or 360 mg kg^-1 hop β-acids during 35 days were slaughtered to sample longissimus dorsi muscle for meat analysis.

RESULTS

No effects (P > 0.05) of dietary hop β-acids were observed on meat physical attributes. Quadratic effects (P < 0.05) of hop β-acids were observed on lipid and protein contents and on thiobarbituric acid-reactive substance (TBARS) values of meatballs, whose equations allowed the estimation of dietary hop β-acid levels of 176, 169 and 181 mg kg^-1 to provide up to 16.20% lipid reduction, 1.95% protein accretion and 23.31% TBARS reduction respectively.

CONCLUSION

Dietary hop β-acids fed to pigs might reduce lipid, increase protein and reduce lipid oxidation without affecting physical attributes of the pork meat. © 2017 Society of Chemical Industry.

Molecular modeling and in vitro approaches towards cholinesterase inhibitory effect of some natural xanthohumol, naringenin, and acyl phloroglucinol derivatives

BACKGROUND

Many natural products, particularly phenolic compounds, have been reported to have a strong inhibition against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), the key enzymes in the pathology of Alzheimer's disease (AD).

HYPOTHESIS

Therefore, we hypothesized that some xanthahumol, naringenin, and acyl phloroglucinol derivatives (1-14) isolated from Humulus lupulus L. (hops) may have an inhibitory potential against AChE and BChE.

METHODS

Inhibitory potential of compounds 1-14 were tested against AChE and BChE using ELISA microtiter assay. Different molecular docking simulations, including IFD and GOLD protocols, were implemented to verify the interactions between the ligands and the active site amino acids and also their binding energies inside the catalytic crevices of AChE and BChE. ADME/Tox analysis were used to determine pharmacological activities of the compounds.

RESULTS

Among them, 3‑hydroxy‑xanthohumol (IC₅₀ = 51.25 ± 0.88 µM) and xanthohumol (IC₅₀ = 71.34 ± 2.09 µM), displayed a moderate AChE inhibition in comparison to that of the reference (galanthamine, IC₅₀ = 2.52 ± 0.15 µM). In addition to 3‑hydroxy‑xanthohumol (IC₅₀ = 63.07 ± 3.76 µM) and xanthohumol (IC₅₀ = 32.67 ± 2.82 µM), 8-prenylnaringenin (IC₅₀ = 86.58 ± 3.74 µM) also showed micromolar-range inhibition against BChE (galanthamine, IC₅₀ = 46.58 ± 0.91 µM). Rest of the compounds were found to be either inactive or having inhibition below 50%. Prediction of pharmacokinetic studies suggested that all the ligands revealed acceptable drug-like profiles. Docking simulations demonstrate not only the prediction of ligand binding energies of the compounds inside the catalytic domains of the targets, but also highlight the critical amino acids contributing to stabilizations of the ligands.

CONCLUSION

Our findings revealed that xanthohumol in particular could be considered as lead molecule to explore new cholinesterase inhibitors for AD.

Production of new activated bio-carbons by chemical activation of residue left after supercritical extraction of hops

A technology of activated bio-carbons production from the residue left after supercritical extraction of hops is described. The effect of the variant of chemical activation and impregnation ratio on the physicochemical properties as well as sorption capacity towards toxic gas of acidic character (nitrogen dioxide), basic organic dye (aqueous solution of methylene blue - MB) and iodine was investigated. The materials obtained were activated bio-carbons of well-developed surface area ranging between 897 and 1095m²/g, showing clearly acidic character of the surface. The sorption tests results proved that chemical activation of the residue left after supercritical extraction of hops allows obtaining activated bio-carbons with very high sorption capacity towards nitrogen dioxide, reaching to 77.2 and 155.3mg/g in dry and wet conditions, respectively. The maximum sorption capacity of the adsorbents towards methylene blue was 328.75mg/g, while towards iodine 1815mg/g. The equilibrium data for aqueous solution of MB were analyzed by the Langmuir and Freundlich models, whereas the kinetics of the adsorption process was studied using pseudo-first and second-order models. According to the obtained data, the adsorption of MB from aqueous solution is better described by Langmuir model and pseudo-second order kinetic model.

