Membrane-related effects underlying the biological activity of the anthraquinones emodin and barbaloin

CC12 Induces Apoptotic Cell Death and Cell Cycle Arrest in Human Glioblastoma Cell Lines and Mouse Xenograft Model

Among central nervous system tumors, glioblastoma (GBM) is the most common and the most malignant type. Even under current standard treatments, the overall survival rate is still low and the recurrence rate is high. Therefore, developing novel and effective therapy is urgently needed. CC12, a synthesized small molecule, was evaluated for the potential anti-GBM effects in two GBM cell lines, U87MG and U118MG. The observations of cell morphology, MTT assay, flow cytometry-based apoptosis after CC12 treatment, were conducted. Western blot was performed for the investigation of the apoptotic mechanism. Positron emission tomography scan analysis and bioluminescent imaging assay using a mouse xenograft model were performed for the effect of CC12 in vivo. After treated by 10 μM CC12 for 24 h, both U118MG and U87MG cells showed tumor cell death. MTT assay results showed that the survival rates decreased when the CC12 concentrations or the treatment periods increased. Ki-67 expression and flow cytometry results indicated that the proliferation was inhibited in GBM cells, and G1 phase arrest was shown. The results of 7-AAD, Br-dUTP, and JC-1 staining all showed the apoptosis of GBM cells after CC12 treatment. Increased γH2AX, caspase-3, and poly (ADP-ribose) polymerase (PARP) levels meant the DNA damage, and increased Bcl2 family proteins after CC12 treatment indicated the intrinsic apoptotic pathway was involved in CC12 induced apoptosis. Furthermore, CC12 can induce the decrease of tumor prognostic marker DcR3. In vivo experiment results showed the effect of CC12 on tumor size reduction of CC12. In addition, the ability to cross the brain-blood barrier of CC12 was also confirmed. CC12 may have anti-tumor ability through the regulation of cell cycle and apoptosis in vitro and in vivo.

Crystal structure and Hirshfeld surface analysis of 3,4-di-hydro-2H-anthra[1,2-b][1,4]dioxepine-8,13-dione

The title compound, C17H12O4, was synthesized from the dye alizarin. The dihedral angle between the mean plane of the anthra-quinone ring system (r.m.s. deviation = 0.039 Å) and the dioxepine ring is 16.29 (8)°. In the crystal, the mol-ecules are linked by C-H⋯O hydrogen bonds, forming sheets lying parallel to the ab plane. The sheets are connected through π-π and C=O⋯π inter-actions to generate a three-dimensional supra-molecular network. Hirshfeld surface analysis was used to investigate inter-molecular inter-actions in the solid-state: the most important contributions are from H⋯H (43.0%), H⋯O/O⋯H (27%), H⋯C/C⋯H (13.8%) and C⋯C (12.4%) contacts.

Potential interventions for novel coronavirus in China: A systematic review

An outbreak of a novel coronavirus (COVID‐19 or 2019‐CoV) infection has posed significant threats to international health and the economy. In the absence of treatment for this virus, there is an urgent need to find alternative methods to control the spread of disease. Here, we have conducted an online search for all treatment options related to coronavirus infections as well as some RNA‐virus infection and we have found that general treatments, coronavirus‐specific treatments, and antiviral treatments should be useful in fighting COVID‐19. We suggest that the nutritional status of each infected patient should be evaluated before the administration of general treatments and the current children's RNA‐virus vaccines including influenza vaccine should be immunized for uninfected people and health care workers. In addition, convalescent plasma should be given to COVID‐19 patients if it is available. In conclusion, we suggest that all the potential interventions be implemented to control the emerging COVID‐19 if the infection is uncontrollable.

Antimicrobial Effects Caused by Aloe barbadensis Miller on Bacteria Associated with Mastitis in Dairy Cattle

It is known that the primary etiological agents associated with bovine mastitis show high levels of antimicrobial resistance. In this paper, we studied a possible alternative to antimicrobial treatment, Aloe barbadensis Miller ( A. vera). Our goal was to determine the viability of bacteria upon treatment with a methanolic extract of A. vera gel, rich in anthraquinones such as aloin A, aloin B, and aloe emodin. To this purpose, we used fluorescence spectrometry to study the following bacteria: Staphylococcus aureus, Escherichia coli, Streptococcus uberis, and Methicillin-resistant Staphylococcus aureus (MRSA). The results show that treatment with A. vera gel extract disrupted the cell membrane causing lysis in 75% of Staphylococcus aureus, in 88% of E. coli, in 97% of Streptococcus uberis, and in 88% of MRSA cells. Cell membrane disruption is attributed to the presence of anthraquinones. Further study is needed to determine whether other phenolic compounds present in the extract, influencing antimicrobial activity, could be used to develop pharmaceutical formulations to treat bovine mastitis.

Dietary Polyphenols and Mitochondrial Function: Role in Health and Disease

Mitochondria are cytoplasmic double-membraned organelles that are involved in a myriad of key cellular regulatory processes. The loss of mitochondrial function is related to the pathogenesis of several human diseases. Over the last decades, an increasing number of studies have shown that dietary polyphenols can regulate mitochondrial redox status, and in some cases, prevent or delay disease progression. This paper aims to review the role of four dietary polyphenols - resveratrol, curcumin, epigallocatechin-3-gallate nd quercetin - in molecular pathways regulated by mitochondria and their potential impact on human health. Cumulative evidence showed that the aforementioned polyphenols improve mitochondrial functions in different in vitro and in vivo experiments. The mechanisms underlying the polyphenols' beneficial effects include, among others, the attenuation of oxidative stress, the regulation of mitochondrial metabolism and biogenesis and the modulation of cell-death signaling cascades, among other mitochondrial-independent effects. The understanding of the chemicalbiological interactions of dietary polyphenols, namely with mitochondria, may have a huge impact on the treatment of mitochondrial dysfunction-related disorders.

