Antimicrobial structure activity relationship of five anthraquinones of emodine type isolated from Vismia laurentii

Gaafar AR, Gurusamy R, Akbar I. Synthesis of anthraquinone-connected coumarin derivatives via grindstone method and their evaluation of antibacterial, antioxidant, tyrosinase inhibitory activities with molecular docking, and DFT calculation studies

Anthraquinones and coumarins have excellent pharmacological activities and are an important class of natural plant metabolites with various biological activities. In this study, anthraquinone-9,10-dione and coumarin derivatives were combined to develop a novel anthraquinone-connected coumarin-derivative sequence. The synthesised novel anthraquinone-connected coumarin derivatives (1a-t) were screened for in vitro antibacterial, antioxidant, and tyrosinase inhibitory activities. The antibacterial activities of the synthesised compounds (1a-t) were tested against both gram-positive and gram-negative bacteria. Specifically, compound 1t was more active against E. aerogenes than ciprofloxacin. With regard to antioxidant activity, compound 1o (50.68 % at 100 μg/mL) was highly active compared to the other compounds, whereas it was less active than the standard BHT (76.74 % at 100 μg/mL). In terms of compound 1r (9.31 ± 0.45 μg/mL) was highly active against tyrosinase inhibitory activity compared with kojic acid (10.42 ± 0.98 μg/mL). In the molecular docking study, compound 1r had a higher docking score (-8.8 kcal mol-1) than kojic acid (-1.7 kcal mol-1). DFT calculations were performed to determine the energy gap of highly active compound 1r (ΔE = 0.11) and weakly active compound 1a (ΔE = 0.12). In this study, we found that every molecule displayed significant antibacterial, antioxidant, and tyrosinase inhibitory properties. Based on these reports, compounds 1r and 1t may act as multi-target agents.

Nano-enabled antimicrobial thin films: design and mechanism of action

Antimicrobial thin films are types of protective coatings that are applied to surfaces such as medical devices, food packaging materials, water-resistant coatings, and other systems. These films prevent and reduce the spread of microbial organisms, including bacteria, fungi, and viruses. Antimicrobial thin films can be prepared from a variety of nanostructured materials including metal nanoparticles, metal oxides, plant materials, enzymes, bacteriocins and polymers. Their antimicrobial mechanism varies mostly based on the types of active agents from which the film is made of. Antimicrobial thin films are becoming increasingly popular microbial treatment methods due to their advantages such as enhanced stability, reduced toxicity levels, extended effectiveness over time and broad spectrum antimicrobial action without side effects on human health or the environment. This popularity and enhanced performance is mainly due to the extended possibility of film designs. Thin films offer convenient formulation methods which makes them suitable for commercial practices aiming at high turnover rates along with residential applications requiring frequent application cycles. This review focuses on recent developments in the possible processing methods and design approaches for assembling the various types of antimicrobial materials into nanostructured thin film-based delivery systems, along with mechanisms of action against microbes.

In Silico and In Vitro Identification of 1,8-Dihydroxy-4,5-dinitroanthraquinone as a New Antibacterial Agent against Staphylococcus aureus and Enterococcus faecalis

Increasing rates of bacterial resistance to antibiotics are a growing concern worldwide. The search for potential new antibiotics has included several natural products such as anthraquinones. However, comparatively less attention has been given to anthraquinones that exhibit functional groups that are uncommon in nature. In this work, 114 anthraquinones were evaluated using in silico methods to identify inhibitors of the enzyme phosphopantetheine adenylyltransferase (PPAT) of Staphylococcus aureus, Enterococcus faecalis, and Escherichia coli. Virtual screenings based on molecular docking and the pharmacophore model, molecular dynamics simulations, and free energy calculations pointed to 1,8-dihydroxy-4,5-dinitroanthraquinone (DHDNA) as the most promising inhibitor. In addition, these analyses highlighted the contribution of the nitro group to the affinity of this anthraquinone for the nucleotide-binding site of PPAT. Furthermore, DHDNA was active in vitro towards Gram-positive bacteria with minimum inhibitory concentration (MIC) values of 31.25 µg/mL for S. aureus and 62.5 µg/mL for E. faecalis against both antibiotic-resistant isolates and reference strains but was ineffective against E. coli. Experiments on kill-time kinetics indicated that, at the tested concentrations, DHDNA produced bacteriostatic effects on both Gram-positive bacteria. Overall, our results present DHDNA as a potential PPAT inhibitor, showing antibacterial activity against antibiotic-resistant isolates of S. aureus and E. faecalis, findings that point to nitro groups as key to explaining these results.

