An antibiotic preorganized for ribosomal binding overcomes antimicrobial resistance

We report the design conception, chemical synthesis, and microbiological evaluation of the bridged macrobicyclic antibiotic cresomycin (CRM), which overcomes evolutionarily diverse forms of antimicrobial resistance that render modern antibiotics ineffective. CRM exhibits in vitro and in vivo efficacy against both Gram-positive and Gram-negative bacteria, including multidrug-resistant strains of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. We show that CRM is highly preorganized for ribosomal binding by determining its density functional theory-calculated, solution-state, solid-state, and (wild-type) ribosome-bound structures, which all align identically within the macrobicyclic subunits. Lastly, we report two additional x-ray crystal structures of CRM in complex with bacterial ribosomes separately modified by the ribosomal RNA methylases, chloramphenicol-florfenicol resistance (Cfr) and erythromycin-resistance ribosomal RNA methylase (Erm), revealing concessive adjustments by the target and antibiotic that permit CRM to maintain binding where other antibiotics fail.

Production of Bioactive Porcine Lactoferrin through a Novel Glucose-Inducible Expression System in Pichia pastoris: Unveiling Antimicrobial and Anticancer Functionalities

Lactoferrin (LF) stands as one of the extensively investigated iron-binding glycoproteins within milk, exhibiting diverse biological functionalities. The global demand for LF has experienced consistent growth. Biotechnological strategies aimed at enhancing LF productivity through microbial expression systems offer substantial cost-effective advantages and exhibit fewer constraints compared to traditional animal bioreactor technologies. This study devised a novel recombinant plasmid, wherein the AOX1 promoter was replaced with a glucose-inducible G1 promoter (PG1) to govern the expression of recombinant porcine LF (rpLF) in Pichia pastoris GS115. High-copy-number PG1-rpLF yeast clones were meticulously selected, and subsequent induction with 0.05 g/L glucose demonstrated robust secretion of rpLF. Scaling up production transpired in a 5 L fermenter, yielding an estimated rpLF productivity of approximately 2.8 g/L by the conclusion of glycerol-fed fermentation. A three-step purification process involving tangential-flow ultrafiltration yielded approximately 6.55 g of rpLF crude (approximately 85% purity). Notably, exceptional purity of rpLF was achieved through sequential heparin and size-exclusion column purification. Comparatively, the present glucose-inducible system outperformed our previous methanol-induced system, which yielded a level of 87 mg/L of extracellular rpLF secretion. Furthermore, yeast-produced rpLF demonstrated affinity for ferric ions (Fe3+) and exhibited growth inhibition against various pathogenic microbes (E. coli, S. aureus, and C. albicans) and human cancer cells (A549, MDA-MB-231, and Hep3B), similar to commercial bovine LF (bLF). Intriguingly, the hydrolysate of rpLF (rpLFH) manifested heightened antimicrobial and anticancer effects compared to its intact form. In conclusion, this study presents an efficient glucose-inducible yeast expression system for large-scale production and purification of active rpLF protein with the potential for veterinary or medical applications.

Discovery of a structural class of antibiotics with explainable deep learning

The discovery of novel structural classes of antibiotics is urgently needed to address the ongoing antibiotic resistance crisis1-9. Deep learning approaches have aided in exploring chemical spaces1,10-15; these typically use black box models and do not provide chemical insights. Here we reasoned that the chemical substructures associated with antibiotic activity learned by neural network models can be identified and used to predict structural classes of antibiotics. We tested this hypothesis by developing an explainable, substructure-based approach for the efficient, deep learning-guided exploration of chemical spaces. We determined the antibiotic activities and human cell cytotoxicity profiles of 39,312 compounds and applied ensembles of graph neural networks to predict antibiotic activity and cytotoxicity for 12,076,365 compounds. Using explainable graph algorithms, we identified substructure-based rationales for compounds with high predicted antibiotic activity and low predicted cytotoxicity. We empirically tested 283 compounds and found that compounds exhibiting antibiotic activity against Staphylococcus aureus were enriched in putative structural classes arising from rationales. Of these structural classes of compounds, one is selective against methicillin-resistant S. aureus (MRSA) and vancomycin-resistant enterococci, evades substantial resistance, and reduces bacterial titres in mouse models of MRSA skin and systemic thigh infection. Our approach enables the deep learning-guided discovery of structural classes of antibiotics and demonstrates that machine learning models in drug discovery can be explainable, providing insights into the chemical substructures that underlie selective antibiotic activity.

DNA binding peptide CF-14 enhances bactericidal efficacy of eugenol/carvacrol nanoparticles to Escherichia coli

To evaluate the bactericidal action of antimicrobial peptide CF-14, Eugenol (EU) and carvacrol (CAR) nanoparticles (NPs) less than 200 nm were surface-modified with CF14, gaining approximately 200 nm of EU-CF and CAR-CF NPs with swollen morphology. EU-CF and CAR-CF NPs were bactericidal to E. coli at dosage of 0.09% and 0.07% (v/v), respectively; while they were just bacteriostatic to Staphylococcus aureus at 0.10% and 0.08% (v/v). Spectral variations in bacterial carbohydrates (1185-900 cm-1), lipids (3000-2800 cm-1) and DNA (1500-1185 cm-1) were obvious as evident from Fourier transform infrared spectroscopy (FTIR). A higher percentage of membrane damaged (non-revivable) E. coli than S. aureus was found, which indicated electrostatic interactions between Gram-negative E. coli with cationic CF conjugated NPs leading to DNA disintegration. Interestingly, EU-CF and CAR-CF NPs inhibited E. coli growth in orange juice without impacting flavour compounds.

Tapping into Tapajos: antibacterial potential of fungal strains isolated from decaying wood in the Brazilian Amazon

The emergence of bacterial resistance to antimicrobials poses a significant health threat. To address this issue, exploring the fungal diversity in freshwater environments in the Amazon Forest has potential in the search for new antimicrobials. This study aimed to investigate the production of antibacterial metabolites by aquatic fungi from Amazon lakes, specifically Lake Juá and Lake Maicá (Brazil-PA). The fungal isolates were obtained from wood fragments submerged in these lakes, and the ethyl acetate extracts were evaluated for antibacterial activity against Staphylococcus aureus ATCC 25923, S. aureus (MRSA), ATCC 43300, Escherichia coli ATCC 25922, and E. coli (ESBL) NCTC 13353. Additionally, toxicity of the extracts (EtOAc with antimicrobial activity) against human fibroblasts MRC-5 was investigated. The study identified 40 fungal strains with antimicrobial screening, and the ethyl acetate extracts of Fluviatispora C34, Helicascus C18, Monodictys C15, and Fusarium solani LM6281 exhibited antibacterial activity. F. solani LM6281 showed the lowest minimum inhibitory concentration (MIC) of 50 µg/mL against S. aureus strains and MIC of 100 µg/mL against E. coli strains including ESBL. The cytotoxicity (IC50) of the extract (EtOAc) of F. solani LM6281 was 34.5 µg/mL. Preliminary studies of the TLC culture and RNM-H from the extract (EtOAc) of F. solani suggested the presence of substances from the class of terpenes, quinones, phenolics, and flavonoids. This study highlights the potential of submerged wood fungi in the Amazon region to produce antibacterial substances, thus identifying them as sources of novel bioactive compounds with potential use in the pharmaceutical industry and regional bioeconomy.

Multifunctional nanofibrous mats: toward antibacterial and anti-inflammatory applications, and visual bacterial diagnosis

In most circumstances, wounds face the challenges of bacterial invasions and inappropriate inflammatory responses when they lack proper wound management. Endowing dressings with both antibacterial and anti-inflammatory functions is a compelling strategy for resolving the above issues. However, seizing the right moment to change the dressings and providing satisfactory management of wounds are still urgently required. Herein, an antibacterial and anti-inflammatory nanofibrous mat is proposed by encapsulating antibiotic gentamicin sulfate (GS) and anti-inflammatory drug ibuprofen (IB) into nanofibers via a coaxial electrospinning technique and is further decorated with Prussian blue nanocrystals (PBNCs) to enhance anti-inflammatory activity and, more importantly, to monitor bacterial infections and guide dressing changes in a timely manner. Such a nanofibrous mat releases most of the therapeutic drugs within 120 min and reveals excellent antibacterial activity and anti-inflammatory ability. Specifically, it can destroy both Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), as well as conspicuously reduce the production of reactive oxygen species (ROS) and the expression of pro-inflammatory cytokines in macrophages. In addition, the nanofibrous mat can be used for point-of-use diagnosis of living bacteria relying on the naked eye or color analysis, which exhibits the potential of monitoring wound infection and guiding dressing changes promptly. This finding demonstrates the theranostic applications of multifunctional nanofibrous mats in wound healing.

