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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.

This study was performed to explore the physicochemical and anti-biofilm properties of rifampin (Rif) and cis-2-decenoic acid (C2DA) co-entrapped in solid lipid nanoparticles, Rif-C2DA-SLN, against staphylococcal biofilm. The formulation was prepared by high-shear homogenization and ultrasound methods and characterized for size, zeta potentials, encapsulation efficacy, drug lipid interaction studies (DSC), shape morphology (TEM), stability studies, and in vitro anti-biofilm activity against Staphylococcus aureus and S. epidermidis biofilm. The zeta potentials, particle sizes, and encapsulation efficacy of final formulations were 19.0 ± 7.64 mV, 127.2 ± 2.8 nm, and approximately 69% (Rif) and 46% (C2DA), respectively. SLN formulations were stable for 12 months. DSC studies showed no chemical interaction between drugs and lipids. SLN formulations showed better in vitro anti-biofilm activity than free forms especially in the stage of biofilm formation. Nanoparticles were not able to remove the formed biofilm. Simultaneous entrapment of Rif and C2DA by SLN is reported for the first time, and Rif-C2DA-SLN can be applied as an efficient nanoparticulate system with potential anti-biofilm activities. These data suggest that the combined strategies for delivery of both C2DA and Rif by nanoparticulate systems would pave the way toward developing the strategies to combat biofilms.

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.

Microbial resistance to classical antibiotics and its rapid progression have raised serious concern in the treatment of infectious diseases. Recently, many studies have been directed towards finding promising solutions to overcome these problems. Phytochemicals have exerted potential antibacterial activities against sensitive and resistant pathogens via different mechanisms of action. In this review, we have summarized the main antibiotic resistance mechanisms of bacteria and also discussed how phytochemicals belonging to different chemical classes could reverse the antibiotic resistance. Next to containing direct antimicrobial activities, some of them have exerted in vitro synergistic effects when being combined with conventional antibiotics. Considering these facts, it could be stated that phytochemicals represent a valuable source of bioactive compounds with potent antimicrobial activities.

Salvia, a member of the Lamiaceae family, represents more than 58 species in Iran. In the present study, antibacterial and cytotoxic activity of extracts obtained from the roots of Salvia tebesana and Salvia sclareopsis were investigated. The antibacterial activity of the extracts was investigated against 4 bacterial strains and yeast using serial dilution method. The petroleum ether and CH(2)Cl(2) extracts of S. tebesana showed a good activity against Gram-positive bacteria particularly Bacillus cereus (MIC 1.25 mg/mL) while Gram-negative bacteria and yeast were resistant to the extracts. Also, the cytotoxic effects of the extracts on A2780 (ovarian), MCF-7 (breast) and DU 145 (prostate) cancer cell lines were examined using AlamarBlue(®) assay. The petroleum ether and CH(2)Cl(2) extracts of S. tebesana were found to be cytotoxic against the tested cell lines, with IC(50) values less than 50 µg/mL. The petroleum ether extract also showed a potent anti-proliferative activity against DU 145 cells with the lowest IC(50) value (6.25 µg/mL).

Today, antivirulence compounds that attenuate bacterial pathogenicity and have no interference with bacterial viability or growth are introduced as the next generation of antibacterial agents. However, the development of such compounds that can be used by humans is restricted by various factors, including the need for extensive economic investments, the inability of many molecules to penetrate the membrane of Gram-negative bacteria, and unfavorable pharmacological properties and cytotoxicity. Here, we take a new and different look into two frequent supplements, vitamin E and K(1), as anti-quorum-sensing agents against Pseudomonas aeruginosa, a pathogen that is hazardous to human life and responsible for several diseases. Both vitamins showed significant anti-biofilm activity (62% and 40.3% reduction by vitamin E and K(1), respectively), and the expression of virulence factors, including pyocyanin, pyoverdine, and protease, was significantly inhibited, especially in the presence of vitamin E. Cotreatment of constructed biofilms with these vitamins plus tobramycin significantly reduced the number of bacterial cells sheltered inside the impermeable matrix (71.6% and 69% by a combination of tobramycin and vitamin E or K(1), respectively). The in silico studies, besides the similarities of chemical structures, reinforce the possibility that both vitamins act through inhibition of the PqsR protein. This is the first report of the antivirulence and antipathogenic activity of vitamin E and K(1) against P. aeruginosa and confirms their potential for further research against other multidrug-resistant bacteria.

