The anti MRSA biofilm activity of Thymus vulgaris essential oil in nanovesicles

A trinuclear Zn (II) schiff base dicyanamide complex attenuates bacterial biofilm formation by ROS generation and membrane damage and exhibits anticancer activity

A trinuclear Zn (II) complex, [(ZnL{N(CN)2})2Zn], termed complex 1 has been synthesized by the reaction of an aqueous solution of sodium dicyanamide to the methanolic solution of Zn (CH3COO)2, 2H2O and corresponding Schiff base (H2L) which is derived from 1:2 condensation of 1, 4 butane diamine with 3-ethoxy salicylaldehyde. Complex 1 is characterized by elemental analysis, IR, UV and Single X-ray diffraction study. Drug resistance is a growing global public health concern that has prompted researchers to look into advanced alternative treatment modalities. In this context, complex 1 has shown promising antibacterial and antibiofilm efficacy against gram-positive Staphylococcus aureus and Methicillin-resistant Staphylococcus aureus strains. Complex 1 attenuated Staphylococcal biofilm formation by reducing several virulence factors including the formation of extracellular polysaccharide matrix, slime, haemolysin, staphyloxanthin, auto-aggregation, cell surface hydrophobicity, and motility. Notably, complex 1 mechanistically potentiated Reactive Oxygen Species (ROS) generation within the bacterial cells, leading to the damage of bacterial cell membrane followed by DNA leakage and thereby impeding the growth of Staphylococcus aureus. Furthermore, complex 1 significantly exhibited anticancer activity by reducing the growth of prostate adenocarcinoma cells. It obstructed the migration of cancer cells by potentiating apoptosis and arresting the cell cycle at the G2/M phase. In summary, complex 1 could act as a potent candidate for the generation of novel antibacterial, antibiofilm as well as anticancer treatment regimens for the management of drug-resistant biofilm-mediated Staphylococcus aureus infection and lethal prostate malignancy.

Combining microfluidics and coaxial 3D-bioprinting for the manufacturing of diabetic wound healing dressings

Diabetic foot ulcers (DFUs) are a crucial complication of diabetes, as in a diabetic wound, each step of the physiological healing process is affected. This entails a more easily infectable wound, and delayed tissue regeneration due to the inflammation that occurs, leading to a drastic decrease in the overall patient's quality of life. As a strategy to manage DFUs, skin alternatives and wound dressings are currently receiving a lot of attention as they keep the wound environment "under control", while providing bioactive compounds that help to manage infection and inflammation and promote tissue repair. This has been made possible thanks to the advent of emerging technologies such as 3D Bioprinting to produce skin resembling constructs or microfluidics (MFs) that allows the manufacture of nanoparticles (NPs) that act as drug carriers, in a prompt and less expensive way. In the present proof-of-concept study, the possibility of combining two novel and appealing techniques in the manufacturing of wound dressings has been demonstrated for first time. The novelty of this work consists in the combination of liposomes (LPs) encapsulating the active pharmaceutical ingredient (API) into a hydrogel that is further printed into a three-dimensional scaffold for wound dressing; to the knowledge of the authors this has never been done before. A grid-shaped scaffold has been produced through the coaxial 3D bioprinting technique which has allowed to combine, in one single filament, two different bioinks. The inner core of the filament is a nanocomposite hydrogel consisting of hydroxyethyl cellulose (HEC) and PEGylated LPs encapsulated with thyme oil (TO) manufactured via MFs for the first time. The outer shell of the filament, instead, is represented by a hybrid hydrogel composed of sodium alginate/cellulose nanocrystals (SA/CNC) and enriched with free TO. This provides a combination of two different release ratios of the API, a bulk release for the first 24 h thanks to the free TO in the shell of the filament and a sustained release for up to 10 days provided from the API inside the LPs. Confocal Microscopy verified the actual presence of the LPs inside the scaffold after printing and evaluation using the zone of inhibition test proved the antibacterial activity of the manufactured scaffolds against both Gram-positive and Gram-negative bacteria.

Effect of thymol on antimicrobial susceptibility, and adhesion genes expression of uropathogenic Escherichia coli isolated from pediatric urinary tract infection

BACKGROUND

Uropathogenic Escherichia coli (UPEC) is a common cause of urinary tract infections (UTI) in children and currently is one of the leading medical problems. Due to the increase in antibiotic resistance rate, herbal medicines with lower side effects were considered.