Antibacterial activities of anthraquinones: structure-activity relationships and action mechanisms

With the increasing prevalence of untreatable infections caused by antibiotic-resistant bacteria, the discovery of new drugs from natural products has become a hot research topic. The antibacterial activity of anthraquinones widely distributed in traditional Chinese medicine has attracted much attention. Herein, the structure and activity relationships (SARs) of anthraquinones as bacteriostatic agents are reviewed and elucidated. The substituents of anthraquinone and its derivatives are closely related to their antibacterial activities. The stronger the polarity of anthraquinone substituents is, the more potent the antibacterial effects appear. The presence of hydroxyl groups is not necessary for the antibacterial activity of hydroxyanthraquinone derivatives. Substitution of di-isopentenyl groups can improve the antibacterial activity of anthraquinone derivatives. The rigid plane structure of anthraquinone lowers its water solubility and results in the reduced activity. Meanwhile, the antibacterial mechanisms of anthraquinone and its analogs are explored, mainly including biofilm formation inhibition, destruction of the cell wall, endotoxin inhibition, inhibition of nucleic acid and protein synthesis, and blockage of energy metabolism and other substances.

Anthraquinone-Based Ligands as MNase Inhibitors: Insights from Inhibition Studies and Generation of a Payload Nanocarrier for Potential Anti-MRSA Therapy

The present study highlights the prospect of an anthraquinone-based ligand (C1) as an inhibitor of micrococcal nuclease (MNase) enzyme secreted by Staphylococcus aureus. MNase inhibition rendered by 5.0 μM C1 was ∼96 % and the ligand could significantly distort the β-sheet conformation present in MNase. Mechanistic studies revealed that C1 rendered non-competitive inhibition, reduced the turnover (Kcat ) and catalytic efficiency (Km /Kcat ) of MNase with an IC50 value of 323 nM. C1 could also inhibit nuclease present in the cell-free supernatant (CFS) of a methicillin-resistant Staphylococcus aureus (MRSA) strain. A C1-loaded human serum albumin (HSA)-based nanocarrier (C1-HNC) was developed, which was amicable to protease-triggered release of payload in presence of the CFS of an MRSA strain. Eluates from C1-HNC could effectively reduce the rate of MNase-catalyzed DNA cleavage. The non-toxic nature of C1-HNC in conjunction with the non-competitive mode of MNase inhibition rendered by C1 offers interesting therapeutic prospect in alleviation of MRSA infections.

Lysosomes as a Target of Anticancer Therapy

Lysosomes are organelles containing acidic hydrolases that are responsible for lysosomal degradation and the maintenance of cellular homeostasis. They play an important role in autophagy, as well as in various cell death pathways, such as lysosomal and apoptotic death. Various agents, including drugs, can induce lysosomal membrane permeability, resulting in the translocation of acidic hydrolases into the cytoplasm, which promotes lysosomal-mediated death. This type of death may be of great importance in anti-cancer therapy, as both cancer cells with disturbed pathways leading to apoptosis and drug-resistant cells can undergo it. Important compounds that damage the lysosomal membrane include lysosomotropic compounds, antihistamines, immunosuppressants, DNA-damaging drugs, chemotherapeutics, photosensitizers and various plant compounds. An interesting approach in the treatment of cancer and the search for ways to overcome the chemoresistance of cancer cells may also be combining lysosomotropic compounds with targeted modulators of autophagy to induce cell death. These compounds may be an alternative in oncological treatment, and lysosomes may become a promising therapeutic target for many diseases, including cancer. Understanding the functional relationships between autophagy and apoptosis and the possibilities of their regulation, both in relation to normal and cancer cells, can be used to develop new and more effective anticancer therapies.

Effect of chemical modifications of tannins on their antimicrobial and antibiofilm effect against Gram-negative and Gram-positive bacteria

Background

Tannins have demonstrated antibacterial and antibiofilm activity, but there are still unknown aspects on how the chemical properties of tannins affect their biological properties. We are interested in understanding how to modulate the antibiofilm activity of tannins and in delineating the relationship between chemical determinants and antibiofilm activity.

Materials and methods

The effect of five different naturally acquired tannins and their chemical derivatives on biofilm formation and planktonic growth of Salmonella Typhimurium, Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus was determined in the Calgary biofilm device.