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.

Ozone has been fascinated by researchers as an outstanding disinfectant due to its oxidizing properties. It can react with unsaturated substrates chemically, which results in active ozonized compounds. In literature, ozonized olive oil was characterized by different factors such as peroxide value (PV), a significant feature to define the quality of oils. It has been proven previously that even minor changes in the reaction conditions can effect on the PV. In this study, peroxide content was evaluated in extra virgin olive oil and its ozonized form under various conditions including variable temperatures, sample amounts and reaction times. The results indicated that although iodometric method is an official technique for determining the PV of oils, but also dependent to the amount, temperature and time for ozonized olive oil.

There has been increasing interest in the food safety, due to growing evidence for several health detriments of chemical additives including preservatives and colors. Since it has already been proven that consumption of chemical colors is associated with complications such as behavior change in children, it is important to evaluate plant pigments as new food colors. In addition to the palatability of their color, in the present study, the antimicrobial and antioxidant characteristics of three carotenoids (annatto, paprika and lutein) were investigated to find out whether can be used to decrease the chemical preservatives content of food products. The antimicrobial activity of these natural pigments was assessed by determination of MIC and MBC against ten microorganisms. The results indicated that all tested carotenoids, especially annatto, have antimicrobial effect particularly against Gram-positive bacteria including Staphylococcus aureus, Staphylococcus epidermidis, Bacillus cereus, Bacillus subtilis, Listeria monocytogenes and Streptococcus pyogenes. Among them, the most susceptible strain was B. subtilis (MIC = 0.093 mg/mL, MBC = 0.187 mg/mL). Moreover, the antioxidant properties were also evaluated using two assays: one in aqueous system (DPPH) and another in lipid system (β-carotene bleaching test, BCB). Both antioxidant assays (DPPH and BCB) confirmed that annatto has potent antioxidant activity (IC50 = 68.52 and 73.12 μg/mL, respectively) in comparison with the tested formulation of paprika and lutein. These findings demonstrated that natural pigments may be interesting additives for use as food colors and co-preservatives to reduce chemicals in food matrices.

Misuse of antibiotics in animal husbandry and presence of their residues in animal foods is a serious crisis worldwide and thus, monitoring the level of them in food samples is vital for human health. Herein, a fluorescent aptasensor was developed for highly sensitive quantification of oxytetracycline (OTC) in food samples. This method is based on OTC aptamer conjugated to magnetic beads, functioned as recognition element, complementary strand of OTC aptamer, and PicoGreen (PG) as a sensitive double-stranded DNA (dsDNA) fluorescent dye. Formation of OTC aptamer-magnetic bead conjugate provides the opportunity of sample condensation and separation technology. Additionally, the presence of complementary strand leads to significant fluorescence signal alteration of aptasensor in the presence or absence of target and a noteworthy improvement of the aptasensor sensitivity. In the absence of target, complementary strand could bind to aptamer and form dsDNA on the surface of magnetic bead. As a consequence, adding PG to the sample leads to observation of high fluorescence signal from sample. In contrast, once OTC is added to the sample, it binds to OTC aptamer-magnetic bead complex and prevents hybridization of OTC aptamer and its complementary strand. Hence, after addition of PG to the sample, a weak fluorescence intensity is measured. Under optimized conditions, the linear ranges for OTC detection were 0.2–2 nM and 2–800 nM. The detection limit was calculated to be as low as 0.15 nM for the fabricated aptasensor. Besides the great sensitivity, proposed method demonstrated superior specificity towards OTC once it was used against several antibiotics. More significantly, the recovery rates of OTC in milk ranged from 96.46% to 101.5%, implying the great feasibility of designed sensor as well as its potential to be employed for analysis of OTC in real samples.

