Antimicrobial activity and synergism of ursolic acid 3-O-α-L-arabinopyranoside with oxacillin against methicillin-resistant Staphylococcus aureus

Hypoglycemic and Hypolipidemic Effects of Triterpenoid Standardized Extract of Agave durangensis Gentry

Diabetes mellitus is a chronic, degenerative, and multifactorial disease characterized by hyperglycemia, and at least 537 million people suffered from diabetes in 2021. Agave durangensis Gentry, a species of agave native to the state of Durango, reports phenolic compounds, flavonols, flavonoids, and saponins and could be an alternative for the treatment of diabetes. The aim of this work was to identify the compounds in the leaves of Agave durangensis Gentry and their potential activity in diabetes. The leaf extract of Agave durangensis Gentry (EAD) was characterized by ultra-performance liquid chromatography-mass spectrometry (UPLC-MS), and different families of bioactive compounds were quantified by analytical methods. Probable pharmacological targets were identified in silico, and the inhibition of dipeptidyl peptidase-4 (DPP4) was validated in vitro. A model of hyperglycemia was established with streptozotocin in male Wistar rats, and we administered EAD intragastrically at a dose of 300 mg/kg, as well as combinations of the extract with metformin and sitagliptin over 30 days. Biochemical and histological parameters were analyzed. We identified thirty-six major compounds, where triterpenes represented 30% of the extract. Molecular docking showed that the extract could interact with α-glucosidases and DPP4 since a large number of compounds in the extract have a Δ G lower than that reported for the controls, and DPP4 inhibition was confirmed by in vitro assays. In vivo assays demonstrated that the administration of the extract was able to significantly decrease glucose levels by 56.75% and glycosylated hemoglobin by 52.28%, which is higher than that reported for sitagliptin with a decrease of 35.22%. In addition, the extract decreased triglycerides by 59.28% and very-low-density lipoprotein (VLDL) cholesterol by 60.27%, and when administered in combination with metformin, it decreased them more than when metformin was administered alone. For all the above reasons, Agave durangensis Gentry extract could be used for the development of phytomedicine for the treatment of diabetes.

Susceptibility of Staphylococcus aureus to Anti-Inflammatory Drugs with a Focus on the Combinatory Effect of Celecoxib with Oxacillin In Vitro

Musculoskeletal infections (MIs) are among the most difficult-to-treat staphylococcal diseases due to antibiotic resistance. This has encouraged the development of innovative strategies, such as combination therapy, to combat MI. The aim of this study was to investigate the in vitro antistaphylococcal activity of anti-inflammatory drugs and the combined antimicrobial effect of celecoxib and oxacillin. The minimum inhibitory concentrations (MICs) of 17 anti-inflammatory drugs against standard strains and clinical isolates of S. aureus, including methicillin-resistant strains (MRSAs), were determined using the broth microdilution method. The fractional inhibitory concentration indices (FICIs) were evaluated using checkerboard assays. Celecoxib produced the most potent antistaphylococcal effect against all tested strains (MICs ranging from 32 to 64 mg/L), followed by that of diacerein against MRSA3 and MRSA ATCC 33592 (MIC 64 mg/L). Several synergistic effects were observed against the tested S. aureus strains, including MRSA (FICI ranging from 0.087 to 0.471). The strongest synergistic interaction (FICI 0.087) was against MRSA ATCC 33592 at a celecoxib concentration of 2 mg/L, with a 19-fold oxacillin MIC reduction (from 512 to 26.888 mg/L). This is the first report on the combined antistaphylococcal effect of celecoxib and oxacillin. These findings suggest celecoxib and its combination with oxacillin as perspective agents for research focused on the development of novel therapies for MI caused by S. aureus. This study further indicates that celecoxib could resensitize certain MRSA strains, in some cases, to be susceptible to β-lactams (e.g., oxacillin) that were not previously tested. It is essential to mention that the in vitro concentrations of anti-inflammatory drugs are higher than those typically obtained in patients. Therefore, an alternative option for its administration could be the use of a drug delivery system for the controlled slow release from an implant at the infection site.

Evaluation of the mechanistic basis for the antibacterial activity of ursolic acid against Staphylococcus aureus

