Anti-quorum sensing and antibiofilm activity of coumarin derivatives against Pseudomonas aeruginosa PAO1: Insights from in vitro and in silico studies.

Objectives: Biofilm-associated infections are challenging to manage or treat since the biofilm matrix is impenetrable to most antibiotics. Therefore, the best approach to deal with biofilm infections is to interrupt the construction during the initial levels. Biofilm formation has been regulated through the quorum sensing (QS) network, making it an attractive target for any antibacterial therapy. Materials and Methods: Here, some coumarin members, including umbelliprenin, 4-farnesyloxycoumarin, gummosin, samarcandin, farnesifrol A, B, C, and auraptan, have been assessed as QS inhibitors in silico and in vitro. Their potential inhibitory effects on biofilm formation and virulence factor production of Pseudomonas aeruginosa PAO1 were evaluated. Results: First, the interaction of these compounds was investigated against one of the major transcriptional regulator proteins, PqsR, using molecular docking and structural analysis methodology. After that, in vitro evaluations indicated that 4-farnesyloxycoumarin and farnesifrol B showed considerable reduction in biofilm formation (62% and 56%, respectively), virulence factor production, and synergistic effects with tobramycin. Moreover, 4-farnesyloxycoumarin significantly (99.5%) reduced PqsR gene expression. Conclusion: The biofilm formation test, virulence factors production assays, gene expression analysis, and molecular dynamic simulations data demonstrated that coumarin derivatives are a potential anti-QS family through PqsR inhibition.

Ultra selective and high-capacity dummy template molecular imprinted polymer to control quorum sensing and biofilm formation of Pseudomonas aeruginosa.

Here a highly selective molecular imprinting polymer was developed to attenuate biofilm formation of the multidrug-resistant pathogen Pseudomonas aeruginosa by disrupting the intermolecular signaling system. Firstly, a dummy template molecular imprinting polymer (MIP) was rationally designed through molecular modeling to capture 2-heptyl-3-hydroxy-4-quinolone (Pseudomonas quinolone signal). This multifunctional signaling molecule interferes with the pathogenicity of P. aeruginosa as an auto-inducer. Then, the synthesized MIP and the non-imprinted polymer (NIP) as reference polymer were evaluated for their binding capacity and biofilm inhibition. The results indicated a significant difference in biofilm inhibition (∼56%) between imprinted (∼67%) and non-imprinted (∼11%) polymer, which is an impressive level, especially for the treatment of various surfaces affected by P. aeruginosa. These results open a new window in the special biological application of MIPs as a promising candidate to reduce concerns in clinical or industrial issues by preventing microbial infections.

Bacterial biofilms and their resistance mechanisms: a brief look at treatment with natural agents.

Biofilm is a complex community of microorganisms residing within a polysaccharide and/or protein matrix. Biofilm can be produced by several microorganisms, including various bacteria and fungi. Nowadays, the resistance of biofilm-growing cells to antimicrobials originated from the structural nature of biofilms, and phenotypic alteration of sessile cells is becoming a global issue. Bacterial biofilms are important in various aspects of human health, including chronic infections, dental plaque, and infection of indwelling medical devices such as catheters. They are also a major problem in other industries, including oil recovery, drinking water distribution, papermaking, metalworking, and food processing. Estimates indicate that more than 80% of infectious diseases are biofilm-derived. The aim of this study is to describe mechanisms of antibiotic resistance to provide a better perspective on how to manage it. Moreover, the current strategies for biofilm inhibition were described. Considering that plants are a valuable source of abundant natural chemicals to create prophylactic and therapeutic medicines against biofilm-based infections, significant natural compounds with anti-biofilm properties were highlighted. Finally, natural anti-biofilm compounds under clinical trial evaluation were summarized to provide a background for more extensive researches and assist in opening a new window to novel treatments.

Anti-quorum sensing potential of ketoprofen and its derivatives against Pseudomonas aeruginosa: insights to in silico and in vitro studies.

Antibiotics are usually used for the treatment of bacterial infections, but multidrug-resistant strains are a phenomenon that has been growing at an increasing rate worldwide. Thus, there is an increasing need for novel strategies for combatting infectious diseases. Many pathogenic bacteria apply quorum sensing (QS) to regulate their pathogenicity and virulence factors production. This circuit makes the QS system an attractive target for antibacterial therapy. In the present study, an important member of non-steroidal anti-inflammatory drugs (NSAIDs), by reducing the biofilm and producing QS-regulated virulence factors, ketoprofen and its synthetic derivatives were screened against the Pseudomonas aeruginosa PAO1. All compounds showed anti-biofilm activity (16-79%) and most of them presented anti-virulence activity. In the co-treatment of ketoprofen, G20, G21, or G77 with tobramycin, biofilm is significantly reduced (potentiated to > 50%) in the number of cells protected inside the impermeable matrix. The in silico studies in addition to the similarities between the chemical structures of PqsR natural ligands and ketoprofen derivatives reinforce the possibility that the mechanism of action is through PqsR inhibition. Based on the results, the anti-pathogenic effect was more appreciable in ketoprofen, G77, and G20.

Preparation and in vivo evaluation of nanoliposomes containing vancomycin after intravitreal injection in albino rabbits.