Aloe vera as an herbal medicine in the treatment of metabolic syndrome: A review

Metabolic syndrome (MS) is a highly prevalent health problem worldwide and is associated with different risk factors, including hyperglycemia, dyslipidemia, hypertension, and obesity. This condition increases the risk of developing type II diabetes mellitus and cardiovascular problems. The MS is one of the most important health concerns in industrialized countries and mainly results from a sedentary lifestyle, high levels of subjective stress, and unhealthy diets. Nowadays, the identification of appropriate health care approaches, such as herbal medicines, with fewer side effects is more favorable, especially with regard to the adverse effects of chemical drugs. Aloe barbadensis Miller known as Aloe vera is a useful plant with two major parts, including leaves that contain high concentrations of anthraquinone compounds and a clear gel. The gel is used as a food with several beneficial properties, such as antiinflammatory, antioxidant, antiviral, antibacterial, and wound-healing features. Other effects of A. vera, such as its lipid-lowering, antihypertensive, antidiabetic, antiobesity, and cardioprotective impacts, have been demonstrated in several studies. The present study was conducted to review the evidence on the pharmacological effects of A. vera on the different components of MS.

The anti-hepatitis B virus therapeutic potential of anthraquinones derived from Aloe vera

Although the approved hepatitis B virus (HBV)-polymerase inhibitors (e.g., lamivudine) often lead to drug-resistance, several natural products have shown promising efficacies. Though Aloe vera (AV) gel and its constituents are shown inhibitors of many viruses, their anti-HBV activity still remains elusive. We therefore, tested the anti-HBV potential of AV extract and its anthraquinones in hepatoma cells, including molecular docking, high-performance thin layer chromatography (HPTLC), and cytochrome P450 (CYP3A4) activation analyses. Our anti-HBV assays (HBsAg/HBeAg Elisa) showed maximal inhibition of viral antigens production by aloe-emodin (~83%) > chrysophanol (~62%) > aloin B (~61%) > AV extract (~37%) in HepG2.2.15 cells. Interestingly, the effect of aloe-emodin was comparable with lamivudine (~86%). Moreover, sequential treatment with lamivudine (pulse) followed by aloe-emodin (chase) enhanced the efficacy of monotherapy by ~12%. Docking (AutoDock Vina) of the anthraquinones indicated strong interactions with HBV-polymerase residues that formed stable complexes with high Gibbs's free energy. Further, identification of aloe-emodin and aloin B by validated HPTLC in AV extract strongly endorsed its anti-HBV potential. In addition, our luciferase-reporter gene assay of transfected HepG2 cells showed moderate induction of CYP3A4 by aloe-emodin. In conclusion, this is the first report on anti-HBV potential of AV-derived anthraquinones, possibly via HBV-polymerase inhibition. Of these, although aloin B exhibits novel antiviral effect, aloe-emodin appears as the most promising anti-HBV natural drug with CYP3A4 activating property towards its enhanced therapeutic efficacy.

Targeting S. mutans biofilms: a perspective on preventing dental caries

The prevalence of biofilm diseases, and dental caries in particular, have encouraged extensive research on S. mutans biofilms, including methods of preventing its formation. Numerous small molecules with specific anti-biofilm activity against this pathogen have been isolated and synthesized. Generally, these molecules can be characterized into three categories: sucrose-dependent anti-adhesion, sucrose-independent anti-adhesion and cellular signaling interference. This review aims to provide an overview of the current small molecule strategies used for targeting S. mutans biofilms, and a perspective of the future for the field.

Emodin Reduces the Activity of (1,3)-β-D-glucan Synthase from Candida albicans and Does Not Interact with Caspofungin

Candidiasis is the most common opportunistic yeast infection, with Candida albicans as a paramount causative species. (1,3)-β-D-glucan is one of the three main targets of clinically available antifungal agents used to treat Candida infections. It is one of the most abundant fungal cell wall components. Echinocandins represent the newest class of antifungals affecting cell wall biosynthesis through non-competitive inhibition of (1,3)-β-D-glucan synthase. Therefore, treatment with echinocandins causes defects in fungal cell integrity. In the present study, similar activity of emodin (6-methyl-1,3,8-trihydroxyanthraquinone) has been revealed. Many reports have already shown the antifungal potential of this pleiotropic molecule, including its activity against C. albicans. The aim of this report was to evaluate the activity of emodin towards a new molecular target, i.e. (1,3)-β-D-glucan synthase isolated from Candida cells. Moreover, given the identical mechanism of the activity of both molecules, interaction of emodin with caspofungin was determined. The study revealed that emodin reduced (1,3)-β-D-glucan synthase activity and increased cell wall damage, which was evidenced by both a sorbitol protection assay and an aniline blue staining assay. Furthermore, the synergy testing method showed mainly independence of the action of both tested antifungal agents, i.e. emodin and caspofungin used in combination.

Do recent research studies validate the medicinal plants used in British Columbia, Canada for pet diseases and wild animals taken into temporary care?

ETHNOPHARMACOLOGICAL RELEVANCE

There are insufficient safe and effective treatments for chronic pain in pets. In cases such as osteoarthritis there is no commercially available cure and veterinarians use NSAIDs to manage pain. Pet owners may have to plan for a lifetime of plant-based treatment for the conditions that lead to chronic pain in pets. Phytopharmacotherapies have the advantage of being less toxic, cheap or free, readily available, are more likely to be safe for long-term use and have the potential to reset the immune system to normal functioning.

AIM OF THE STUDY

To examine the recently published medicinal plant research that matches unpublished data on ethnoveterinary medicines (EVM) used for pets in Canada (British Columbia) to see if the EVM data can provide a lead to the development of necessary drugs.

MATERIALS AND METHODS

In 2003 semi-structured interviews were conducted with 60 participants who were organic farmers or holisitic medicinal/veterinary practitioners obtained using a purposive sample. A draft manual prepared from the data was then evaluated by participants at a participatory workshop that discussed the plant-based treatments. A copy of the final version of the manual was given to all research participants. In 2018, the recently published research matching the EVM data was reviewed to see if the EVM practices could serve as a lead for further research.