The aim of this study was to investigate volatile composition of the essential oil (EO) of Nepeta sintenisii Bornm. ( N. sintenisiig ), and its antioxidant, antimicrobial and cytotoxic activities. The EO was obtained by means of hydrodistillation and its components were analyzed using gas chromatography and mass spectrometry (GC/MS). The main constituents of the EO were found to be 4aα,7α,7aβ-Nepetalactone (51.74%), β-Farnesene (12.26%), 4aα,7α,7aα-Nepetalactone (8.01%), Germacrene-D (5.01%), and 4aα,7β,7aα-Nepetalactone (3.71%); these together constituted 95.81% of the extracted oil. The antimicrobial activity of the EO against eleven bacterial strains and one fungus was studied. The EO showed potent and broad-spectrum antibacterial effects against both Gram-positive and Gram-negative bacteria, and also possessed antifungal activity against Candida albicans . In vitro cytotoxicity evaluation against four cell lines of human ovarian carcinoma (A2780), cervical cancer (Hela), human colon adenocarcinoma (LS180), and human breast adenocarcinoma (MCF-7), and Human Umbilical Vein Endothelial Cells (HUVEC (as a normal cell line), showed a potent anti-proliferative activity of the oil with the lowest IC 50 value (20.37 μg/mL) belonging to the Hela cells. The IC 50 value for normal human cell line (HUVEC) was 219 μg/mL. Also, antioxidant activity of the EO was evaluated using 1,1-diphenyl-2-picrilhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) methods. The oil exhibited weak antioxidant activity in DPPH test (IC 50: 7.16 mg/mL) and FRAP (IC 50: 0.82 mM Fe 2+ /mg EO) assay. The present results suggested promising cytotoxic, antibacterial, and antifungal properties for the N. sintenisii EO.

Aptamers specific for the antibiotic streptomycin were identified by a modified SELEX procedure that employs magnetic beads. After eight rounds of selection, twenty-six aptamers were identified and clustered into seven groups according to similarities in their sequences. The binding constant of three sequences from different groups were determined by colorimetric assays using unmodified gold nanoparticles (AuNPs). These most suitable aptamers were then truncated, and finally a 23-base sequence was identified that has the highest affinity (Kd = 132.3 nM) and selectivity. The assay was employed to analyze streptomycin residue in raw milk samples by ratiometric spectrophotometry at 520 and 660 nm, respectively. The analytical range extends from 180 to 1000 nM, and the LOD is 47.2 nM which is better than that of HPLC (4 μM). The interaction between aptamer and streptomycin was studied by molecular modeling. In our perception, this colorimetric assay provides a viable method for fast analysis of streptomycin in raw milk.

The use of some Stachys genus as herbal remedies is known and the aerial parts have a pharmaceutical interest, being used in Anatolia and Iran as wild tea. In this study, chemical composition, antimicrobial, antioxidant, and antiproliferative activities of the methanolic extract and essential oil (EO) of Stachys parviflora L. (S. parviflora) were evaluated. Qualitative analysis of metabolites of S. parviflora methanolic extract was studied using liquid chromatography coupled to high resolution mass spectrometry (LC-ESI/LTQOrbitrap/MS), evidencing the presence of phenolic acids and flavonoids derivatives. The EO was analyzed using gas chromatography coupled to mass spectrometry (GC/MS). Eighty-seven compounds were characterized in the EO of S. parviflora, of which α-terpenyl acetate (23.6%), β-caryophyllene (16.8%), bicyclogermacrene (9.3%), spathulenol (4.9%) and α-pinene (4.2%) were found to be the major components. The highest antimicrobial effect of EO was found to S. aureus and B. cereus (MIC = 0.01 μg/ml), while the highest activity of extract was against B. cereus (MIC = 125 μg/ml). The methanolic extract exhibited strong antioxidant activity in DPPH (IC50 = 76.87 μg/ml) and β-carotene/linoleic acid assay (BCB, IC50 = 188.47 μg/ml) methods. Furthermore, in vitro cytotoxicity evaluation against three cell lines namely human ovarian carcinoma (A2780), human colon carcinoma (HCT), and mouse melanoma cell line (B16F10), showed an anti-proliferative activity of the EO ranging from IC50 value 30.95 μg/ml to 16.55 μg/ml. The results from this study have demonstrated the promising cytotoxic, antibacterial, and antifungal properties of S. parviflora, which could have wide potential applications in food and pharmaceutical industries.