OBJECTIVE

This study aimed to identify the afa, fimH, and sfa genes of UPEC bacteria isolated from pediatric UTI to investigate the effect of the thyme on the expression of fimH gene.

STUDY DESIGN

In this cross-sectional study, 160 UPEC were isolated from pediatric UTIs. An antibiotic susceptibility test was performed on six families of antibiotics, including beta-lactams, quinolones, aminoglycosides, carbapenems, sulfonamides, and nitrofurantoin. The micro-broth dilution method was used to determine MIC of thymol. The biofilm production ability of isolated strains was quantified by the microtiter plate method. The PCR technique was used to detectfimH, afa, and sfa adhesion genes, and real-time PCR was used to measure the fimHgene expression.

RESULTS

The results of the antibiogram showed that the lowest and highest resistance related to meropenem and imipenem (zero), and 72.5% for cephalothin. MIC showed 80.7% of the isolates were sensitive to thymol. The biofilm production results showed that 3.12%, 53.75%, and 43.12% of the isolates were strong, weak, and no-biofilm (Zero) producers, respectively. After thymol treatment, 26.25% and 73.75% of isolates were weak and no-producer (Zero) biofilms, respectively and there was a significant correlation (P-value = 0.042) compared to the control group. The frequency of fimH, sfa, and afa genes was 53.1%, 49.4%, and 29.4%, respectively. The expression of fimHgene after 48 h thymol treatment decreased significantly (P-value< 0.05).

CONCLUSION

Due to the significant effects of thymol in preventing the expression of the adhesion gene (fimH) of UPEC bacteria, our study is a proof-of-concept study evaluating bacterial sensitivity to Thymol and its effect on biofilm production in vitro. Given the demonstrated promising results of Thymol's effectiveness and the increase in bacterial antibiotic resistance, further studies should be undertaken to determine the safety and effectiveness of Thymol use in the clinical treatment of urinary tract infection. We believe that Thymol may prove to be an effective adjunct to the treatment of bacterial urinary tract infections.

In-vitro antibacterial activity and mechanism of Monarda didyma essential oils against Carbapenem-resistant Klebsiella pneumoniae

To fight the global epidemic of drug-resistant bacteria, essential oils have gained increasing attention as a new source of antibiotics. The antimicrobial activity of Monarda didyma essential oils (MDEO) for the Carbapenem-resistant Klebsiella pneumoniae (CRKP) strains were determined by agar disc diffusion assay and broth microdilution assay. To further understand MDEO efficacy, a time-growth curve was performed. The biofilm formation of CRKP were determined by crystalline violet staining method, additionally, changes in intracellular Adenosine triphosphate (ATP), protein, Alkaline phosphatase (AKP) activities, and membrane integrity were investigated to assess the influence of MDEO on cell membrane damage. Finally, the activities of key enzymes in the tricarboxylic acid (TCA) pathways and pentose phosphate (PPP) pathways were examined to determine the effect of MDEO on the respiratory metabolism of CRKP. This study presents the antibacterial mechanism of MDEO against CRKP with a minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of 1.25 mg/ml. To understand MDEO efficacy, a time-kill kinetics approach was performed. The bactericidal effect of MDEO was evident at 2 h compared to the control at its MIC and 2MIC. Surface electron microscopic and ATP assay studies provided evidence for the multi-target action of MDEO against CRKP. MDEO could inhibit CRKP biofilm formation. MDEO could also cause irreversible damage to the CRKP cell membrane, resulting in the leakage of biological macromolecules (protein, ATP) and the reduction of intracellular enzymes (AKP) activities. Finally, MDEO affected the pathways of respiratory metabolism, such as PPP and TCA pathways. MDEO could reduce the activity of key enzymes (Glucose-6-phosphate dehydrogenase, citrate synthase, isocitrate dehydrogenase, and α-ketoglutarate dehydrogenase) in the PPP and TCA pathways to exert its biological effects against CRKP. These results suggest MDEO can exert inhibitory effects on CRKP, and potential mechanisms of action including inhibition of biofilm formation, damage of cell membrane structure and inhibition of energy metabolism.