RESULTS AND CONCLUSION

Medicinal plants are used to treat a range of conditions. The injuries treated in pets in British Columbia included abscesses (resulting from an initial injury), sprains and abrasions. Dogs were also treated with medicinal plants for rheumatoid arthritis, joint pain and articular cartilage injuries. More than 40 plants were used. Anal gland problems were treated with Allium sativum L., Aloe vera L., Calendula officinalis L., Plantago major L., Ulmus fulva Michx., Urtica dioica L. and Usnea longissima Ach. Arctium lappa, Hydrangea arborescens and Lactuca muralis were used for rheumatoid arthritis and joint pain in pets. Asthma was treated with: Linum usitatissimum L., Borago officinalis L., Verbascum thapsus L., Cucurbita pepo L., Lobelia inflata L., and Zingiber officinale Roscoe. Pets with heart problems were treated with Crataegus oxyacantha L., Cedronella canariensis (L.) Willd. ex Webb & Berth, Equisetum palustre L., Cypripedium calceolus L., Pinus ponderosa Douglas ex Lawson, Humulus lupulus L., Valeriana officinalis L., Lobelia inflata L., Stachys officinalis (L.) Trev., and Viscum album L. The following plants were used for epilepsy, motion sickness and anxiety- Avena sativa L., Valeriana officinalis, Lactuca muralis (L.) Fresen., Scutellaria lateriflora L., Satureja hortensis L., and Passiflora incarnata L. Plants used for cancer treatment included Phytolacca decandra, Ganoderma lucidum, Lentinula edodes, Rumex acetosella, Arctium lappa, Ulmus fulva, Rheum palmatum, Frangula purshiana, Zingiber officinale, Glycyrrhiza glabra, Ulmus fulva, Althea officinalis, Rheum palmatum, Rumex crispus and Plantago psyllium. Trifolium pratense was used for tumours in the prostate gland. Also used were Artemisia annua, Taraxacum officinale and Rumex crispus. This review of plants used in EVM was possible because phytotherapy research of the plants described in this paper has continued because few new pharmaceutical drugs have been developed for chronic pain and because treatments like glucocorticoid therapy do not heal. Phytotherapuetic products are also being investigated to address the overuse of antibiotics. There have also been recent studies conducted on plant-based functional foods and health supplements for pets, however there are still gaps in the knowledge base for the plants Stillingia sylvatica, Verbascum thapsus, Yucca schidigera and Iris versicolor and these need further investigation.

Anti-Herpetic, Anti-Dengue and Antineoplastic Activities of Simple and Heterocycle-Fused Derivatives of Terpenyl-1,4-Naphthoquinone and 1,4-Anthraquinone

Quinones are secondary metabolites of higher plants associated with many biological activities, including antiviral effects and cytotoxicity. In this study, the anti-herpetic and anti-dengue evaluation of 27 terpenyl-1,4-naphthoquinone (NQ), 1,4-anthraquinone (AQ) and heterocycle-fused quinone (HetQ) derivatives was done in vitro against Human Herpesvirus (HHV) type 1 and 2, and Dengue virus serotype 2 (DENV-2). The cytotoxicity on HeLa and Jurkat tumor cell lines was also tested. Using plaque forming unit assays, cell viability assays and molecular docking, we found that NQ 4 was the best antiviral compound, while AQ 11 was the most active and selective molecule on the tested tumor cells. NQ 4 showed a fair antiviral activity against Herpesviruses (EC₅₀: <0.4 µg/mL, <1.28 µM) and DENV-2 (1.6 µg/mL, 5.1 µM) on pre-infective stages. Additionally, NQ 4 disrupted the viral attachment of HHV-1 to Vero cells (EC₅₀: 0.12 µg/mL, 0.38 µM) with a very high selectivity index (SI = 1728). The in silico analysis predicted that this quinone could bind to the prefusion form of the E glycoprotein of DENV-2. These findings demonstrate that NQ 4 is a potent and highly selective antiviral compound, while suggesting its ability to prevent Herpes and Dengue infections. Additionally, AQ 11 can be considered of interest as a leader for the design of new anticancer agents.

Natural Products Isolated from Oriental Medicinal Herbs Inactivate Zika Virus

Zika virus (ZIKV) has been associated with serious health conditions, and an intense search to discover different ways to prevent and treat ZIKV infection is underway. Berberine and emodin possess several pharmacological properties and have been shown to be particularly effective against the entry and replication of several viruses. We show that emodin and berberine trigger a virucidal effect on ZIKV. When the virus was exposed to 160 µM of berberine, a reduction of 77.6% in the infectivity was observed; when emodin was used (40 µM), this reduction was approximately 83.3%. Dynamic light scattering data showed that both compounds significantly reduce the hydrodynamic radius of virus particle in solution. We report here that berberine and emodin, two natural compounds, have strong virucidal effect in Zika virus.

Traditional Chinese Medicine as a Potential Source for HSV-1 Therapy by Acting on Virus or the Susceptibility of Host

Herpes simplex virus type 1 (HSV-1) is the most common virus, with an estimated infection rate of 60–95% among the adult population. Once infected, HSV-1 can remain latent in the host for a lifetime and be reactivated in patients with a compromised immune system. Reactivation of latent HSV-1 can also be achieved by other stimuli. Though acyclovir (ACV) is a classic drug for HSV-1 infection, ACV-resistant strains have been found in immune-compromised patients and drug toxicity has also been commonly reported. Therefore, there is an urge to search for new anti-HSV-1 agents. Natural products with potential anti-HSV-1 activity have the advantages of minimal side effects, reduced toxicity, and they exert their effect by various mechanisms. This paper will not only provide a reference for the safe dose of these agents if they are to be used in humans, referring to the interrelated data obtained from in vitro experiments, but also introduce the main pharmacodynamic mechanisms of traditional Chinese medicine (TCM) against HSV-1. Taken together, TCM functions as a potential source for HSV-1 therapy by direct (blocking viral attachment/absorption/penetration/replication) or indirect (reducing the susceptibility to HSV-1 or regulating autophagy) antiviral activities. The potential of these active components in the development of anti-HSV-1 drugs will also be described.

