Synthesis, antimicrobial properties and in silico studies of aryloxyacetic acid derivatives with hydrazone or thiazolidine-4-one scaffold

In this work, twenty hydrazide-hydrazone and 4-thiazolidinone derivatives were synthesized starting from m-cresol. Antimicrobial evaluation was carried out by microdilution method against Enterococcus faecalis and Staphylococcus aureus as Gram-positive bacteria and Escherichia coli and Pseudomonas aeruginosa as Gram-negative bacteria, and three pathogenic fungi Candida albicans, Candida parapsilosis and Candida krusei. Some compounds possessed considerable antimicrobial properties against the tested microorganisms, particularly against E. coli. 4-Thiazolidinones containing 3-methoxyphenyl and 3,5-dichlorophenyl moieties (4h and 4i) were found to be the most active derivatives with MICs of 2 μg/mL against E. coli. N'-[(3,5-dichlorophenyl)methylidene]-2-(3-methylphenoxy)acetohydrazide (3i) also displayed antifungal activity against Candida krusei that was comparable to fluconazole. Calculated drug-likeness and ADMET parameters of the most active compounds confirmed their potential as antimicrobial drug candidates. Molecular docking investigations were carried out in the thiamine diphosphate-binding site of pyruvate dehydrogenase multienzyme complex E1 component (PDHc-E1) to clarify the potential antibacterial mechanism against E. coli. The results showed the potential and importance of developing new hydrazones and 4-thiazolidinones that would be effective against microbial strains.Communicated by Ramaswamy H. Sarma.

Sensitive quantification of short-chain fatty acids combined with global metabolomics in microbiome cultures

The microbiome has been identified to have a key role for the physiology of their human host. One of the major impacts is the clearance of bacterial pathogens. We have now developed a chemoselective probe methodology for the absolute quantification of short-chain fatty acids at low nM concentrations, with high reproducibility and spiked isotope labelled internal standards. Immobilization to magnetic beads allows for separation from the matrix and the tagged metabolites upon bioorthogonal cleavage can be analyzed via UHPLC-MS. The major advantage of our sensitive method is the simple combination with global metabolomics analysis as only a small sample volume is required. We have applied this chemical metabolomics strategy for targeted SCFA analysis combined with global metabolomics on gut microbiome co-cultures with Salmonella and investigated the effect of antibiotic treatment.

Azoles containing naphthalene with activity against Gram-positive bacteria: in vitro studies and in silico predictions for flavohemoglobin inhibition

Azoles are first-line drugs used in fungal infections. Topical antifungals, such as miconazole and econazole, are known to be active against Gram-positive bacteria, which was reported to result from bacterial flavohemoglobin (flavoHb) inhibition. Dual antibacterial/antifungal action is believed to have benefits for antimicrobial chemotherapy. In this study, we tested antibacterial effects of an in-house library of naphthalene-bearing azoles, some of which were reported as potent antifungals, in an attempt to find dual-acting hits. Several potent derivatives were obtained against the Gram-positive bacteria, Enterococcus faecalis and Staphylococcus aureus. 9 was active at a minimum inhibitor concentration (MIC) less than 1 µg/ml against E. faecalis and S. aureus, and 10 against S. aureus. 16 was also potent against E. faecalis and S. aureus (MIC = 1 and 2 µg/ml, respectively). Six more were active against S. aureus with MIC ≤ 4 µg/ml. In vitro cytotoxicity studies showed that the active compounds were safe for healthy cells within their MIC ranges. According to the calculated descriptors, the library was found within the drug-like chemical space and free of pan-assay interference compounds (PAINS). Molecular docking studies suggested that the compounds might be bacterial flavohemoglobin (flavoHb) inhibitors and the azole and naphthalene rings were important pharmacophores, which was further supported by pharmacophore modeling study. As a result, the current study presents several non-toxic azole derivatives with antibacterial effects. In addition to their previously reported antifungal properties, they could set a promising starting point for the future design of dual acting antimicrobials. Communicated by Ramaswamy H. Sarma.

