Chemical components with antibacterial properties found in sanchen powder from traditional Tibetan medicine

ETHNOPHARMACOLOGICAL RELEVANCE

Sanchen powder is a traditional Tibetan medicine comprising Bambusae Concretio Silicea, Carthami Flos, and Bovis Calculus Artifactus. Bambusae Concretio Silicea is the dried mass of secreted fluid in the stalks of Gramineae plants such as Bambusa textilis McClure or Schizostachyum chinense Rendle. Carthami Flos is the dried flower of Carthamus tinctorius L. in the Compositae plant. Bovis Calculus Artifactus is made from ox bile powder, cholic acid, hyodeoxycholic acid, taurine, bilirubin, cholesterol, and trace elements. Research has evidenced the antibacterial efficacy of Sanchen powder, albeit its active constituents for this effect are yet to be established.

AIM OF THE STUDY

To investigate effective compounds, potential targets, and molecular mechanism of Sanchen powder for its antibacterial properties by using network pharmacology combined with in vitro validation, with the aims of observing the action of effective compounds in Sanchen powder and exploring new therapeutic strategies for antibacterial.

MATERIALS AND METHODS

In this study, UPLC-Q-TOF-MS was utilized to identify the chemical composition in Sanchen powder and its blood-borne chemical ingredients post-oral intake. A network pharmacology analysis was used to establish the chemical compound in the blood following oral administration-target-disease network. The study aimed to identify antibacterial active ingredients, which were then subjected to molecular docking and pharmacodynamic experiments to verify their efficacy.

RESULTS

The findings demonstrate that following oral administration, the blood contains seven key components of Sanchen powder, including bilirubin, glycochenodeoxycholic acid, glycocholic acid, taurocholic acid, phenylalanine, safflomin A, and tryptophan. Additionally, the network pharmacology and molecular docking study results indicate the potential antibacterial effects of bilirubin, glycocholic acid, and glycochenodeoxycholic acid. In vitro antibacterial experiments revealed that bilirubin, glycocholic acid, and glycochenodeoxycholic acid could restrict the growth of the Staphylococcus aureus cell membrane at a certain concentration. Moreover, they exhibited antibacterial effects on Staphylococcus aureus, Pseudomonas aeruginosa, Staphylococcus epidermidis, and Escherichia coli.

CONCLUSIONS

Bilirubin, glycocholic acid, and glycochenodeoxycholic acid could be effective therapeutic ingredients for the antibacterial effects of Sanchen powder. These results offer a foundation for further clinical application and research on the antibacterial effect of Sanchen powder, a Traditional Tibetan Medicine.

Characterization and in vitro antibacterial activity of grass carp (Ctenopharyngodon idella) serum amyloid A

Serum amyloid A (SAA) predominantly synthesized by hepatocytes is a classical acute phase protein and has been extensively studied in mammals. However, the studies on the structure and properties of fish SAA are limited although SAA genes have been cloned and identified from various fishes. In the present study, a cDNA of grass carp (Ctenopharyngodon idella) SAA (gcSAA) was cloned and characterized, displaying a high homology with its counterparts in vertebrates. gcSAA mRNA was expressed with highest abundance in the liver and its levels were increased by a 24-hour infection of Aeromonas hydrophila (A. hydrophila) for more than 5 folds in the intestine, 15 folds in the spleen, 75 folds in the head kidney and 100 folds in the liver, implying that it is an acute phase protein in grass carp. Subsequently, recombinant gcSAA protein (rgcSAA) was prepared from a prokaryotic expression system after codon optimization of its coding sequence. The direct antibacterial activity assay and the plate count assay disclosed that gcSAA inhibited the growth and survival of A. hydrophila but not Edwardsiella piscicida (E. piscicida) which both are common bacterial pathogens in aquaculture. The propidium iodide (PI) uptake assay confirmed the bactericidal property of gcSAA, showing that it is able to enhance the uptake of PI in A. hydrophila but not E. piscicida. These findings revealed the molecular features of gcSAA and its roles in host defense against bacterial infection.

S-scheme MOF-on-MOF heterojunctions for enhanced photo-Fenton Cr(VI) reduction and antibacterial effects

The photocatalytic efficiency is commonly restrained by inferior charge separation rate. Herein, the S-scheme MIL-100(Fe)/NH2-MIL-125(Ti) (MN) photo-Fenton catalyst with the built-in electric field (BEF) was successfully constructed by a simple ball-milling technique. As a result, the MN-3 (the mass ratio of MIL-100(Fe) to NH2-MIL-125(Ti) was 3) composite presented the best visible-light-induced photocatalytic ability, in contrast to pure MIL-100(Fe) and NH2-MIL-125(Ti). The reduction efficiency of Cr(VI) almost reached 100% within 35 min of illumination. Moreover, the MN-3 heterojunction also exhibited the highest antibacterial activity, and about 100% E. coli and more than 90% S. aureus were killed within 60 min of illumination. In photo-Fenton system, In the photo-Fenton system, e-, O2•- and Fe2+ played vital roles for Cr(VI) reduction, and •OH, h+ and O2•- and 1O2 were responsible for sterilization. Additionally, 5 cyclic tests and relevant characterizations confirmed the excellent repeatability and stability of the composite. Also, the S-scheme charge transfer process was put forward. This work offers a novel idea for establishing the MOF-on-MOF photo-Fenton catalyst for high-efficiency environmental mitigation.