Results

Most of the unmodified tannins exhibited specific antibiofilm activity against the assayed bacteria. The chemical modifications were found to alter the antibiofilm activity level and spectrum of the tannins. A positive charge introduced by derivatization with higher amounts of ammonium groups shifted the anti-biofilm spectrum toward Gram-negative bacteria, and derivatization with lower amounts of ammonium groups and acidifying derivatization shifted the spectrum toward Gram-positive bacteria. Furthermore, the quantity of phenolic OH-groups per molecule was found to have a weak impact on the anti-biofilm activity of the tannins.

Conclusion

We were able to modulate the antibiofilm activity of several tannins by specific chemical modifications, providing a first approach for fine tuning of their activity and antibacterial spectrum.

An In-Silico Evaluation of Anthraquinones as Potential Inhibitors of DNA Gyrase B of Mycobacterium tuberculosis

The World Health Organization reported that tuberculosis remains on the list of the top ten threats to public health worldwide. Among the main causes is the limited effectiveness of treatments due to the emergence of resistant strains of Mycobacterium tuberculosis. One of the main drug targets studied to combat M. tuberculosis is DNA gyrase, the only enzyme responsible for regulating DNA topology in this specie and considered essential in all bacteria. In this context, the present work tested the ability of 2824 anthraquinones retrieved from the PubChem database to act as competitive inhibitors through interaction with the ATP-binding pocket of DNA gyrase B of M. tuberculosis. Virtual screening results based on molecular docking identified 7122772 (N-(2-hydroxyethyl)-9,10-dioxoanthracene-2-sulfonamide) as the best-scored ligand. From this anthraquinone, a new derivative was designed harbouring an aminotriazole moiety, which exhibited higher binding energy calculated by molecular docking scoring and free energy calculation from molecular dynamics simulations. In addition, in these last analyses, this ligand showed to be stable in complex with the enzyme and further predictions indicated a low probability of cytotoxic and off-target effects, as well as an acceptable pharmacokinetic profile. Taken together, the presented results show a new synthetically accessible anthraquinone with promising potential to inhibit the GyrB of M. tuberculosis.

Quinones as an Efficient Molecular Scaffold in the Antibacterial/Antifungal or Antitumoral Arsenal

Quinone-based compounds constitute several general classes of antibiotics that have long shown unwavering efficiency against both Gram-positive and Gram-negative microbial infections. These quinone-based antibiotics are increasingly popular due to their natural origins and are used in natural beverages from herbs or plants in African, Chinese and Indian traditional medicines to treat and prevent various diseases. Quinone-based antibiotics display different bioactive profiles depending on their structures and exert specific biocidal and anti-biofilm properties, and based on recent literature, will be discussed herein.

Harnessing the Role of Bacterial Plasma Membrane Modifications for the Development of Sustainable Membranotropic Phytotherapeutics

Membrane-targeted molecules such as cationic antimicrobial peptides (CAMPs) are amongst the most advanced group of antibiotics used against drug-resistant bacteria due to their conserved and accessible targets. However, multi-drug-resistant bacteria alter their plasma membrane (PM) lipids, such as lipopolysaccharides (LPS) and phospholipids (PLs), to evade membrane-targeted antibiotics. Investigations reveal that in addition to LPS, the varying composition and spatiotemporal organization of PLs in the bacterial PM are currently being explored as novel drug targets. Additionally, PM proteins such as Mla complex, MPRF, Lpts, lipid II flippase, PL synthases, and PL flippases that maintain PM integrity are the most sought-after targets for development of new-generation drugs. However, most of their structural details and mechanism of action remains elusive. Exploration of the role of bacterial membrane lipidome and proteome in addition to their organization is the key to developing novel membrane-targeted antibiotics. In addition, membranotropic phytochemicals and their synthetic derivatives have gained attractiveness as popular herbal alternatives against bacterial multi-drug resistance. This review provides the current understanding on the role of bacterial PM components on multidrug resistance and their targeting with membranotropic phytochemicals.

Emodin Sensitizes Cervical Cancer Cells to Vinblastine by Inducing Apoptosis and Mitotic Death

In recent years, studies on the effects of combining novel plant compounds with cytostatics used in cancer therapy have received considerable attention. Since emodin sensitizes tumor cells to chemotherapeutics, we evaluated changes in cervical cancer cells after its combination with the antimitotic drug vinblastine. Cellular changes were demonstrated using optical, fluorescence, confocal and electron microscopy. Cell viability was assessed by MTT assay. The level of apoptosis, caspase 3/7, Bcl-2 protein, ROS, mitochondrial membrane depolarization, cell cycle and degree of DNA damage were analyzed by flow cytometry. The microscopic image showed indicators characteristic for emodin- and vinblastine-induced mitotic catastrophe, i.e., multinucleated cells, giant cells, cells with micronuclei, and abnormal mitotic figures. These compounds also increased blocking of cells in the G2/M phase, and the generated ROS induced swelling and mitochondrial damage. This translated into the growth of apoptotic cells with active caspase 3/7 and inactivation of Bcl-2 protein and active ATM kinase. Emodin potentiated the cytotoxic effect of vinblastine, increasing oxidative stress, mitotic catastrophe and apoptosis. Preliminary studies show that the combined action of both compounds, may constitute an interesting form of anticancer therapy.