Metabolomics-driven Approaches on Interactions Between Enterococcus faecalis and Candida albicans Biofilms

Objectives

This study aimed to determine the effect of Enterococcus faecalis on the cell growth and hyphal formation of Candida albicans and to understand the exact mechanism of candidal inhibition by the existence of E. faecalis by metabolomic analysis.

Materials and Methods

Single- and dual-species biofilms of E. faecalis and C. albicans were formed in a microtiter plate, and the metabolomic profiles of both biofilms was determined by gas chromatography-mass spectrometry. The hyphal cell growth of C. albicans after treatment with both the supernatant and biofilm cells of E. faecalis was examined microscopically. The expression levels of Efg1 and the images of C. albicans cell wall in single- and dual-species biofilms were determined by real-time quantitative polymerase chain reaction and transmission electron microscopy, respectively. The violacein levels produced by Chromobacterium violaceum were measured to determine the quorum sensing (QS) inhibitory activity of single- and dual-species biofilms.

Results

The biofilm cell growth, Efg1 expression, and hyphal development of C. albicans were inhibited by E. faecalis. Compared to single-species biofilms, alterations in carbohydrate, amino acid, and polyamine metabolites were observed in the dual-species biofilm for both microorganisms. Putrescine and pipecolic acid were detected at high levels in dual-species biofilm. A thicker β-glucan chitin and a denser and narrower fibrillar mannan layer of C. albicans cell wall were observed in dual-species biofilm. QS inhibitory activity was higher in dual-species biofilm suspensions of E. faecalis and C. albicans than in their single-species biofilms.

Conclusion

E. faecalis inhibited the hyphal development and biofilm formation of C. albicans. Biofilm suspensions of C. albicans and E. faecalis showed an anti-QS activity, which increased even further in the environment where the two species coexisted. Investigation of putrescine and pipecolic acid can be an important step to understand the inhibition of C. albicans by bacteria.

Functional Nanomaterials and 3D-Printable Nanocomposite Hydrogels for Enhanced Cell Proliferation and for the Reduction of Bacterial Biofilm Formation

Biomaterial-associated infections are a major cause of biomaterial implant failure. To prevent the initial attachment of bacteria to the implant surface, researchers have investigated various surface modification methods. However, most of these approaches also prevent the attachment, spread, and growth of mammalian cells, resulting in tissue integration failure. Therefore, the success of biomaterial implants requires an optimal balance between tissue integration (cell adhesion to biomaterial implants) and inhibition of bacterial colonization. In this regard, we synthesize bifunctional nanomaterials by functionalizing the pores and outer surfaces of periodic mesoporous organosilica (PMO) with antibacterial tetracycline (Tet) and antibacterial and cell-adhesive bipolymer poly-d-lysine (PDL), respectively. Then, the fabricated ^TetPMO-PDL nanomaterials are incorporated into alginate-based hydrogels to create injectable and 3D-printable nanocomposite (NC) hydrogels (AlgL-^TetPMO-PDL). These bifunctional nanomaterial and 3D-printable NC hydrogel show pH-dependent release of Tet over 7 days. They also enhance the proliferation of eukaryotic cells (fibroblasts). ^TetPMO-PDL is inactive in reducing Pseudomonas aeruginosa, Staphylococcus aureus, and Enterococcus faecalis biofilms. However, AlgL-^TetPMO-PDL shows significant antibiofilm activity against P. aeruginosa. These results suggest that the incorporation of ^TetPMO-PDL into AlgL may have a synergistic effect on the inhibition of the Gram-negative bacterial (P. aeruginosa) biofilm, while this has no effect on the reduction of the Gram-positive bacterial (S. aureus and E. faecalis) biofilm.