Oligomeric phloroglucinols with hAChE inhibitory and antibacterial activities from tropic Rhodomyrtus tomentosa

Alzheimer's diseases (AD) and other infectious diseases caused by drug-resistance bacteria have posed a serious threat to human lives and global health. With the aim to search for human acetylcholinesterase (hAChE) inhibitors and antibacterial agents from medicinal plants, 16 phloroglucinol oligomers, including two new phloroglucinol monomers (1a and 1b), four new phloroglucinol dimers (3a, 3b, 4b, and 5a), six new phloroglucinol trimers (6a, 6b, 7a, 7b, 8a, and 8b), and two naturally occurring phloroglucinol monomers (2a and 2b), along with two known congeners (4a and 5b), were purified from the leaves of tropic Rhodomyrtus tomentosa. The structures and absolute configurations of these new isolates were unequivocally established by comprehensive analyses of their spectroscopic data (NMR and HRESIMS), ECD calculation, and single crystal X-ray diffraction. Structurally, 3a/3b shared a rare C-5' formyl group, whereas 6a/6b possessed a unique C-7' aromatic ring. In addition, 7a/7b and 8a/8b were rare phloroglucinol trimers with a bis-furan and a C-6' hemiketal group. Pharmacologically, the mixture of 3a and 3b showed the most potent human acetylcholinesterase (hAChE) inhibitory activity with an IC50 value of 1.21 ± 0.16 μM. The molecular docking studies of 3a and 3b in the hAChE binding sites were performed, displaying good agreement with the in vitro inhibitory effects. In addition, the mixture of 3a and 3b displayed the most significant anti-MRSA (methicillin-resistant Staphylococcus aureus) with MIC and MBC values of both 0.50 μg/mL, and scanning electron microscope (SEM) studies revealed that they could destroy the biofilm structures of MRSA. The findings provide potential candidates for the further development of anti-AD and anti-bacterial agents.

Effects of various light-emitting diode wavelengths on periodontopathic bacteria and gingival fibroblasts: An in vitro study

BACKGROUND

In recent years, light has been used for bacterial control of periodontal diseases. This in vitro study evaluated the effects of light-emitting diode (LED) irradiation at different wavelengths on both Porphyromonas gingivalis and human gingival fibroblasts (HGF-1).

METHODS

P. gingivalis suspension was irradiated with LEDs of 365, 405, 450, 470, 565, and 625 nm at 50, 100, 150, and 200 mW/cm2 for 3 min (radiant exposure: 9, 18, 27, 36 J/cm2, respectively). Treated samples were anaerobically cultured on agar plates, and the number of colony-forming units (CFUs) was determined. Reactive oxygen species (ROS) levels were measured after LED irradiation. The viability and damage of HGF-1 were measured through WST-8 and lactate dehydrogenase assays, respectively. Gene expression in P. gingivalis was evaluated through quantitative polymerase chain reaction.

RESULTS

The greatest reduction in P. gingivalis CFUs was observed on irradiation at 365 nm with 150 mW/cm2 for 3 min (27 J/cm2), followed by 450 and 470 nm under the same conditions. While 365-nm irradiation significantly decreased the viability of HGF-1 cells, the cytotoxic effects of 450- and 470-nm irradiation were comparatively low and not significant. Further, 450-nm irradiation indicated increased ROS production and downregulated the genes related to gingipain and fimbriae. The 565- and 625-nm wavelength groups exhibited no antibacterial effects; rather, they significantly activated HGF-1 proliferation.

CONCLUSIONS

The 450- and 470-nm blue LEDs showed high antibacterial activity with low cytotoxicity to host cells, suggesting promising bacterial control in periodontal therapy. Additionally, blue LEDs may attenuate the pathogenesis of P. gingivalis.

Evaluation of the biocontrol potential of a collagen peptide/trehalose-based Cronobacter sakazakii phage powder in rehydrated powdered infant formula

Cronobacter sakazakii is a major foodborne pathogen that is mainly transmitted through powdered infant formula (PIF) and has a high mortality rate of up to 80%, particularly in fetuses and neonates. Bacteriophages have emerged as an effective biocontrol agent for antibiotic-resistant bacteria. In this study, lytic phage SG01 was newly characterized and loaded into collagen peptide/trehalose-based powders to develop an antibacterial agent against C. sakazakii contamination in PIF. The phage belongs to the Siphoviridae family, has an icosahedral head and a flexible tail, and showed rapid and persistent antibacterial activity up to 17 h. It was specifically active against C. sakazakii and also exhibited effective anti-biofilm properties. The phage was freeze-dried to a collagen peptide/trehalose-based powder and the phage was tested for viability, storage stability, and antibacterial activity. The optimal composition was 5% (w/v) collagen peptides and 1% (w/v) trehalose, which demonstrated the highest phage viability after freeze-drying. The phage remained stable in the collagen peptide/trehalose-based powder for up to four weeks at 4 °C and 25 °C, indicating that this is a desirable formulation for phage protection. Furthermore, the phage powder showed significant antibacterial efficacy in PIF, with a 4-log CFU/mL reduction within 6 h. Overall, the tested phage powder has the potential to be used as an antimicrobial agent in the food industry, particularly in powdered foods such as PIF.

Biocontrol of Salmonella Typhimurium in milk, lettuce, raw pork meat and ready-to-eat steamed-chicken breast by using a novel bacteriophage with broad host range

Salmonella spp., one of the most frequently reported bacteria, causes foodborne illness and economic losses. Due to the threat of increasing antibiotic resistant foodborne pathogens, application of bacteriophages as novel antibacterial agents in food matrices has become an emerging strategy. In this study, a novel Salmonella phage PS3-1 with high lytic activity against Salmonella Typhimurium was identified from previously isolated phages. PS3-1 belonged to the class Caudoviricetes with a broad host range, and had relatively short latent period (15 min), large burst size (92 PFU/cell), high pH stability (pH 3.0-11.0) and thermal tolerance (4-60 °C). Genome sequencing analysis showed that PS3-1 genome consisted of 107,110 bp DNA, without antibiotic resistance and virulence related genes. The results of growth curve and time-kill assay showed that PS3-1 not only inhibited the growth of S. Typhimurium, but also effectively decreased the viable cell counts (0.30-4.72 log) after 24-h incubation at 7, 25 and 37 °C (P < 0.05). Moreover, >1.28 log of established biofilm cells were effectively removed after 24-h treatment with PS3-1. Besides, PS3-1 significantly reduced the viability of S. Typhimurium in milk, lettuce, raw pork meat and ready-to-eat steamed-chicken breast at different temperatures (P < 0.05). These results demonstrated that PS3-1 may be an excellent antibacterial agent for controlling S. Typhimurium in food industry.