Catechin-mediated restructuring of a bacterial toxin inhibits activity

BACKGROUND

Catechins, polyphenols derived from tea leaves, have been shown to have antibacterial properties, through direct killing of bacteria as well as through inhibition of bacterial toxin activity. In particular, certain catechins have been shown to have bactericidal effects on the oral bacterium, Aggregatibacter actinomycetemcomitans, as well as the ability to inhibit a key virulence factor of this organism, leukotoxin (LtxA). The mechanism of catechin-mediated inhibition of LtxA has not been shown.

METHODS

In this work, we studied the ability of six catechins to inhibit LtxA-mediated cytotoxicity in human white blood cells, using Trypan blue staining, and investigated the mechanism of action using a combination of techniques, including fluorescence and circular dichroism spectroscopy, confocal microscopy, and surface plasmon resonance.

RESULTS

We found that all the catechins except (-)-catechin inhibited the activity of this protein, with the galloylated catechins having the strongest effect. Pre-incubation of the toxin with the catechins increased the inhibitory action, indicating that the catechins act on the protein, rather than the cell. The secondary structure of LtxA was dramatically altered in the presence of catechin, which resulted in an inhibition of toxin binding to cholesterol, an important initial step in the cytotoxic mechanism of the toxin.

CONCLUSIONS

These results demonstrate that the catechins inhibit LtxA activity by altering its structure to prevent interaction with specific molecules present on the host cell surface.

GENERAL SIGNIFICANCE

Galloylated catechins modify protein toxin structure, inhibiting the toxin from binding to the requisite molecules on the host cell surface.

Photodynamic Inactivation of Herpes Simplex Viruses

Herpes simplex virus (HSV) infections can be treated with direct acting antivirals like acyclovir and foscarnet, but long-term use can lead to drug resistance, which motivates research into broadly-acting antivirals that can provide a greater genetic barrier to resistance. Photodynamic inactivation (PDI) employs a photosensitizer, light, and oxygen to create a local burst of reactive oxygen species that inactivate microorganisms. The botanical plant extract Orthoquin^TM is a powerful photosensitizer with antimicrobial properties. Here we report that Orthoquin also has antiviral properties. Photoactivated Orthoquin inhibited herpes simplex virus type 1 (HSV-1) and herpes simplex virus type 2 (HSV-2) infection of target cells in a dose-dependent manner across a broad range of sub-cytotoxic concentrations. HSV inactivation required direct contact between Orthoquin and the inoculum, whereas pre-treatment of target cells had no effect. Orthoquin did not cause appreciable damage to viral capsids or premature release of viral genomes, as measured by qPCR for the HSV-1 genome. By contrast, immunoblotting for HSV-1 antigens in purified virion preparations suggested that higher doses of Orthoquin had a physical impact on certain HSV-1 proteins that altered protein mobility or antigen detection. Orthoquin PDI also inhibited the non-enveloped adenovirus (AdV) in a dose-dependent manner, whereas Orthoquin-mediated inhibition of the enveloped vesicular stomatitis virus (VSV) was light-independent. Together, these findings suggest that the broad antiviral effects of Orthoquin-mediated PDI may stem from damage to viral attachment proteins.

Barbaloin inhibits ventricular arrhythmias in rabbits by modulating voltage-gated ion channels

Barbaloin (10-β-D-glucopyranosyl-1,8-dihydroxy-3-(hydroxymethyl)-9(10H)-anthracenone) is extracted from the aloe plant and has been reported to have anti-inflammatory, antitumor, antibacterial, and other biological activities. Here, we investigated the effects of barbaloin on cardiac electrophysiology, which has not been reported thus far. Cardiac action potentials (APs) and ionic currents were recorded in isolated rabbit ventricular myocytes using whole-cell patch-clamp technique. Additionally, the antiarrhythmic effect of barbaloin was examined in Langendorff-perfused rabbit hearts. In current-clamp recording, application of barbaloin (100 and 200 μmol/L) dose-dependently reduced the action potential duration (APD) and the maximum depolarization velocity (Vmax), and attenuated APD reverse-rate dependence (RRD) in ventricular myocytes. Furthermore, barbaloin (100 and 200 μmol/L) effectively eliminated ATX II-induced early afterdepolarizations (EADs) and Ca²⁺-induced delayed afterdepolarizations (DADs) in ventricular myocytes. In voltage-clamp recording, barbaloin (10-200 μmol/L) dose-dependently inhibited L-type calcium current (I_Ca.L) and peak sodium current (I_Na.P) with IC₅₀ values of 137.06 and 559.80 μmol/L, respectively. Application of barbaloin (100, 200 μmol/L) decreased ATX II-enhanced late sodium current (I_Na.L) by 36.6%±3.3% and 71.8%±6.5%, respectively. However, barbaloin up to 800 μmol/L did not affect the inward rectifier potassium current (I_K1) or the rapidly activated delayed rectifier potassium current (I_Kr) in ventricular myocytes. In Langendorff-perfused rabbit hearts, barbaloin (200 μmol/L) significantly inhibited aconitine-induced ventricular arrhythmias. These results demonstrate that barbaloin has potential as an antiarrhythmic drug.

Rheum australe, an endangered high-value medicinal herb of North Western Himalayas: a review of its botany, ethnomedical uses, phytochemistry and pharmacology

Rheum australe (Himalayan Rhubarb) is a multipurpose, endemic and endangered medicinal herb of North Western Himalayas. It finds extensive use as a medicinal herb since antiquity in different traditional systems of medicine to cure a wide range of ailments related to the circulatory, digestive, endocrine, respiratory and skeletal systems as well as to treat various infectious diseases. The remedying properties of this plant species are ascribed to a set of diverse bioactive secondary metabolite constituents, particularly anthraquinones (emodin, chrysophanol, physcion, aloe-emodin and rhein) and stilbenoids (piceatannol, resveratrol), besides dietary flavonoids known for their putative health benefits. Recent studies demonstrate the pharmacological efficacy of some of these metabolites and/or their derivatives as lead molecules for the treatment of various human diseases. Present review comprehensively covers the literature available on R. australe from 1980 to early 2018. The review provides up-to-date information available on its botany for easy identification of the plant, and origin and historical perspective detailing its trade and commerce. Distribution, therapeutic potential in relation to traditional uses and pharmacology, phytochemistry and general biosynthesis of major chemical constituents are also discussed. Additionally, efficient and reproducible in vitro propagation studies holding vital significance in preserving the natural germplasm of the plant and for its industrial exploitation have also been highlighted. The review presents a detailed perspective for future studies to conserve and sustainably make use of this endangered plant species at a commercial scale.