Antimicrobial, Antibiofilm, and Anticancer Activities of Syzygium aromaticum Essential Oil Nanoemulsion

In the current study, clove oil nanoemulsion (CL-nanoemulsion) and emulsion (CL-emulsion) were prepared through an ecofriendly method. The prepared CL-nanoemulsion and CL-emulsion were characterized using dynamic light scattering (DLS) and a transmission electron microscope (TEM), where results illustrated that CL-nanoemulsion droplets were approximately 32.67 nm in size and spherical in shape, while CL-nanoemulsion droplets were approximately 225.8 nm with a spherical shape. The antibacterial activity of CL-nanoemulsion and CL-emulsion was carried out using a microbroth dilution method. Results revealed that the preferred CL-nanoemulsion had minimal MIC values between 0.31 and 5 mg/mL. The antibiofilm efficacy of CL-nanoemulsion against S. aureus significantly decreased the development of biofilm compared with CL-emulsion. Furthermore, results illustrated that CL-nanoemulsion showed antifungal activity significantly higher than CL-emulsion. Moreover, the prepared CL-nanoemulsion exhibited outstanding antifungal efficiency toward Candida albicans, Cryptococcus neoformans, Aspergillus brasiliensis, A. flavus, and A. fumigatus where MICs were 12.5, 3.12, 0.78, 1.56, and 1.56 mg/mL, respectively. Additionally, the prepared CL-nanoemulsion was analyzed for its antineoplastic effects through a modified MTT assay for evaluating apoptotic and cytotoxic effects using HepG2 and MCF-7 cell lines. MCF-7 breast cancer cells showed the lowest IC50 values (3.4-fold) in CL-nanoemulsion relative to that of CL-emulsion. Thus, CL-nanoemulsion induces apoptosis in breast cancer cells by inducing caspase-8 and -9 activity and suppressing VEGFR-2. In conclusion, the prepared CL-nanoemulsion had antibacterial, antifungal, and antibiofilm as well as anticancer properties, which can be used in different biomedical applications after extensive studies in vivo.

The anticancer, anti-oxidant, and antibacterial activities of chitosan-lecithin-coated parthenolide/tyrosol hybrid nanoparticles

Tyrosol (TYR) and parthenolide (PLT) have been used as synthetic antioxidant and natural anticancer compounds. In the current study, we aimed to synthesize an encapsulated complex of both PLT and TYR in a hybrid coating layer consisting of lecithin and chitosan molecules, a proper biocompatible drug delivery system to evaluate its antibacterial and anticancer potentials on human liver HepG2 and pancreatic Panc cancer cell lines. The chitosan-lecithin-coated PLT/TYR nanoparticles (clPT-NPs) were synthesized applying an auto-self-assembling method. The clPT-NPs were characterized utilizing DLS, FTIR, zeta potential, and TEM analysis. The clPT-NPs' antioxidant activity was measured by running ABTS and DPPH antioxidant assays. Moreover, the antibacterial potential of clPT-NPs was evaluated by applying disk diffusion, MIC, and MBC assays. Finally, the nanoparticles' cytotoxicity and apoptotic activity were studied by conducting MTT, Flow cytometry, AO/PI cell staining, and real-time PCR techniques. The clPT-NPs (38 nm) exhibited significant antioxidant activity by inhibiting ABTS and DPPH radicals at 187 and 290 μg/mL IC50 concentrations, respectively. Also, the nanoparticles induced a notable antibacterial activity against Staphylococcus aureus at 0.0625 mg/mL MIC and 0.125 mg/mL MBC concentrations. The clPT-NPs selectively decreased the cancer cells' survival and increased the apoptotic dead cells by up-regulating apoptotic gene expression (BAX and Cas-8) and down-regulating BCL-2 anti-apoptotic gene expression. The PLT toxicity has been merged with improved TYR antioxidant activity, which has been functionalized in a safe, biocompatible hybrid nano-delivery system.

Identification of inhibitors for Agr quorum sensing system of Staphylococcus aureus by machine learning, pharmacophore modeling, and molecular dynamics approaches

CONTEXT

Staphylococcus aureus is a highly pathogenic organism that is the most common cause of postoperative complications as well as severe infections like bacteremia and infective endocarditis. By mediating the formation of biofilms and the expression of virulent genes, the quorum sensing (QS) mechanism is a major contributor to the development of these diseases. By hindering its QS network, an innovative approach to avoiding this bacterial infection is taken. Targeting the AgrA of the Agr system serves as beneficial in holding the top position in the QS system cascade.

METHODS

Using known AgrA inhibitors, the machine learning algorithms (artificial neural network, naïve Bayes, random forest, and support vector machine) and pharmacophore model were developed. The potential lead compounds were screened against the Zinc and COCONUT databases using the best pharmacophore hypothesis. The hits were then subjected second screening process using the best machine learning model. The predicted active compounds were then reranked based on the docking score. The stability of AgrA-lead compounds was studied using molecular dynamics approaches, and an ADME profile was also carried out. Five lead compounds, namely, CNP02386963,4,5-trihydroxy-2-[({7,13,14-trihydroxy-3,10-dioxo-2,9-dioxatetracyclo[6.6.2.04,16.011,15]hexadeca-1(14),4,6,8(16),11(15),12-hexaen-6-yl}oxy)methyl]benzoic acid, CNP0129274 4-(dimethylamino)-1,5,6,10,12,12a-hexahydroxy-6-methyl-3,11-dioxo-3,4,4a,5,5a,6,11,12a-octahydrotetracene-2-carboxamide, CNP0242717 3-Hydroxyasebotin, CNP0361624 3,4,5-trihydroxy-6-[(2,4,5,6,7-pentahydroxy-1-oxooctan-3-yl)oxy]oxane-2-carboxylic acid, and CNP0285058 2-{[4,5-dihydroxy-6-(hydroxymethyl)-3-[(3,4,5-trihydroxy-6-methyloxan-2-yl)oxy]oxan-2-yl]oxy}-2-(4-hydroxyphenyl)acetonitrile were obtained using the two-step virtual screening process. The molecular dynamics study revealed that the CNP0238696 was found to be stable in the binding pocket of AgrA. ADME profiles show that this compound has two Lipinski violations and low bioavailability. Further studies should be performed to assess the anti-biofilm activity of the lead compound in vitro.

Flexible Curcumin-Loaded Zn-MOF Hydrogel for Long-Term Drug Release and Antibacterial Activities

Management of chronic inflammation and wounds has always been a key issue in the pharmaceutical and healthcare sectors. Curcumin (CCM) is an active ingredient extracted from turmeric rhizomes with antioxidant, anti-inflammatory, and antibacterial activities, thus showing significant effectiveness toward wound healing. However, its shortcomings, such as poor water solubility, poor chemical stability, and fast metabolic rate, limit its bioavailability and long-term use. In this context, hydrogels appear to be a versatile matrix for carrying and stabilizing drugs due to their biomimetic structure, soft porous microarchitecture, and favorable biomechanical properties. The drug loading/releasing efficiencies can also be controlled via using highly crystalline and porous metal-organic frameworks (MOFs). Herein, a flexible hydrogel composed of a sodium alginate (SA) matrix and CCM-loaded MOFs was constructed for long-term drug release and antibacterial activity. The morphology and physicochemical properties of composite hydrogels were analyzed by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-Vis), Raman spectroscopy, and mechanical property tests. The results showed that the composite hydrogel was highly twistable and bendable to comply with human skin mechanically. The as-prepared hydrogel could capture efficient CCM for slow drug release and effectively kill bacteria. Therefore, such composite hydrogel is expected to provide a new management system for chronic wound dressings.

Silver nanoparticles decorated ZnO-CuO core-shell nanowire arrays with low water adhesion and high antibacterial activity

Nanostructured surfaces based on silver nanoparticles decorated ZnO-CuO core-shell nanowire arrays, which can assure protection against various environmental factors such as water and bacteria were developed by combining dry preparation techniques namely thermal oxidation in air, radio frequency (RF) magnetron sputtering and thermal vacuum evaporation. Thus, high-aspect-ratio ZnO nanowire arrays were grown directly on zinc foils by thermal oxidation in air. Further ZnO nanowires were coated with a CuO layer by RF magnetron sputtering, the obtained ZnO-CuO core-shell nanowires being decorated with Ag nanoparticles by thermal vacuum evaporation. The prepared samples were comprehensively assessed from morphological, compositional, structural, optical, surface chemistry, wetting and antibacterial activity point of view. The wettability studies show that native Zn foil and ZnO nanowire arrays grown on it are featured by a high water droplet adhesion while ZnO-CuO core-shell nanowire arrays (before and after decoration with Ag nanoparticles) reveal a low water droplet adhesion. The antibacterial tests carried on Escherichia coli (a Gram-negative bacterium) and Staphylococcus aureus (a Gram-positive bacterium) emphasize that the nanostructured surfaces based on nanowire arrays present excellent antibacterial activity against both type of bacteria. This study proves that functional surfaces obtained by relatively simple and highly reproducible preparation techniques that can be easily scaled to large area are very attractive in the field of water repellent coatings with enhanced antibacterial function.

Neobavaisoflavone Inhibits Biofilm Formation and α-Toxin Activity of Staphylococcus aureus

Neobavaisoflavone had antimicrobial activities against Gram-positive multidrug-resistant (MDR) bacteria, but the effect of neobavaisoflavone on the virulence and biofilm formation of S. aureus has not been explored. The present study aimed to investigate the possible inhibitory effect of neobavaisoflavone on the biofilm formation and α-toxin activity of S. aureus. Neobavaisoflavone presented strong inhibitory effect on the biofilm formation and α-toxin activity of both methicillin-sensitive S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA) strains at 25 µM, but did not affect the growth of S. aureus planktonic cells. Genetic mutations were identified in four coding genes, including cell wall metabolism sensor histidine kinase walK, RNA polymerase sigma factor rpoD, tetR family transcriptional regulator, and a hypothetical protein. The mutation of WalK (K570E) protein was identified and verified in all the neobavaisoflavone-induced mutant S. aureus isolates. The ASN501, LYS504, ILE544 and GLY565 of WalK protein act as hydrogen acceptors to form four hydrogen bonds with neobavaisoflavone by molecular docking analysis, and TRY505 of WalK protein contact with neobavaisoflavone to form a pi-H bond. In conclusion, neobavaisoflavone had excellent inhibitory effect on the biofilm formation and α-toxin activity of S. aureus. The WalK protein might be a potential target of neobavaisoflavone against S. aureus.