The antibiotics are generally regarded as the first choice approach to treat dairy mastitis, targeting the public health problems associated with the food safety and the emergence of antibioticresistant bacteria. The objective of the study was to evaluate the antibacterial efficacy of ursolic acid (UA) when used to treat Staphylococcus aureus and other isolates associated with bovine mastitis and to clarify the mechanistic basis for these effects. The bacteriostatic properties of UA extracted from Rosmarinus officinalis L. at four different purity levels were assessed by calculating minimum inhibitory concentration (MIC) values, while the synergistic effects of combining 98% UA with antibiotics were evaluated by measuring the fractional inhibitory concentration index (FICI). Changes in biofilm formation and the growth curves of the clinical isolates were assessed to clarify the bacteriostatic effect of UA. Furthermore, the cell wall integrity, protein synthesis, and reactive oxygen species (ROS) production were assessed to determine the antibacterial mechanism of UA treatment. Ultimately, UA was revealed to exhibit robust activity against Gram-positive bacteria including S. aureus (ATCC 25923), Streptococcus dysgalactiae (ATCC27957), Streptococcus agalactiae (ATCC13813), Enterococcus faecalis (ATCC29212), and Streptococcus mutans (ATCC25175). However, it did not affect Escherichia coli (ATCC 25922). The MIC values of UA preparations that were 98, 50, 30, and 10% pure against S. aureus were 39, 312, 625, and 625 μg/mL, respectively, whereas the corresponding MIC for E. coli was >5,000 μg/mL. The minimum bactericidal concentrations of 98% UA when used to treat three clinical S. aureus isolates (S4, S5, and S6) were 78, 78, and 156 μg/mL, respectively. Levels of biofilm formation for clinical S. aureus isolates decreased with increasing 98% UA concentrations. Above the MIC dose, UA treatment resulted in the dissolution of bacterial cell walls and membranes, with cells becoming irregularly shaped and exhibiting markedly impaired intracellular protein synthesis. S. aureus treated with 98% UA was able to rapidly promote intracellular ROS biogenesis. Together, these data highlight the promising utility of UA as a compound that can be used together with other antibiotics for the treatment of infections caused by S. aureus.

Inhibition of pathogenic microbes in oral infectious diseases by natural products: Sources, mechanisms, and challenges

The maintenance of oral health is of utmost importance for an individual's holistic well-being and standard of living. Within the oral cavity, symbiotic microorganisms actively safeguard themselves against potential foreign diseases by upholding a multifaceted equilibrium. Nevertheless, the occurrence of an imbalance can give rise to a range of oral infectious ailments, such as dental caries, periodontitis, and oral candidiasis. Presently, clinical interventions encompass the physical elimination of pathogens and the administration of antibiotics to regulate bacterial and fungal infections. Given the limitations of various antimicrobial drugs frequently employed in dental practice, the rising incidence of oral inflammation, and the escalating bacterial resistance to antibiotics, it is imperative to explore alternative remedies that are dependable, efficacious, and affordable for the prevention and management of oral infectious ailments. There is an increasing interest in the creation of novel antimicrobial agents derived from natural sources, which possess attributes such as safety, cost-effectiveness, and minimal adverse effects. This review provides a comprehensive overview of the impact of natural products on the development and progression of oral infectious diseases. Specifically, these products exert their influences by mitigating dental biofilm formation, impeding the proliferation of oral pathogens, and hindering bacterial adhesion to tooth surfaces. The review also encompasses an examination of the various classes of natural products, their antimicrobial mechanisms, and their potential therapeutic applications and limitations in the context of oral infections. The insights garnered from this review can support the promising application of natural products as viable therapeutic options for managing oral infectious diseases.

A Review on Five and Six-Membered Heterocyclic Compounds Targeting the Penicillin-Binding Protein 2 (PBP2A) of Methicillin-Resistant Staphylococcus aureus (MRSA)

Staphylococcus aureus is a common human pathogen. Methicillin-resistant Staphylococcus aureus (MRSA) infections pose significant and challenging therapeutic difficulties. MRSA often acquires the non-native gene PBP2a, which results in reduced susceptibility to β-lactam antibiotics, thus conferring resistance. PBP2a has a lower affinity for methicillin, allowing bacteria to maintain peptidoglycan biosynthesis, a core component of the bacterial cell wall. Consequently, even in the presence of methicillin or other antibiotics, bacteria can develop resistance. Due to genes responsible for resistance, S. aureus becomes MRSA. The fundamental premise of this resistance mechanism is well-understood. Given the therapeutic concerns posed by resistant microorganisms, there is a legitimate demand for novel antibiotics. This review primarily focuses on PBP2a scaffolds and the various screening approaches used to identify PBP2a inhibitors. The following classes of compounds and their biological activities are discussed: Penicillin, Cephalosporins, Pyrazole-Benzimidazole-based derivatives, Oxadiazole-containing derivatives, non-β-lactam allosteric inhibitors, 4-(3H)-Quinazolinones, Pyrrolylated chalcone, Bis-2-Oxoazetidinyl macrocycles (β-lactam antibiotics with 1,3-Bridges), Macrocycle-embedded β-lactams as novel inhibitors, Pyridine-Coupled Pyrimidinones, novel Naphthalimide corbelled aminothiazoximes, non-covalent inhibitors, Investigational-β-lactam antibiotics, Carbapenem, novel Benzoxazole derivatives, Pyrazolylpyridine analogues, and other miscellaneous classes of scaffolds for PBP2a. Additionally, we discuss the penicillin-binding protein, a crucial target in the MRSA cell wall. Various aspects of PBP2a, bacterial cell walls, peptidoglycans, different crystal structures of PBP2a, synthetic routes for PBP2a inhibitors, and future perspectives on MRSA inhibitors are also explored.