Salbutamol Delivered by Jet Nebulizer: Closed System Design and Impact of a Model Biofilm

BACKGROUND

Aerosol therapy is commonly used by intensivists during invasive mechanical ventilation. More information is needed to optimize outcomes. The first aim of this study was to assess the deposition of salbutamol on components of a closed mechanical ventilation system, both in the presence and absence of biofilm generated by Acinetobacter baumannii. The second aim was to evaluate the deposition of salbutamol, using a single dose and a double dose, delivered via a jet nebulizer placed between the flexible tube and the heat and moisture exchanger.

METHODS

A mechanical ventilator was connected to a standard system, and a jet nebulizer was placed between the heat and moisture exchanger and the flexible tube. Clinical isolates of A. baumanii were used to generate a biofilm layer on the endotracheal tube. Two amounts of salbutamol were delivered via the jet nebulizer. An analytical liquid chromatography tandem mass spectrometry method was developed to evaluate salbutamol deposition.

RESULTS

The presence of a biofilm on the endotracheal tube had no impact on salbutamol deposition (P = .83). There was no difference in surface deposition of salbutamol on component parts of the closed system in a comparison of a single dose and a double dose delivered via a jet nebulizer.

CONCLUSIONS

Our findings indicate that an A. baumannii biofilm had no impact on the extent of salbutamol deposition. Salbutamol deposition was comparatively low and could be delivered without removal of the heat and moisture exchanger.

The effect of gamma and microwave radiation sterilization on periodontological grafts for microbiological evaluation

Periodontological grafts are materials used in dentistry to regenerate lost gingival soft tissues or bone parts. In the case of direct contact with blood, the possibility of disease transmission from the source to the patient is high. This source can be an animal or a human. Therefore, the sterilization of grafts before implanting to the patient is of significant importance. The purpose of this study was to evaluate gamma radiation and microwave sterilization processes from microbiological and sterility perspectives and to compare the effectiveness of these two sterilization methods. Grafts were irradiated with 2, 4, 5, 10, 25 and 50 kGy doses of gamma radiation. Another group of same materials was irradiated by microwave for 1, 2, 3 and 4 min at 24,500 MHz and 900 W. Gamma radiation and microwave sterilization methods were evaluated as successful at minimum doses as 5 kGy and 3 min, respectively. Both gamma and microwave sterilization successfu lly sterilized periodontological grafts coded as PBG1, HBG1, HL1, PDG1, MBG3, MDG2 and PDG3. Moreover, microwave sterilization can be used as an alternative novel method to gamma radiation sterilization.

Alleviating the toxicity concerns of antibacterial cinnamon-polycaprolactone biomaterials for healthcare-related biomedical applications

Fibrous constructs with incorporated cinnamon-extract have previously been shown to have potent antifungal abilities. The question remains to whether these constructs are useful in the prevention of bacterial infections in fiber form and what the antimicrobial effects means in terms of toxicity to the native physiological cells. In this work, cinnamon extract containing poly (ε-caprolactone) (PCL) fibers were successfully manufactured by pressurized gyration and had an average size of ∼2 μm. Cinnamon extract containing PCL fibers were tested against Escherichia coli, Staphylococcus aureus, Methicillin resistant staphylococcus aureus, and Enterococcus faecalis bacterial species to assess their antibacterial capacity; it was found that these fibers were able to reduce viable cell numbers of the bacterial species up to two orders of magnitude lower than the control group. The results of the antibacterial tests were assessed by scanning electron microscopy (SEM). The constructs were also tested under indirect MTT tests where they showed little to no toxicity, similar to the control groups. Additionally, cell viability fluorescent imaging displayed no significant toxicity issues with the fibers, even at their highest tested concentration. Here we present a viable method for the production the non-toxic and naturally abundant cinnamon extracted fibers for numerous biomedical applications.

Sub-Inhibitory Concentrations of Ciprofloxacin Alone and Combinations with Plant-Derived Compounds against P. aeruginosa Biofilms and Their Effects on the Metabolomic Profile of P. aeruginosa Biofilms

INTRODUCTION

Alternative anti-biofilm agents are needed to combat Pseudomonas aeruginosa infections. The mechanisms behind these new agents also need to be revealed at a molecular level.