Assessment of antimycobacterial activities of pure compounds extracted from Thai medicinal plants against clarithromycin-resistant Mycobacterium abscessus

Background

Infection with Mycobacterium abscessus is usually chronic and is associated with clarithromycin resistance. Increasing drug resistance is a major public-health problem and has led to the search for new antimycobacterial agents. We evaluated the antimycobacterial activity, toxicity, and synergistic effects of several plant secondary metabolites against M. abscessus.

Methods

Twenty-three compounds were evaluated for antimycobacterial activity against thirty M. abscessus clinical isolates by broth microdilution to determine their minimum inhibitory concentration (MIC) values. Toxicity was evaluated using red and white blood cells (RBCs and WBCs). The compounds were used in combination with clarithromycin to investigate the possibility of synergistic activity.

Results

Five out of twenty-three compounds (RL008, RL009, RL011, RL012 and RL013) exhibited interesting antimycobacterial activity against M. abscessus, with MIC values ranging from <1 to >128 μg/mL. These extracts did not induce hemolytic effect on RBCs and displayed low toxicity against WBCs. The five least-toxic compounds were tested for synergism with clarithromycin against seven isolates with inducible clarithromycin resistance and seven with acquired clarithromycin resistance. The best synergistic results against these isolates were observed for RL008 and RL009 (8/14 isolates; 57%).

Conclusions

This study demonstrated antimycobacterial and synergistic activities of pure compounds extracted from medicinal plants against clarithromycin-resistant M. abscessus. This synergistic action, together with clarithromycin, may be effective for treating infections and should be further studied for the development of novel antimicrobial agents.

Natural Methoxyphenol Compounds: Antimicrobial Activity against Foodborne Pathogens and Food Spoilage Bacteria, and Role in Antioxidant Processes

The antibacterial and antioxidant activities of three methoxyphenol phytometabolites, eugenol, capsaicin, and vanillin, were determined. The in vitro antimicrobial potential was tested on three common foodborne pathogens (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus) and three food spoilage bacteria (Shewanella putrefaciens, Brochothrix thermosphacta, and Lactobacillus plantarum). The antioxidant assays were carried out for studying the free radical scavenging capacity and the anti-lipoperoxidant activity. The results showed that eugenol and capsaicin were the most active against both pathogens and spoilage bacteria. S. aureus was one of the most affected strains (median concentration of growth inhibition: IC50 eugenol = 0.75 mM; IC50 capsaicin = 0.68 mM; IC50 vanillin = 1.38 mM). All phytochemicals slightly inhibited the growth of L. plantarum. Eugenol was the most active molecule in the antioxidant assays. Only in the oxygen radical absorbing capacity (ORAC) test did vanillin show an antioxidant activity comparable to eugenol (eugenol ORAC value = 2.12 ± 0.08; vanillin ORAC value = 1.81 ± 0.19). This study, comparing the antimicrobial and antioxidant activities of three guaiacol derivatives, enhances their use in future applications as food additives for contrasting both common pathogens and spoilage bacteria and for improving the shelf life of preserved food.

Explorations of ATP-Binding Cassette Transporters and Apoptosis Signal Pathways of 2-Hydroxyanthraquinone Substituted Cyclotriphosphazenes in MCF-7 and DLD-1 Cell Lines

BACKGROUND

As a class with biological properties, such as anti-cancer, anti-bacterial, anti-HIV, and various physical effects, phosphazene derivatives constitute the most striking part of inorganic compounds. Anthraquinones, on the other hand, are a broad family of compounds with a wide variety of biological properties; the biologically active anthraquinones have been used as valuable tool compounds for biochemical and pharmacological research.

OBJECTIVE

In this study, we aimed to investigate the effect of the anthraquinone substituted cyclotriphosphazene compounds on apoptosis and drug resistance in MCF-7 and DLD-1 cells.