Draft genome sequence of Staphylococcus aureus sequence type 5 SA01 isolated from bloodstream infection and comparative analysis with reference strains

A Staphylococcus aureus isolate (SA01) obtained from bloodstream infection exhibited a remarkable drug resistance profile. In this study, we report the draft genome sequence of S. aureus ST 5 SA01, a multidrug-resistant isolate, and analyzed the genes associated with drug resistance and virulence. The genome sketch of S. aureus ST5 SA01 was sequenced with Illumina and annotated using the Prokka software. Rapid Annotation Subsystem Technology (RAST) was used to verify the gene functions in the genome subsystems. The Comprehensive Antibiotic Resistance Database (CARD) and Virulence Factor Database (VFDB) were used in the analysis. The RAST indicated a contribution of 25 proteins to host adenine, fibronectin-binding protein A (FnbA), and biofilm formation as an intercellular polysaccharide adhesive system (PIA). The MLST indicated that S. aureus ST 5 SA01 belongs to ST5 (CC5). In silico analyses also showed an extensive repertoire of genes associated with toxins, such as LukGH leukocidin, enterotoxins, and superantigen staphylococcal classes (SSL). The 11 genes for antimicrobial resistance in S. aureus ST 5 SA01 showed similarity and identity above ≥ 99% with nucleotide sequences deposited in GenBank. Although studies on ST5 clones in Brazil are scarce, monitoring the clone of S. aureus ST 5 SA01 is essential, as it has become a problem in pediatrics in several countries.

Albalawi H, Darwish DBE, Sharaf EM. Inhibition Mechanism of Methicillin-Resistant Staphylococcus aureus by Zinc Oxide Nanorods via Suppresses Penicillin-Binding Protein 2a

Methicillin-resistant Staphylococcus aureus (MRSA) causes life-threatening infections. Zinc oxide is well known as an effective antibacterial drug against many bacterial strains. We investigated the performance of zinc oxide nanorods synthesized by Albmiun as a biotemplate as an antibacterial drug in this study; the fabrication of zinc oxide nanorods was synthesized by sol-gel methods. We performed physicochemical characterization of zinc oxide nanorods by physiochemical techniques such as FTIR spectroscopy, X-ray diffraction, and TEM and investigation of their antimicrobial toxicity efficiency by MIC, ATPase activity assay, anti-biofilm activity, and kill time assays, as well as the mecA, mecR1, blaR1, blaZ, and biofilm genes (ica A, ica D, and fnb A) by using a quantitative RT-PCR assay and the penicillin-binding protein 2a (PBP2a) level of MRSA by using a Western blot. The data confirmed the fabrication of rod-shaped zinc oxide nanorods with a diameter in the range of 50 nm, which emphasized the formation of zinc oxide nanoparticles with regular shapes. The results show that zinc oxide nanorods inhibited methicillin-resistant S. aureus effectively. The MIC value was 23 μg/mL. The time kill of ZnO-NRs against MRSA was achieved after 2 h of incubation at 4MIC (92 μg/mL) and after 3 h of incubation at 2MIC (46 μg/mL), respectively. The lowest concentration of zinc oxide nanorods with over 75% biofilm killing in all strains tested was 32 μg/mL. Also, we examined the influence of the zinc oxide nanorods on MRSA by analyzing mecA, mecR1, blaR1, and blaZ by using a quantitative RT-PCR assay. The data obtained revealed that the presence of 2× MIC (46 μg/mL) of ZnO-NRs reduced the transcriptional levels of blaZ, blaR1, mecA, and mecR1 by 3.4-fold, 3.6-fold, 4-fold, and 3.8-fold, respectively. Furthermore, the gene expression of biofilm encoding genes (ica A, ica B, ica D, and fnb A) was tested using quantitative real-time reverse transcriptase-polymerase chain reaction (rt-PCR). The results showed that the presence of 2× MIC (46 μg/mL) of ZnO-NRs reduced the transcriptional levels of ica A, ica B, ica D, and fnb A. Also, the PBP2a level was markedly reduced after treatment with ZnO-NRs.

Synthesis, biological evaluation and structure-activity relationship of 2-(2-hydroxyaryl)alkenylphosphonium salts with potency as anti-MRSA agents

Here we report the synthesis, in vitro antimicrobial activity, preliminary toxicity and mechanism study of a new series of 2-(2-hydroxyaryl)alkenylphosphonium salts with the variation of phosphonium moiety obtained by a two-step synthetic method from phosphine oxides. The salts showed pronounced activity against Gram-positive bacteria, including MRSA strains, and some fungi. Mechanism of action against S. aureus was studied by CV test, TEM and proteomic assay. No cell wall integrity loss was observed while proteomic assay results suggested interference in different metabolic processes of S. aureus. For this series, lipophilicity was determined as a key factor for the inhibition of Gram-positive bacteria growth and S. aureus killing. Biological properties of methylated derivatives were notably different with manifested action against Gram-negative bacteria.