MATERIALS AND METHODS

The anti-biofilm effects of 10 plant-derived compounds on P. aeruginosa biofilms were investigated using minimum biofilm eradication concentration (MBEC) and virulence assays. The effects of ciprofloxacin and compound combinations on P. aeruginosa in mono and triple biofilms were compared. A metabolomic approach and qRT-PCR were applied to the biofilms treated with ciprofloxacin in combination with baicalein, esculin hydrate, curcumin, and cinnamaldehyde at sub-minimal biofilm inhibitory concentration (MBIC) concentrations to highlight the specific metabolic shifts between the biofilms and to determine the quorum sensing gene expressions, respectively.

RESULTS

The combinations of ciprofloxacin with curcumin, baicalein, esculetin, and cinnamaldehyde showed more reduced MBICs than ciprofloxacin alone. The quorum sensing genes were downregulated in the presence of curcumin and cinnamaldehyde, while upregulated in the presence of baicalein and esculin hydrate rather than for ciprofloxacin alone. The combinations exhibited different killing effects on P. aeruginosa in mono and triple biofilms without affecting its virulence. The findings of the decreased metabolite levels related to pyrimidine and lipopolysaccharide synthesis and to down-regulated alginate and lasI expressions strongly indicate the role of multifactorial mechanisms for curcumin-mediated P. aeruginosa growth inhibition.

CONCLUSIONS

The use of curcumin, baicalein, esculetin, and cinnamaldehyde with ciprofloxacin will help fight against P. aeruginosa biofilms. To the best of our knowledge, this is the first study of its kind to define the effect of plant-based compounds as possible anti-biofilm agents with low MBICs for the treatment of P. aeruginosa biofilms through metabolomic pathways.

Antibacterial azole derivatives: Antibacterial activity, cytotoxicity, and in silico mechanistic studies

Azole antifungal drugs are commonly used in antifungal chemotherapy. Antibacterial effects of some topical antifungals, such as miconazole and econazole, have lately been revealed, which suggests a promising venue in antimicrobial chemotherapy. In this study, we tested an in-house azole collection with antifungal properties for their antibacterial activity to identify dual-acting hits using the broth microdilution method. The in vitro screen yielded a number of potent derivatives against gram-positive bacteria, Enterococcus faecalis and Staphylococcus aureus. Compound 73's minimum inhibitory concentration (MIC) value less than 1 μg/ml against S. aureus; however, none of the compounds showed noteworthy activity against methicillin-resistant S. aureus (MRSA). All the active compounds were found safe at their MIC values against the healthy fibroblast cells in the in vitro cytotoxicity test. Molecular docking studies of the most active compounds using a set of docking programs with flavohemoglobin (flavoHb) structure, the proposed target of the azole antifungals with antibacterial activity, presented striking similarities regarding the binding modes and interactions between the tested compounds and the antifungal drugs with crystallographic data. In addition to being noncytotoxic, the library was predicted to be drug-like and free of pan-assay interference compounds (PAINS). As a result, the current study revealed several potential azole derivatives with both antifungal and antibacterial activities. Inhibition of bacterial flavoHb was suggested as a possible mechanism of action for the title compounds.

Evaluation of the biofilm formation of Staphylococcus aureus and Pseudomonas aeruginosa on human umbilical cord CD146+ stem cells and stem cell-based decellularized matrix