METHODS

In breast and colon cells, mRNA levels of multi-drug resistance genes (ABCB1, ABCC3, ABCC10, ABCC11, and ABCG2), apoptotic genes (BAX, BCL-2, p53, and PARP), heat shock (HSP27, HSP40, HSP60, HSP90α) and endoplasmic reticulum chaperone genes (GRP78, and GRP94) were determined by the qPCR method. The amount of proteins of the cell cycle, HSPs, apoptosis, and related signaling pathways were measured by the membrane array kits.

RESULTS

Compounds 2, 3, 4, and 7 showed the most potent results on the ATP-binding cassette genes in both breast and colon cancer cells. These compounds have a remarkable effect on apoptotic, heat shock, and ER chaperone genes in cancer cells. Besides, these compounds induced protein levels of pro-apoptotic pathways, leading to apoptosis by inhibiting anti-apoptotic pathways. Also, these compounds decreased HSPs.

CONCLUSION

These compounds have potential properties that eliminate drug resistance, suppress heat shock and ER chaperone genes, and drag cells to apoptotic cell death and are notable for drug studies.

Bioguided Isolation of Active Compounds from Rhamnus alaternus against Methicillin-Resistant Staphylococcus aureus (MRSA) and Panton-Valentine Leucocidin Positive Strains (MSSA-PVL)

Despite intensified efforts to develop an effective antibiotic, S. aureus is still a major cause of mortality and morbidity worldwide. The multidrug resistance of bacteria has considerably increased the difficulties of scientific research and the concomitant emergence of resistance is to be expected. In this study we have investigated the in vitro activity of 15 ethanol extracts prepared from Moroccan medicinal plants traditionally used for treatment of skin infections. Among the tested species I. viscosa, C. oxyacantha, R. tinctorum, A. herba alba, and B. hispanica showed moderate anti-staphylococcal activity. However, R. alaternus showed promising growth-inhibitory effects against specific pathogenic bacteria especially methicillin-susceptible Staphylococcus aureus Panton-Valentine leucocidin positive (MSSA-PVL) and methicillin-resistant S. aureus (MRSA). The bioguided fractionation of this plant using successive chromatographic separations followed by nuclear magnetic resonance (NMR) and mass spectrometry (MS) including EIMS and HREIMS analysis yielded the emodin (1) and kaempferol (2). Emodin being the most active with MICs ranging between 15.62 and 1.95 µg/mL and showing higher activity against the tested strains in comparison with the crude extract, its mechanism of action and the structure-activity relationship were interestingly discussed. The active compound has not displayed toxicity toward murine macrophage cells. The results obtained in the current study support the traditional uses of R. alaternus and suggest that this species could be a good source for the development of new anti-staphylococcal agents.

Chlorinated bianthrones from the cyanolichen Nephroma laevigatum

While depsidones, depsides or dibenzofuran-like compounds dominate the chemical composition of lichens, the cyanolichen Nephroma laevigatum affords a diversity of quinoid pigments represented by chlorinated anthraquinones derived from emodin and new bianthrones resulting from the homo- or heterodimerization of monomers. Bianthrones were pointed out from the dichloromethane extract by MS/MS-based molecular networking, then isolated and characterized on the basis of extensive spectroscopic analyzes and GIAO NMR shift calculation followed by CP3 analyzes.

Are antibacterial effects of non-antibiotic drugs random or purposeful because of a common evolutionary origin of bacterial and mammalian targets?

Purpose

Advances in structural biology, genetics, bioinformatics, etc. resulted in the availability of an enormous pool of information enabling the analysis of the ancestry of pro- and eukaryotic genes and proteins.

Methods

This review summarizes findings of structural and/or functional homologies of pro- and eukaryotic enzymes catalysing analogous biological reactions because of their highly conserved active centres so that non-antibiotics interacted with bacterial targets.

Results

Protease inhibitors such as staurosporine or camostat inhibited bacterial serine/threonine or serine/tyrosine protein kinases, serine/threonine phosphatases, and serine/threonine kinases, to which penicillin-binding-proteins are linked, so that these drugs synergized with β-lactams, reverted aminoglycoside-resistance and attenuated bacterial virulence. Calcium antagonists such as nitrendipine or verapamil blocked not only prokaryotic ion channels but interacted with negatively charged bacterial cell membranes thus disrupting membrane energetics and inducing membrane stress response resulting in inhibition of P-glycoprotein such as bacterial pumps thus improving anti-mycobacterial activities of rifampicin, tetracycline, fluoroquinolones, bedaquilin and imipenem-activity against Acinetobacter spp. Ciclosporine and tacrolimus attenuated bacterial virulence. ACE-inhibitors like captopril interacted with metallo-β-lactamases thus reverting carbapenem-resistance; prokaryotic carbonic anhydrases were inhibited as well resulting in growth impairment. In general, non-antibiotics exerted weak antibacterial activities on their own but synergized with antibiotics, and/or reverted resistance and/or attenuated virulence.