Ozonated Oil in Liposome Eyedrops Reduces the Formation of Biofilm, Selection of Antibiotic-Resistant Bacteria, and Adhesion of Bacteria to Human Corneal Cells

The recent attention to the risk of potential permanent eye damage triggered by ocular infections has been leading to a deeper investigation of the current antimicrobials. An antimicrobial agent used in ophthalmology should possess the following characteristics: a broad antimicrobial spectrum, prompt action even in the presence of organic matter, and nontoxicity. The objective of this study is to compare the antimicrobial efficacy of widely used ophthalmic antiseptics containing povidone-iodine, chlorhexidine, and liposomes containing ozonated sunflower oil. We determined the minimum inhibitory concentration (MIC) on various microbial strains: Staphylococcus aureus (ATCC 6538), methicillin-resistant Staphylococcus aureus (ATCC 33591), Staphylococcus epidermidis (ATCC 12228), Pseudomonas aeruginosa (ATCC 9027), and Escherichia coli (ATCC 873). Furthermore, we assessed its efficacy in controlling antibiotic resistance, biofilm formation, and bacterial adhesion. All three antiseptic ophthalmic preparations showed significant anti-microbicidal and anti-biofilm activity, with the liposomes containing ozonated sunflower oil with the highest ability to control antibiotic resistance and bacteria adhesion to human corneal cells.

Current State of Knowledge Regarding WHO High Priority Pathogens-Resistance Mechanisms and Proposed Solutions through Candidates Such as Essential Oils: A Systematic Review

Combating antimicrobial resistance (AMR) is among the 10 global health issues identified by the World Health Organization (WHO) in 2021. While AMR is a naturally occurring process, the inappropriate use of antibiotics in different settings and legislative gaps has led to its rapid progression. As a result, AMR has grown into a serious global menace that impacts not only humans but also animals and, ultimately, the entire environment. Thus, effective prophylactic measures, as well as more potent and non-toxic antimicrobial agents, are pressingly needed. The antimicrobial activity of essential oils (EOs) is supported by consistent research in the field. Although EOs have been used for centuries, they are newcomers when it comes to managing infections in clinical settings; it is mainly because methodological settings are largely non-overlapping and there are insufficient data regarding EOs' in vivo activity and toxicity. This review considers the concept of AMR and its main determinants, the modality by which the issue has been globally addressed and the potential of EOs as alternative or auxiliary therapy. The focus is shifted towards the pathogenesis, mechanism of resistance and activity of several EOs against the six high priority pathogens listed by WHO in 2017, for which new therapeutic solutions are pressingly required.

Anti-Inflammatory and Antimicrobial Properties of Thyme Oil and Its Main Constituents

Thyme oil (TO) is derived from the flowers of various plants belonging to the genus Thymus. It has been used as a therapeutic agent since ancient times. Thymus comprises numerous molecular species exhibiting diverse therapeutic properties that are dependent on their biologically active concentrations in the extracted oil. It is therefore not surprising that oils extracted from different thyme plants present different therapeutic properties. Furthermore, the phenophase of the same plant species has been shown to yield different anti-inflammatory properties. Given the proven efficacy of TO and the diversity of its constituents, a better understanding of the interactions of the various components is warranted. The aim of this review is to gather the latest research findings regarding TO and its components with respect to their immunomodulatory properties. An optimization of the various components has the potential to yield more effective thyme formulations with increased potency.

Ether lipids from archaeas in nano-drug delivery and vaccination

Archaea are microorganisms more closely related to eukaryotes than bacteria. Almost 50 years after being defined as a new domain of life on earth, new species continue to be discovered and their phylogeny organized. The study of the relationship between their genetics and metabolism and some of their extreme habitats has even positioned them as a model of extraterrestrial life forms. Archaea, however, are deeply connected to the life of our planet: they can be found in arid, acidic, warm areas; on most of the earth's surface, which is cold (below 5 °C), playing a prominent role in the cycles of organic materials on a global scale and they are even part of our microbiota. The constituent materials of these microorganisms differ radically from those produced by eukaryotes and bacteria, and the nanoparticles that can be manufactured using their ether lipids as building blocks exhibit unique properties that are of interest in nanomedicine. Here, we present for the first time a complete overview of the pre-clinical applications of nanomedicines based on ether archaea lipids, focused on drug delivery and adjuvancy over the last 25 years, along with a discussion on their pros, cons and their future industrial implementation.