Sodium alginate/polycaprolactone co-axial wet-spun microfibers modified with N-carboxymethyl chitosan and the peptide AAPV for Staphylococcus aureus and human neutrophil elastase inhibition in potential chronic wound scenarios

In chronic wound (CW) scenarios, Staphylococcus aureus-induced infections are very prevalent. This leads to abnormal inflammatory processes, in which proteolytic enzymes, such as human neutrophil elastase (HNE), become highly expressed. Alanine-Alanine-Proline-Valine (AAPV) is an antimicrobial tetrapeptide capable of suppressing the HNE activity, restoring its expression to standard rates. Here, we proposed the incorporation of the peptide AAPV within an innovative co-axial drug delivery system, in which the peptide liberation was controlled by N-carboxymethyl chitosan (NCMC) solubilization, a pH-sensitive antimicrobial polymer effective against Staphylococcus aureus. The microfibers' core was composed of polycaprolactone (PCL), a mechanically resilient polymer, and AAPV, while the shell was made of the highly hydrated and absorbent sodium alginate (SA) and NCMC, responsive to neutral-basic pH (characteristic of CW). NCMC was loaded at twice its minimum bactericidal concentration (6.144 mg/mL) against S. aureus, while AAPV was loaded at its maximum inhibitory concentration against HNE (50 μg/mL), and the production of fibers with a core-shell structure, in which all components could be detected (directly or indirectly), was confirmed. Core-shell fibers were characterized as flexible and mechanically resilient, and structurally stable after 28-days of immersion in physiological-like environments. Time-kill kinetics evaluations revealed the effective action of NCMC against S. aureus, while elastase inhibitory activity examinations proved the ability of AAPV to reduce HNE levels. Cell biology testing confirmed the safety of the engineered fiber system for human tissue contact, with fibroblast-like cells and human keratinocytes maintaining their morphology while in contact with the produced fibers. Data confirmed the engineered drug delivery platform as potentially effective for applications in CW care.

Rapid synthesis of bismuth-organic frameworks as selective antimicrobial materials against microbial biofilms

Antibiotic resistance is a global public health threat, and urgent actions should be undertaken for developing alternative antimicrobial strategies and approaches. Notably, bismuth drugs exhibit potent antimicrobial effects on various pathogens and promising efficacy in tackling SARS-CoV-2 and related infections. As such, bismuth-based materials could precisely combat pathogenic bacteria and effectively treat the resultant infections and inflammatory diseases through a controlled release of Bi ions for targeted drug delivery. Currently, it is a great challenge to rapidly and massively manufacture bismuth-based particles, and yet there are no reports on effectively constructing such porous antimicrobial-loaded particles. Herein, we have developed two rapid approaches (i.e., ultrasound-assisted and agitation-free methods) to synthesizing bismuth-based materials with ellipsoid- (Ellipsoids) and rod-like (Rods) morphologies respectively, and fully characterized physicochemical properties. Rods with a porous structure were confirmed as bismuth metal-organic frameworks (Bi-MOF) and aligned with the crystalline structure of CAU-17. Importantly, the formation of Rods was a 'two-step' crystallization process of growing almond-flake-like units followed by stacking into the rod-like structure. The size of Bi-MOF was precisely controlled from micro-to nano-scales by varying concentrations of metal ions and their ratio to the ligand. Moreover, both Ellipsoids and Rods showed excellent biocompatibility with human gingival fibroblasts and potent antimicrobial effects on the Gram-negative oral pathogens including Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis and Fusobacterium nucleatum. Both Ellipsoids and Rods at 50 ​μg/mL could disrupt the bacterial membranes, and particularly eliminate P. gingivalis biofilms. This study demonstrates highly efficient and facile approaches to synthesizing bismuth-based particles. Our work could enrich the administration modalities of metallic drugs for promising antibiotic-free healthcare.

Effective control of microbial spoilage in soybeans by water-soluble ZnO nanoparticles

The microbial spoilage of soybeans during soaking process severely deteriorates the quality of soybean products and threatens human health. Herein, water-soluble aminated zinc oxide nanoparticles (ZnO NPs) were developed to effectively control the microbial spoilage in soybeans during soaking. ZnO NPs achieved significant inactivation of three dominant spoilage bacteria (bacillus cereus, bacillus megaterium and enterococcus faecium) isolated from the deteriorated soybeans, which could adhere to the bacterial surface and damage the cell wall/membrane, but also generate large amounts of reactive oxygen species (ROS). Compared to two commercial ZnO, water-soluble ZnO exhibited superior antibacterial properties due to producing more ROS and bacteria-adhered ability. After ZnO NPs treatment, the content of the residual Zn (51.1 mg/kg) in soybeans was the safety standards of Zn element in soybeans products for human). Therefore, the water-soluble ZnO NPs showed great potentials as efficient and safe antimicrobial agents for soybeans preservation during soaking process.

Biocompatibility, cytotoxicity and antibacterial effects of meropenem-loaded mesoporous silica nanoparticles against carbapenem-resistant Enterobacteriaceae

BACKGROUND

The ever-increasing resistance to antimicrobial agents among bacteria associated with nosocomial infections indicate the necessity of new antimicrobial therapy. The nanoparticles are considered as new drug delivery systems to increase the efficiency and decrease the unfavourable effects of the antimicrobial agents.