Monomer and Oligomer Transition of Zinc Phthalocyanine Is Key for Photobleaching in Photodynamic Therapy

Photodynamic therapy (PDT) is recognized as a powerful method to inactivate cells. However, the photosensitizer (PS), a key component of PDT, has suffered from undesired photobleaching. Photobleaching reduces reactive oxygen species (ROS) yields, leading to the compromise of and even the loss of the photodynamic effect of the PS. Therefore, much effort has been devoted to minimizing photobleaching in order to ensure that there is no loss of photodynamic efficacy. Here, we report that a type of PS aggregate showed neither photobleaching nor photodynamic action. Upon direct contact with bacteria, the PS aggregate was found to fall apart into PS monomers and thus possessed photodynamic inactivation against bacteria. Interestingly, the disassembly of the bound PS aggregate in the presence of bacteria was intensified by illumination, generating more PS monomers and leading to an enhanced antibacterial photodynamic effect. This demonstrated that on a bacterial surface, the PS aggregate photo-inactivated bacteria via PS monomer during irradiation, where the photodynamic efficiency was retained without photobleaching. Further mechanistic studies showed that PS monomers disrupted bacterial membranes and affected the expression of genes related to cell wall synthesis, bacterial membrane integrity, and oxidative stress. The results obtained here are applicable to other types of PSs in PDT.

Impact on S. aureus and E. coli Membranes of Treatment with Chlorhexidine and Alcohol Solutions: Insights from Molecular Simulations and Nuclear Magnetic Resonance

Membranes form the first line of defence of bacteria against potentially harmful molecules in the surrounding environment. Understanding the protective properties of these membranes represents an important step towards development of targeted anti-bacterial agents such as sanitizers. Use of propanol, isopropanol and chlorhexidine can significantly decrease the threat imposed by bacteria in the face of growing anti-bacterial resistance via mechanisms that include membrane disruption. Here we have employed molecular dynamics simulations and nuclear magnetic resonance to explore the impact of chlorhexidine and alcohol on the S. aureus cell membrane, as well as the E. coli inner and outer membranes. We identify how sanitizer components partition into these bacterial membranes, and show that chlorhexidine is instrumental in this process.

Abundant tannic acid modified gelatin/sodium alginate biocomposite hydrogels with high toughness, antifreezing, antioxidant and antibacterial properties

The acidity of high tannic acid (TA) content solution can destroy the structure of protein, such as gelatin (G). This causes a big challenge to introduce abundant TA into the G-based hydrogels. Here, the G-based hydrogel system with abundant TA as hydrogen bonds provider was constructed by a "protective film" strategy. The protective film around the composite hydrogel was first formed by the chelation of sodium alginate (SA) and Ca2+. Subsequently, abundant TA and Ca2+ were successively introduced into the hydrogel system by immersing method. This strategy effectively protected the structure of the designed hydrogel. After treatment with 0.3 w/v TA and 0.06 w/v Ca2+ solutions, the tensile modulus, elongation at break and toughness of G/SA hydrogel increased about 4-, 2-, and 6-fold, respectively. Besides, G/SA-TA/Ca2+ hydrogels exhibited good water retention, anti-freezing, antioxidant, antibacterial properties and low hemolysis ratio. Cell experiments showed that G/SA-TA/Ca2+ hydrogels possessed good biocompatibility and could promote cell migration. Therefore, G/SA-TA/Ca2+ hydrogels are expected to be used in the field of biomedical engineering. The strategy proposed in this work also provides a new idea for improving the properties of other protein-based hydrogels.

Natural photosensitizer-loaded in micellar copolymer to prevent bovine mastitis: A new post-dipping protocol on milking

Good management practices such as post-dipping applications (post-milking immersion bath) contribute to the dairy cattle health during lactation and minimize the appearance of mastitis (an infection in the mammary gland). The post-dipping procedure is performed conventionally using iodine-based solutions. The search for therapeutic modalities that are not invasive and do not cause resistance to the microorganisms that cause bovine mastitis instigates the interest of the scientific community. In this regard, antimicrobial Photodynamic Therapy (aPDT) is highlighted. The aPDT is based on combining a photosensitizer (PS) compound, light of adequate wavelength, and molecular oxygen (3O2), which triggers a series of photophysical processes and photochemical reactions that generate reactive oxygen species (ROS) responsible for the inactivation of microorganisms. The present investigation explored the photodynamic efficiency of two natural PS: Chlorophyll-rich spinach extract (CHL) and Curcumin (CUR), both incorporated into the Pluronic® F127 micellar copolymer. They were applied in post-dipping procedures in two different experiments. The photoactivity of formulations mediated through aPDT was conducted against Staphylococcus aureus, and obtained a minimum inhibitory concentration (MIC) of 6.8 mg mL-1 for CHL-F127 and 0.25 mg mL-1 for CUR-F127. Only CUR-F127 inhibited Escherichia coli growth with MIC 0.50 mg mL-1. Concerning the count of microorganisms during the days of the application, a significant difference was observed between the treatments and control (Iodine) when the teat surface of cows was evaluated. For CHL-F127 there was a difference for Coliform and Staphylococcus (p < 0.05). For CUR-F127 there was a difference for aerobic mesophilic and Staphylococcus (p < 0.05). Such application decreased bacterial load and maintained the milk quality, being evaluated via total microorganism count, physical-chemical composition, and somatic cell count (SCC).

Yttrium Oxide Nanoparticle-Loaded, Self-Assembled Peptide Gel with Antibacterial, Anti-Inflammatory, and Proangiogenic Properties for Wound Healing

Chronic wounds are a major healthcare challenge owing to their complex healing mechanism and number of impediments to the healing process, like infections, unregulated inflammation, impaired cellular functions, poor angiogenesis, and enhanced protease activity. Current topical care strategies, such as surgical debridement, absorption of exudates, drug-loaded hydrogels for infection and inflammation management, and exogenous supply of growth factors for angiogenesis and cell proliferation, slow the progression of wounds and reduce patient suffering but suffer from low overall cure rates. Therefore, we have developed a proteolytically stable, multifunctional nanoparticle loaded-peptide gel with inherent anti-inflammatory, antibacterial, and pro-angiogenic properties to provide a favorable wound healing milieu by restoring impaired cellular functions. We have fabricated a self-assembled, lauric acid-peptide conjugate gel, LA-LLys-DPhe-LLys-NH2, loaded with yttrium oxide (Y2O3) nanoparticles (NLG). Gel formed a nanofibrous structure, and nanoparticles were passively entrapped within the network. The surface morphology, stability, viscoelastic, and self-healing characteristics of gels were characterized. It showed a high stability against degradation by proteolytic enzymes and highly potent antibacterial activities against E. coli and S. aureus due to the presence of positively charged side chains of lysine in the peptide chain. It also exhibited an excellent antioxidant activity as well as ability to stimulate cell proliferation in murine fibroblast (L929) cells and human umbilical vein endothelial cells (HUVECs). The incorporation of nanoparticles promoted angiogenesis by upregulating pro-angiogenic genes, vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF2), and epidermal growth factor (EGFR), and the gel caused complete wound closure in cells. In summary, the Y2O3 nanoparticle-loaded lauric acid-peptide conjugate gel is able to elicit the desired tissue regeneration responses and, therefore, has a strong potential as a matrix for the treatment of chronic wounds.

Synergistic Enhancement of Filtering Efficiency and Antibacterial Performance of a Nanofiber Air Filter Decorated with Electropolarized Lithium-Doped ZnO Nanorods

According to clinical case reports, bacterial co-infection with COVID-19 can significantly increase mortality, with Staphylococcus aureus (S. aureus) being one of the most common pathogens causing complications such as pneumonia. Thus, during the pandemic, research on imparting air filters with antibacterial properties was actively initiated, and several antibacterial agents were investigated. However, air filters with inorganic nanostructures on organic nanofibers (NFs) have not been investigated extensively. This study aimed to demonstrate the efficiency of electropolarized poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) NFs decorated with Li-doped ZnO nanorods (NRs) to improve the filtering ability and antibacterial activity of the ultrathin air filter. The surfactant was loaded onto the ZnO─known for its biocompatibility and low toxicity─nanoparticles (NPs) and transferred to the outer surface of the NFs, where Li-doped ZnO NRs were grown. The Li-doped ZnO NR-decorated NF effectively enhanced the physical filtration efficiency and antibacterial properties. Additionally, by exploiting the ferroelectric properties of Li-doped ZnO NRs and PVDF-TrFE NFs, the filter was electropolarized to increase its Coulombic interaction with PMs and S. aureus. As a result, the filter exhibited a 90% PM1.0 removal efficiency and a 99.5% sterilization rate against S. aureus. The method proposed in this study provides an effective route for simultaneously improving the air filter performance and antibacterial activity.