Exploring Possible Ways to Enhance the Potential and Use of Natural Products through Nanotechnology in the Battle against Biofilms of Foodborne Bacterial Pathogens

Biofilms enable pathogenic bacteria to survive in unfavorable environments. As biofilm-forming pathogens can cause rapid food spoilage and recurrent infections in humans, especially their presence in the food industry is problematic. Using chemical disinfectants in the food industry to prevent biofilm formation raises serious health concerns. Further, the ability of biofilm-forming bacterial pathogens to tolerate disinfection procedures questions the traditional treatment methods. Thus, there is a dire need for alternative treatment options targeting bacterial pathogens, especially biofilms. As clean-label products without carcinogenic and hazardous potential, natural compounds with growth and biofilm-inhibiting and biofilm-eradicating potentials have gained popularity as natural preservatives in the food industry. However, the use of these natural preservatives in the food industry is restricted by their poor availability, stability during food processing and storage. Also there is a lack of standardization, and unattractive organoleptic qualities. Nanotechnology is one way to get around these limitations and as well as the use of underutilized bioactives. The use of nanotechnology has several advantages including traversing the biofilm matrix, targeted drug delivery, controlled release, and enhanced bioavailability, bioactivity, and stability. The nanoparticles used in fabricating or encapsulating natural products are considered as an appealing antibiofilm strategy since the nanoparticles enhance the activity of the natural products against biofilms of foodborne bacterial pathogens. Hence, this literature review is intended to provide a comprehensive analysis of the current methods in nanotechnology used for natural products delivery (biofabrication, encapsulation, and nanoemulsion) and also discuss the different promising strategies employed in the recent and past to enhance the inhibition and eradication of foodborne bacterial biofilms.

Recent advances to combat ESKAPE pathogens with special reference to essential oils

Biofilm-associated bacteria, especially ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.), are a serious challenge worldwide. Due to the lack of discovery of novel antibiotics, in the past two decades, it has become necessary to search for new antibiotics or to study synergy with the existing antibiotics so as to counter life-threatening infections. Nature-derived compounds/based products are more efficient than the chemically synthesized ones with less resistance and lower side effects. In this descriptive review, we discuss the most promising therapeutics for the treatment of ESKAPE-related biofilms. The first aspect includes different types of natural agents [botanical drugs, essential oils (EOs), antimicrobial peptides, bacteriophages, and endolysins] effective against ESKAPE pathogens. The second part of the review deals with special references to EOs/essential oil components (EOCs) (with some exclusive examples), mode of action (via interfering in the quorum-sensing pathways, disruption of biofilm and their inhibitory concentrations, expression of genes that are involved, other virulence factors), existing in literature so far. Moreover, different essential oils and their major constituents were critically discussed using in vivo models to target ESKAPE pathogens along with the studies involving existing antibiotics.

Potential of Aromatic Plant-Derived Essential Oils for the Control of Foodborne Bacteria and Antibiotic Resistance in Animal Production: A Review

Antibiotic resistance has become a severe public threat to human health worldwide. Supplementing antibiotic growth promoters (AGPs) at subtherapeutic levels has been a commonly applied method to improve the production performance of livestock and poultry, but the misuse of antibiotics in animal production plays a major role in the antibiotic resistance crisis and foodborne disease outbreaks. The addition of AGPs to improve production performance in livestock and poultry has been prohibited in some countries, including Europe, the United States and China. Moreover, cross-resistance could result in the development of multidrug resistant bacteria and limit therapeutic options for human and animal health. Therefore, finding alternatives to antibiotics to maintain the efficiency of livestock production and reduce the risk of foodborne disease outbreaks is beneficial to human health and the sustainable development of animal husbandry. Essential oils (EOs) and their individual compounds derived from aromatic plants are becoming increasingly popular as potential antibiotic alternatives for animal production based on their antibacterial properties. This paper reviews recent studies in the application of EOs in animal production for the control of foodborne pathogens, summarizes their molecular modes of action to increase the susceptibility of antibiotic-resistant bacteria, and provides a promising role for the application of nanoencapsulated EOs in animal production to control bacteria and overcome antibiotic resistance.

Effect of Thymus vulgaris L. essential oil and thymol on the microbiological properties of meat and meat products: A review

Since foodborne diseases are often considered as one of the biggest public health threats worldwide, effective preservation strategies are needed to inhibit the growth of undesirable microorganisms in food commodities. Up to now, several techniques have been adopted for the production of safe and high-quality products. Although the traditional methods can improve the reliability, safety, and shelf-life of food, some of them cannot be applied without rising health concerns. Thereby, the addition of various phytochemicals has gained much attention during the last decades, especially for meat products that may be contaminated with pathogenic and spoilage organisms.