OBJECTIVES: The in vivo efficacy of nanoliposomal formulation of vancomycin against methicillin-resistant Staphylococcus aureus (MRSA) assessed. MATERIALS AND METHODS: Nanoliposomal formulations were prepared and characterized. The in vivo study was carried out on rabbits which received liquid culture medium containing MRSA under anesthesia. After 48 hr, the eyes treated with the liposomal and free form of vancomycin. The rabbits were euthanized at predesignate intervals at 12, 24, 48, 96, 144 hr intervals injection. The antibacterial activity of different vancomycin formulations was assayed by the time killing method. RESULTS: The zeta potential, mean sizes and encapsulation efficacy of liposomal vancomycin were 29.7 mV, 381.93±30.13 nm and 47%, respectively. The results of time-killing studies indicated that the liposomal formula was more effective than the free form of vancomycin. CONCLUSION: The results of this study revealed that liposomal vancomycin formulation is a powerful nano-antibacterial agent to combat infectious endophthalmitis.

Anti-PqsR compounds as next-generation antibacterial agents against Pseudomonas aeruginosa: A review.

Nowadays, due to spreading antibiotic resistance among clinically relevant pathogens, the requirement of novel therapeutic approaches is felt more than ever. One of the alternative strategies is anti-virulence therapy without affecting bacterial growth or viability. In Pseudomonas aeruginosa, an opportunistic human pathogen that exhibits intrinsic multi-drug resistance, both virulence factors' production and biofilm formation depends on its quorum sensing (QS) network. Therefore, targeting the key proteins involved in QS system is an attractive method to overcome P. aeruginosa pathogenicity and resistance. The transcriptional regulator PqsR, also called MvfR, is one of these major proteins which employs 3,4-dihydroxy-2-heptylquinoline (PQS) and 4-hydroxy-2-heptylquinoline (HHQ) as signaling molecules. Reviewing the advances in development of small molecules inhibit this protein, assist to open a new window to smart molecule design that may revolutionize treatment of P. aeruginosa infections.

Evaluation of the Sleep-Prolonging Effect of Lagenaria vulgaris and Cucurbita pepo Extracts on Pentobarbital-Induced Sleep and Possible Mechanisms of Action.

Introduction: Sleeplessness is the most common sleep disorder. In this study, the hypnotic effect of macerated (HAME) and soxhlet (HASE) extract of Lagenaria vulgaris (fruit and seed) and Cucurbita pepo (fruit) were studied in mice. Methods: Extracts and fractions were administered intra-peritoneally (i.p.) in mice 30 min before the sodium pentobarbital (30 mg/kg, i.p.). Moreover, the influence of flumazenil or naloxone on the hypnotic effects of the extract and its toxic effects were evaluated. Results: The HAME and HASE of C. pepo prolonged the pentobarbital-induced sleep duration at dose of 200 mg/kg. The HAME of L. vulgaris (fruit) at dose of 200 mg/kg increased the sleeping time. The HAME and HASE of L. vulgaris (seed) increased sleep duration at doses of 50 and 100 mg/kg. Besides, flumazenil (2 mg/kg) reversed the effects of both diazepam (P < 0.001 vs. diazepam group), 200 mg/kg of HAME of C. pepo and 50 mg/kg of HAME and HASE of L. vulgaris (seed). All fractions especially ethyl-acetate fraction (EAF) of L. vulgaris (seed) increased the sleep duration. Naloxone reversed the hypnotic effect of HAME and HASE of L. vulgaris (seed). The extracts showed no neurotoxic effects on PC12 and L929 cell lines. Conclusion: The results showed that L. vulgaris (seed and fruit) and C. pepo potentiated pentobarbital hypnosis without toxic influence. The hypnotic effects of L. vulgaris seed was greater than its fruit and C. pepo. The GABA and opioid receptors may play role in the sleep-induction of L. vulgaris seed.

Designing and Development of a DNA Vaccine Based On Structural Proteins of Hepatitis C Virus.

BACKGROUND: Hepatitis C virus (HCV) infection is one of the most prevalent infectious diseases responsible for high morbidity and mortality worldwide. Therefore, designing new and effective therapeutics is of great importance. The aim of the current study was to construct a DNA vaccine containing structural proteins of HCV and evaluation of its expression in a eukaryotic system. METHODS: Structural proteins of HCV (core, E1, and E2) were isolated and amplified from JFH strain of HCV genotype 2a using PCR method. The PCR product was cloned into pCDNA3.1 (+) vector and finally were confirmed by restriction enzyme analysis and sequencing methods. The eukaryotic expression of the vector was confirmed by RT-PCR. RESULTS: A recombinant vector containing 2241bp fragment of HCV structural genes was constructed. The desired plasmid was sequenced and corresponded to 100% identity with the submitted sequences in GenBank. RT-PCR results indicated that the recombinant plasmid could be expressed efficiently in the eukaryotic expression system. CONCLUSION: Successful cloning of structural viral genes in pCDNA3.1 (+) vector and their expression in the eukaryotic expression system facilitates the development of new DNA vaccines against HCV. A DNA vaccine encoding core-E1-E2 antigens was designed. The desired expression vector can be used for further attempts in the development of vaccines.