Essential Oil Composition of Grindelia squarrosa from Southern Idaho

Grindelia squarrosa is an arid lands herb that has been used in Native American traditional medicine, is a potential source of pharmacologically active compounds, and has been explored as a source of biofuel. The purpose of this work was to examine the essential oil composition of G. squarrosa from southern Idaho. Gas chromatographic methods revealed the essential oil of G. squarrosa var. serrulata to be rich in monoterpenoids, α-pinene (21.9%), limonene (17.1%), terpinolene (10.6%), and borneol (6.5%). The essential oil composition of G. squarrosa from Idaho is similar to that previously reported from specimens collected from Montana and confirms the volatile phytochemistry of plants growing in North America. The major essential oil components were screened for antimicrobial activity against respiratory and dermal pathogens. (-)-β-Pinene showed strong antibacterial activity against Streptococcus pneumoniae (MIC 39.1 μg/mL) and (-)-borneol showed strong activity against Staphylococcus aureus (MIC 78.1 μg/mL).

Expression, purification and investigation of antibacterial activity of a novel hybrid peptide LL37/hBD-129 by applied comprehensive computational and experimental approaches

Antibiotic-resistant pathogens have become a great universal health concern. Antimicrobial peptides (AMPs) are small amphipathic and cationic polypeptides with high therapeutic potential against various microorganisms containing drug-resistant strains. Two major groups of these peptides, which have antibacterial activity against Gram-positive and Gram-negative bacteria, antiviral activity, and even antifungal activity, are defensins and cathelicidins. Hybridization of various AMPs is an appropriate approach to achieving new fusion AMPs with high antibacterial activity but low cellular toxicity. In the current research, the amino-acid sequence of human cathelicidin LL-37 (2-31) and Human beta-defensin (hBD)-129 were combined, and the fusion protein was evaluated by bioinformatics tool. The designed AMP gene sequence was commercially synthesized and cloned in the pET-28a expression vector. The LL-37/hBD-129 fusion protein was expressed in E.coli BL21-gold (DE3). The expression of the recombinant protein was evaluated using the SDS-PAGE method. The LL37/hBD-129 was successfully expressed as a recombinant hybrid AMP in E.coli BL21-gold (DE3) strain. Purification of the expressed AMP was performed by Ni-NTA column affinity chromatography, and the purified AMP was validated using the Western blot technic. Finally, the antimicrobial activity of the fusion AMP against Staphylococcus aureus and Escherichia coli bacteria was assessed. Based on the in silico analysis and experimental evaluations, the fusion AMP showed a significant antimicrobial effect on E. coli and Staphylococcus aureus bacteria.

Syntheses and Antibacterial Evaluation of New Penicillium Metabolites Gregatins G and Thiocarboxylics C

Two pairs of side-chain epimeric 3-methoxycarbonyl-dihydrofuran-4-ones with structures purported for thiocarboxylics C1/2 and gregatins G1/2 , isolated from Penicillium sp. Sb62, were synthesised for the first time in five steps and 17-25 % yield. Key steps were a Suzuki cross-coupling, a Yamaguchi esterification, and a base-induced Knoevenagel-type condensation. The optimum protecting group for the 10-OH group in the dienyl side-chain, orthogonal to necessary protecting groups on O-10 of the furanone, was found to be t-butyldiphenylsilyl (TBDPS). The specific rotations of our synthetic products deviated markedly from those reported for the natural isolates. In contrast to the isolates, the synthetic products were not active against Escherichia coli and Staphylococcus aureus bacteria.

Actinomycin-X2-Immobilized Silk Fibroin Film with Enhanced Antimicrobial and Wound Healing Activities

Actinomycin is a family of chromogenic lactone peptides that differ in their peptide portions of the molecule. An antimicrobial peptide, actinomycin X2 (Ac.X2), was produced through the fermentation of a Streptomyces cyaneofuscatus strain. Immobilization of Ac.X2 onto a prepared silk fibroin (SF) film was done through a carbodiimide reaction. The physical properties of immobilized Ac.X2 (antimicrobial films, AMFs) were analyzed by ATR-FTIR, SEM, AFM, and WCA. The findings from an in vitro study showed that AMFs had a more broad-spectrum antibacterial activity against both S. aureus and E. coli compared with free Ac.X2, which showed no apparent strong effect against E. coli. These AMFs showed a suitable degradation rate, good hemocompatibility, and reduced cytotoxicity in the biocompatibility assay. The results of in vivo bacterially infected wound healing experiments indicated that wound inflammation was prevented by AMFs, which promoted wound repair and improved the wound microenvironment. This study revealed that Ac.X2 transformation is a potential candidate for skin wound healing.

Antibacterial Activity and Mechanism of Oxidized Bacterial Nanocellulose with Different Carboxyl Content

Oxidized bacterial nanocellulose (OBC) is reported to prevent microbial growth, but its antibacterial characteristics and mechanism are still unclear. Here, the antibacterial mechanism of OBC is explored by detecting and assessing the interaction of OBC with different carboxyl content on Staphylococcus aureus and Escherichia coli. The results show that OBC has strong antibacterial activity and antibiofilm activity against S. aureus and E. coli, which is positively correlated with the carboxyl content of OBC. After OBC treatment, the bacteria adhesion is inhibited and the cell membrane is destroyed leading to increased permeability. Further investigation reveals that the concentration of cyclic diguanosine monophosphate (c-di-GMP) that induced biofilm formation is significantly decreased to 1.81 pmol mg^-1 after OBC treatment. In addition, OBC inactivates mature biofilms, with inactivation rates up to 79.3%. This study suggests that OBC has excellent antibacterial and antiadhesion properties, which can increase the cell membrane permeability and inhibit c-di-GMP formation. In addition, OBC also has a strong inactivation effect on mature biofilm, which can be used as an effective antibiofilm agent.

Antibacterial Activity of Juglone Revealed in a Wound Model of Staphylococcus aureus Infection

A serious problem currently facing the field of wound healing is bacterial infection, especially Staphylococcus aureus (S. aureus) infection. Although the application of antibiotics has achieved good effects, their irregular use has resulted in the emergence of drug-resistant strains. It is thus the purpose of this study to analyze whether the naturally extracted phenolic compound, juglone, can inhibit S. aureus in wound infection. The results show that the minimum inhibitory concentration (MIC) of juglone against S. aureus was 1000 μg/mL. Juglone inhibited the growth of S. aureus by inhibiting membrane integrity and causing protein leakage. At sub-inhibitory concentrations, juglone inhibited biofilm formation, the expression of α-hemolysin, the hemolytic activity, and the production of proteases and lipases of S. aureus. When applied to infected wounds in Kunming mice, juglone (50 μL juglone with a concentration of 1000 μg/mL) significantly inhibited the number of S. aureus and had a significant inhibitory effect on the expression of inflammatory mediators (TNF-α, IL-6 and IL-1β). Moreover, the juglone-treated group promoted wound healing. At the same time, in animal toxicity experiments, juglone had no obvious toxic effects on the main tissues and organs of mice, indicating that juglone has good biocompatibility and has the potential to be used in the treatment of wounds infected with S. aureus.

Efflux Pump (QacA, QacB, and QacC) and β-Lactamase Inhibitors? An Evaluation of 1,8-Naphthyridines against Staphylococcus aureus Strains

The bacterial species Staphylococcus aureus presents a variety of resistance mechanisms, among which the expression of β-lactamases and efflux pumps stand out for providing a significant degree of resistance to clinically relevant antibiotics. The 1,8-naphthyridines are nitrogen heterocycles with a broad spectrum of biological activities and, as such, are promising research targets. However, the potential roles of these compounds on bacterial resistance management remain to be better investigated. Therefore, the present study evaluated the antibacterial activity of 1,8-naphthyridine sulfonamides, addressing their ability to act as inhibitors of β-lactamases and efflux pump (QacA/B and QacC) against the strains SA-K4414 and SA-K4100 of S. aureus. All substances were prepared at an initial concentration of 1024 μg/mL, and their minimum inhibitory concentrations (MIC) were determined by the broth microdilution method. Subsequently, their effects on β-lactamase- and efflux pump-mediated antibiotic resistance was evaluated from the reduction of the MIC of ethidium bromide (EtBr) and β-lactam antibiotics, respectively. The 1,8-naphthyridines did not present direct antibacterial activity against the strains SA-K4414 and SA-K4100 of S. aureus. On the other hand, when associated with antibiotics against both strains, the compounds reduced the MIC of EtBr and β-lactam antibiotics, suggesting that they may act by inhibiting β-lactamases and efflux pumps such as QacC and QacA/B. However, further research is required to elucidate the molecular mechanisms underlying these observed effects.

Evaluation of the Synthetic Multifunctional Peptide Hp-MAP3 Derivative of Temporin-PTa

In recent years, antimicrobial peptides isolated from amphibian toxins have gained attention as new multifunctional drugs interacting with different molecular targets. We aimed to rationally design a new peptide from temporin-PTa. Hp-MAP3 (NH2-LLKKVLALLKKVL-COOH), net charge (+4), hydrophobicity (0.69), the content of hydrophobic residues (69%), and hydrophobic moment (0.73). For the construction of the analog peptide, the physicochemical characteristics were reorganized into hydrophilic and hydrophobic residues with the addition of lysines and leucines. The minimum inhibitory concentration was 2.7 to 43 μM against the growth of Gram-negative and positive bacteria, and the potential for biofilm eradication was 173.2 μM. Within 20 min, the peptide Hp-MAP3 (10.8 μM) prompted 100% of the damage to E. coli cells. At 43.3 μM, eliminated 100% of S. aureus within 5 min. The effects against yeast species of the Candida genus ranged from 5.4 to 86.6 μM. Hp-MAP3 presents cytotoxic activity against tumor HeLa at a concentration of 21.6 μM with an IC50 of 10.4 µM. Furthermore, the peptide showed hemolytic activity against murine erythrocytes. Structural studies carried out by circular dichroism showed that Hp-MAP3, while in the presence of 50% trifluoroethanol or SDS, an α-helix secondary structure. Finally, Amphipathic Hp-MAP3 building an important model for the design of new multifunctional molecules.