METHODS

Herein we report the preparation and characterization of mesoporous silica nanoparticles (MSNs) loaded with meropenem against carbapenem-resistant Enterobacteriaceae. The antimicrobial effect of meropenem-loaded MSNs was determined against Enterobacteriaceae using the minimum inhibitory (MIC) method. The biocompatibility of meropenem-loaded MSNs was studied by the impact on the haemolysis and sedimentation rates of human red blood cells (HRBCs). Cytotoxicity of the meropenem-loaded MSNs was studied by the MTT test (hBM-MSC cell viability).

RESULTS

The meropenem-loaded MSNs have shown antibacterial activity on all isolates at different MIC values lower than MICs of meropenem. Free MSNs did not show any significant antibacterial effect. Meropenem-loaded MSNs have no significant effect on haemolysis and ESR of HRBCs. The viability of hBM-MSC cells treated with serial concentrations of meropenem-loaded MSNs was 92-100%.

CONCLUSION

Due to the desirable biocompatibility, low cytotoxicity and the improved antibacterial effect, MSNs can be considered as a promising drug delivery system for meropenem as a potential antimicrobial agent.

Silver-hydroxyapatite nanocomposites prepared by three sequential reaction steps in one pot and their bioactivities in vitro

Hydroxyapatite (HA) combined with antimicrobial agents for biomedical application can effectively avoid the bacteria infection, while HA have the good performance. In this study, we prepared silver-hydroxyapatite (Ag-HA) nanocomposites using a one-pot method consisting of three sequential steps of wet chemical precipitation, ion exchange, and a silver mirror reaction. The HA nanoparticles used as the precursor for Ag ion doping were first synthesised by wet chemical precipitation. Next, Ag⁺ absorbed on HA surface through ion exchange reaction. Glucose was then added to initiate the silver mirror reaction, which made the Ag⁺ ions reduce to Ag⁰ and Ag nanoparticles in situ formed on HA nanoparticles. Subsequently, Ag-HA nanocomposites with different Ag content were prepared. X-ray diffraction, SEM, EDX mapping and TEM imaging confirmed that spherical Ag nanoparticles ~20-40 nm in diameter were adhered to the surface of HA nano-rods (0.4-0.8 μm in length and 15-40 nm in diameter). The Ag content (1.9-15.2 wt%) in the Ag-HA nanocomposites was adjusted by varying the feeding Ag/Ca molar ratio (2.0-20%). The cell viability evaluation in vitro proved that Ag-HA nanocomposites had low cytotoxicity to L929 normal cells. Meanwhile, the antibacterial examinations in vitro demonstrated that Ag-HA nanocomposites had obvious antibacterial effects on Gram-positive bacteria, Gram-negative bacteria, and fungus. The antibacterial results were dose-dependent on the accumulation of silver content. The Ag-HA nanocomposites loaded PMMA resins also demonstrated a potential antibacterial activity against S. mutans. This paper presents a convenient and bio-friendly approach for preparing Ag-HA nanocomposites with adjustable Ag content, which are a promising material for biomedical applications.

Antibacterial Assessment of Zinc Sulfide Nanoparticles against Streptococcus pyogenes and Acinetobacter baumannii

BACKGROUND

Due to the appearance of resistant bacterial strains against the antimicrobial drugs and the reduced efficiency of these valuable resources, the health of a community and the economies of countries have been threatened.

OBJECTIVE

In this study, the antibacterial assessment of zinc sulfide nanoparticles (ZnS NPs) against Streptococcus pyogenes and Acinetobacter baumannii has been performed.

METHODS

ZnS NPs were synthesized through a co-precipitation method using polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA) and polyethylene glycol (PEG-4000). The size and morphology of the synthesized ZnS NPs were determined by a scanning electron microscope (SEM) and it was found that the average size of the applied NPs was about 70 nm. In order to evaluate the antibacterial effect of the synthesized ZnS NPs, various concentrations (50μg/mL, 100 μg/mL and 150 μg/mL) of ZnS NPs were prepared. Antibacterial assessments were performed through the disc diffusion method in Mueller Hinton Agar (MHA) culture medium and also the optical density (OD) method was performed by a UV-Vis spectrophotometer in Trypticase™ Soy Broth (TSB) medium. Then, in order to compare the antibacterial effects of the applied NPs, several commercial antibiotics including penicillin, amikacin, ceftazidime and primaxin were used.

RESULTS

The achieved results indicated that the antibacterial effects of ZnS NPs had a direct relation along with the concentrations and the concentration of 150 μg/mL showed the highest antibacterial effect in comparison with others. In addition, the ZnS NPs were more effective on Acinetobacter baumannii.

CONCLUSION

The findings of this research suggest a novel approach against antibiotic resistance.

The biomedical potential of cellulose acetate/polyurethane nanofibrous mats containing reduced graphene oxide/silver nanocomposites and curcumin: Antimicrobial performance and cutaneous wound healing

In this study, nanofibrous scaffolds were prepared from polyurethane and cellulose acetate using electrospinning. Reduced graphene oxide/silver nanocomposites, rGO/Ag, were also used into the mats due to the strong antibacterial activity of rGO/Ag nanocomposites. In order to prevent the agglomeration of silver nanoparticles, AgNPs, the nanoparticles were decorated onto the reduced graphene oxide (rGO) sheets. Initially, Graphene oxide, briefly GO, was synthesized by the improved Hummer method. Then, nanocomposites of reduced graphene oxide were decorated with Ag and were fabricated via a green and facile hydrothermal method. Thereafter, the scaffold containing rGO/Ag nanocomposites, curcumin or both of them were prepared using the electrospinning method. The obtained scaffolds were characterized by scanning electron microscopy (SEM), contact angle, tensile analysis, porosity, and water vapor transmission rate (WVTR). 3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide assay, MTT, confirmed the biocompatibility of the composite nanofibers. The scaffolds were able to hinder both of the Gram-negative and Gram-positive bacteria through direct contact with them. In vivo histopathological studies indicated that the scaffold incorporated rGO/Ag nanocomposites and curcumin has the most effect on wound healing and can promote the healing rate of artificial wounds, which indicates the good biomedical potential of nanomaterial in wound healing.