Surface Attachment of Natural Antimicrobial Coatings onto Conventional Polypropylene Nonwoven Fabric and Its Antimicrobial Performance Assessment

The growing number of microbial cross-contamination events necessitates the development of novel antimicrobial strategies in the food industry. In this study, a polypropylene nonwoven fabric (PPNWF) was grafted with a natural antimicrobial component, aloe emodin (AE), and its antimicrobial performance was evaluated. The grafted samples (PPNWF-g-AE) were examined using Fourier transform infrared spectroscopy and scanning electron microscopy. AE was effectively grafted onto the surface of the PPNWF through the adsorption covalent effect. Compared with nongrafted PPNWF, the antimicrobial activity of PPNWF-g-AE against Staphylococcus aureus, Escherichia coli, and Candida albicans was significantly enhanced. Scanning electron micrographs confirmed that the inhibitory mechanism of PPNWF-g-AE was the microbicidal function of the grafted AE. These findings indicate that PPNWF-g-AE has potential as an effective antimicrobial material in food applications.

Experimental and theoretical studies of emodin interacting with a lipid bilayer of DMPC

Emodin is one of the most abundant anthraquinone derivatives found in nature. It is the active principle of some traditional herbal medicines with known biological activities. In this work, we combined experimental and theoretical studies to reveal information about location, orientation, interaction and perturbing effects of Emodin on lipid bilayers, where we have taken into account the neutral form of the Emodin (EMH) and its anionic/deprotonated form (EM^-). Using both UV/Visible spectrophotometric techniques and molecular dynamics (MD) simulations, we showed that both EMH and EM^- are located in a lipid membrane. Additionally, using MD simulations, we revealed that both forms of Emodin are very close to glycerol groups of the lipid molecules, with the EMH inserted more deeply into the bilayer and more disoriented relative to the normal of the membrane when compared with the EM^-, which is more exposed to interfacial water. Analysis of several structural properties of acyl chains of the lipids in a hydrated pure DMPC bilayer and in the presence of Emodin revealed that both EMH and EM^- affect the lipid bilayer, resulting in a remarkable disorder of the bilayer in the vicinity of the Emodin. However, the disorder caused by EMH is weaker than that caused by EM^-. Our results suggest that these disorders caused by Emodin might lead to distinct effects on lipid bilayers including its disruption which are reported in the literature.

Modulation of oncogenic transcription factors by bioactive natural products in breast cancer

Carcinogenesis, a multi-step phenomenon, characterized by alterations at genetic level and affecting the main intracellular pathways controlling cell growth and development. There are growing number of evidences linking oncogenes to the induction of malignancies, especially breast cancer. Modulations of oncogenes lead to gain-of-function signals in the cells and contribute to the tumorigenic phenotype. These signals yield a large number of proteins that cause cell growth and inhibit apoptosis. Transcription factors such as STAT, p53, NF-κB, c-JUN and FOXM1, are proteins that are conserved among species, accumulate in the nucleus, bind to DNA and regulate the specific genes targets. Oncogenic transcription factors resulting from the mutation or overexpression following aberrant gene expression relay the signals in the nucleus and disrupt the transcription pattern. Activation of oncogenic transcription factors is associated with control of cell cycle, apoptosis, migration and cell differentiation. Among different cancer types, breast cancer is one of top ten cancers worldwide. There are different subtypes of breast cancer cell-lines such as non-aggressive MCF-7 and aggressive and metastatic MDA-MB-231 cells, which are identified with distinct molecular profile and different levels of oncogenic transcription factor. For instance, MDA-MB-231 carries mutated and overexpressed p53 with its abnormal, uncontrolled downstream signalling pathway that account for resistance to several anticancer drugs compared to MCF-7 cells with wild-type p53. Appropriate enough, inhibition of oncogenic transcription factors has become a potential target in discovery and development of anti-tumour drugs against breast cancer. Plants produce diverse amount of organic metabolites. Universally, these metabolites with biological activities are known as "natural products". The chemical structure and function of natural products have been studied since 1850s. Investigating these properties leaded to recognition of their molecular effects as anticancer drugs. Numerous natural products extracted from plants, fruits, mushrooms and mycelia, show potential inhibitory effects against several oncogenic transcription factors in breast cancer. Natural compounds that target oncogenic transcription factors have increased the number of candidate therapeutic agents. This review summarizes the current findings of natural products in targeting specific oncogenic transcription factors in breast cancer.

Sub-Minimum Inhibitory Concentrations of Rhubarb Water Extracts Inhibit Streptococcus suis Biofilm Formation

Streptococcus suis is one of the most important swine pathogens, which can cause persistent infection by forming biofilms. In this study, sub-minimum inhibitory concentration (sub-MIC) of rhubarb water extracts were found to inhibit biofilm formation. Two-component signal transduction systems (TCSs), transcriptional regulators, and DNA binding proteins were compared under two conditions: (1) cells treated with sub-MIC rhubarb water extracts and (2) untreated cells. Using an isobaric tags for relative and absolute quantitation (iTRAQ) strategy, we found that TCSs constituent proteins of histidine kinase and response regulator were significantly down-regulated. This down-regulation can affect the transfer of information during biofilm formation. The transcriptional regulators and DNA binding proteins that can interact with TCSs and interrupt gene transcription were also significantly altered. For these reasons, the levels of protein expressions varied in different parts of the treated vs. untreated cells. In summary, rhubarb water extracts might serve as potential inhibitor for the control of S. suis biofilm formation. The change in TCSs, transcriptional regulators, and DNA binding proteins may be important factors in S. suis biofilm inhibition.