Human serum albumin (HSA) is the most frequent protein in blood plasma. Albumin transports various compounds, preserves osmotic pressure, and buffers pH. A unique feature of albumin is its ability to bind drugs and other bioactive molecules. However, it is important to consider binary and ternary systems of two pharmaceuticals to estimate the effect of the first drug on the second one and physicochemical properties. Different techniques including time-resolved, second-derivative and anisotropy fluorescence spectroscopy, resonance light scattering (RLS), critical induced aggregation concentration (C CIAC), particle size, zeta potential and stability analysis were employed in this assessment to elucidate the binding behavior of Amlodipine and Aspirin to HSA. Moreover, isothermal titration calorimetric techniques were performed and the QSAR properties were applied to analyze the hydration energy and log P. Multiple sequence alignments were also used to predict the structure and biological characteristics of the HSA binding site. Time-resolved fluorescence spectroscopy showed interaction of both drugs to HSA based on a static quenching mechanism. Subsequently, second-derivative fluorescence spectroscopy presented different values of parameter H in binary and ternary systems, which were suggested that tryptophan was in a more polar environment in the ternary system than in a binary system. Moreover, the polydispersity index and results from mean number measurements revealed that the presence of the second drug caused a decrease in the stability of systems and increased the heterogeneity of complex. It is also, observed that the gradual addition of HSA has led to a marked increase in fluorescence anisotropy (r) of Amlodipine and Aspirin which can be suggested that the drugs were located in a restricted environment of the protein as confirmed by Red Edge Excitation Shift (REES) studies. The isothermal titration calorimetric technique demonstrated that the interaction of the drugs with HSA was an enthalpically-driven process. The present experiment showed that the binding of Amlodipine and Aspirin to HSA induced a conformational change of HSA. It was also identified that the protein binding of the first drug could be affected by the second drug. Such results can be of great use for understanding the pharmacokinetic and pharmacodynamic mechanisms of drugs.

Chemical composition, antibacterial activity, and cytotoxicity of essential oil (EO) obtained from the aerial parts of Nepeta ucrainica L. spp. kopetdaghensis was investigated in the present study. Chemical composition of the EO was analyzed using GC–MS method. Sixty compounds representing 98.7% of the total oil were characterized. The oil was predominated by sesquiterpene hydrocarbons, and the main components were germacrene D (53.0%), bicyclogermacrene (6.4%), β-bourbonene (4.3%), β-elemene (3.3%), spathulenol (3.2%), cubenol (2.8%), trans -caryophyllene (2.8%), germacrene A (2.1%), and δ-cadinene (2.0%). The antibacterial activity of the EO was investigated against 6 bacterial strains using serial dilution method. The essential oil showed a good activity against Gram-positive bacteria particularly Staphylococcus aureus (minimum inhibitory concentration [MIC] = 14 μg/mL, minimum bactericidal concentration [MBC] = 14 μg/mL), but Gram-negative bacteria were resistant to the oil. Also, the cytotoxic effects of the EO on human ovarian carcinoma A2780 cell line and human breast adenocarcinoma MCF-7 cell line were examined using 3-(4,5-dimethylthiazole-2-yl)-2,5-biphenyl tetrazolium bromide [MTT] assay. The EO was found to be cytotoxic against the tested cell lines, with IC 50 values less than 50 μg/mL for both A2780 and MCF-7 cells.