Structural basis of broad-spectrum β-lactam resistance in Staphylococcus aureus

Broad-spectrum β-lactam antibiotic resistance in Staphylococcus aureus is a global healthcare burden1,2. In clinical strains, resistance is largely controlled by BlaR13, a receptor that senses β-lactams through the acylation of its sensor domain, inducing transmembrane signalling and activation of the cytoplasmic-facing metalloprotease domain4. The metalloprotease domain has a role in BlaI derepression, inducing blaZ (β-lactamase PC1) and mecA (β-lactam-resistant cell-wall transpeptidase PBP2a) expression3-7. Here, overcoming hurdles in isolation, we show that BlaR1 cleaves BlaI directly, as necessary for inactivation, with no requirement for additional components as suggested previously8. Cryo-electron microscopy structures of BlaR1-the wild type and an autocleavage-deficient F284A mutant, with or without β-lactam-reveal a domain-swapped dimer that we suggest is critical to the stabilization of the signalling loops within. BlaR1 undergoes spontaneous autocleavage in cis between Ser283 and Phe284 and we describe the catalytic mechanism and specificity underlying the self and BlaI cleavage. The structures suggest that allosteric signalling emanates from β-lactam-induced exclusion of the prominent extracellular loop bound competitively in the sensor-domain active site, driving subsequent dynamic motions, including a shift in the sensor towards the membrane and accompanying changes in the zinc metalloprotease domain. We propose that this enhances the expulsion of autocleaved products from the active site, shifting the equilibrium to a state that is permissive of efficient BlaI cleavage. Collectively, this study provides a structure of a two-component signalling receptor that mediates action-in this case, antibiotic resistance-through the direct cleavage of a repressor.

Per- and polyfluoroalkyl substances enhance Staphylococcus aureus pathogenicity and impair host immune response

Per- and Poly-fluoroalkyl substances (PFAS) are major persistent environmental contaminants. Epidemiological studies have linked PFAS exposures to altered immunity and increased occurrence of infections in children. However, the mechanisms leading to immune susceptibility to bacterial infections remains unclear. To elucidate the mechanism, transcriptional alteration in the Caenorhabditis elegans model caused by a PFAS contaminated environmental water and two reconstituted PFAS solutions were evaluated using RNA-sequencing. PFAS affected the expression of several genes involved in C. elegans immune surveillance to Gram-positive bacteria (cpr-2, tag-38, spp-1, spp-5, clec-7, clec-172). The combined exposure to PFAS and Staphylococcus aureus significantly reduced C. elegans survival and increased intestinal membrane permeability. Furthermore, the growth of S. aureus in the presence of PFAS increased the expression of virulence genes, specifically, the virulence gene regulator saeR and α-hemolysin, hla, which resulted in increased hemolytic activity. The present study demonstrated that PFAS exposure not only increased C. elegans susceptibility to pathogens by reducing host immunity and increasing intestinal membrane permeability, but also increased bacteria virulence. This presents a broader implication for humans and other animals, where environmental contaminants simultaneously reduce host resilience, while, increasing microbial pathogenicity.

Effects of Calcium Ions on the Antimicrobial Activity of Gramicidin A

Gramicidin A (gA) is a linear antimicrobial peptide that can form a channel and specifically conduct monovalent cations such as H⁺ across the lipid membrane. The antimicrobial activity of gA is associated with the formation of hydroxyl free radicals and the imbalance of NADH metabolism, possibly a consequence caused by the conductance of cations. The ion conductivity of gramicidin A can be blocked by Ca²⁺ ions. However, the effect of Ca²⁺ ions on the antimicrobial activity of gA is unclear. To unveil the role of Ca²⁺ ions, we examined the effect of Ca²⁺ ions on the antimicrobial activity of gramicidin A against Staphylococcus aureus (S. aureus). Results showed that the antimicrobial mechanism of gA and antimicrobial activity by Ca²⁺ ions are concentration-dependent. At the low gA concentration (≤1 μM), the antimicrobial mechanism of gA is mainly associated with the hydroxyl free radical formation and NADH metabolic imbalance. Under this mode, Ca²⁺ ions can significantly inhibit the hydroxyl free radical formation and NADH metabolic imbalance. On the other hand, at high gA concentration (≥5 μM), gramicidin A acts more likely as a detergent. Gramicidin A not only causes an increase in hydroxyl free radical levels and NAD⁺/NADH ratios but also induces the destruction of the lipid membrane composition. At this condition, Ca²⁺ ions can no longer reduce the gA antimicrobial activity but rather enhance the bacterial killing ability of gramicidin A.

Design, synthesis, and antibacterial activity of derivatives of Tryptophanyl-tRNA synthetase inhibitor indolmycin

In this study, indlomycin, an inhibitor of tryptophanyl-tRNA synthetase (TrpRS), and 29 racemic indolmycin derivatives were synthesized, their antibacterial activity were evaluated against methicillin-resistant Staphylococcus aureus (S. aureus) NRS384, ATCC29213, and Escherichia coli (E. coli) ATCC25922 strains. Compounds (±)-7a, (±)-7b, (±)-7c and (±)-7e exhibited minimum inhibitory concentration (MIC) values of 1-2 μg/mL against S. aureus NRS384 and ATCC29213, exhibiting significant antibacterial activity, but none of the compounds exhibited antibacterial activity against E. coli. To investigate the effect of conformation on antibacterial activity, seven racemic compounds with good antibacterial activity were separated, and the antibacterial activity of these 14 compounds was evaluated on 25 bacterial strains. This revealed that the isomers with natural conformations (1'R, 5S) had significantly better antibacterial activity than the enantiomeric isomers and racemates. Compounds 7aa, 7ba, 7ca, and 7ea exhibited good antibacterial activity against 21 strains of S. aureus and S. epidermidis with MIC values of 0.125-2 μg/mL, which were superior to that of vancomycin, used in clinical practice. The compounds 7aa, 7ba, 7ca and 7ea were moderately bound to plasma proteins and were stable in the whole blood of CD-1 mice. In conclusion, a series of new indomycin derivatives with stronger antibacterial activity against G⁺ bacteria were obtained.

Total Syntheses and Antibacterial Evaluations of Neocyclomorusin and Related Flavones

Neocyclomorusin (1), a natural bioactive pyranoflavone mainly isolated from plants of the Moraceae family, was synthesized for the first time using a Friedel-Crafts reaction, a Baker-Venkataraman (BK-VK) rearrangement, a selective epoxidation, and a novel SN2-type cyclization as the key steps. The present protocol was also successfully applied for the total synthesis of oxyisocyclointegrin (2). Structurally related natural products morusin (23) and cudraflavone B (24) were also prepared. We investigated the antibacterial activities of these natural compounds against both Gram-negative and Gram-positive strains. The prenylated flavones, morusin (23) and cudraflavone B (24), showed comparable activity to ampicillin and kanacycin A against Staphylococcus aureus. Both morusin (23) and cudraflavone B (24) showed better antibacterial activities than ampicillin against the Gram-positive bacteria Staphylococcus epidermidis and Bacillus subtilis. Both neocyclomorusin (1) and oxyisocyclointegrin (2) displayed disappointing antimicrobial activities against Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, and Bacillus subtilis strains.

Phytochemical characterization and antimicrobial activity of Nigella sativa seeds

Nigella sativa is one of the medicinal plant species that gained popularity for a wide range of medicinal applications due to its seeds which are rich in phytoconstituents. Continuous scientific investigations on N. sativa seeds are needed to better understand its many medicinal potentials. This will also form a composition-based foundation that support several old and/or new case beneficial histories of its seeds. In this study, the antimicrobial activity of N. sativa seeds was phytochemically characterized and evaluated. Different extracts of N. sativa seeds were obtained by maceration and soxhlet extraction methods using different extraction solvents. The obtained extracts were tested using UV-Vis, FTIR, TLC, and GC-MS techniques. Antimicrobial analysis against pathogenic bacterial strains (E. coli, P. aeruginosa, S. aureus and B. subtilis) was carried out by disc diffusion method using different preparations of N. sativa seeds. The screening analysis revealed the presence of all the tested phytochemicals. FT-IR analysis of N. sativa seeds oil extracted with absolute ethanol revealed functional groups that are associated with active ingredients of medicinal value. The GC-MS chromatograms revealed different chemical constituents whose known bioactivities and/or applications are essential in the management of life-threatening infections. Different extracts of N. sativa seeds showed antimicrobial activity with different efficacy against the tested pathogenic bacterial strains. Therefore, this study shows that extracts of N. sativa seeds contain a variety of chemical components and functional groups linked to their antimicrobial properties, and they might be natural precursors of nutraceuticals.