Toxicological and behavioral responses as a tool to assess the effects of natural and synthetic dyes on zebrafish early life

Organic dyes extracted from natural sources have been widely used to develop safety and eco-friendly dyes as an alternative to synthetic ones, since the latter are usually precursors of mutagenic compounds. Thereby, toxicity tests to non-target organisms are critical step to develop harmless dyes to environment and in this context, zebrafish early life stages are becoming an important alternative model. We aimed to assess the toxic effects of the synthetic dye Basic Red 51 (BR51, used in cosmetic industry), the natural dye erythrostominone (ERY, a potential commercial dye extracted from fungi) and its photodegradation product (DERY), using zebrafish early life assays. Developmental malformations on embryos and behavioral impairment on larvae were explored. Our results showed that embryos exposed to BR51 and ERY exhibited a large yolk sac (LOEC = 7.5 mg L^-1), possibly due to a deformity or delayed resorption. ERY also induced pericardial and yolk sac edemas at high concentrations (LOEC = 15 and 30 mg L^-1, respectively). Moreover, larvae swan less distance and time when exposed to ERY (LOEC = 7.5 mg L^-1) and BR51 (LOEC = 1.875 mg L^-1). The lowest larvae locomotion have been associated with impairment of the yolk sac, important tissue of the energy source. Interestingly, DERY did not affect neither development nor behavior of zebrafish, showing that ERY photodegradation is sufficient to prevent its toxic effects. In conclusion, both natural and synthetic dyes impaired development and behavior of zebrafish early life, therefore, a simple treatment of the natural dye can prevent the aquatic life impact.

Evaluation of the intestinal permeability of rosemary (Rosmarinus officinalis L.) extract polyphenols and terpenoids in Caco-2 cell monolayers

Rosemary (Rosmarinus officinalis) is grown throughout the world and is widely used as a medicinal herb and to season and preserve food. Rosemary polyphenols and terpenoids have attracted great interest due to their potential health benefits. However, complete information regarding their absorption and bioavailability in Caco-2 cell model is scarce. The permeation properties of the bioactive compounds (flavonoids, diterpenes, triterpenes and phenylpropanoids) of a rosemary extract (RE), obtained by supercritical fluid extraction, was studied in Caco-2 cell monolayer model, both in a free form or liposomed. Compounds were identified and quantitated by liquid chromatography coupled to quadrupole time-of-flight with electrospray ionization mass spectrometry analysis (HPLC-ESI-QTOF-MS), and the apparent permeability values (P_app) were determined, for the first time in the extract, for 24 compounds in both directions across cell monolayer. For some compounds, such as triterpenoids and some flavonoids, P_app values found were reported for the first time in Caco-2 cells.Our results indicate that most compounds are scarcely absorbed, and passive diffusion is suggested to be the primary mechanism of absorption. The use of liposomes to vehiculize the extract resulted in reduced permeability for most compounds. Finally, the biopharmaceutical classification (BCS) of all the compounds was achieved according to their permeability and solubility data for bioequivalence purposes. BCS study reveal that most of the RE compounds could be classified as classes III and IV (low permeability); therefore, RE itself should also be classified into this category.

Inhibition of Bacterial Toxin Activity by the Nuclear Stain, DRAQ5™

The repeats-in-toxin family of toxins includes proteins produced by Gram negative bacteria such as Escherichia coli (α-hemolysin), Bordetella pertussis (adenylate cyclase toxin), and Aggregatibacter actinomycetemcomitans (LtxA), which contribute to the pathogenesis of these organisms by killing host cells. In the case of LtxA produced by A. actinomycetemcomitans, white blood cells are targeted, allowing the bacteria to avoid clearance by the host immune system. In its association with target cells, LtxA binds to a receptor, lymphocyte function-associated antigen-1, as well as membrane lipids and cholesterol, before being internalized via a lysosomal-mediated pathway. The motivation for this project comes from our discovery that DRAQ5™, a membrane-permeable nuclear stain, prevents the internalization of LtxA in a Jurkat T cell line. We hypothesized that DRAQ5™, in crossing the plasma membrane, alters the properties of the membrane to inhibit LtxA internalization. To investigate how DRAQ5™ interacts with the lipid membrane to prevent LtxA internalization, we used studied DRAQ5™-mediated membrane changes in model membranes using a variety of techniques, including differential scanning calorimetry and fluorescence spectroscopy. Our results suggest that DRAQ5™ inhibits the activity of LtxA by decreasing the fluidity of the cellular lipid membrane, which decreases LtxA binding. These results present an interesting possible anti-virulence strategy; by altering bacterial toxin activity by modifying membrane fluidity, it may be possible to inhibit the pathogenicity of A. actinomycetemcomitans.

Membrane Interactions of Phytochemicals as Their Molecular Mechanism Applicable to the Discovery of Drug Leads from Plants

In addition to interacting with functional proteins such as receptors, ion channels, and enzymes, a variety of drugs mechanistically act on membrane lipids to change the physicochemical properties of biomembranes as reported for anesthetic, adrenergic, cholinergic, non-steroidal anti-inflammatory, analgesic, antitumor, antiplatelet, antimicrobial, and antioxidant drugs. As well as these membrane-acting drugs, bioactive plant components, phytochemicals, with amphiphilic or hydrophobic structures, are presumed to interact with biological membranes and biomimetic membranes prepared with phospholipids and cholesterol, resulting in the modification of membrane fluidity, microviscosity, order, elasticity, and permeability with the potencies being consistent with their pharmacological effects. A novel mechanistic point of view of phytochemicals would lead to a better understanding of their bioactivities, an insight into their medicinal benefits, and a strategic implication for discovering drug leads from plants. This article reviews the membrane interactions of different classes of phytochemicals by highlighting their induced changes in membrane property. The phytochemicals to be reviewed include membrane-interactive flavonoids, terpenoids, stilbenoids, capsaicinoids, phloroglucinols, naphthodianthrones, organosulfur compounds, alkaloids, anthraquinonoids, ginsenosides, pentacyclic triterpene acids, and curcuminoids. The membrane interaction’s applicability to the discovery of phytochemical drug leads is also discussed while referring to previous screening and isolating studies.