Thyme (Thymus vulgaris L.), as an important medicinal and culinary herb, is a promising source of bioactive compounds that have a great impact on the microbiological stability of meat by suppressing the undesirable microflora. However, the use of these antimicrobials is still facing difficulties due to their aromatic properties and variable efficacy against targeted species.

In this paper, we provide an overview on the potential effects of thyme essential oil (EO) and thymol as bio-preservative agents in meat products. Furthermore, this paper provides insights into the limitations and current challenges of the addition of EOs and their constituents to meat commodities and suggests viable solutions that can improve the applicability of these phytochemicals.

Thymol Increases Sensitivity of Clinical Col-R Gram-Negative Bacteria to Colistin

Colistin-resistant (Col-R) bacteria are increasing sharply, which poses a serious threat to public health. Thymol is a phenolic compound used for its wide-spectrum antimicrobial activity, while the combination of nontraditional drugs to restore colistin activity is an attractive strategy to treat infections caused by these pathogens. This study showed that thymol could play a synergistic role with colistin against Gram-negative bacteria (GNB), including nonfermenting bacteria and Enterobacteriaceae. According to antimicrobial resistance profiles, most of the colistin-resistant strains we collected showed multidrug-resistant (MDR) phenotypes. The checkerboard method and time-kill curve confirmed the synergistic effect of thymol combined with colistin against Col-R GNB. The synergistic antibiofilm activity of thymol combined with colistin was assessed via crystal violet staining and scanning electron microscopy (SEM) assays. Results showed that compared with a single drug, the combination partially destroyed bacterial cells and inhibit the formation of bacterial biofilms. Mechanismly, the thymol/colistin combination synergistically potentiated the antibacterial activity by accelerating the damage and permeability of the bacterial outer membrane. Preliminary data indicated that the thymol/colistin combination could decrease the number of bacteria ≥2 log10 CFU/mL after 24 h of therapy in a mouse thigh infection model. Our results fully prove that thymol and colistin combination possesses a promising treatment option against colistin-resistant GNB infections. IMPORTANCE Colistin is being considered "the last ditch" treatment in many infections caused by multidrug-resistant GNB clinical isolates, but colistin-resistant (Col-R) strains with different drug resistance mechanisms have appeared worldwide. Hence, it is of great significance to rejuvenate sensitization of clinical Col-R Gram-negative bacteria to colistin. In this study, the thymol/colistin combination showed notable antibacterial activity in vitro and in vivo. These findings suggest that the thymol/colistin combination may have promise as a treatment approach for treating the infections caused by Col-R pathogens.

Thymus vulgaris essential oil + tobramycin within nanostructured archaeolipid carriers: A new approach against Pseudomonas aeruginosa biofilms

BACKGROUND

Pseudomonas aeruginosa biofilms in the respiratory tract of patients with an excessive inflammatory context are difficult to eradicate. New medicines that simultaneously target biofilms and inflammation should be developed.

HYPOTHESIS

Co-delivery of Thymus vulgaris essential oil (EOT) and tobramycin (TB) by nanostructured archaeolipids carriers (NAC) could support nebulization as well as improve EOT and TB antioxidant, anti-inflammatory and antibiofilm activity.

METHODS

NAC_(EOT+TB) were prepared by loading EOT and TB in NAC having a compritol and miglyol core, covered with a shell of archaeolipids, extracted from the hyperhalophylic archaebacteria Halorubrum tebenquichense, and Tween 80. NAC_(EOT+TB) were structurally characterized, including DSC thermograms, Raman spectra, TB release profile, EOT volatilization and in vitro antioxidant activity. In addition, stability upon nebulization, autoclaving and storage were assessed. The antibiofilm activity on P. aeruginosa PAO1 established biofilm of NAC_(EOT+TB) and the cytotoxicity on human lung epithelial cells and macrophage were determined, as well as intracellular reactive oxygen species (ROS) production and cytokines release on LPS stimulated cells.