Comprehensive Analysis of Eleutherococcus senticosus (Rupr. & Maxim.) Maxim. Leaves Based on UPLC-MS/MS: Separation and Rapid Qualitative and Quantitative Analysis

Eleutherococcus senticosus (Rupr. & Maxim.) Maxim. leaves (ESL) have long been people’s favorite as a natural edible green vegetable, in which phenols and saponins are the main characteristic and bioactive components. This study was first carried out to comprehensively analyze the phenols and saponins in ESL, including phytochemical, qualitative, quantitative, and bioactivity analysis. The results showed that 30 compounds, including 20 phenolic compounds and 7 saponins, were identified. Twelve of them were isolated from Eleutherococcus Maxim. for the first time. In the qualitative analysis, 30 phenolic compounds and 28 saponins were accurately detected. Their characteristic cleavage processes were described by UPLC-QTOF-MS/MS. Ten representative ingredients were quantitated in 29 different regions via a 4000 QTRAP triple quadrupole tandem mass spectrometer (UPLC-QTRAP-MS/MS), and it was found that S19 (69.89 ± 1.098 mg/g) and S1 (74.28 ± 0.733 mg/g) had the highest contents of total phenols and saponins, respectively. The newly developed analysis method for the quantitative determination was validated for linearity, precision, and limits of detection and quantification, which could be applied to the quality assessment of ESL. In vitro experiment, the α-glucosidase inhibitory effect of the phenolic fraction was higher than others, indicating that the phenolic content may be related to the hypoglycemic activity. It was also suggested that ESL could be developed as a natural potential effective drug or functional food.

The Synergistic Effect of Triterpenoids and Flavonoids-New Approaches for Treating Bacterial Infections?

Currently, the pharmaceutical industry is well-developed, and a large number of chemotherapeutics are being produced. These include antibacterial substances, which can be used in treating humans and animals suffering from bacterial infections, and as animal growth promoters in the agricultural industry. As a result of the excessive use of antibiotics and emerging resistance amongst bacteria, new antimicrobial drugs are needed. Due to the increasing trend of using natural, ecological, and safe products, there is a special need for novel phytocompounds. The compounds analysed in the present study include two triterpenoids ursolic acid (UA) and oleanolic acid (OA) and the flavonoid dihydromyricetin (DHM). All the compounds displayed antimicrobial activity against Gram-positive (Staphylococcus aureus ATCC 6538, Staphylococcus epidermidis ATCC 12228, and Listeria monocytogenes ATCC 19115) and Gram-negative bacteria (Escherichia coli ATCC 25922, Proteus hauseri ATCC 15442, and Campylobacter jejuni ATCC 33560) without adverse effects on eukaryotic cells. Both the triterpenoids showed the best antibacterial potential against the Gram-positive strains. They showed synergistic activity against all the tested microorganisms, and a bactericidal effect with the combination OA with UA against both Staphylococcus strains. In addition, the synergistic action of DHM, UA, and OA was reported for the first time in this study. Our results also showed that combination with triterpenoids enhanced the antimicrobial potential of DHM.

Anti-Planktonic and Anti-Biofilm Properties of Pentacyclic Triterpenes-Asiatic Acid and Ursolic Acid as Promising Antibacterial Future Pharmaceuticals

Due to the ever-increasing number of multidrug-resistant bacteria, research concerning plant-derived compounds with antimicrobial mechanisms of action has been conducted. Pentacyclic triterpenes, which have a broad spectrum of medicinal properties, are one of such groups. Asiatic acid (AA) and ursolic acid (UA), which belong to this group, exhibit diverse biological activities that include antioxidant, anti-inflammatory, diuretic, and immunostimulatory. Some of these articles usually contain only a short section describing the antibacterial effects of AA or UA. Therefore, our review article aims to provide the reader with a broader understanding of the activity of these acids against pathogenic bacteria. The bacteria in the human body can live in the planktonic form and create a biofilm structure. Therefore, we found it valuable to present the action of AA and UA on both planktonic and biofilm cultures. The article also presents mechanisms of the biological activity of these substances against microorganisms.