Preparation and preliminary evaluation of bio-nanocomposites based on hydroxyapatites with antibacterial properties against anaerobic bacteria

Hexagonal nanocrystalline powders of the non-doped Ca₁₀(PO₄)₆(OH)₂ as well as activated with Ag⁺ and Eu³⁺ ions were synthesized by using different wet chemistry methods. Moreover, the obtained hydroxyapatite was loaded with Ag⁰, as well as nitroimidazole antimicrobials: metronidazole and tinidazole. The structural properties of the products were analyzed by X-ray diffraction (XRD), scanning (SEM) and transmission (TEM) electron microscopy as well as infrared (IR) and Raman spectroscopy. The photoluminescence properties of the Eu³⁺ and Ag⁺ co-doped Ca₁₀(PO₄)₆(OH)₂ were characterized via the PL emission, excitation spectra and the luminescence decay curve. The antimicrobial activity of the obtained materials against Prevotella bivia and Parabacteroides distasonis was studied. The cytotoxicity assessment was carried out on the human osteosarcoma cell line (U2OS) as well as human red blood cells (RBC). The choice of the in vitro model was based on the fact that U2OS is a cancer cell line derived from bone tissue which is rich in apatites that play a pivotal role in the extracellular matrix formation. RBCs are the most abundant blood cells and they are used as a cell model in the study of biocompatibility of new prepared biocompounds with potential medical applications. The obtained multifunctional materials do not exhibit the haemolytic activity, therefore, they could be used as a promising antimicrobial agent and for anaerobic bacteria.

Novel eugenol bearing oxypropanolamines: Synthesis, characterization, antibacterial, antidiabetic, and anticholinergic potentials

Five oxypropanol amine derivatives that four of them are novel have been synthesized with high yields and practical methods. in vitro antibacterial susceptibility of Acinetobacter baumannii, Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus strains to synthesized substances were evaluated with agar well-diffusion method by comparison with commercially available drugs. Most of the bacteria were multidrug resistant. It was concluded that these compounds are much more effective than reference drugs. These eugenol bearing oxypropanolamine derivatives were also effective inhibitors against α-glycosidase, cytosolic carbonic anhydrase I and II isoforms (hCA I and II), and acetylcholinesterase (AChE) enzymes with K_i values in the range of 0.80 ± 0.24-3.52 ± 1.01 µM for hCA I, 1.08 ± 0.15-3.64 ± 0.92 µM for hCA II, 5.18 ± 0.84-12.46 ± 2.08 µM for α-glycosidase, and 11.33 ± 2.83-32.81 ± 9.73 µM for AChE, respectively.

Bactericidal effects of nanopatterns: A systematic review

We systematically reviewed the currently available evidence on how the design parameters of surface nanopatterns (e.g. height, diameter, and interspacing) relate to their bactericidal behavior. The systematic search of the literature resulted in 46 studies that satisfied the inclusion criteria of examining the bactericidal behavior of nanopatterns with known design parameters in absence of antibacterial agents. Twelve of the included studies also assessed the cytocompatibility of the nanopatterns. Natural and synthetic nanopatterns with a wide range of design parameters were reported in the included studies to exhibit bactericidal behavior. However, most design parameters were in the following ranges: heights of 100-1000 nm, diameters of 10-300 nm, and interspacings of  <500 nm. The most commonly used type of nanopatterns were nanopillars, which could kill bacteria in the following range of design parameters: heights of 100-900 nm, diameters of 20-207 nm, and interspacings of 9-380 nm. The vast majority of the cytocompatibility studies (11 out of 12) showed no adverse effects of bactericidal nanopatterns with the only exception being nanopatterns with extremely high aspect ratios. The paper concludes with a discussion on the evidence available in the literature regarding the killing mechanisms of nanopatterns and the effects of other parameters including surface affinity of bacteria, cell size, and extracellular polymeric substance (EPS) on the killing efficiency. STATEMENT OF SIGNIFICANCE: The use of nanopatterns to kill bacteria without the need for antibiotics represents a rapidly growing area of research. However, the optimum design parameters to maximize the bactericidal behavior of such physical features need to be fully identified. The present manuscript provides a systematic review of the bactericidal nanopatterned surfaces. Identifying the effective range of dimensions in terms of height, diameter, and interspacings, as well as covering their impact on mammalian cells, has enabled a comprehensive discussion including the bactericidal mechanisms and the factors controlling the bactericidal efficiency. Overall, this review helps the readers have a better understanding of the state-of-the-art in the design of bactericidal nanopatterns, serving as a design guideline and contributing to the design of future experimental studies.