Structural elucidation of some antimicrobial constituents from the leaf latex of Aloe trigonantha L.C. Leach

Background

The incidents of drug resistant microorganisms and the need of treatments for newly emerging pathogens are of great concern to the global community. Our ability to treat infectious diseases is dependent on the development of new pharmaceuticals, and one potential source being medicinal plants with traditional claims. The leaves of Aloe trigonantha L.C. Leach, an endemic Ethiopian plant, are locally used for the treatment of infectious and inflammatory diseases. This study explores the potential of the latex of this plant and compounds isolated thereof for their in vitro antibacterial and antifungal properties.

Methods

Analytical RP-HPLC and silica gel preparative TLC were used for identification and isolation of active constituents, respectively. Characterization of the compounds was based on UV, IR, HR-ESIMS, ¹H and ¹³C NMR, and 2D-NMR spectral assignments. Antimicrobial activity studies were carried out against 21 pathogenic bacterial and 4 fungal strains using the disk diffusion method. Minimum inhibitory concentrations (MICs) were determined by the broth dilution method.

Results

A C-glycosylated chromone identified as aloesin, and three C-glycosylated anthrones characterized as 8-O-methy-7-hydroxyaloin A/B, aloin A/B and aloin-6’-O-acetate A/B were isolated. The latex and isolated compounds exhibited in vitro antibacterial activity against the tested pathogens. In some cases the activity of the isolated compounds (MIC = 10 μg/mL) was comparable with that of the standard drug ciprofloxacin, particularly against some of the Gram-negative bacterial strains tested. However, their activity towards the fungal pathogens tested was relatively weaker showing maximum activity against Candida albicans with MIC value of 400 μg/mL.

Conclusion

The present findings can be used for further research aimed at the development of new antibacterial agents, and may also justify the ethnomedicinal claim of the plant for the treatment of infectious diseases.

Aloin delivery on buccal mucosa: ex vivo studies and design of a new locoregional dosing system

CONTEXT

Chemoprevention of potential malignant disorders or cancerous lesions that affect oral mucosae requires extended duration of treatment. Locoregional delivery of natural products could represent a promising strategy for this purpose.

OBJECTIVE

To investigate the aptitude of aloin to permeate through, or accumulate in, the buccal mucosa and to develop a new prolonged oro-mucosal drug delivery system.

MATERIALS AND METHODS

Permeation/accumulation of aloin from Curacao Aloe (containing 50% barbaloin) was evaluated ex vivo, using porcine buccal mucosa as the most useful model to simulate human epithelium. Oro-mucosal matrix tablets were prepared by dispersing aloin (10% w/w) in Eudragit® RS 100 as, biocompatible, low permeable, pH-independent, and non-swelling polymer. The prepared tablets were evaluated for drug-polymer compatibility, weight variation, drug uniformity content, diameter, thickness, hardness, friability, swelling, mucoadhesive strength, and drug release.

RESULTS

Aloin has low tendency to cross buccal mucosa, permeation is marginal, and high drug amounts remain entrapped into the epithelium. Matrix tablets characteristics were in agreement with pharmacopoeial requirements. Drug release showed highly reproducible Higuchian profile. Delivery through matrix tablets promoted drug accumulation in the mucosal tissue.

DISCUSSION AND CONCLUSION

Following application of matrix tablets on porcine buccal mucosa, the amount of discharged drug recovered in the tissue should be sufficient to produce the desired effects, providing therapeutic drug levels directly at the site of action. Aloin-loaded tablets are valid candidates for prevention/treatment of potentially malignant disorders and oral cancer and could potentially lead to clinically relevant drug delivery system as coadjuvant of conventional chemotherapy/radiation therapy.

Barbaloin: a concise report of its pharmacological and analytical aspects

Barbaloin is C-glucoside of aloe emodin anthrone which is found in the plant name as Aloe vera is a perennial succulent (Liliaceal), also called the healing plant. Barbaloin have variety of pharmacological activity such as strong inhibitory effect on histamine release, anti-inflammatory, cathartic, antiviral, antimicrobial, anticancer, antioxidant activity and alternative for pharmaceutical or cosmetic applications. The peak amount of barbaloin was reached about 3 h after oral administration. Concentration of barbaloin in Aloe vera leaves was shown to depend on the leaf part, age, and position of the leaf. Young leaves contain more barbaloin compared to old one. Various researches have been done on barbaloin but still the relationship between the barbaloin and its overall effect has not been clarified. A more specific perceptive of the pharmacological activities of barbaloin is required to develop for pharmaceutical purpose. Many attempts have been made regarding its isolation, biological activity to examine their effects, and clarify their functional mechanism. This review gives a brief idea about its uses, ethnomedicinally and commercially important analytical techniques and their pharmacological activities.

Effect of Aloe vera on the lipid stability and storage quality of chicken nuggets

Purpose

– The purpose of this study was to explore the potential of Aloe vera as a novel source of natural antioxidant and preservative in the muscle foods and to evaluate the effect of Aloe vera on the storage quality of aerobically packaged chicken nuggets.

Design/methodology/approach

– The Aloe vera pulp was incorporated at various levels, namely, 0, 5, 10 and 15 per cent, replacing lean meat in the formulation. The products were analyzed for proximate composition, physicochemical and sensory parameters. Chicken nuggets incorporated with optimum level of Aloe vera (10 per cent) along with control nuggets (0 per cent Aloe vera) were aerobically packaged and assessed for lipid oxidation, physicochemical and microbiological characteristics under refrigerated (4°C) conditions.

Findings

– pH, crude protein, ether extract and ash content of the nuggets showed significant (p < 0.05) decreasing trend with increasing levels of Aloe vera; however, there was a significant (p < 0.05) increase in the moisture content, emulsion stability and cooking yield. Aloe vera-enriched nuggets showed significantly (p < 0.05) lower values than control nuggets for almost all the lipid oxidation and microbiological parameters, i.e. free fatty acid, thiobarbituric acid-reactive substances value, total plate count, psychrophillic count and yeast and mould count. No significant (p > 0.05) difference was observed in the sensory parameters of the Aloe vera-enriched nuggets and the control samples throughout the period of storage.