Conclusions

Data summarized in this review support the theory that prokaryotic proteins represent targets for non-antibiotics because of a common evolutionary origin of bacterial- and mammalian targets resulting in highly conserved active centres of both, pro- and eukaryotic proteins with which the non-antibiotics interact and exert antibacterial actions.

Biosynthesis of Rhamnosylated Anthraquinones in Escherichia coli

Rhamnose is a naturally occurring deoxysugar present as a glycogenic component of plant and microbial natural products. A recombinant mutant Escherichia coli strain was developed by overexpressing genes involved in the TDP-L-rhamnose biosynthesis pathway of different bacterial strains and Saccharothrix espanaensis rhamnosyl transferase to conjugate intrinsic cytosolic TDP-L-rhamnose with anthraquinones supplemented exogenously. Among the five anthraquinones (alizarin, emodin, chrysazin, anthrarufin, and quinizarin) tested, quinizarin was biotransformed into a rhamoside derivative with the highest conversion ratio by whole cells of engineered E. coli. The quinizarin glycoside was identified by various chromatographic and spectroscopic analyses. The anti-proliferative property of the newly synthesized rhamnoside, quinizarin-4-O-α-L-rhamnoside, was assayed in various cancer cells.

Vismione B Interferes with Trypanosoma cruzi Infection of Vero Cells and Human Stem Cell-Derived Cardiomyocytes

Traditional African medicine is a source of new molecules that might be useful in modern therapeutics. We tested ten limonoids, six quinones, one xanthone, one alkaloid, and one cycloartane, isolated from four Cameroonian medicinal plants, and one plant-associated endophytic fungus, against Trypanosoma cruzi, the etiological agent of Chagas disease (CD). Vero cells, or human-induced pluripotent stem cells (hiPSC)-derived cardiomyocytes (hiPSC-CM) were infected with T. cruzi trypomastigotes (discrete typing unit types I or II). Infection took place in the presence of drugs, or 24 hours before drug treatment. Forty-eight hours after infection, infection rates and parasite multiplication were evaluated by Giemsa stain. Cell metabolism was measured to determine functional integrity. In Vero cells, several individual molecules significantly affected T. cruzi infection and multiplication with no, or minor, effects on cell viability. Reduced infection rates and multiplication by the quinone vismione B was superior to the commonly used therapeutic benznidazole (BNZ). The vismione B concentration inhibiting 50% of T. cruzi infection (IC₅₀) was 1.3 µM. When drug was applied after infection, anti-Trypanosoma effects of vismione B [10 µM) were significantly stronger than effects of BNZ (23 µM). Furthermore, in hiPSC-CM cultures, infection and multiplication rates in the presence of vismione B (10 µM) were significantly lower than in BNZ (11.5 µM), without showing signs of cytotoxicity. Our data indicate that vismione B is more potent against T. cruzi infection and multiplication than BNZ, with stronger effects on established infection. Vismione B, therefore, might become a promising lead molecule for treatment development for CD.

Health functions and structure-activity relationships of natural anthraquinones from plants

Anthraquinone compounds with the anthraquinone ring structure are widely found in traditional Chinese medicines and they are attracting a lot of attention due to their good pharmacological activity. Diversities of anthraquinones depend on their chemical structures, such as the number of anthraquinone rings and the substituents; what's more, the difference in chemical structure determines the difference in physiological activity. Based on results of previous studies, this review summarizes several natural anthraquinones identified from Chinese herbal medicines and their physiological activities including anti-cancer, anti-pathogenic microorganisms, anti-inflammatory, anti-oxidation, anti-osteoporosis, anti-depression, and anti-constipation. The source, effect, model, and action mechanism of the active anthraquinones are described in detail, from which their structure-activity relationship is summarized. By analyzing the relationship between anthraquinone structure and function, we found that, on the whole structure, the anthraquinone ring and anthraquinone glycosides have significant anticancer activity and anti-constipation activity, while for their substituents, anthraquinones substituted by alizarin have significant antioxidant activity and the polarity of the substituents is closely related to their antibacterial activities.