Efficacy of Ursolic Acid-Enriched Water-Soluble and Not Cytotoxic Nanoparticles against Enterococci

Ursolic acid (UA), a pentacyclic triterpenoid acid found in many medicinal plants and aromas, is known for its antibacterial effects against multi-drug-resistant (MDR) Gram-positive bacteria, which seriously threaten human health. Unfortunately, UA water-insolubility, low bioavailability, and systemic toxicity limit the possibilities of its application in vivo. Consequently, the beneficial activities of UA observed in vitro lose their potential clinical relevance unless water-soluble, not cytotoxic UA formulations are developed. With a nano-technologic approach, we have recently prepared water-soluble UA-loaded dendrimer nanoparticles (UA-G4K NPs) non-cytotoxic on HeLa cells, with promising physicochemical properties for their clinical applications. In this work, with the aim of developing a new antibacterial agent based on UA, UA-G4K has been tested on different strains of the Enterococcus genus, including marine isolates, toward which UA-G4K has shown minimum inhibitory concentrations (MICs) very low (0.5-4.3 µM), regardless of their resistance to antibiotics. Time-kill experiments, in addition to confirming the previously reported bactericidal activity of UA against E. faecium, also established it for UA-G4K. Furthermore, cytotoxicity experiments on human keratinocytes revealed that nanomanipulation of UA significantly reduced the cytotoxicity of UA, providing UA-G4K NPs with very high LD50 (96.4 µM) and selectivity indices, which were in the range 22.4-192.8, depending on the enterococcal strain tested. Due to its physicochemical and biological properties, UA-G4K could be seriously evaluated as a novel oral-administrable therapeutic option for tackling difficult-to-treat enterococcal infections.

Effect of Ursolic and Oleanolic Acids on Lipid Membranes: Studies on MRSA and Models of Membranes

Staphylococcus aureus is an opportunistic pathogen and the major causative agent of life-threatening hospital- and community-acquired infections. A combination of antibiotics could be an opportunity to address the widespread emergence of antibiotic-resistant strains, including Methicillin-Resistant S. aureus (MRSA). We here investigated the potential synergy between ampicillin and plant-derived antibiotics (pentacyclic triterpenes, ursolic acid (UA) and oleanolic acid (OA)) towards MRSA (ATCC33591 and COL) and the mechanisms involved. We calculated the Fractional Inhibitory Concentration Index (FICI) and demonstrated synergy. We monitored fluorescence of Bodipy-TR-Cadaverin, propidium iodide and membrane potential-sensitive probe for determining the ability of UA and OA to bind to lipoteichoic acids (LTA), and to induce membrane permeabilization and depolarization, respectively. Both pentacyclic triterpenes were able to bind to LTA and to induce membrane permeabilization and depolarization in a dose-dependent fashion. These effects were not accompanied by significant changes in cellular concentration of pentacyclic triterpenes and/or ampicillin, suggesting an effect mediated through lipid membranes. We therefore focused on membranous effects induced by UA and OA, and we investigated on models of membranes, the role of specific lipids including phosphatidylglycerol and cardiolipin. The effect induced on membrane fluidity, permeability and ability to fuse were studied by determining changes in fluorescence anisotropy of DPH/generalized polarization of Laurdan, calcein release from liposomes, fluorescence dequenching of octadecyl-rhodamine B and liposome-size, respectively. Both UA and OA showed a dose-dependent effect with membrane rigidification, increase of membrane permeabilization and fusion. Except for the effect on membrane fluidity, the effect of UA was consistently higher compared with that obtained with OA, suggesting the role of methyl group position. All together the data demonstrated the potential role of compounds acting on lipid membranes for enhancing the activity of other antibiotics, like ampicillin and inducing synergy. Such combinations offer an opportunity to explore a larger antibiotic chemical space.

Eleutheroside K Isolated from Acanthopanax henryi (Oliv.) Harms Inhibits the Expression of Virulence-Related Exoproteins in Methicillin-Resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus (S.) aureus (MRSA) is a representative pathogen that produces numerous virulence factors involving manifold cytotoxins and exotoxins. The present study was designed to investigate the influence of Eleutheroside K (ETSK), a single compound isolated from the leaves of Acanthopanax (A.) henryi (Oliv.) Harms, on the exotoxins secreted by MRSA. The transcription and translation of the exotoxins (α-hemolysin and staphylococcal enterotoxins) related to virulence in S. aureus were determined via quantitative RT-PCR and western blot analysis. The effect of ETSK on the production of tumor necrosis factor (TNF)-α was evaluated using enzyme-linked immunosorbent assay. As a result, ETSK at sub-MIC concentrations could reduce the protein expression of α-hemolysin and enterotoxin, and the expression of genes that regulate virulence factors was also inhibited. In addition, the TNF-inducing activity of S. aureus was attenuated by ETSK in a dose-dependent manner. These results revealed that ETSK not only reduced the protein and gene expression levels of related exotoxins but also suppressed the ability of S. aureus to induce macrophages to release cytokines. This study indicated that the inhibition of MRSA infection by ETSK may be achieved by reducing the virulence of S. aureus and highlighted the potential of ETSK as an innovative strategy for the prevention and treatment of MRSA infections.