Originality/value

– The paper has demonstrated the use of Aloe vera as a potential natural antioxidant without any marginal decline in the sensorial characteristics and nutritive value of the muscle foods.

Natural peptide anti-glycation effect in the presence of Aloe vera phenolic components on human serum albumin

This study explores the anti-glycation effect of aloin, in the presence and absence of casein-derived peptides, on human serum albumin HSA.

DFT/TDDFT investigation on the UV-vis absorption and fluorescence properties of alizarin dye

Potential energy curve for the ESIPT. Top inset: vibrationally resolved emission spectra computed for both tautomers. Bottom insets: main vibrational modes.

Anti-cytomegalovirus activity of the anthraquinone atanyl blue PRL

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The anthraquinone atanyl blue PRL inhibits human cytomegalovirus replication.

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The block to viral replication appears early after entry and substantially reduces viral immediate early gene expression.

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In vitro, atanyl blue PRL inhibits the nuclease activity of purified viral alkaline nuclease, UL98.

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The antiviral activity of atanyl blue PRL may be manifested through inhibition of UL98’s nuclease activity.

Human cytomegalovirus (CMV) causes significant disease in immunocompromised patients and serious birth defects if acquired in utero. Available CMV antivirals target the viral DNA polymerase, have significant toxicities, and suffer from resistance. New drugs targeting different pathways would be beneficial. The anthraquinone emodin is proposed to inhibit herpes simplex virus by blocking the viral nuclease. Emodin and related anthraquinones are also reported to inhibit CMV. In the present study, emodin reduced CMV infectious yield with an EC₅₀ of 4.9 μM but was cytotoxic at concentrations only twofold higher. Related anthraquinones acid blue 40 and alizarin violet R inhibited CMV at only high concentrations (238–265 μM) that were also cytotoxic. However, atanyl blue PRL inhibited infectious yield of CMV with an EC₅₀ of 6.3 μM, significantly below its 50% cytotoxic concentration of 216 μM. Atanyl blue PRL reduced CMV infectivity and inhibited spread. When added up to 1 h after infection, it dramatically reduced CMV immediate early protein expression and blocked viral DNA synthesis. However, it had no antiviral activity when added 24 h after infection. Interestingly, atanyl blue PRL inhibited nuclease activities of purified CMV UL98 protein with IC₅₀ of 4.5 and 9.3 μM. These results indicate that atanyl blue PRL targets very early post-entry events in CMV replication and suggest it may act through inhibition of UL98, making it a novel CMV inhibitor. This compound may provide valuable insights into molecular events that occur at the earliest times post-infection and serve as a lead structure for antiviral development.

The anthraquinone rhein exhibits synergistic antibacterial activity in association with metronidazole or natural compounds and attenuates virulence gene expression in Porphyromonas gingivalis

OBJECTIVE

Rhein is a major anthraquinone found in rhubarb root. As a continuation of our ongoing studies aimed to identify beneficial properties of this anthraquinone for periodontal disease, in this study, we investigated the ability of rhein to (i) exhibit antibacterial synergy towards the periodontopathogen Porphyromonas gingivalis when used in combination with metronidazole or polyphenols belonging to different families, and (ii) attenuate virulence factor gene expression in P. gingivalis.

METHODS

The minimal inhibitory concentrations (MIC) of compounds under investigation were determined by a broth microdilution assay. The synergistic effects of rhein in association with either metronidazole or polyphenols of various families were evaluated using the chequerboard technique to determine the fractional inhibitory concentration index (FICI). The effect of rhein on virulence factor gene expression in P. gingivalis was determined by quantitative RT-PCR.

RESULTS

Rhein showed a MIC of 2.5 μg/mL, which was similar to that of metronidazole. Except for the association with epigallocatechin-3-gallate that gave an additive effect, all the other combinations (licochalcone A, glabridin, myricetin, and metronidazole) resulted in synergistic effects. The strongest synergy was observed when rhein was used in association with myricetin (FICI=0.12) and licochalcone A (FICI=0.19). At a sub-MIC of rhein (0.5 μg/mL), a significant decrease in the expression of fimA, hagA, and hagB genes, which are involved in host colonization, was observed. Moreover, the expression of rgpA and kgp, two protease genes related to inactivation of host defense mechanisms, tissue destruction, and nutrient acquisition, was also down-regulated.

CONCLUSION

The data presented in our study indicate that rhein possessed antibacterial activity, which can be potentiated in combination with metronidazole or other polyphenols. In addition, rhein can impair the pathogenicity of P. gingivalis by reducing transcription of genes coding for important virulence factors.

Vibrational spectra, molecular structure, NBO, HOMO-LUMO and first order hyperpoalarizability analysis of 1,4-bis(4-formylphenyl)anthraquinone by density functional theory

Anthraquinone derivatives are most important class of a system that absorb in the visible region. Infrared and Raman spectroscopic analyses were carried out on 1,4-bis(4-formylphenyl)anthraquinone. The interpretation of the spectra was aided by DFT calculations of the molecule. The vibrational wavenumbers were examined theoretically using the Gaussian09 set of quantum chemistry codes, and the normal modes were assigned by potential energy distribution (PED) calculations. A computation of the first hyperpolarizability of the compound indicates that this class of substituted anthraquinones may be a good candidate as a NLO material. Optimized geometrical parameters of the compound are in agreement with similar reported structures. The HOMO and LUMO analysis is used to determine the charge transfer within the molecule. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis.

Effect of emodin on the cariogenic properties of Streptococcus mutans and the development of caries in rats

Emodin is an active herbal component traditionally used in East Asian countries for treating a variety of diseases. The present study investigated the effects of emodin on specific virulence factors of Streptococcus mutans (S. mutans) in vitro and on caries development in vivo. The growth and acid production of S. mutans were significantly inhibited by emodin (0.5–2 mg/ml). Emodin also significantly suppressed the synthesis of insoluble glucans by S. mutans. Furthermore, the topical application of emodin reduced the incidence and severity of carious lesions in rats. These results suggest that the natural compound emodin may be a novel pharmacological agent for the prevention and treatment of dental caries.