RESULTS

NAC_(EOT+TB) showed a size of 197 ± 16 nm with PdI of 0.3 ± 0.1 and ζ Potential of -38 ± 3 mV. Structural characterization suggested that EOT was trapped in the compritol-miglyol core and TB was distributed between the surface of nanoparticles and free in solution. NAC_(EOT+TB) displayed a dual release profile of TB, a delayed release of EOT and improved EOTs in vitro antioxidant activity. While NAC_(EOT+TB) preserved its structural features after nebulization, autoclaving and 18 months of storage, carriers without archaeolipids gelled at room temperature and showed a significant increase of size after the same storage time. Below cytotoxic concentration, NAC_(EOT+TB) decreased bacteria viability and enhanced the disruption of established PAO1 biofilms compared to free TB and EOT. Also, the strong entrapment of EOT in NAC_(EOT+TB) delayed its volatilization, decreased intracellular ROS production and maintained its anti-inflammatory activity in LPS stimulated cells.

CONCLUSION

Combination of EOT + TB within NAC_(EOT+TB) result in a stable and nebulizable formulation that enhanced the antioxidant and anti-biofilm activity of free ingredients, improved their ability to decrease intracellular ROS and provided anti-inflammatory activity, at non-cytotoxic concentrations on eukaryotic cells.

Plant-derived nanotherapeutic systems to counter the overgrowing threat of resistant microbes and biofilms

Since antiquity, the survival of human civilization has always been threatened by the microbial infections. An alarming surge in the resistant microbial strains against the conventional drugs is quite evident in the preceding years. Furthermore, failure of currently available regimens of antibiotics has been highlighted by the emerging threat of biofilms in the community and hospital settings. Biofilms are complex dynamic composites rich in extracellular polysaccharides and DNA, supporting plethora of symbiotic microbial life forms, that can grow on both living and non-living surfaces. These enforced structures are impervious to the drugs and lead to spread of recurrent and non-treatable infections. There is a strong realization among the scientists and healthcare providers to work out alternative strategies to combat the issue of drug resistance and biofilms. Plants are a traditional but rich source of effective antimicrobials with wider spectrum due to presence of multiple constituents in perfect synergy. Other than the biocompatibility and the safety profile, these phytochemicals have been repeatedly proven to overcome the non-responsiveness of resistant microbes and films via multiple pathways such as blocking the efflux pumps, better penetration across the cell membranes or biofilms, and anti-adhesive properties. However, the unfavorable physicochemical attributes and stability issues of these phytochemicals have hampered their commercialization. These issues of the phytochemicals can be solved by designing suitably constructed nanoscaled structures. Nanosized systems can not only improve the physicochemical features of the encapsulated payloads but can also enhance their pharmacokinetic and therapeutic profile. This review encompasses why and how various types of phytochemicals and their nanosized preparations counter the microbial resistance and the biofouling. We believe that phytochemical in tandem with nanotechnological innovations can be employed to defeat the microbial resistance and biofilms. This review will help in better understanding of the challenges associated with developing such platforms and their future prospects.

Simultaneous Hydrodistillation-Steam Distillation of Rosmarinus officinalis, Lavandula angustifolia and Citrus aurantium from Morocco, Major Terpenes: Impact on Biological Activities

Interest in the use of essential oils (EOs) in the biomedical and food industries have seen growing over the last decades due to their richness in bioactive compounds. The challenges in developing an EO extraction process that assure an efficient levels of monoterpenes with impact on biological activities have driven the present study, in which the EO extraction process of rosemary, lavender and citrus was performed by simultaneous hydrodistillation-steam distillation, and the influence of EO composition on biological activities, namely antioxidant, anti-inflammatory, antidiabetic, anti-acetylcholinesterase, anti-tyrosinase, antibacterial, and antibiofilm activity, were evaluated. The EO yields of combinations were generally higher than the individual plants (R. officinalis (Ro), L. angustifolia (La), and C. aurantium (Ca)) extracted by the conventional hydrodistillation. The EOs obtained by this process generally had a better capacity for scavenging the free radicals, inhibiting α-glucosidase, and acetylcholinesterase activities than the individual EOs. The combination of EOs did not improve the ability for scavenging peroxide hydrogen or the capacity for inhibiting lipoxygenase activity. The antioxidant activity or the enzyme inhibition activity could not only be attributed to their major compounds because they presented lower activities than the EOs. The chemical composition of the combination Ro:La:Ca, at the ratio 1/6:1/6:2/3, was enriched in 1,8-cineole, linalool, and linalyl acetate and resulted in lower MIC values for all tested strains in comparison with the ratio 1/6:2/3:1/6 that was deprived on those components. The biofilm formation of Gram positive and Gram negative bacteria was impaired by the combination Ro:La:Ca at a sub-inhibitory concentration.