Chemical characterization and bioactive potential of Thymus×citriodorus (Pers.) Schreb. preparations for anti-acne applications: Antimicrobial, anti-biofilm, anti-inflammatory and safety profiles

ETHNOPHARMACOLOGICAL RELEVANCE

Thymus × citriodorus (Pers.) Schreb. is an interspecific hybrid between Thymus pulegioides and Thymus vulgaris, known for its pharmacological activities as diaphoretic, deodorant, antiseptic and disinfectant, the last mostly related with its antimicrobial activity. The folk use of other extracts, as hydrolates, have also been disseminated, as regulators of oily skin with anti-acne effect.

AIM OF THE STUDY

We aimed to evaluate the anti-acne potential of two Thymus x citriodorus (TC) preparations, the essential oil (EO) and the hydrolate, to be used as active ingredients for skin applications. Specifically, we intend to validate their anti-acne potential by describing their activity on acne related bacteria, bacterial virulence, anti-oxidant and anti-inflammatory potential, and biocompatibility on inflammatory cells. Additionally, we aimed to report their ecotoxicity under the Globally Harmonized System of Classification and Labelling of Chemicals (GHS), thus focusing not only on the consumer, but also on environmental safety assessment.

MATERIALS AND METHODS

Minimum inhibitory concentration (MIC) against C. acnes, S. aureus and S. epidermidis was evaluated. Minimum lethal concentration (MLC) was also determined. The effect on C. acnes biofilm formation and disruption was evaluated with crystal violet staining. Anti-inflammatory activity was investigated on LPS-stimulated mouse macrophages (RAW 264.7), by studying nitric oxide (NO) production (Griess reagent) and cellular biocompatibility through MTT assay. In-vitro NO and 2,2-Diphenyl-1-picrylhydrazyl (DPPH) scavenging potential were also evaluated. The ecotoxicity was evaluated using Daphnia magna acute toxicity assays.

RESULTS

EO presented direct antimicrobial activity, with visual MICs ranging from 0.06% for S. epidermidis and C. acnes to 0.125% for S. aureus. MLCs were higher than the obtained MICs. Hydrolate revealed visual MIC only for C. acnes. TC essential oil was effective in preventing biofilm formation and disrupting preformed biofilms even at sub-inhibitory concentrations. Hydrolate showed a more modest anti-biofilm effect. Regarding anti-inflammatory activity, TC hydrolate has a higher cellular biocompatibility. Still, both plant preparations were able to inhibit at least 50% of NO production at non-cytotoxic concentrations. Both EO and hydrolate have poor anti-oxidant activities. Regarding the ecotoxicity, TC essential oil was classified under acute 3 category, while the hydrolate has proved to be nontoxic, in accordance to the GHS.

CONCLUSIONS

These results support the anti-acne value of different TC preparations for different applications. TC hydrolate by presenting higher biocompatibility, anti-inflammatory potential and the ability to modulate C. acnes virulence, can be advantageous in a product for everyday application. On the other hand, EO by presenting a marked antimicrobial, anti-biofilm and anti-inflammatory activities, still with some cytotoxicity, may be better suited for application in acute flare-ups, for short treatment periods.

Risk assessment of in vitro cytotoxicity, antioxidant and antimicrobial activities of Mentha piperita L. essential oil

The objective of this study was to determine the chemical composition as well as antioxidant, antibacterial, and cytotoxic properties of the essential oil of Mentha piperita L. (peppermint). Fifteen chemical constituents were identified in the essential oil, for a total of 99.99% of the compounds. The essential oil exhibited antimicrobial activity against two Gram-positive bacteria Staphylococcus aureus and Listeria monocytogenes. The minimum inhibitory concentration (MIC) of essential oil of Mentha piperita L. for Staphylococcus aureus and Listeria monocytogenes was 1.84 μg/ml, whereas the minimum bactericidal concentration (MBC) values were 3.7 and 7.43 μg/ml, respectively. The oil displayed potent antioxidant activity inhibiting up to approximately73% of 2,2'-azinothiobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radicals. In the cytotoxicity assay, the highest essential oil concentration (100 μg/ml) resulted in viability of approximately 90% human epidermal keratinocyte (HaCaT) cells. With respect to antitumor activity in C6 rat glioma cells, there was significant reduction in cell viability: 56-74% in 24 hr, and 71-77% in 48 hr. Data suggest that in presence of the essential oil of Mentha piperita L. antioxidant, antibacterial, antitumor and non-cytotoxic properties were noted.

A novel method of creating thermoplastic chitosan blends to produce cell scaffolds by FDM additive manufacturing

Due to its remarkable and promising biological and structural properties, chitosan has been widely studied in several potential applications in the biomedical sector. Attempts are being made to use this polymer and its properties in thermoplastics dedicated to 3D printing in FDM technology. However, chitosan can be processed only from acid solution, which limits its applications. The paper presents a new path for the production of filaments based on unstable chitosan hydrogel obtained by carbon dioxide saturation, as well as synthetic polymers such as polyvinyl alcohol and polycaprolactone. The results confirm that the absence of acid allows formation of thermally stable and printable filaments containing from 5% to 15% of chitosan, capable of reducing S. aureus and E. coli bacteria by 0.41-1.43 in logarithmic scale (56-94%) and 0.28-0.94 in logarithmic scale (36-89%), respectively.

Sustainable Antibacterial and Anti-Inflammatory Silk Suture with Surface Modification of Combined-Therapy Drugs for Surgical Site Infection

Silk sutures with antibacterial and anti-inflammatory functions were developed for sustained dual-drug delivery to prevent surgical site infections (SSIs). The silk sutures were prepared with core-shell structures braided from degummed silk filaments and then coated with a silk fibroin (SF) layer loaded with berberine (BB) and artemisinin (ART). Both the rapid release of drugs to prevent initial biofilm formation and the following sustained release to maintain effective concentrations for more than 42 days were demonstrated. In vitro assays using human fibroblasts (Hs 865.Sk) demonstrated cell proliferation on the materials, and hemolysis was 2.4 ± 0.8%, lower than that required by ISO 10993-4 standard. The sutures inhibited platelet adhesion and promoted collagen deposition and blood vessel formation. In vivo assessments using Sprague-Dawley (SD) rats indicated that the coating reduced the expression of pro-inflammatory cytokines interleukin-10 (IL-10) and tumor necrosis factor-α (TNF-α), shortening the inflammatory period and promoting angiogenesis. The results demonstrated that these new sutures exhibited stable structures, favorable biocompatibility, and sustainable antibacterial and anti-inflammatory functions with potential for surgical applications.

Dendritic Hydrogels with Robust Inherent Antibacterial Properties for Promoting Bacteria-Infected Wound Healing

Bacterial infections are a common problem associated with wound treatment that imposes a significant burden on healthcare systems and patients. As a result, healthcare providers urgently need new treatment strategies to protect people. Hydrogel biomaterials with inherent antimicrobial properties offer an attractive and viable solution to this issue. Here, for the first time, we have developed a new efficient synthetic strategy to prepare cationic hydrogels (PHCI) with intrinsically efficient antimicrobial properties by chemically cross-linking trans-1,4-cyclohexanediamine with 1,3-dibromo-2-propanol using a condensation reaction without the use of toxic cross-linking agents. As expected, the prepared PHCI hydrogel possessed an inherent antibacterial ability that can adsorb and kill Staphylococcus aureus and Escherichia coli electrostatically. Notably, in vivo experiments on normal and diabetic rat models confirmed that the PHCI hydrogel can quickly stop bleeding, efficiently kill bacteria, promote the conversion of macrophages from the proinflammatory M1 phenotype to the repaired M2 phenotype, and accelerate collagen deposition and blood vessel formation, thereby achieving rapid wound healing. Overall, this work presents an effective antibacterial dressing that might provide a facile but effective approach for clinical wound management.

Interspecies transfer of plasmid-borne gentamicin resistance between Staphylococcus isolated from domestic dogs to Staphylococcus aureus

As preconized by the One Health concept, the intimate relationship between pets and owners is a common source for the trade of microorganisms with zoonotic potential, and with them, antimicrobial resistance genes. In this work, we evaluated the presence of antimicrobial resistance genes, that are usually within mobile genetic elements, in a laboratory collection of 79 canine Staphylococcus strains, mostly Staphylococcus pseudintermedius and Staphylococcus coagulans. Resistance to tetracycline was observed in 34% of the strains, followed by resistance to erythromycin (21%) and gentamicin (19%). These phenotypes were partially correlated with the presence of the tetracycline resistance genes tet(M) and tet(K) in 64% and 44% of all strains, respectively; erythromycin resistance genes erm(A) and erm(C) in 53% and 23%; and gentamicin resistance gene aac(6')-aph(2″) in 26% of the strains. At least 45% of the strains harbored high- and/or low-molecular weight plasmids, whose transfer may be facilitated by their widespread biofilm-forming capacity, and absence of restrictive CRISPR systems. We selected eight plasmid-bearing and multidrug resistant strains, which were submitted to plasmid curing by stress with SDS. No strain lost resistance during stressing cultivation but, by conjugation experiments, the S. pseudintermedius strain 27 transferred its plasmid-borne resistance to gentamicin, conferred by the aac(6')-aph(2″) gene, to Staphylococcus aureus. The frequent empirical use of gentamicin to treat skin and ear infections in domestic dogs is likely to select resistant strains. Also, as demonstrated by our study, these strains can serve as gene reservoirs for human pathogens, such as S. aureus.