This study aims to evaluate the CD146+ stem cells obtained from the human umbilical cord and their extracellular matrix proteins on in vitro Pseudomonas aeruginosa and Staphylococcus aureus biofilms to understand their possible antimicrobial activity. CD146+ stem cells were determined according to cell surface markers and differentiation capacity. Characterization of the decellularized matrix was done with DAPI, Masson's Trichrome staining and proteome analysis. Cell viability/proliferation of cells in co-cultures was evaluated by WST-1 and crystal-violet staining. The effects of cells and decellularized matrix proteins on biofilms were investigated on a drip flow biofilm reactor and their effects on gene expression were determined by RT-qPCR. We observed that CD146/105+ stem cells could differentiate adipogenically and decellularized matrix showed negative DAPI and positive collagen staining with Masson' s Trichrome. Proteome analysis of the decellularized matrix revealed some matrix components and growth factors. Although the decellularized matrix significantly reduced the cell counts of P. aeruginosa, no significant difference was observed for S. aureus cells in both groups. Supporting data was obtained from the gene expression results of P. aeruginosa with the significant down-regulation of rhlR and lasR. For S. aureus, icaADBC genes were significantly up-regulated when grown on the decellularized matrix.

Microbial Stresses on Human Umbilical Cord Stem Cells

Umbilical cord and cord blood are acceptable as attractive sources of mesenchymal and hematopoietic stem cells, since their collection is non-invasive, painless, and does not evoke the ethical concerns. Microorganism-stem cell interaction plays an important role in stem cell self-renewal, differentiation, secretion profile and death. In the literature, few researchers are examining the relationship between pathogenic and commensal bacteria with umbilical cord-derived Mesenchymal Stem Cells (MSCs). These relationships vary depending on the bacterial load and the presence of the immune cell in the environment. Several bacterial pathogens act in the regenerative capacity of MSCs by changing their phenotype, development and viability due to several stress factors that are created by a microorganism such as hypoxia, oxidative stress, etc. On the other hand, the anti-inflammatory and antibacterial effects of MSCs were shown and these phenomena increased when the number of bacteria was high but decreased in the presence of low amounts of bacteria. The antibacterial effects of MSCs increased in the early period of infection, while their effects were decreased in the late period with high inflammatory response and bacterial load. In this review, we discussed the microbial stresses on human umbilical cord stem cells.

p-Trifluoroacetophenone Oxime Ester Derivatives: Synthesis, Antimicrobial and Cytotoxic Evaluation and Molecular Modeling Studies

Background:

Azole antifungals are among the first-line drugs clinically used for the treatment of systemic candidiasis, a deadly type of fungal infection that threatens mostly immunecompromised and hospitalized patients. Some azole derivatives were also reported to have antiproliferative effects on cancer cells.

Objective:

In this study, 1-(4-trifluoromethylphenyl)-2-(1H-imidazol-1-yl)ethanone (3), its oxime (4), and a series of its novel oxime ester derivatives (5a-v) were synthesized and tested for their in vitro antimicrobial activities against certain ATCC standard strains of Candida sp. fungi and bacteria. The compounds were also tested for their cytotoxic effects against mouse fibroblast and human neuroblastoma cell lines. Molecular modeling studies were performed to provide insights into their possible mechanisms for antifungal and antibacterial actions.

Methods:

The compounds were synthesized by the reaction of various oximes with acyl chlorides. Antimicrobial activity of the compounds was determined according to the broth microdilution method. For the determination of cytotoxic effect, we used MTS assay. Molecular docking and QM/MM studies were performed to predict the binding mechanisms of the active compounds in the catalytic site of C. albicans CYP51 (CACYP51) and S. aureus flavohemoglobin (SAFH), the latter of which was created via homology modeling.

Results:

5d, 5l, and 5t showed moderate antifungal activity against C. albicans, while 3, 5c, and 5r showed significant antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa. Most of the compounds showed approximately 40-50% inhibition against the human neuroblastoma cells at 100 µM. In this line, 3 was the most potent with an IC50 value of 82.18 μM followed by 5a, 5o, and 5t. 3 and 5a were highly selective to the neuroblastoma cells. Molecular modelling results supported the hypothesis that our compounds were inhibitors of CAYP51 and SAFH.

Conclusion:

This study supports that oxime ester derivatives may be used for the development of new antimicrobial and cytotoxic agents.