Identification of carbapenems resistant genes on biofilm forming K. pneumoniae from urinary tract infection

The multi-drug resistant effect of the Gram negative bacteria K. pneumoniae was identified by disc diffusion method using specific UTI panel discs of Kleb 1 HX077 and Kleb 2 HX090 HEXA. Among the multi-drug resistant bacteria, the carbapenem resistant (CR) effect of the K. pneumoniae was screened by specific carbapenem detection antibiotics of HEXA HX066 and HX0103 HEXA by disc diffusion method. In addition, the effective antibiotics were further performed against K. pneumoniae by minimum inhibition concentration method. Further, the carbapenemase genes of VIM 1 and IMP 1 were detected from the isolated strains by multiplex PCR method. Furthermore, the biofilm forming ability of selected carbapenem resistant K. pneumoniae was initially identified by tissue culture plate method and confirmed by exopolysaccharide arrest ability of congo red agar assay. Finally, our result was proved that the identified K. pneumoniae is carbapenemase producing strain, and its virulence was extended with strong biofilm formation.

Effectiveness and mechanisms of essential oils for biofilm control on food-contact surfaces: An updated review

Microbial biofilms represent a constant source of contamination in the food industry, being also a real threat for human health. In fact, most of biofilm-producing bacteria are becoming resistant to sanitizers, thus arousing the interest in natural alternatives to prevent biofilm formation on foods and food-contact surfaces. In particular, studies on biofilm control by essential oils (EOs) application are increasing, being EOs characterized by unique mixtures of compounds able to impair the mechanisms of biofilm development. This review reports the anti-biofilm properties of EOs in bacterial biofilm control (inhibition, removal and prevention of biofilm dispersion) on food-contact surfaces. The relationship between EOs effect and composition, concentration, involved bacteria, and surfaces is discussed, and the possible sites of action are also elucidated. The findings prove the high biofilm controlling capability of EOs through the regulation of genes and proteins implicated in motility, Quorum Sensing and exopolysaccharides (EPS) matrix. Moreover, incorporation in nanosized delivery systems, formulation of blends and combination of EOs with other strategies can increase their anti-biofilm activity. This review provides an overview of the current knowledge of the EOs effectiveness in controlling bacterial biofilm on food-contact surfaces, providing valuable information for improving EOs use as sanitizers in food industries.

Thymol and Thyme Essential Oil-New Insights into Selected Therapeutic Applications

Thymol (2-isopropyl-5-methylphenol) belongs to the phenolic monoterpenes and mostly occurs in thyme species. It is one of the main compounds of thyme essential oil. Both thymol and thyme essential oil have long been used in traditional medicine as expectorant, anti-inflammatory, antiviral, antibacterial, and antiseptic agents, mainly in the treatment of the upper respiratory system. The current search for new directions of biological or therapeutic activities of natural plant substances with known structures includes thyme essential oil and thymol. Novel studies have demonstrated their antibiofilm, antifungal, antileishmanial, antiviral, and anticancer properties. Also, their new therapeutic formulations, such as nanocapsules containing these constituents, can be beneficial in medicinal practice and create opportunities for their extensive use. Extensive application of thymol and thyme essential oil in the healthcare sector is very promising but requires further research and analysis.

High Efficacy of Ozonated Oils on the Removal of Biofilms Produced by Methicillin-Resistant Staphylococcus aureus (MRSA) from Infected Diabetic Foot Ulcers

Ozone has a high wound healing capacity and antibacterial properties and can be used as a complementary treatment in infections. Methicillin-resistant S. aureus (MRSA) is the most common pathogen found in infected diabetic foot ulcers. Most of MRSA are resistant to several classes of antibiotics and, therefore, there is a need for new, effective, and well-tolerated agents. Thus, we aimed evaluate the antimicrobial and antibiofilm potentials of ozonated vegetable oils against MRSA strains isolated from diabetic foot ulcers. Six ozonated oils were produced with concentrations of ozone ranging from 0.53 to 17 mg of ozone/g of oil. The peroxide values were determined for each oil. Ozonated oils content on fatty acid was determined by gas chromatography equipped with a flame ionization detector. The antimicrobial susceptibility testing was performed by the Kirby–Bauer disk diffusion method and the effect of ozonated oils on biofilm formation ability and on established biofilms was investigated. In general, the content in identified unsaturated fatty acid in oils decreased with the increase of ozonation time and, consequently, the peroxide value increased. Most bacterial strains were inhibited by ozonated oil at a concentration of 4.24 mg/g. Ozonated oils had moderate to high ability to remove adhered cells and showed a high capacity to eradicate 24 h old biofilms. Our results show promising use of ozonated oils on the treatment of infections, in particular those caused by multidrug-resistant MRSA strains.