Comparisons of the restoring and reinforcement effects of carboxymethyl chitosan-silk fibroin (Bombyx Mori/Antheraea Yamamai/Tussah) on aged historic silk

This work presents the results of the reinforcement effects of regenerated silk fibroin solutions (SF) of Bombyx-Mori, Antheraea-Yamamai and Tussah on aged historic silk. Furthermore, Carboxymethyl-chitosan (CMC) was utilized as reinforcement and antibacterial filler to further improving the mechanical properties and antibacterial effects. To clarify the rationale behind this process, comprehensive characterization was applied, and a speculative explanation was provided. The results showed that Bombyx-mori and Tussah have better restoring effects than Antheraea-yamamai. CMC has good compatibility to the SF, and the addition of CMC has significantly contributed to the improvement the mechanical properties and thermal stability of the restored silk, which is due to the formation of chemical bonding, strong hydrogen bonding and the construction of polymer network structure. The enhancement of crystallinity and reduction of β-turns structure indicate that the micro-defects in the crystallization zone of the aged silk has been restored, and the ordered arrangement in the long-range ordered structure has been improved within a certain range. It was found that the CMC acted as antifungal agents when introduced on the aged historic silk, reducing the growth of Aspergillus niger, Aspergillus flavus and Paecilomyces variotii to a certain extent, which were commonly found in storage areas of libraries.

Novel thymol bearing oxypropanolamine derivatives as potent some metabolic enzyme inhibitors - Their antidiabetic, anticholinergic and antibacterial potentials

A series of classical and newly synthesized thymol bearing oxypropanolamine compounds were synthesized and characterized. Their in vitro antibacterial activity on A. baumannii, P. aeruginosa, E. coli and S. aureus strains were investigated with agar well diffusion method. The results were compared with commercially available drug active compounds. As well as 3a, 3b and 3c have the most significant antibacterial effect among all the tested compounds; approximately all of them have more antibacterial activity than the reference drugs. These novel thymol bearing oxypropanolamine derivatives were effective inhibitors of the α-glycosidase, cytosolic carbonic anhydrase I and II isoforms (hCA I and II), and acetylcholinesterase enzymes (AChE) with K_i values in the range of 463.85-851.05 µM for α-glycosidase, 1.11-17.34 µM for hCA I, 2.97-17.83 µM for hCA II, and 13.58-31.45 µM for AChE, respectively.

Graphene oxide/silver nanohybrid: Optimization, antibacterial activity and its impregnation on bacterial cellulose as a potential wound dressing based on GO-Ag nanocomposite-coated BC

Recently, bacterial cellulose (BC) based wound dressing have raised significant interests in medical fields. However, to our best knowledge, it is apparent that the BC itself has no antibacterial activity. In this study, we optimized graphene oxide-silver (GO-Ag) nanohybrid synthesis using Response Surface Methodology and impregnate it to BC and carefully investigate their antibacterial activities against both the Gram-negative bacteria Escherichia coli and the Gram-positive bacteria Staphylococcus aureus. We discover that, compared to silver nanoparticles, GO-Ag nanohybrid with an optimal GO suspension's pH and [ G O ] [ A g N O 3 ] ratio is much more effective and shows synergistically enhanced, strong antibacterial activities at rather low dose. The GO-Ag nanohybrid is more toxic to E. coli than that to S. aureus. The antibacterial and mechanical properties of BC/GO-Ag composite are further investigated.

The interaction of copper ions with Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli: an X-ray absorption near-edge structure (XANES) spectroscopy study

The antimicrobial properties of copper ions have been known for a long time. However, the exact mechanism of action of the transition metal on microorganisms has long been unclear. X-ray absorption near-edge structure (XANES) spectroscopy at the Cu K edge allows the determination of copper speciation in Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa that have been treated with Cu(II) and Cu(I) solutions. The death/inactivation of the bacteria was observed using plate counting and light microscopy. The Cu K-XANES spectra of the two Gram-negative bacteria are different than those of the Gram-positive strain. The results clearly show that the Cu⁺-S bond contributes to the antibacterial activity of copper, as in the case of silver. The detailed evaluation of the differentiated absorption spectra shows that Cu⁺ (not Cu²⁺) is the dominant ion that binds to the bacteria. Because Cu⁺ is not the most common copper ion, copper is not as effective an antibacterial agent as silver, whose common valency is actually + 1. Any reaction of copper with phosphorus from the bacteria can be excluded after the evaluation of the absorption spectra.

The Antibacterial Effects of Antimicrobial Peptides OP-145 against Clinically Isolated Multi-Resistant Strains

OP-145 is a synthetic antimicrobial peptide developed from the human cathelicidin LL-37. The purpose of this investigation was to evaluate the effect of the antimicrobial peptide OP-145 against clinically isolated drug-resistant strains. Ten methicillin-resistant Staphylococcus aureus (MRSA) strains were obtained from our hospital's clinical inspection center, and the activity of OP-145 on growth and biofilm formation of these strains was evaluated by colony counts and scanning electron microscopy. The antimicrobial peptide OP-145 showed significant antibacterial activity against 9 MRSA strains. For the biofilm experiments, MRSA counts in the biofilms decreased significantly after 24 h (P ＜ 0.05). OP-145 strongly reduced growth and biofilm formation of clinically isolated drug-resistant strains in vitro, and the use of this class of antimicrobial agents may be an important new approach in controlling bacterial infections.

Surface characterization and antibacterial response of silver nanowire arrays supported on laser-treated polyethylene naphthalate

Polymeric biomaterials with antibacterial effects are requisite materials in the fight against hospital-acquired infections. An effective way for constructing a second generation of antibacterials is to exploit the synergic effect of (i) patterning of polymeric materials by a laser, and (ii) deposition of noble metals in their nanostructured forms. With this approach, we prepared highly-ordered periodic structures (ripples) on polyethylene naphthalate (PEN). Subsequent deposition of Ag under the glancing angle of 70° resulted in the formation of self-organized, fully separated Ag nanowire (Ag NW) arrays homogenously distributed on PEN surface. Surface properties of these samples were characterized by AFM and XPS. Vacuum evaporation of Ag at the glancing angle geometry of 70° caused that Ag NWs were formed predominantly from one side of the ripples, near to the top of the ridges. The release of Ag⁺ ions into physiological solution was studied by ICP-MS. The results of antibacterial tests predetermine these novel structures as promising materials able to fight against a broad spectrum of microorganisms, however, their observed cytotoxicity warns about their applications in the contact with living tissues.