Chemical Composition and In Vitro Antioxidant and Antimicrobial Activities of the Marine Cyanolichen Lichina pygmaea Volatile Compounds

Volatile compounds from the marine cyanolichen Lichina pygmaea, collected from the Moroccan Atlantic coast, were extracted by hydrodistillation and their putative chemical composition was investigated by gas chromatography coupled to mass spectrometry (GC/MS). Based on the obtained results, Lichina pygmaea volatile compounds (LPVCs) were mainly dominated by sesquiterpenes compounds, where γ-himachalene, β-himachalene, (2E,4E)-2,4 decadienal and α-himachalene were assumed to be the most abundant constituents, with percentage of 37.51%, 11.71%, 8.59% and 7.62%, respectively. LPVCs depicted significant antimicrobial activity against all tested strains (Staphylococcus aureus CCMM B3, Pseudomonas aeruginosa DSM 50090, Escherichia coli ATCC 8739 and Candida albicans CCMM-L4) with minimum inhibitory concentration (MIC) values within the range of 1.69–13.5 mg/mL. Moreover, this LPVC showed interesting scavenging effects on the 2,2-diphenyl-1-picrylhydrazyl radical with an IC₅₀ of 0.21 mg/mL. LPVCs could be an approving resource with moderate antimicrobial potential and interesting antioxidant activity for cosmetics and pharmaceutical applications.

Recombinant HNP-1 Produced by Escherichia coli Triggers Bacterial Apoptosis and Exhibits Antibacterial Activity against Drug-Resistant Bacteria

Human neutrophil peptide-1 (HNP-1) is a promising antibiotic candidate, but its clinical applications have been hampered by challenges during mass production and an inadequate understanding of its bactericidal mechanisms. In this study, we demonstrated that Escherichia coli expressing full-length preproHNP-1 secretes a soluble form of HNP-1, which can be recovered from the total cell lysate after isopropyl thio-β-d-galactoside (IPTG) induction and ultrafiltration. Label-free quantitative proteomics and co-immunoprecipitation experiments revealed that HNP-1 induces cell apoptosis in bacteria by causing DNA and membrane damage. Notably, we found that HNP-1 disrupts the DNA damage response pathway by interfering with the binding of RecA to single-stranded DNA (ssDNA). Further experiments demonstrated that HNP-1 encapsulated in liposomes inhibits the growth of methicillin-resistant Staphylococcus aureus (MRSA) and meropenem-resistant Pseudomonas aeruginosa (MRPA). These results indicated that recombinant protein expression may be a simple and cost-effective solution to produce HNP-1 and that RecA inhibition via HNP-1 may serve as an alternative strategy to counteract antibiotic resistance. IMPORTANCE Human neutrophil peptide-1 (HNP-1) is a promising antibiotic candidate, but its clinical application has been hampered by the difficulty of mass production and an inadequate understanding of its bactericidal mechanisms. In this study, we demonstrated that recombinant protein expression combined with ultrafiltration may be a simple and cost-effective solution to HNP-1 production. We further found that HNP-1 induces bacterial apoptosis and prevents its SOS repair pathway from binding to the RecA protein, which may be a new antibacterial mechanism. In addition, we showed that HNP-1 encapsulated in liposomes inhibits the growth of methicillin-resistant Staphylococcus aureus (MRSA) and meropenem-resistant Pseudomonas aeruginosa (MRPA). These results provide new insights into the production and antibacterial mechanism of HNP-1, both of which may promote its clinical application.

Immunomodulatory effects of berberine on Staphylococcus aureus-induced septic arthritis through down-regulation of Th17 and Treg signaling pathways

OBJECTIVES

The preseaant study was aimed to investigate the immunomodulatory effects of berberine on Staphylococcus aureus-induced septic arthritis through the downstream signaling mechanism of Th17 and Treg, in the control and prevention of disease progression of Staphylococcus aureus induced septic arthritis of blood, spleen and synovial joints.

METHODS

The study was conducted in mice induced with septic arthritis by S. aureus for 15 days. The infected mice were treated with berberine (50 or 100 or 200 mg/Kg) to evaluate the effects on the isolated cells of Th17 and Treg from synovial joints, blood and spleen against the septic arthritic induced mice followed by JNK, RANKL and NF-κB expressions in the lysates of Th17 and Tregs isolated cells. The evaluation of serum IL-21 and TGF-β levels was also conducted after 15 days post-infection in Th17 and Treg population.

RESULTS

Our findings showed that berberine exerted excellent inhibitory effects on the S. aureus (AS-789) strain for inducing sepsis-induced arthritis. The results from the S. aureus testing revealed that at concentrations below 640 μg/mL, the strain was more resistant to berberine, as it had an increased rate of growth. The assessment of S. aureus induced septic arthritis (joint swelling and arthritis index) substantial reduction in the joint swelling and arthritis index (p<0.01) in the berberine-treated groups. The percentage of Th17 cells with CD4 and RORγt; Treg cells with CD4, CD25 and FOXp3 in the synovial joints, blood and spleen was substantially declined in the drug-treated groups (p<0.01) as compared to the S. aureus infected mice. The TGF-β and IL-21 serum levels determinations in S. aureus induced septic arthritis revealed a substantial decrease in serum TGF-β levels (p<0.01) in drug-treated groups compared to the infected animals. The post hoc test revealed a substantial decrease in JNK, NF-κB and RANKL expressions in the lysates of Th17 and Treg isolated cells in the drug-treated animals (p<0.01) when compared to the S. aureus-infected cluster.

CONCLUSION

Our findings demonstrated that a possible strategy for combating disease severity with berberine treatment in Staphylococcus aureus induced septic arthritis in mice, which targets the Th17 and Treg cells have driven the NF-κB/JNK-RANKL axis.

Antiplatelet therapy for Staphylococcus aureus bacteremia: Will it stick?

Staphylococcus aureus bacteremia (SAB) remains a clinically challenging infection despite extensive investigation. Repurposing medications approved for other indications is appealing as clinical safety profiles have already been established. Ticagrelor, a reversible adenosine diphosphate receptor antagonist that prevents platelet aggregation, is indicated for patients suffering from acute coronary syndrome (ACS). However, some clinical data suggest that patients treated with ticagrelor are less likely to have poor outcomes due to S. aureus infection. There are several potential mechanisms by which ticagrelor may affect S. aureus virulence. These include direct antibacterial activity, up-regulation of the innate immune system through boosting platelet-mediated S. aureus killing, and prevention of S. aureus adhesion to host tissues. In this Pearl, we review the clinical data surrounding ticagrelor and infection as well as explore the evidence surrounding these proposed mechanisms of action. While more evidence is needed before antiplatelet medications formally become part of the arsenal against S. aureus infection, these potential mechanisms represent exciting pathways to target in the host/pathogen interface.

Nanobased Antibacterial Drug Discovery to Treat Skin Infections of Staphylococcus aureus Using Moringa oleifera-Assisted Zinc Oxide Nanoparticle and Molecular Simulation Study

In addition to the physical barrier, the epidermis acts as a natural barrier against microbial proliferation. It is prone to bacterial infections on the skin and in the nose, such as Staphylococcus aureus, as well as a variety of other skin illnesses. Green nanomaterial production, which eliminates the use of harmful chemicals while simultaneously reducing time, is gaining popularity in the nanotechnology area. Using the leaf extract of the pharmacologically valuable plant Moringa oleifera, we described a green synthesis of ZnO NPs (zinc oxide nanoparticles). ZnO NPs had a particle size of 201.6 nm and a zeta potential of -56.80 mV, respectively. A novel aminoketone antibacterial medication was synthesized and tested for antibacterial activity using ZnO NPs as a phytocatalyst in this work. This method produces high yields while maintaining efficient and gentle reaction conditions. Moringa oleifera extract can reduce ZnO to ZnO NPs in a straightforward manner. FT-IR, 1H-NMR, 13C-NMR, mass spectra, elemental analysis, and morphological analysis were used to synthesize and describe the antibacterial medicines (1a-1g) and (2a-2g). In addition, antibacterial activity was evaluated against bacteria such as Enterococcus faecalis and Staphylococcus aureus, and compound 1c (63 μg/mL, E. faecalis) and compound 2e (0.12 μg/mL, S. aureus) were found to be very active when compared to other medications. mupirocin is used as a reference. In addition, studies of in silico molecular docking for the bacterial DsbA protein were conducted. The strong molecules 1c (-4.3 kcal/mol) and 2e (-5.1 kcal/mol) exhibit a high binding affinity through hydrogen bonding, according to docking tests.

Biomineralized Cascade Enzyme-Encapsulated ZIF-8 Nanoparticles Combined with Antisense Oligonucleotides for Drug-Resistant Bacteria Treatment

The unrestrained use of antibiotics accelerates the development of drug-resistant bacteria and leads to an increasing threat to human health. Therefore, there is an urgent need to explore novel and effective strategies for the treatment of bacterial infections. Herein, zeolite imidazole framework-8 (ZIF-8) material was utilized to construct biomineralized nanomaterial (GOx&HRP@ZIF-8/ASO) by encapsulating biological cascade enzymes and combining with antisense oligonucleotides (ASOs), which achieved effective and synergistic antidrug-resistant bacteria therapy. Various in vitro assays confirmed that GOx&HRP@ZIF-8/ASO exhibited excellent antibacterial properties against Escherichia coli, Staphylococcus aureus, methicillin-resistant S. aureus (MRSA) during catalysis of glucose (Glu), especially the minimum inhibitory concentration (MIC) against MRSA was only 16 μg/mL. Compared with simple ZIF-8 (32.85%) and ftsZ ASO (58.65%), GOx&HRP@ZIF-8/ASO+Glu exhibited superb biofilm destruction ability, and the bacteria removal efficiency of the MRSA biofilm could be as high as 88.2%, indicating that the reactive oxygen species (ROS) produced by the cascade enzyme reaction imparted the main synergistic antibacterial capability, and simultaneously, ftsZ ASO significantly enhanced the antibacterial effect by inhibiting the expression of the ftsZ gene. In vivo anti-infection treatment experiments revealed that GOx&HRP@ZIF-8/ASO exhibited the best wound repairing performance and excellent biocompatibility in the presence of Glu. These findings suggested that GOx&HRP@ZIF-8/ASO has favorably realized high-efficiency treatment of MRSA infection and filled the gap in the antibacterial application of biological enzymes.