Review on the Antibacterial Mechanism of Plant-Derived Compounds against Multidrug-Resistant Bacteria (MDR)

Microbial resistance has progressed rapidly and is becoming the leading cause of death globally. The spread of antibiotic-resistant microorganisms has been a significant threat to the successful therapy against microbial infections. Scientists have become more concerned about the possibility of a return to the pre-antibiotic era. Thus, searching for alternatives to fight microorganisms has become a necessity. Some bacteria are naturally resistant to antibiotics, while others acquire resistance mainly by the misuse of antibiotics and the emergence of new resistant variants through mutation. Since ancient times, plants represent the leading source of drugs and alternative medicine for fighting against diseases. Plants are rich sources of valuable secondary metabolites, such as alkaloids, quinones, tannins, terpenoids, flavonoids, and polyphenols. Many studies focus on plant secondary metabolites as a potential source for antibiotic discovery. They have the required structural properties and can act by different mechanisms. This review analyses the antibiotic resistance strategies produced by multidrug-resistant bacteria and explores the phytochemicals from different classes with documented antimicrobial action against resistant bacteria, either alone or in combination with traditional antibiotics.

Acanthopanax henryi: Review of Botany, Phytochemistry and Pharmacology

Acanthopanax henryi (Oliv.) Harms (Araliaceae), also known as Eleutherococcus henryi and Caoyewujia (Hengliwujia) in Chinese, is a widely used traditional Chinese herb with the effects of expelling wind and removing dampness, relaxing the muscles and stimulating the blood circulation, and regulating the flow of qi to alleviate pain in the theory of Traditional Chinese Medicine. Acanthopanax henryi (AH, thereafter) possesses ginseng-like activities and is known as ginseng-like herb. In the past decade, a great number of phytochemical and pharmacological studies on AH have been carried out. Several kinds of chemical compositions have been reported, including terpenoids (monoterpenoids, diterpenoids, and triterpenoid saponins), phenylpropanoids, caffeoyl quinic acid derivatives, flavonoids, lignans, sterols, fatty acids, etc., among which, triterpenoid saponins were considered to be the most active components. Considerable pharmacological experiments in vitro have demonstrated that AH possessed anti-neuroinflammatory, anti-adipogenic, anti-inflammatory, antibacterial, anti-cancer, anti-oxidation, anti-AChE, anti-BuChE, and antihyaluronidase activities. The present review is an up-to-date and comprehensive analysis of the botany, phytochemistry, and pharmacology of AH.

Study on Demethoxycurcumin as a Promising Approach to Reverse Methicillin-Resistance of Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) has always been a threatening pathogen. Research on phytochemical components that can replace antibiotics with limited efficacy may be an innovative method to solve intractable MRSA infections. The present study was devoted to investigate the antibacterial activity of the natural compound demethoxycurcumin (DMC) against MRSA and explore its possible mechanism for eliminating MRSA. The minimum inhibitory concentrations (MICs) of DMC against MRSA strains was determined by the broth microdilution method, and the results showed that the MIC of DMC was 62.5 μg/mL. The synergistic effects of DMC and antibiotics were investigated by the checkerboard method and the time–kill assay. The ATP synthase inhibitors were employed to block the metabolic ability of bacteria to explore their synergistic effect on the antibacterial ability of DMC. In addition, western blot analysis and qRT-PCR were performed to detect the proteins and genes related to drug resistance and S. aureus exotoxins. As results, DMC hindered the translation of penicillin-binding protein 2a (PBP2a) and staphylococcal enterotoxin and reduced the transcription of related genes. This study provides experimental evidences that DMC has the potential to be a candidate substance for the treatment of MRSA infections.

Synthesis, anticancer evaluation and mechanism studies of novel indolequinone derivatives of ursolic acid

A series of novel indolequinone derivatives of ursolic acid bearing ester, hydrazide, or amide moieties were designed, synthesized, and screened for their in vitro antiproliferative activities against three cancer cell lines (MCF-7, HeLa, and HepG2) and a normal gastric mucosal cell line (Ges-1). A number of compounds showed significant activity against tested cancer cell lines. Among them, compound 6t exhibited the most potent activity against three cancer cell lines with IC50 values of 1.66 ± 0.21, 3.16 ± 0.24, and 10.35 ± 1.63 µM, respectively, and considerably lower cytotoxicity to Ges-1 cells. Especially, compound 6t could arrest cell cycle at S phase, suppress the migration of MCF-7 cells, elevate intracellular reactive oxygen species (ROS) level, and decrease mitochondrial membrane potential. Western blot analysis showed that compound 6t upregulated Bax, cleaved caspase-3/9, cleaved PARP levels and downregulated Bcl-2 level of MCF-7 cells. All these results indicated that compound 6t could significantly induce the apoptosis of MCF-7 cells. Meanwhile, compound 6t markedly decreased p-AKT and p-mTOR expression, which revealed that compound 6t probably exerted its cytotoxicity through targeting PI3K/AKT/mTOR signaling pathway. Therefore, compound 6t could be a promising lead for the discovery of novel anticancer agents.