The efficacy of Mentha arvensis L. and M. piperita L. essential oils in reducing pathogenic bacteria and maintaining quality characteristics in cashew, guava, mango, and pineapple juices

This study evaluated the ability of the essential oil from Mentha arvensis L. (MAEO) and M. piperita L. (MPEO) to induce ≥5-log reductions in counts (CFU/mL) of E. coli, L. monocytogenes, and Salmonella enterica serovar Enteritidis in Brain-Heart Infusion broth (BHIB) and cashew, guava, mango, and pineapple juices during refrigerated storage (4±0.5°C). The effects of the incorporation of these essential oils on some physicochemical and sensory parameters of juices were also evaluated. The incorporation of 5, 2.5, 1.25, or 0.625μL/mL of MAEO in BHIB caused a ≥5-log reduction in counts of E. coli and Salmonella Enteritidis after 24h of storage; but only 5μL/mL was able to cause the same reduction in counts of L.monocytogenes. The incorporation of 10μL/mL of MPEO in BHIB caused a ≥5-log reduction in counts of E. coli, Salmonella Enteritidis, and L. monocytogenes after 24h of storage; smaller reductions were observed in BHIB containing 5, 2.5, and 1.25μL/mL of MPEO. Similar reductions were observed when the MAEO or MPEO was incorporated at the same concentrations in mango juice. The incorporation of MAEO or MPEO at all tested concentrations in cashew, guava, and pineapple juices resulted in a ≥5-log reduction in pathogen counts within 1h. The incorporation of MAEO and MPEO (0.625 and 1.25μL/mL, respectively) in fruit juices did not induce alterations in °Brix, pH, and acidity, but negatively affected the taste, aftertaste, and overall acceptance. The use of MAEO or MPEO at low concentrations could constitute an interesting tool to achieve the required 5-log reduction of pathogenic bacteria in cashew, guava, mango, and pineapple fruit juices. However, new methods combining the use of MAEO or MPEO with other technologies are necessary to reduce their negative impacts on specific sensory properties of these juices.

A clinical and microbiological study on the enantiomers of delmopinol

Objective The clinical part of this study aimed to investigate whether the racemate of delmopinol [(±)-delmopinol] is equivalent to its two enantiomers [(+)-delmopinol and (-)-delmopinol] with respect to efficiency and to determine and compare their pharmacokinetic properties. The purpose of the pre-clinical part was to elucidate possible differences in antimicrobial efficiency. Materials and methods The compounds were tested clinically in a double-blind, randomized, cross-over study comprising three treatment periods of 4 days each. The antimicrobial efficacy of the enantiomers was compared in vitro with respect to planktonic and biofilm bacteria of different species. Results No statistically significant differences in prevention of plaque formation were observed. Except for a somewhat higher systemic exposure in terms of AUC and Cmax indicated for (-)-delmopinol compared to (+)-delmopinol, the pharmacokinetic properties were similar. The most common adverse event was a transient anaesthetic feeling in the mouth. This event was reported with the same frequency for all three test solutions. The enantiomers showed similar antimicrobial effects on planktonic bacteria and their biofilms. Conclusions The enantiomers were found to be equally effective with respect to inhibition of plaque development and only minor differences were observed with respect to their pharmacokinetic properties. No differences could be observed in the adverse events reports. There is, therefore, no reason to use one of the enantiomers of delmopinol instead of the racemate. This was further supported by the antimicrobial tests. It is suggested that the combined action of cationic and neutral delmopinol is important for its effect on biofilms.

A short-type peptidoglycan recognition protein from tongue sole (Cynoglossus semilaevis) promotes phagocytosis and defense against bacterial infection

Peptidoglycan recognition proteins (PGRPs) are members of the innate immune system that interact with bacteria by binding to bacterial peptidoglycan. In this study, we examined the expression and function of a short type of PGRP, CsPGRP-SC2, from tongue sole (Cynoglossus semilaevis). CsPGRP-SC2 contains 164 amino acid residues and shares 54.5%-65.3% overall sequence identities with other teleost PGRPs. CsPGRP-SC2 possesses an amidase domain with a conserved zinc binding site. CsPGRP-SC2 expression occurred in multiple tissues and was upregulated by bacterial and viral infection. Purified recombinant CsPGRP-SC2 (rCsPGRP-SC2) was able to bind and agglutinate Gram-positive bacteria in a Zn(2+)-dependent manner. rCsPGRP-SC2 enhanced the uptake of the bound bacteria by host phagocytes and reduced bacterial dissemination and colonization in host tissues. These results indicate that CsPGRP-SC2 is an innate immune factor that participates in host defense against bacterial infection.

Analysis of effects of MCB3681, the antibacterially active substance of prodrug MCB3837, on human resident microflora as proof of principle

The water-soluble prodrug MCB3837 is rapidly converted to MCB3681, active against Gram-positive bacterial species, after intravenous infusion. The aim of this study was to prove the principle that MCB3681 is efficacious in vivo by demonstrating its effect on the resident microflora or colonizers of the human skin, nose, oropharynx and intestine. MCB3837 was infused at a daily dose of 6 mg/kg for 5 days. MCB3681 was active against clostridia, bifidobacteria, lactobacilli, enterococci and Staphylococcus aureus, thus proving the principle that MCB3681 is antibacterially efficacious in vivo without affecting the Gram-negative microflora.