Potential biomedical applications of marine algae

Functional components extracted from algal biomass are widely used as dietary and health supplements with a variety of applications in food science and technology. In contrast, the applications of algae in dermal-related products have received much less attention, despite that algae also possess high potential for the uses in anti-infection, anti-aging, skin-whitening, and skin tumor treatments. This review, therefore, focuses on integrating studies on algae pertinent to human skin care, health and therapy. The active compounds in algae related to human skin treatments are mentioned and the possible mechanisms involved are described. The main purpose of this review is to identify serviceable algae functions in skin treatments to facilitate practical applications in this high-potential area.

Strong antimicrobial activity of xanthohumol and other derivatives from hops (Humulus lupulus L.) on gut anaerobic bacteria

Anaerobic bacteria, such as Bacteroides fragilis or Clostridium perfringens, are part of indigenous human flora. However, Clostridium difficile represents also an important causative agent of nosocomial infectious antibiotic-associated diarrhoea. Treatment of C. difficile infection is problematic, making it imperative to search for new compounds with antimicrobial properties. Hops (Humulus lupulus L.) contain substances with antibacterial properties. We tested antimicrobial activity of purified hop constituents humulone, lupulone and xanthohumol against anaerobic bacteria. The antimicrobial activity was established against B. fragilis, C. perfringens and C. difficile strains according to standard testing protocols (CLSI, EUCAST), and the minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBC) were calculated. All C. difficile strains were toxigenic and clinically relevant, as they were isolated from patients with diarrhoea. Strongest antimicrobial effects were observed with xanthohumol showing MIC and MBC values of 15-107 μg/mL, which are close to those of conventional antibiotics in the strains of bacteria with increased resistance. Slightly higher MIC and MBC values were obtained with lupulone followed by higher values of humulone. Our study, thus, shows a potential of purified hop compounds, especially xanthohumol, as alternatives for treatment of infections caused by select anaerobic bacteria, namely nosocomial diarrhoea caused by resistant strains.

Protective effect of xanthohumol against age-related brain damage

It has been recently shown that xanthohumol, a flavonoid present in hops, possesses antioxidant, anti-inflammatory and chemopreventive properties. However, its role in the aging brain has not been addressed so far. Therefore, this study aimed to investigate the possible neuroprotective activity of xanthohumol against age-related inflammatory and apoptotic brain damage in male senescence-accelerated prone mice (SAMP8). Animals were divided into 4 groups: Untreated young mice, untreated old mice and old mice treated either with 1 mg kg^-1 day^-1 or 5 mg kg^-1 day^-1 xanthohumol. Young and old senescence accelerated resistant mice (SAMR1) were used as controls. After 30 days of treatment, animals were sacrificed and their brains were collected and immediately frozen in liquid nitrogen. mRNA (GFAP, TNF-α, IL-1β, AIF, BAD, BAX, XIAP, NAIP and Bcl-2) and protein (GFAP, TNF-α, IL-1β, AIF, BAD, BAX, BDNF, synaptophysin and synapsin) expressions were measured by RT-PCR and Western blotting, respectively. Significant increased levels of pro-inflammatory (TNF-α, IL-1β) and pro-apoptotic (AIF, BAD, BAX) markers were observed in both SAMP8 and SAMR1 old mice compared to young animals (P<.05) and also in SAMP8 untreated old mice compared to SAMR1 (P<.05). These alterations were significantly less evident in animals treated with both doses of xanthohumol (P<.05). Also, a reduced expression of synaptic markers was observed in old mice compared to young ones (P<.05) but it significantly recovered with 5 mg kg^-1 day^-1 xanthohumol treatment (P<.05). In conclusion, xanthohumol treatment modulated the inflammation and apoptosis of aged brains, exerting a protective effect on damage induced by aging.