Chemical composition and biological (antimicrobial, antioxidant and cytotoxic) activities of essential oils (EO) obtained from the aerial parts of Glycyrrhiza triphylla Fisch. & C.A.Mey (G. triphylla) were evaluated in the present study. The EO was isolated and analyzed using gas chromatography-mass spectrometry (GC-MS). Fifty-five compounds representing 99.3% of the total oil composition were identified. Major components of the oil were β-caryophyllene (25.4%), limonene (16.7%), β-myrcene (16.0%) and α-humulene (4.4%). The oil composition was dominated by the presence of sesquiterpene hydrocarbons comprising 43.6% of the total oil. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the oil were determined against eight bacterial strains and one fungus. The EO showed a good antibacterial activity against both Gram-positive and Gram-negative bacteria. The most susceptible strain was Micrococcus luteus (MIC = 2.7 μg/mL, MBC = 43.6 μg/mL). The antioxidant potential of the EO was examined using DPPH and β-carotene/linoleic acid (BCB) assays. The oil was considerably active in the DPPH assay (IC50 = 100.40 ± 0.03 μg/mL). Moreover, in vitro cytotoxic activity was assessed against six cancer cell lines using MTT assay. The EO showed no significant cytotoxic activity. In light of the present findings, G. triphylla oil may deserves to be further investigated for its potential therapeutic effects and also as a natural preservative in food industry.

Microbial biofilms are a main cause of many chronic infections and mortalities, such as dental caries, cystic fibrosis, osteoradionecrosis, urinary tract infections and native valve endocarditis. These polymeric matrices are sessile communities with different rules from those forms via known planktonic bacteria. One of the important biofilm-producing human pathogens is Pseudomonas aeruginosa, which causes death in the majority of people who suffer from cystic fibrosis, AIDS, burns and neutropenic cancer. To find a method for controlling the growth and resistance of P. aeruginosa biofilm, this study investigated the dispersion induction of this microorganism with a diffusible signal factor (DSF), cis-2-decenoic acid (CDA), in combination with Tobramycin as a useful antibiotic. Our findings confirmed that although CDA did not act as a dispersion inducer in this experiment, it did show an antimicrobial effect and decreased the MIC of Tobramycin. These results suggested that research on the probable new effects of DSF molecules will result in advances in the control of biofilm infections.

Pseudomonas aeruginosa is an opportunistic human pathogen and a common Gram-negative bacterium in hospital-acquired infections. It causes death in many burn victims, cystic-fibrosis and neutropenic-cancer patients. It is known that P. aeruginosa biofilm maturation and production of cell-associated and extracellular virulence factors such as pyocyanin, elastase and rhamnolipids are under the control of a quorum-sensing (QS) system. Among several proteins involved in the Pseudomonas QS mechanism, LasR and PqsE play an important role in its cascade signaling system. They can cause increases in QS factors, biofilm maturation, and the production of virulence factors. Therefore, inhibition of these proteins can reduce the pathogenicity of P. aeruginosa. According to the structure of corresponding auto-inducers bound to these proteins, in silico calculations were performed with some non-steroidal anti-inflammatory drugs (NSAIDs) to estimate possible interactions and find the co-inhibitors of LasR and PqsE. The results showed that oxicams (Piroxicam and Meloxicam) can interact well with active sites of both proteins with the Ki of 119.43 nM and 4.0 μM for Meloxicam and 201.39 nM and 4.88 μM against LasR and PqsE, respectively. These findings suggested that Piroxicam and Meloxicam can be used as potential inhibitors for control of the P. aeruginosa QS signaling system and biofilm formation, and may be used in the design of multiple inhibitors.

Background: Today, the use of cyclodextrins (CDs) is a major concern in drug formulations to improve solubility and stability of compounds. It has been known that CDs can reduce the antimicrobial effectiveness of preservatives by formation of inclusion complexes. Objectives: In this study the interaction between commonly used preservatives, benzalkonium chloride (BZCl) or methyl paraben (MP), with synthetic CDs (HP γ-CD or SBE β-CD) in the presence or absence of ethylene diamine tetra acetic acid (EDTA), as a preservative potentiator, and fluorometholone was investigated. Materials and Methods: The tests were performed during a 4 week period according to the preservative effectiveness test of USP 2010. Results: The results showed that CDs reduce the effectiveness of BZCl and MP even in the presence of drug molecules. The only exception was HP γ-CD 5% solution with BZCl and EDTA which was effective against tested microorganisms both in the presence and absence of drug molecules. Conclusions: The solution of HP γ-CD 5% with BZCl 0.02% and EDTA 0.1% was selected as a good carrier for dissolving fluorometholone for use as an eye drop.