Altered metabolomic profile of dual-species biofilm: Interactions between Proteus mirabilis and Candida albicans

In this study, we aimed to determine the interspecies interactions between Proteus mirabilis and Candida albicans. Mono and dual-species biofilms were grown in a microtiter plate and metabolomic analysis of the biofilms was performed. The effects of togetherness of two species on the expression levels of candidal virulence genes and urease and swarming activities of P.mirabilis were investigated. The growth of C.albicans was inhibited by P.mirabilis whereas the growth and swarming activity of P.mirabilis were increased by C.albicans. The inhibition of Candida cell growth was found to be biofilm specific. The alteration was not detected in urease activity. The expressions of EFG1, HWP1 and SAP2 genes were significantly down-regulated, however, LIP1 was upregulated by P.mirabilis. In the presence of P.mirabilis carbonhydrates, amino acids, polyamine and lipid metabolisms were altered in C.albicans. Interestingly, the putrescine level was increased up to 230 fold in dual-species biofilm compared to monospecies C.albicans biofilm. To our knowledge, this is the first study to investigate the impact of each microbial pathogen on the dual microbial environment by integration of metabolomic data.

Propolis loaded liposomes: evaluation of antimicrobial and antioxidant activities

Propolis, a natural bee product, has both antimicrobial/antifungal and antioxidant characteristics. Active substances having antimicrobial and antifungal effects are used to avoid infections, which develop during long treatment process of chronic wounds. Antioxidant substances protect wound areas against the effect of free radicals and accelerate the healing process. For this purpose, propolis was used to develop topical liposome formulations for wound treatment. Characterization studies (particle size distribution, polydispersity index, Zeta Potential, morphology pH, loading capacity, encapsulation efficiency, in-vitro release behaviour) as well as stability studies were performed. Then in-vitro antioxidant (free radical scavenging capacity and trolox equivalent antioxidant capacity) and antimicrobial/antifungal activities of formulations have been evaluated. The particle size of formulations was found within the range of 300-750 nm depending on the concentration of lipid and water phase in the formulation. The Zeta Potential and pH values of optimum formulation were -23.0 ± 0.666 and 6.34, respectively. Loading capacity and encapsulation efficiency were 66.535 ± 2.705% and 57.321 ± 2.448%. At the end of 8 h, 48.16% of propolis was released and the formulations were found stable during 3 months at +4 °C. Drug loaded liposome formulations significantly scavenged the ABTS⁺ radical in a dose-dependent manner of propolis when compared with unloaded liposome formulations (p < 0.05). The minimum inhibitory concentration (MIC) values of liposomes ranged from 512 to 128 μg/mL for bacteria and 256 to 128 μg/mL for fungi. Overall results showed that effective and innovative alternative was developed for topical application in wound treatment with propolis loaded liposomal formulations having antioxidant and antimicrobial effects.

Investigation of Gelatinase Gene Expression and Growth of Enterococcus faecalis Clinical Isolates in Biofilm Models

Objectives

Enterococcus faecalis is the major reason for biofilm-related infections and it also interacts with Staphylococcus aureus in biofilms. Gelatinase (gelE) enzyme is an important virulence factor of E. faecalis for biofilm formation. This study aimed to compare the biofilm producing E. faecalis isolates from urine and urinary catheters. The influence of S. aureus on the growth of E. faecalis biofilm cells was also investigated in a dual biofilm model in vitro. Another aim was to evaluate E. faecalis gelE gene expression during biofilm formation.

Materials and Methods

Firstly, crystal violet staining was used to measure the total biofilm biomass of the isolates. Secondly, plate counting was performed to determine the biofilm formation ability of E. faecalis isolates and the effect of S. aureus on E. faecalis biofilm formation. Finally, the gelE expression profile of the isolates was assessed by quantitative real time-polymerase chain reaction.

Results

According to crystal violet staining and plate counting, all E. faecalis isolates were biofilm producers and the number of E. faecalis sessile cells increased in the presence of S. aureus. Among the 21 E. faecalis isolates, ten expressed high levels of the gelE gene, while eight of them had low expression profiles (p<0.05).