Synergistic Antibacterial Effects of Chitosan-Caffeic Acid Conjugate against Antibiotic-Resistant Acne-Related Bacteria

The object of this study was to discover an alternative therapeutic agent with fewer side effects against acne vulgaris, one of the most common skin diseases. Acne vulgaris is often associated with acne-related bacteria such as Propionibacterium acnes, Staphylococcus epidermidis, Staphylococcus aureus, and Pseudomonas aeruginosa. Some of these bacteria exhibit a resistance against commercial antibiotics that have been used in the treatment of acne vulgaris (tetracycline, erythromycin, and lincomycin). In the current study, we tested in vitro antibacterial effect of chitosan-phytochemical conjugates on acne-related bacteria. Three chitosan-phytochemical conjugates used in this study exhibited stronger antibacterial activity than that of chitosan (unmodified control). Chitosan-caffeic acid conjugate (CCA) showed the highest antibacterial effect on acne-related bacteria along with minimum inhibitory concentration (MIC; 8 to 256 μg/mL). Additionally, the MIC values of antibiotics against antibiotic-resistant P. acnes and P. aeruginosa strains were dramatically reduced in combination with CCA, suggesting that CCA would restore the antibacterial activity of the antibiotics. The analysis of fractional inhibitory concentration (FIC) indices clearly revealed a synergistic antibacterial effect of CCA with antibiotics. Thus, the median sum of FIC (∑FIC) values against the antibiotic-resistant bacterial strains ranged from 0.375 to 0.533 in the combination mode of CCA and antibiotics. The results of the present study suggested a potential possibility of chitosan-phytochemical conjugates in the control of infections related to acne vulgaris.

Selective Bactericidal Activity of Divalent Metal Salts of Lauric Acid

Bacteria play a crucial role in skin health. For example, Staphylococcus aureus and Propionibacterium acnes cause skin roughness and acne, whereas Staphylococcus epidermidis enhances innate barrier immunity. Therefore, controlling the bacterial flora is important in dermatology and cosmetic chemistry. In this study, the bactericidal activities of different metal salts of lauric acid were evaluated. The bactericidal behavior of the salts changed according to the type of metal ion. Specifically, the Mg-, Ca-, and Mn-containing salts effectively sterilized only S. aureus and P. acnes. Their Co, Ni, and Cu salts sterilized all bacteria, including S. epidermidis, whereas the Zn salt proved ineffective. The Cu salt displayed the strongest bactericidal activity. Spin-trapping, detected using electron spin resonance, showed that this salt catalyzed the generation of hydroxyl radicals, which can destroy bacterial cell membranes. These findings demonstrate that metal-ion selection is an important factor in the design of bactericidal agents for healthcare products.

Tetrahydro-iso-alpha Acids Antagonize Estrogen Receptor Alpha Activity in MCF-7 Breast Cancer Cells

Tetrahydro-iso-alpha acids commonly called THIAA or Tetra are modified hop acids extracted from hop (Humulus lupulus L.) which are frequently used in brewing industry mainly in order to provide beer bitterness and foam stability. Interestingly, molecular structure of tetrahydro-iso-alpha acids is close to a new type of estrogen receptor alpha (ERα) antagonists aimed at disrupting the binding of coactivators containing an LxxLL motif (NR-box). In this work we show that THIAA decreases estradiol-stimulated proliferation of MCF-7 (ERα-positive breast cancer cells). Besides, we show that it inhibits ERα transcriptional activity. Interestingly, this extract fails to compete with estradiol for ERα binding and does not significantly impact the receptor turnover rate in MCF-7 cells, suggesting that it does not act like classical antiestrogens. Hence, we demonstrate that THIAA is able to antagonize ERα estradiol-induced recruitment of the LxxLL binding motif.

Oxidative stress response in canine in vitro liver, kidney and intestinal models with seven potential dietary ingredients