A novel Pickering emulsion system as the carrier of tocopheryl acetate for its application in cosmetics

Pickering emulsion (PE) stabilized by bio-compatible polymer nanoparticles (NPs) was first developed for the encapsulation of lipophilic tocopheryl acetate (TA) for its application in cosmetics. The poly(lactide-co-glycolide) (PLGA)/poly(styrene-co-4-styrene-sulfonate) (PSS) NPs were prepared by solvent displacement, and then they were used as emulsifier particles to fabricate TA-encapsulated PE. It was found that the TA encapsulation efficiency was >98%. Scanning electron microscope analysis showed that the obtained PE exhibited 'shell' structure. The PE droplets had spherical shape with diameter around 2 μm and good dispersibility as evidenced by laser scanning confocal microscope. In addition, the PE was stable at the pH range of 4.29-7.07 which was compatible to skin pH. Meanwhile, the PE also showed good storage stability since there was no obvious change in its diameter, PDI and TA retention after storage at 4 °C for 30 days. The DPPH method confirmed that TA retained its antioxidation in the PE preparation process. Moreover, an improved UV irradiation stability was observed for the TA after being encapsulated in the PE. The results of cytotoxicity test suggested that the PE was compatible to the Hacat cell line (human immortalized keratinocytes). And there is negligible influence in the cellular uptake of TA after its encapsulation in the PE. However, the cellular antioxidant activity (CAA) of encapsulated TA presented a significant increase from 1.32 to 1.56 μM quercetin equivalent/mg·mL^-1. Hence, the prepared PE was promising as the carrier of TA for its cosmetic application.

New Tricks for Old Guys: Recent Developments in the Chemistry, Biochemistry, Applications and Exploitation of Selected Species from the Lamiaceae Family

Lamiaceae is one of the largest families of flowering plants comprising about 250 genera and over 7,000 species. Most of the plants of this family are aromatic and therefore important source of essential oils. Lamiaceae are widely used as culinary herbs and reported as medicinal plants in several folk traditions. In the Mediterranean area oregano, sage, rosemary, thyme and lavender stand out for geographical diffusion and variety of uses. The aim of this review is to provide recent data dealing with the phytochemical and pharmacological studies, and the more recent applications of the essential oils and the non-volatile phytocomplexes. This literature survey suggests how the deeper understanding of biomolecular processes in the health and food sectors as per as pest control bioremediation of cultural heritage, or interaction with human microbiome, fields, leads to the rediscovery and new potential applications of well-known plants.

The alarming antimicrobial resistance in ESKAPEE pathogens: Can essential oils come to the rescue?

Antibiotics, considered as a backbone of modern clinical-medicines, are facing serious threats from emerging antimicrobial-resistance (AMR) in several bacteria from nosocomial and community origins and is posing a serious human-health concern. Recent commitment by the Heads of States at the United Nations General Assembly (UNGA, 2016) for coordinated efforts to curb such infections illustrates the scale of this problem. Amongst the drug-resistant microbes, major threat is posed by the group named as ESKAPEE, an acronym for Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp., and Escherichia coli, comprising high to critical drug-resistant, World Health Organization Critical Priority I and II pathogens. The drying pipeline of effective and new antibiotics has worsened the situation with looming threat of heading to a 'post-antibiotic era'. This necessitates novel and effective approaches to combat this life-threatening issue. Medicinal and aromatic plants are hailed as the reservoir of bioactive compounds and can serve as a source of antimicrobial compounds, and some recent leads show that essential oils (EOs) may provide an effective solution for tackling AMR. EOs have shown wide-spectrum antimicrobial potentials via targeting the major determinants of pathogenicity, drug-resistance and its spread including cell membrane, drug efflux pumps, quorum sensing, biofilms and R-plasmids. Latest reports confirm the EOs having strong direct-killing or re-sensitizing potentials to replace or rejuvenate otherwise fading antibiotics arsenal. We discuss herein possibilities of using EOs directly for antimicrobial potentials or in combination with antibiotics to potentiate the later for combating AMR in ESKAPEE pathogens. The current understandings, success stories and challenges for translational success have also been discussed.