Conclusion

When they grow together, S. aureus may give some advantages to E. faecalis such as increasing sessile cell growth. The expression of the gelE gene was not affected by E. faecalis biofilm formation of the isolates collected from the patients with urinary tract infections.

Antifungal screening and in silico mechanistic studies of an in-house azole library

Systemic Candida infections pose a serious public health problem with high morbidity and mortality. C. albicans is the major pathogen identified in candidiasis; however, non-albicans Candida spp. with antifungal resistance are now more prevalent. Azoles are first-choice antifungal drugs for candidiasis; however, they are ineffective for certain infections caused by the resistant strains. Azoles block ergosterol synthesis by inhibiting fungal CYP51, which leads to disruption of fungal membrane permeability. In this study, we screened for antifungal activity of an in-house azole library of 65 compounds to identify hit matter followed by a molecular modeling study for their CYP51 inhibition mechanism. Antifungal susceptibility tests against standard Candida spp. including C. albicans revealed derivatives 12 and 13 as highly active. Furthermore, they showed potent antibiofilm activity as well as neglectable cytotoxicity in a mouse fibroblast assay. According to molecular docking studies, 12 and 13 have the necessary binding characteristics for effective inhibition of CYP51. Finally, molecular dynamics simulations of the C. albicans CYP51 (CACYP51) homology model's catalytic site complexed with 13 were stable demonstrating excellent binding.

Liposome-based combination therapy for acne treatment

Acne vulgaris is one of the most common chronic diseases worldwide with the high prevalence ratio of about 80-85% in patients who are in puberty period. For the treatment options, many conventional dosage forms are available; however, existing limitations of systemic administration of drugs (oral antibiotics), such as adverse events and resistance, led for seek of new formulation options. In this study, liposomes containing tetracycline HCl and tretinoin were prepared by the film formation method. In vitro characterization studies revealed that liposomes (111.10 ± 8.02 nm; P.D.I.=0.198 ± 0.03; Z.P.=25.83 ± 0.40 mV) with an encapsulation efficiency more than 80% for both APIs were formulated. In order to maintain a suitable viscosity for topical application, optimized liposomal formulations were dispersed in carbopol-based gel. In vitro release of APIs was sustained for 24 hours with released amounts of 56.44% and 58.44% for tetracycline HCl and tretinoin, respectively. Stability evaluation of both liposomes and liposomes in hydrogels was investigated for 6 months at 4 °C and 25 °C; and no statistically significant change was observed in terms of particle size, zeta potential, encapsulation efficiency, appearance, pH, and viscosity. Cytotoxicity tests confirmed the nontoxic structure of liposomal gel formulations on mice fibroblast cells. In addition, antibacterial efficacy has been proven with Staphylococcus aureus and Streptococcus epidermidis strains as well as the effect on biofilm formation and eradication. As a result, we hereby presented a new combination drug product, which consists of dual active ingredients having comedolytic and bacteriostatic effects in a single, safe, and stable liposome formulation.

Structure Elucidation and Antimicrobial Activities of Secondary Metabolites from the Flowery Parts of Verbascum mucronatum Lam

Objectives

To determine the secondary metabolites from Verbascum mucronatum Lam. and evaluate their antimicrobial activity.

Materials and Methods

Antimicrobial activities of the isolated metabolites were determined using broth microdilutions against the bacteria (Escherichia coli ATCC 25922, Enterococcus faecalis ATCC 29212, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 29213) and fungi (Candida albicans ATCC 90028, Candida krusei ATCC 6258, Candida parapsilosis ATCC 90018).

Results

Four iridoid glycosides; ajugol (1), aucubin (2), lasianthoside I (3), catalpol (4), two triterpenic saponins; ilwensisaponin C (5), ilwensisaponin A (=mimengoside A) (6), and one phenylethanoid glycoside; verbascoside (=acteoside) (7) were isolated from the water soluble parts of the methanolic extract gained flowery parts of V. mucronatum Lam.

Conclusion

Within the obtained compounds, ajugol and ilwensisaponin A showed moderate antimicrobial activity, especially against fungi.