In vitro cell culture systems are a useful tool to rapidly assess the potential safety or toxicity of chemical constituents of food. Here, we investigated oxidative stress and organ-specific antioxidant responses by 7 potential dietary ingredients using canine in vitro culture of hepatocytes, proximal tubule cells (CPTC), bone marrow-derived mesenchymal stem cells (BMSC) and enterocyte-like cells (ELC). Cellular production of free radical species by denatonium benzoate (DB), epigallocatechin gallate (EPI), eucalyptol (EUC), green tea catechin extract (GTE) and sodium copper chlorophyllin (SCC), tetrahydroisohumulone (TRA) as well as xylitol (XYL) were continuously measured for reactive oxygen/nitrogen species (ROS/RNS) and superoxide (SO) for up to 24h. DB and TRA showed strong prooxidant activities in hepatocytes and to a lesser degree in ELC. DB was a weak prooxidant in BMSC. In contrast DB and TRA were antioxidants in CPTC. EPI was prooxidant in hepatocytes and BMSC but showed prooxidant and antioxidant activity in CPTC. SCC in hepatocytes (12.5mg/mL) and CPTC (0.78mg/mL) showed strong prooxidant and antioxidant activity in a concentration-dependent manner. GTE was effective antioxidant only in ELC. EUC and XYL did not induce ROS/RNS in all 4 cell types. SO production by EPI and TRA increased in hepatocytes but decreased by SCC in hepatocytes and ELC. These results suggest that organ-specific responses to oxidative stress by these potential prooxidant compounds may implicate a mechanism of their toxicities.

Supercritical carbon dioxide hops extracts with antimicrobial properties

Extracts obtained from hops (Humulus lupulus L., Cannabaceae) by supercritical fluid extraction (SFE), SFE followed by isomerization, as well as by conventional technique, were investigated for their chemical composition and antibacterial activity against selected foodborne pathogens and microorganisms capable to cause the food spoilage. The antibacterial activity of the extracts was compared with the antibacterial activity of xanthohumol, compound known for its broad pharmacological properties, isolated from the raw material remained after the SFE. Xanthohumol (XH, 96%) proved to posses the most prominent activity against all the tested strains, with the MIC values ranged between 2.5 and 20 μg mL-1. Supercritical hops extract and potassium isomerized supercritical hops extract showed strong antibacterial activity against the tested strains as well. Escherichia coli was not affected by the extracts, meaning that their oral admission would not cause the same problem as antibiotic application in intestinal flora. The chemical composition of the investigated hops extracts was analysed by GC-MS. Contents of α-acids, β-acids, iso-α-acids and xanthohumol in the samples were determined by HPLC.

Pharmacological profile of xanthohumol, a prenylated flavonoid from hops (Humulus lupulus)

The female inflorescences of hops (Humulus lupulus L.), a well-known bittering agent used in the brewing industry, have long been used in traditional medicines. Xanthohumol (XN) is one of the bioactive substances contributing to its medical applications. Among foodstuffs XN is found primarily in beer and its natural occurrence is surveyed. In recent years, XN has received much attention for its biological effects. The present review describes the pharmacological aspects of XN and summarizes the most interesting findings obtained in the preclinical research related to this compound, including the pharmacological activity, the pharmacokinetics, and the safety of XN. Furthermore, the potential use of XN as a food additive considering its many positive biological effects is discussed.

New perspectives on antiacne plant drugs: contribution to modern therapeutics

Acne is a common but serious skin disease, which affects approximately 80% adolescents and young adults in 11-30 age group. 42.5% of men and 50.9% of women continue to suffer from this disease into their twenties. Bacterial resistance is now at the alarming stage due to the irrational use of antibiotics. Hence, search for new lead molecule/bioactive and rational delivery of the existing drug (for better therapeutic effect) to the site of action is the need of the hour. Plants and plant-derived products have been an integral part of health care system since time immemorial. Therefore, plants that are currently used for the treatment of acne and those with a high potential are summarized in the present review. Most active plant extracts, namely, P. granatum, M. alba, A. anomala, and M. aquifolium exhibit minimum inhibitory concentration (MIC) in the range of 4-50 µg/mL against P. acnes, while aromatic oils of C. obovoides, C. natsudaidai, C. japonica, and C. nardus possess MICs 0.005-0.6 μL/mL and phytomolecules such as rhodomyrtone, pulsaquinone, hydropulsaquinone, honokiol, magnolol, xanthohumol lupulones, chebulagic acid and rhinacanthin-C show MIC in the range of 0.5-12.5 μg/mL. Novel drug delivery strategies of important plant leads in the treatment of acne have also been discussed.