Nanocolumnar coatings with selective behavior towards osteoblast and Staphylococcus aureus proliferation

Bacterial colonization and biofilm formation on orthopedic implants is one of the worst scenarios in orthopedic surgery, in terms of both patient prognosis and healthcare costs. Tailoring the surfaces of implants at the nanoscale to actively promote bone bonding while avoiding bacterial colonization represents an interesting challenge to achieving better clinical outcomes. Herein, a Ti6Al4V alloy of medical grade has been coated with Ti nanostructures employing the glancing angle deposition technique by magnetron sputtering. The resulting surfaces have a high density of nanocolumnar structures, which exhibit strongly impaired bacterial adhesion that inhibits biofilm formation, while osteoblasts exhibit good cell response with similar behavior to the initial substrates. These results are discussed on the basis of a "lotus leaf effect" induced by the surface nanostructures and the different sizes and biological characteristics of osteoblasts and Staphylococcus aureus.

Antibacterial activity of clove, gall nut methanolic and ethanolic extracts on Streptococcus mutans PTCC 1683 and Streptococcus salivarius PTCC 1448

INTRODUCTION

Antimicrobial compounds from herbal sources have good therapeutic potential. In this study, the antibacterial effects of clove and gall nut, methanolic and ethanolic extractions, were evaluated for their effect on Streptococcus mutans PTCC 1683 and Streptococcus salivarius PTCC 1448, as both the two cause oral diseases.

METHOD

The clove and gall nut methanolic and ethanolic extracts were prepared and antibacterial activity was evaluated for S. mutans and S. salivarius in the base of inhibition zone diameter using agar diffusion method. In this part minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were assessed.

RESULTS

These extracts showed effective antibacterial activity on bacteria. Antibacterial activity of Methanolic extract of clove was more than that of ethanolic extract, and ethanolic extracts of gall nut had antibacterial activity more than that of methanolic extracts. MIC and MBC results for clove methanolic extract were 1.5 mg/ml and 3 mg/ml for S. mutans and 6.25 mg/ml and 12.5 mg/ml for S. salivarius, respectively. These results for clove ethanolic extracts were 12.5 mg/ml and 25 mg/ml for S. mutans and 25 mg/ml and 50 mg/ml for S. salivarius, respectively. MIC and MBC results for gall nut methanolic extract were 25 mg/ml and 50 mg/ml for S. mutans and 12.5 mg/ml and 25 mg/ml for S. salivarius, respectively. These results for gall nut ethanolic extracts were 3.1 mg/ml and 6.2 mg/ml for S. mutans and 25 mg/ml and 50 mg/ml for S. salivarius, respectively.

DISCUSSION

The results showed effective antibacterial activity using clove and gall nut methanolic extracts. If other properties such as tolerance of tissue can also be studied, these extracts can be used as a mouthwash.

In vitro antibacterial analysis of phenoloxidase reaction products from the sea cucumber Apostichopus japonicus

Three phenoloxidases (POs) of Apostichopus japonicus, AjPOs (AjPO1, AjPO2 and AjPO3), were partially purified from the coelomocytes with an electrophoretic method, and then employed for the in vitro antibacterial analysis. Using L-3,4-dihydroxyphenylalanine (L-DOPA) as a substrate, AjPO1 and AjPO2-derived compounds inhibited the growth of Vibrio splendidus and Staphylococcus aureus, while AjPO3-derived compounds only inhibited the growth of V. splendidus. When dopamine was used as a substrate, AjPO1 and AjPO3-derived compounds inhibited the growth of V. splendidus and Vibrio harveyi, while AjPO2-derived compounds only inhibited the growth of V. splendidus. Moreover, AjPO1-derived compounds showed stronger inhibition in V. harveyi than AjPO3-derived compounds did. However, all of the three AjPO reaction products showed no inhibitions on the growth of Pseudoalteromonas nigrifaciens, Shewanella baltica, Micrococcus lysodeikticus, Streptococcus dysgalactiae and Nocardiopsis sp. with L-DOPA or dopamine as a substrate. Scanning electron microscope (SEM) observation of V. harveyi treated by AjPOs and dopamine showed that AjPO1-derived compounds resulted in massive bacteriolysis, AjPO2-derived compounds caused no obvious alteration on bacterial morphology, and AjPO3-derived compounds increased the ratio of spheroidal bacteria. All these results suggested that AjPO reaction products derived by L-DOPA and dopamine had different but limited antibacterial spectrum, and the different antibacterial effects observed among three AjPOs resulted from the different reaction products generated by AjPOs with the same substrate.

Evaluation of antibacterial effects of pulp capping agents with direct contact test method

Objectives:

Calcium hydroxide has been used in dentistry as a major capping material having the capacity to introduce the formation of a mineralized dentin bridge, but it has no direct inducing effect to the pulp cells. The purpose of this study was to evaluate the antibacterial properties of three different pulp capping agents using a direct contact test (DCT).

Materials and Methods:

The antibacterial properties of three pulp capping agents were evaluated a DCT. For the DCT, wells (n = 12) of 96-microtiter plates were coated with the tested cements (Dycal, Dentsply, USA; DiaRoot BioAggregate, Diadent, Holland; Calcimol LC, Voco, Germany) and Kalzinol (zinc oxide/eugenol cement, Dentsply, USA) was used as control material. A Lactobacillus casei suspension was placed on the surface of each specimen for 1 h at 37°C. Bacterial growth was monitored for 16 h with a temperature-controlled microplate spectrophotometer. The kinetics of the outgrowth in each well were recorded continuously at 650 nm every 30 min. The data were analyzed by one-way ANOVA, and Tamhane's T2 multiple comparison test. The level of significance was determined as P < 0.05.

Results:

All pulp capping agents showed an increase in the logarithmic growth rate of L. casei when compared with the control group (P < 0.05). Therefore, all pulp capping agents did not show antibacterial activity.

Conclusions:

The tested pulp capping agents haven't got antibacterial properties. Therefore, they should be used carefully when pulp is exposed or only very thin dentin remained over the pulp to avoid bacterial contamination.