Evaluation of Antimicrobial Durability and Anti-Biofilm Effects in Urinary Catheters Against Enterococcus faecalis Clinical Isolates and Reference Strains

BACKGROUND

Enterococcus faecalis, Escherichia coli, Staphylococcus epidermidis, Pseudomonas aeruginosa and Candida albicans biofilms are major causes of catheter-associated urinary tract infections. Antimicrobial-coated or impregnated urinary catheters are seen as a possible way to prevent these infections.

AIMS

To determine the biofilm-forming ability of 89 E. faecalis isolates from urinary tract infections and to compare several urinary catheters for antimicrobial durability and the inhibitory effects on biofilm formation of different laboratory strains and clinical isolates of E. faecalis.

STUDY DESIGN

In vitro experimental study.

METHODS

The biofilm forming ability of E. faecalis isolates was determined by the crystal violet staining and plate counting methods. For comparison of urinary catheters, biofilms of 45 E. faecalis isolates from the catheter samples of hospitalized patients and five laboratory strains of E. coli ATCC25922, S. epidermidis ATCC35984, P. aeruginosa ATCC27853, E. faecalis ATCC29212 and C. albicans ATCC90028 were formed on the catheters in 24-well tissue culture plates. Scanning electron microscopy analysis was performed to observe biofilms.

RESULTS

All 89 E. faecalis isolates were found to be biofilm positive. Nitrofurazone-impregnated catheters significantly reduced the cell counts of E. faecalis isolates and completely inhibited the formation of P. aeruginosa and S. epidermidis biofilms compared with the others. Regarding reduction of biofilm cell counts, a hydrophilic-coated catheter was more effective against P. aeruginosa, whereas a silver-coated catheter was found to be more effective against S. epidermidis. The nitrofurazone-impregnated catheter had the best antimicrobial durability.

CONCLUSION

Urine isolates of E. faecalis had considerable ability with respect to biofilm formation. The nitrofurazone-impregnated catheter was the most effective against all tested bacteria; however, the effect of a hydrophilic or silver-coated catheter depends on the species present in it.

Nano drug delivery systems and gamma radiation sterilization

In recent years, drug delivery systems such as liposomes and microparticles have been used in clinic for the treatment of different diseases and from a regulatory point of view, a parenterally applied drug and drug delivery systems must be sterile and pyrogen free. Radiation sterilization is a method recognized by pharmacopoeias to achieve sterility criteria of parenterals. It has the ability to kill microorganisms in therapeutic products. The ability of, however, irradiation might also affect the performance of drug delivery systems. One of the most critical points is irradiation dose, because certain undesirable chemical and physical changes may accompany with the irradiation, especially with the traditionally applied dose of 25 kGy. Its ionizing property may cause fragmentation of covalent bond. The care must be paid to the applied dose. In this research, the effects of gamma irradiation on different drug delivery systems such as chitosan microparticles, liposomes, niosomes and sphingosomes were investigated. According to the experimental data, it can be concluded that gamma irradiation can be a suitable sterilization technique for liposome, niosome and sphingosome dispersions. When all irradiated drug carrier systems were taken into consideration, chitosan glutamate microparticles were found as the most radioresistant drug delivery system among the others.

Activity of disinfectants against multispecies biofilms formed by Staphylococcus aureus, Candida albicans and Pseudomonas aeruginosa

Microbial biofilms are a serious threat to human health. Recent studies have indicated that many clinically relevant biofilms are polymicrobial. In the present study, multispecies biofilms were grown in a reproducible manner in a 96-well microtiter plate. The efficacy of nine commercially available disinfectants against Staphylococcus aureus, Candida albicans, and Pseudomonas aeruginosa in multispecies biofilms was determined and compared. The results showed that the direction and the magnitude of the effect in a multispecies biofilm depend on the strain and the disinfectant used and challenge the common belief that organisms in multispecies biofilms are always less susceptible than in monospecies biofilms.