Antibacterial activity and synergy of antibiotics with sanguisorbigenin isolated from Sanguisorba officinalis L. against methicillin-resistant Staphylococcus aureus

The present study evaluated the antibacterial activity and the synergy of the sanguisorbigenin (SGB) from the dried root of Sanguisorba officinalis L. combined with β-lactam antibiotics against methicillin-resistant Staphylococcus aureus. A total of six strains of reference strain and clinical isolates were used to determine the antibacterial activity using a broth microdilution assay, and the synergistic effects were determined using a checkerboard assay. To analyse the mechanism of synergy, we conducted the level of penicillin-binding protein 2a by western blot. In addition, quantitative RT-PCR was performed to analyse the mecA gene expression. The minimal inhibitory concentration values of SGB against six strains of S. aureus were in the range of 12·5-50 μg ml^-1 , and there were synergy, or partial synergy effects when SGB was combined with antibiotics. Furthermore, when treated with SGB, the level of penicillin-binding protein 2a and the expression of the mecA gene was reduced significantly. In conclusion, this study demonstrated that SGB is a potential natural antibacterial agent against methicillin-resistant S. aureus that represents a considerable burden on the healthcare system worldwide, and may an exceptionally modulator of β-lactam antibiotics.

Antimicrobial and cytotoxic effects of ammonium derivatives of diterpenoids steviol and isosteviol

Antimicrobial and cytotoxic activities of several ammonium derivatives of diterpenoids steviol and isosteviol have been investigated in vitro. The results have showed that these compounds possess high antibacterial activity against MRSA strains and cytotoxic effect against cancer cell lines MCF-7, M-HeLa, A-549, PC3, HepG2, T98G. Lead compounds 4 and 5 were detected, which, in the case of the MCF-7 cell line (human breast adenocarcinoma), showed IC₅₀ at the doxorubicin level with a selectivity index of 5.0-5.2. Flow cytometry and laser confocal microscopy analysis demonstrated that the mechanism of cytotoxic effects of the tested compounds on MCF-7 cells could be associated with the induction of apoptosis along the mitochondrial pathway. At the same time, they did not cause hemolysis and showed only slight cytotoxicity with respect to normal human cells of embryonic lung (Wi-38). The obtained results allow us to consider the studied compounds as promising scaffolds for the design of new effective antibacterial drugs and anticancer agents targeting mitochondria.

Eleutheroside K isolated from Acanthopanax henryi (Oliv.) Harms suppresses methicillin resistance of Staphylococcus aureus

Acanthopanax (A.) henryi (Oliv.) Harms contain many bioactive compounds commonly used in traditional Chinese medicine. The objective of the present study was to investigate the antibacterial activity of the single constituent, Eleutheroside K (ETSK) isolated from the leaves of A. henryi (Oliv.) Harms, against methicillin-resistant Staphylococcus (S.) aureus (MRSA). Broth microdilution assay was used to measure the minimal inhibitory concentration (MIC) and the MIC values of ETSK against eight clinical S. aureus strains were all 50 µg ml^-1 . At sub-inhibitory concentrations, a synergistic effect between oxacillin (OXA) and ETSK was confirmed using checkerboard dilution assay and time-kill curve analysis. The bacteriostatic effect became more pronounced when ETSK was used in combination with detergent (Triton X-100) or ATPase inhibitor (N, N'-dicyclohexylcarbodiimide). According to western blot analysis, the down-regulated expression of Penicillin-binding protein 2a (PBP2a) further validated that the bacterial activity was inhibited when treated with ETSK in a dose-dependent manner. Results based on our study verified that ETSK significantly suppressed MRSA infections and emphasized the potential application of ETSK as a novel anti-MRSA natural drug.

The Mechanism of Bisdemethoxycurcumin Enhances Conventional Antibiotics against Methicillin-Resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) infection has posed a serious threat to public health, therefore, the development of new antibacterial drugs is imperative. Bisdemethoxycurcumin (BDMC) is a curcumin analog that exists in nature and possesses extensive pharmacological actions. This review focuses on investigating the antibacterial activity of BDMC alone or in combination with three antibiotics against MRSA. We determined the minimal inhibitory concentration of BDMC, with a broth microdilution assay, and the value against all six strains was 7.8 μg/mL. The synergistic effect of BDMC combined with the antibiotics was determined using a checkerboard dilution test and a time–kill curve assay. The results showed that the antimicrobial effect of BDMC combined with antibiotics was superior to treatment with that of a single agent alone. We examined the antibacterial activity of BDMC in the presence of a membrane-permeabilizing agent and an ATPase-inhibiting agent, respectively. In addition, we analyzed the mecA transcription gene and the penicillin-binding protein 2a (PBP2a) level of MRSA treated with BDMC by quantitative RT-PCR or Western blot assay. The gene transcription and the protein level were significantly inhibited. This study demonstrated that BDMC has potent antibacterial activity, and proved that BDMC may be a potential natural modulator of antibiotics.