Magnetic Responsive Release of Nitric Oxide from an MOF-Derived Fe3O4@PLGA Microsphere for the Treatment of Bacteria-Infected Cutaneous Wound

Nitric oxide (NO) is an essential endogenous signaling molecule regulating multifaceted physiological functions in the (cardio)vascular, neuronal, and immune systems. Due to the short half-life and location-/concentration-dependent physiological function of NO, translational application of NO as a novel therapeutic approach, however, awaits a strategy for spatiotemporal control on the delivery of NO. Inspired by the magnetic hyperthermia and magneto-triggered drug release featured by Fe₃O₄ conjugates, in this study, we aim to develop a magnetic responsive NO-release material (MagNORM) featuring dual NO-release phases, namely, burst and steady release, for the selective activation of NO-related physiology and treatment of bacteria-infected cutaneous wound. After conjugation of NO-delivery [Fe(μ-S-thioglycerol)(NO)₂]₂ with a metal-organic framework (MOF)-derived porous Fe₃O₄@C, encapsulation of obtained conjugates within the thermo-responsive poly(lactic-co-glycolic acid) (PLGA) microsphere completes the assembly of MagNORM. Through continuous/pulsatile/no application of the alternating magnetic field (AMF) to MagNORM, moreover, burst/intermittent/slow release of NO from MagNORM demonstrates the AMF as an ON/OFF switch for temporal control on the delivery of NO. Under continuous application of the AMF, in particular, burst release of NO from MagNORM triggers an effective anti-bacterial activity against both Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli). In addition to the magneto-triggered bactericidal effect of MagNORM against E. coli-infected cutaneous wound in mice, of importance, steady release of NO from MagNORM without the AMF promotes the subsequent collagen formation and wound healing in mice.

Identification of Antibacterial Metabolites from Endophytic Fungus Aspergillus fumigatus, Isolated from Albizia lucidior Leaves (Fabaceae), Utilizing Metabolomic and Molecular Docking Techniques

The rapid spread of bacterial infection caused by Staphylococcus aureus has become a problem to public health despite the presence of past trials devoted to controlling the infection. Thus, the current study aimed to explore the chemical composition of the extract of endophytic fungus Aspergillus fumigatus, isolated from Albizia lucidior leaves, and investigate the antimicrobial activity of isolated metabolites and their probable mode of actions. The chemical investigation of the fungal extract via UPLC/MS/MS led to the identification of at least forty-two metabolites, as well as the isolation and complete characterization of eight reported metabolites. The antibacterial activities of isolated metabolites were assessed against S. aureus using agar disc diffusion and microplate dilution methods. Compounds ergosterol, helvolic acid and monomethyl sulochrin-4-sulphate showed minimal inhibitory concentration (MIC) values of 15.63, 1.95 and 3.90 µg/mL, respectively, compared to ciprofloxacin. We also report the inhibitory activity of the fungal extract on DNA gyrase and topoisomerase IV, which led us to perform molecular docking using the three most active compounds isolated from the extract against both enzymes. These active compounds had the required structural features for S. aureus DNA gyrase and topoisomerase IV inhibition, evidenced via molecular docking.

Photonic Hydrogels for Synergistic Visual Bacterial Detection and On-Site Photothermal Disinfection

Rapid and sensitive diagnostics in the early stage of bacterial infection and immediate treatment play critical roles in the control of infectious diseases. However, it remains challenging to develop integrated systems with both rapid detection of bacterial infection and timely on-demand disinfection ability. Herein, we demonstrate a photonic hydrogel platform integrating visual diagnosis and on-site photothermal disinfection by incorporating Fe₃O₄@C nanoparticles into a poly(hydroxyethyl methacrylate)-co-polyacrylamide (PHEMA-co-PAAm) matrix. In vitro experiments demonstrate that such a hydrogel can respond to pH variation caused by bacterial metabolism and generate the corresponding color changes to realize naked-eye observation. Meanwhile, its excellent photothermal conversion ability enables it to effectively kill bacteria by destroying cell membranes under near-infrared irradiation. Moreover, the pigskin infection wound model also verifies the bacterial detection performance and disinfection ability of the hydrogel in vivo. Our strategy demonstrates a new approach for visual diagnosis and treatment of bacterial infections.

Inhibition of the sea Gene Expression in Staphylococcus aureus Using the Aqueous and Alcoholic Extracts of the Grapevine (Vitis vinifera L.) Seeds

Staphylococcus aureus is an important etiological agent for causing food poisoning leading to high mortality in the world. The sea gene is encoded in a polymorphic family of temperate bacteriophage chromosomes and became a prophage, and the transcription of this gene is associated with the life cycle of this prophage. It has been suggested that the grape polyphenols can eradicate the enterotoxin production of food-borne bacteria. This study aimed to evaluate the activity of the aqueous and alcoholic extracts of the grape seeds in inhibiting the expression of the sea gene encoding staphylococcal enterotoxin type A in S. aureus isolated from different sources. This study used five enterotoxin A producing isolates belonging to S. aureus. The results showed that minimum inhibition concentration and sub-minimum inhibition concentration of the aqueous extract were 32 and 16 µg/mL for all isolates, respectively. However, in the case of the alcoholic extract, these concentrations were 16 and 8 µg/mL for all isolates, respectively, and the results of the chemical analysis of the aqueous and alcoholic extracts confirmed that they contain active chemical compounds, such as flavonoids, alkaloids, tannins, and glycosides; moreover, they contain many functional groups according to the analysis of the infrared spectrum. Both extracts were shown to be active in inhibiting the expression of the sea gene in the isolates under study. As the results indicated, the gene expression of these isolates was inhibited by approximately 0.31-0.63 fold, and all pathogenic and environmental isolates showed a decrease in the expression of this gene. These results practically open the door to the possibility of using these extracts to inhibit the ability of S. aureus to produce these dangerous enterotoxins; thereby decreasing or preventing their pathogenicity, especially their food poisoning infections.

Antibacterial effect of bacteriocin XJS01 and its application as antibiofilm agents to treat multidrug-resistant Staphylococcus aureus infection

Multidrug-resistant (MDR) Staphylococcus aureus biofilms have emerged as a serious threat to human health. Recently, the development of antibiotic replacement therapy has gained much attention due to the potential application of bacteriocin. The present study sought to evaluate the antibacterial effect of bacteriocin XJS01 against MDR S. aureus, a previously reported bacteriocin against S. aureus strain 2612:1606BL1486 (S. aureus_26, an MDR strain demonstrated here), and its potential application as an antibiofilm agent. The minimum bactericide concentration of XJS01 against MDR S. aureus_26 was 33.18 μg/mL. XJS01 exhibited excellent storage stability and resistance against acid and reduced the density of established MDR S. aureus_26 biofilm. The hemolytic and HEK293T cytotoxicity activities of XJS01 and the histological analyses in mice confirmed its safety. Moreover, XJS01 effectively disrupted the MDR S. aureus_26 biofilm established on the skin wound surface and reduced the biofilm-isolated bacteria, thereby decreasing the release of pro-inflammatory cytokines and the proliferation of alternatively activated macrophages. Compared to mupirocin, XJS01 exhibited an excellent therapeutic effect on mice skin wounds, confirming it to be a potential alternative to antibiotics.

Gwanakosides A and B, 6-Deoxy-α-l-talopyranose-Bearing Aromatic Metabolites from a Streptomyces sp. and Coculture with Pandoraea sp

Single-strain cultivation of a mountain soil-derived Streptomyces sp. GA02 and its coculture with Pandoraea sp. GA02N produced two aromatic products, gwanakosides A and B (1 and 2, respectively). Their spectroscopic analysis revealed that 1 is a new dichlorinated naphthalene glycoside and 2 is a pentacyclic aromatic glycoside. The assignment of the two chlorine atoms in 1 was confirmed by the analysis of its band-selective CLIP-HSQMBC spectrum. The sugars in the gwanakosides were identified as 6-deoxy-α-l-talopyranose based on 1H-1H coupling constants, Rotating frame Overhauser enhancement spectroscopy (ROESY) NMR correlations, and chemical derivatization followed by spectroscopic and chromatographic analyses. The absolute configuration of 2, whose production was enhanced approximately 100-fold in coculture, was proposed based on a quantum mechanics-based chemical shift analysis method, DP4 calculations, and the chemically determined configuration of 6-deoxy-α-l-talopyranose. Gwanakoside A displayed inhibitory activity against pathogenic bacteria, including Staphylococcus aureus (MIC = 8 μg/mL) and Mycobacterium tuberculosis (MIC50 = 15 μg/mL), and antiproliferative activity against several human cancer cell lines (IC50 = 5.6-19.4 μM).