Investigation of inclusion complex of honokiol with sulfobutyl ether-β-cyclodextrin

This study aimed to prepare and characterize an inclusion complex of honokiol (HNK) with sulfobutyl ether-β-cyclodextrin (SB-β-CD). The inclusion complex (HNK/CD COMP) was prepared utilizing a freeze-drying method. Phase-solubility curves were employed to obtain stability constants and thermodynamic parameters. The phase-solubility diagram showed a typical A(L)-type, indicating that the 1:1 (HNK:SB-β-CD) inclusion complex was formed. The solid inclusion complex was then characterized by differential scanning calorimetry and Fourier transform infrared spectroscopy. Results showed that HNK/CD COMP exhibited a higher drug release rate than free HNK in vitro. A comparative study of the pharmacokinetics between HNK/CD COMP and free HNK was also performed in rats. In vivo results indicated that AUC0-t and Cmax of HNK/CD COMP increased by approximately 158% and 123% compared with those of the free HNK, respectively. These results suggest that SB-β-CD will be potentially useful in the delivery of poorly soluble drugs, such as HNK.

In vitro and in vivo antioxidant and antimutagenic activities of polyphenols extracted from hops (Humulus lupulus L.)

BACKGROUND

Hops (Humulus lupulus L.) contain 40-140 mg g(-1) polyphenols. The objective of this study was to determine the phenolic composition of a high-purity (total phenolic content = 887 mg g(-1) ) hop polyphenol extract (HPE) and evaluate its antioxidant activities in vivo and in vitro and its antimutagenic activity. The antioxidant activity of HPE was compared with the activity of green tea polyphenols.

RESULTS

The phenolic compositions of HPE were more than 55% proanthocyanidins and more than 28% flavonoid glycosides. In vitro, HPE effectively scavenged α,α-diphenyl-β-picrylhydrazyl, hydroxyl and superoxide anion radicals, and inhibited DNA oxidative damage. In vivo, oral HPE at a polyphenol dose of 200-800 mg kg(-1) body weight significantly prevented a bromobenzene-induced decrease in liver superoxide dismutase and glutathione peroxidase activity, and decreased levels of liver thiobarbituric acid reactive substances in bromobenzene-treated mice. An oral dose of 20-80 mg kg(-1) body weight HPE significantly reduced the frequency of bone marrow micronuclei induced by cyclophosphamide. The antioxidant activities of hop polyphenols in vitro and in vivo were higher than green tea polyphenols at the same concentration.

CONCLUSION

Hop polyphenols had the same or higher antioxidant activity than tea polyphenols. Hop polyphenols might be useful as natural antioxidants and antimutagens.

Carrier-based drug delivery system for treatment of acne

Approximately 95% of the population suffers at some point in their lifetime from acne vulgaris. Acne is a multifactorial disease of the pilosebaceous unit. This inflammatory skin disorder is most common in adolescents but also affects neonates, prepubescent children, and adults. Topical conventional systems are associated with various side effects. Novel drug delivery systems have been used to reduce the side effect of drugs commonly used in the topical treatment of acne. Topical treatment of acne with active pharmaceutical ingredients (API) makes direct contact with the target site before entering the systemic circulation which reduces the systemic side effect of the parenteral or oral administration of drug. The objective of the present review is to discuss the conventional delivery systems available for acne, their drawbacks, and limitations. The advantages, disadvantages, and outcome of using various carrier-based delivery systems like liposomes, niosomes, solid lipid nanoparticles, and so forth, are explained. This paper emphasizes approaches to overcome the drawbacks and limitations associated with the conventional system and the advances and application that are poised to further enhance the efficacy of topical acne formulations, offering the possibility of simplified dosing regimen that may improve treatment outcomes using novel delivery system.

Electrochemical versus spectrophotometric assessment of antioxidant activity of hop (Humulus lupulus L.) products and individual compounds