Design, Synthesis, and Anticancer Evaluation of Novel Indole Derivatives of Ursolic Acid as Potential Topoisomerase II Inhibitors

In this study, a series of new indole derivatives of ursolic acid bearing different N-(aminoalkyl)carboxamide side chains were designed, synthesized, and evaluated for their in vitro cytotoxic activities against two human hepatocarcinoma cell lines (SMMC-7721 and HepG2) and normal hepatocyte cell line (LO2) via MTT assay. Among them, compound 5f exhibited the most potent activity against SMMC-7721 and HepG2 cells with IC50 values of 0.56 ± 0.08 μM and 0.91 ± 0.13 μM, respectively, and substantially lower cytotoxicity to LO2 cells. A follow-up enzyme inhibition assay and molecular docking study indicated that compound 5f can significantly inhibit the activity of Topoisomerase IIα. Further mechanistic studies performed in SMMC-7721 cells revealed that compound 5f can elevate the intracellular ROS levels, decrease mitochondrial membrane potential, and finally lead to the apoptosis of SMMC-7721 cells. Collectively, compound 5f is a promising Topoisomerase II (Topo II) inhibitor, which exhibited the potential as a lead compound for the discovery of novel anticancer agents.

Three Novel Monoterpenoid Glycosides From Fruits Of Eleutherococcus Henryi

The phytochemical investigation on the fruits of Eleutherococcus henryi (Araliaceae) resulted in the discovery of three novel monoterpene glycosides, eleuhenryiside A (1), eleuhenryiside B (2), and eleuhenryiside C (3), as well as a known lignan, (-)-kobusin (4). Their chemical structures were elucidated by mass, 1 D- and 2 D-NMR spectroscopy. The chemical structures of new compounds 1-3 were determined to be (2E,6R)-6-hydroxy-2,6-dimethyl-2,7-octadien-1-yl-(6'-O-acetyl)-O-β-glucopyranoside, (2Z,6R)-6-hydroxy-2,6-dimethyl-2,7-octadien-1-yl-(6'-O-acetyl)-O-β-glucopyranoside, and (-)-(4 R)-4,7-dihydroxy-1-menthene 7-O-β-glucopyranoside, respectively. The anti-neuroinflammatory and anti-inflammatory activities of these compounds were evaluated with LPS-stimulated BV2 microglia and RAW264.7 macrophage, respectively. The results showed that new compounds 1 and 3 have inhibitory effects of NO production with IC₅₀ values of 32.50 ± 1.60 and 3.54 ± 0.20 μM in LPS-stimulated BV2 microglia. Also, (-)-kobusin (4) has abilities to inhibit NO production with the IC₅₀ values of 14.25 ± 2.69 and 36.35 ± 6.27 μM in BV2 and RAW264.7 cells, respectively, which indicated that it may possess the potential anti-neuroinflammatory and anti-inflammatory activities.

Staphylococcus aureus colonisation in patients from a primary regional hospital

Staphylococcus aureus (SA or S. aureus) is a common pathogen that leads to local and systemic infections in communitarian and hospitalised patients. Staphylococcus colonizing nasal or pharyngeal sites can become virulent and cause severe infections. In this study, we collected 322 pharyngeal exudates and 142 nasal exudates from hospitalised and outpatients for screening purposes. The carriage rates in the pharynx were 27.06% for S. aureus, 11.55% for methicillin-resistant S. aureus (MRSA) and 5.61% for methicillin-oxacillin resistant S. aureus (MORSA). The carriage rates in the nose were 35.38% for S. aureus, 18.46% for MRSA and 13.85% for MORSA. The median multiple antibiotic resistance (MAR) index of SA was 33.33%. The MAR of MRSA was significantly higher than that of methicillin-susceptible strains (MSSA) (45.45% vs. 18.75%, P<0.0001) and the MAR of MORSA was 57.14%. Hierarchical clustering analysis revealed differences in the resistance of methicillin-sensitive, MRSA and MORSA strains. On the whole, our study demonstrates the pattern of distribution of nasal and pharyngeal colonisation with SA, MRSA and MORSA in adults vs. children, inpatients vs. outpatients, ICU patients vs. non-ICU patients, and females vs. males, which can be used for adjusting the screening and decontamination protocols in a hospital. SA is a pervasive pathogen with constantly changing trends in resistance and epidemiology and thus requires constant monitoring in healthcare facilities.