Antioxidant (AO) activity of extracts of hop cones (Serbian domestic varieties) and commercial hop products (Saaz, Spalter, Spalter select, and Magnum pellets) was determined by parallel application of recently developed direct current (DC) polarographic and widely used DPPH assay. Correlations between 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) scavenging and total phenolics (TPC) determined by the Folin-Ciocalteu assay (FC) (0.99), and between H2O2 scavenging (HPS) and humulone content (H) determined by conductometric method (0.94), total resins (TR) (0.85), and hop storage index (HIS) (-0.90), were found statistically significant at p < 0.05 level while complete lack of HPS correlation with TPC and DPPH was observed. To obtain an insight into differences between results of AO assays applied, activity of individual compounds, prevalent hop phenolics, and bitter acids was determined. By far superior HPS activity of humulone was followed by catechin, quercetin, xanthohumol, lupulone, and rutin. In contrast, DPPH scavenging activity of phenolics (quercetin > catechin > rutin > xantohumol) was found substantially higher than activity of bitter acids. According to ferric reducing antioxidant power (FRAP) and scavenging of 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), higher AO activity was ascribed to phenolics, while almost neglecting humulone. Besides reliability, low cost, and an easy-to-handle procedure, an ability to recognize humulone as the major contributor of hop AO activity could allow DC polarographic assay to be applied in analysis of various hop-derived products.

Antiadherent and antibiofilm activity of Humulus lupulus L. derived products: new pharmacological properties

New antimicrobial properties of products derived from Humulus lupulus L. such as antiadherent and antibiofilm activities were evaluated. The growth of gram-positive but not gram-negative bacteria was inhibited to different extents by these compounds. An extract of hop cones containing 51% xanthohumol was slightly less active against S. aureus strains (MIC range 31.2-125.0  μg/mL) than pure xanthohumol (MIC range 15.6-62.5  μg/mL). The spent hop extract, free of xanthohumol, exhibited lower but still relevant activity (MIC range 1-2 mg/mL). There were positive coactions of hop cone, spent hop extracts, and xanthohumol with oxacillin against MSSA and with linezolid against MSSA and MRSA. Plant compounds in the culture medium at sub-MIC concentrations decreased the adhesion of Staphylococci to abiotic surfaces, which in turn caused inhibition of biofilm formation. The rate of mature biofilm eradication by these products was significant. The spent hop extract at MIC reduced biofilm viability by 42.8%, the hop cone extract by 74.8%, and pure xanthohumol by 86.5%. When the hop cone extract or xanthohumol concentration was increased, almost complete biofilm eradication was achieved (97-99%). This study reveals the potent antibiofilm activity of hop-derived compounds for the first time.

A study of the antioxidant properties of beers using electron paramagnetic resonance

The antioxidant properties of various kinds of beers were investigated using electron paramagnetic resonance (EPR) spectroscopy. This was possible by measuring the changes in the intensity of the EPR spectrum that resulted from the interaction of the stable radical DPPH (1,1-diphenyl-2-picrylhydrazyl) with the antioxidants found in a beer sample. The antioxidant capacity was then presented in Trolox Equivalents, e.g. μM trolox in a beer sample of 100ml. The influence of the type, colour, the content of the extract and alcohol on the antioxidant activities of commercial beer samples was investigated using two-way hierarchical clustering and analysis of variance. The results showed that all of the beers investigated exhibit antioxidant properties. By performing an analysis of variance, it was found that the value of the antioxidant capacity significantly (0.05 level of significance) depends on the content of the extract and the colour of the beer. It seems that additives also influence the antioxidant properties to some extent, but neither the alcohol content nor the kind of fermentation affects the antioxidant properties of beer.

Fungal metabolites of xanthohumol with potent antiproliferative activity on human cancer cell lines in vitro

Xanthohumol (1) and xanthohumol D (2) were isolated from spent hops. Isoxanthohumol (3) was obtained from xanthohumol by isomerisation in alkaline solution. Six metabolites were obtained as a result of transformation of xanthohumol (1) by selected fungal cultures. Their structures were established on the basis of their spectral data. One of them: 2″-(2'''-hydroxyisopropyl)-dihydrofurano-[4″,5″:3',4']-4',2-dihydroxy-6'-methoxy-α,β-dihydrochalcone (6) has not been previously reported in the literature. The antioxidant properties of hops flavonoids and xanthohumol derivatives were investigated using the 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging method. The effects of these compounds on proliferation of MCF-7, PC-3 and HT-29 human cancer cell lines were determined by the SRB assay. With the exception of one metabolite, all tested compounds showed antiproliferative activity against the tested human cancer lines. α,β-Dihydroxanthohumol (4), obtained through the biotransformation of xanthohumol, showed higher antiproliferative activity against MCF-7 human breast carcinoma cell line than cisplatin, a widely used anticancer therapeutic agent, and a comparably high activity against PC-3 human prostate cancer cell line.

Xanthohumol suppresses inflammatory response to warm ischemia-reperfusion induced liver injury

Liver ischemia/reperfusion (I/R) leads to formation of reactive oxygen species (ROS), which cause hepatic injury and initiate an inflammatory response, which is a critical problem after liver surgery and transplantation. Xanthohumol, the major prenylated chalcone found in hops, has been discussed for its anti-inflammatory and ROS-scavenging properties, and thus, we aimed to investigate the effect of xanthohumol in a model of warm I/R liver injury. Xanthohumol was applied to BALB/c mice orally at a dose of 1 mg/g body weight for 5 days before I/R-injury was induced by clamping the vascular blood supply to the median and left lateral liver lobe for 1 h followed by a 6 h period of reperfusion. At this time, HPLC analysis revealed hepatic xanthohumol levels of approximately 2 μM, a concentration which has been shown to inhibit inflammatory effects in vitro. Assessment of hepatic HMOX1 expression, hepatic glutathione content and immunohistochemical analysis for proteins conjugated with the reactive aldehyde 4-hydroxynonenal indicated that I/R-induced oxidative stress was significantly inhibited in xanthohumol-fed compared to control mice. Histological analysis, TUNEL staining and determination of transaminase serum levels revealed no significant effects of xanthohumol on acute hepatocellular injury. However, at the same time point, pretreatment with xanthohumol almost completely blunted the I/R-induced AKT and NFκB activation and the expression of the proinflammatory genes IL-1alpha, IL-6, MCP-1 and ICAM-1, which are known to play a crucial role in the subacute phase of I/R-induced liver damage. In conclusion, these data indicate the potential of xanthohumol application to prevent adverse inflammatory responses to I/R-induced liver damage such as after surgical liver resection or transplantation.

Hop (Humulus lupulus L.) extract inhibits obesity in mice fed a high-fat diet over the long term

Hops (Humulus lupulus L.) are traditionally used to add bitterness and flavour to beer. Although the isomerised hop extracts produced by the brewing process have been thought to ameliorate lipid and glucose metabolism, the influence of untreated hop extracts on high-fat (HF) diet-induced obesity is unclear. The present study examined the anti-obesity effects of a hop extract in male C57BL/6J mice fed a HF diet, or HF diet plus 2 or 5 % hop extract for 20 weeks. The oral glucose tolerance test was performed at week 19. Furthermore, water excretion was evaluated in water-loaded Balb/c male mice. The effects of the extract on lipid accumulation and PPARγ expression in 3T3-L1 adipocytes were examined. The hop extract inhibited the increase in body and adipose tissue weight, adipose cell diameter and liver lipids induced by the HF diet. Furthermore, it improved glucose intolerance. The extract enhanced water excretion in water-loaded mice. Various fractions of the hop extract inhibited lipid accumulation and PPARγ expression in 3T3-L1 adipocytes. Hop extracts might be useful for preventing obesity and glucose intolerance caused by a HF diet.

The extract from hop cones in plasma protects against changes following exposure to peroxynitrite

Humulus lupulus (Cannabaceae) is well known throughout the world as a raw material in the brewing industry. The antioxidative action of hop cones is poorly understood, therefore the aim of our present study was to investigate in vitro changes in human plasma induced by peroxynitrite in the presence of the highly purified extract from hop cones (Humulus lupulus). The aim of our study was also to explain the effect of the extract from hop cones on coagulation activity of human plasma treated with peroxynitrite. The action of the extract from hop cones was compared with the properties of a well-characterized commercial monomeric polyphenol — resveratrol (3,4′,5-trihydroxystilbene). The tested plant extract, like resveratrol, significantly inhibited protein carbonylation and nitration in plasma treated with ONOO−(0.1 mM). The extract from hop cones, like resveratrol, also caused a distinct reduction of plasma lipid peroxidation induced by ONOO−. Moreover, the tested extract modulated the coagulation properties of plasma treated with peroxynitrite. It seems that antioxidative activities of the highly purified extract from hop cones may be responsible for its medicinal properties.