Sugar-Based Monoester Surfactants: Synthetic Methodologies, Properties, and Biological Activities.

Glycolipids are biocompatible and biodegradable amphiphilic compounds characterized by a great scientific interest for their potential applications in various technological areas, including pharmaceuticals, cosmetics, agriculture, and food production. This report summarizes the available synthetic methodologies, physicochemical properties, and biological activity of sugar fatty acid ester surfactants, with a particular focus on 6-O-glucose, 6-O-mannose, 6-O-sucrose, and 6'-O-lactose ones. In detail, the synthetic approaches to this class of compounds, such as enzymatic lipase-catalyzed and traditional chemical (e.g., acyl chloride, Steglich, Mitsunobu) esterifications, are reported. Moreover, aspects related to the surface activity of these amphiphiles, such as their ability to decrease surface tension, critical micelle concentration, and emulsifying and foaming ability, are described. Biological applications with a focus on the permeability-enhancing effect across the skin or mucosa, antimicrobial and antifungal activities, as well as antibiofilm properties, are also presented. The information reported here on sugar-based ester surfactants is helpful to broaden the interest and the possible innovative applications of this class of amphiphiles in different technological fields in the future.

Efficacy of UV and UV-LEDs Irradiation Models for Microbial Inactivation Applicable to Automated Sterile Drug Compounding.

LEDs development has attracted attention over conventional mercury lamps for the tiny size, high efficiency, long lifetime, low operating temperature. The antimicrobial effectiveness of traditional UV-lamps radiation (wavelength of 254 nm) compared to UV-C LEDs (LED1 wavelength range 275-286 nm and LED2 range 260-270 nm) was carried out, for possible applications to automated sterile drug compounding. The UV lamp and the tested UV-LED devices remarkably reduced microbial load, following a time-dose response, but the best performance was evidenced by LED1, which guaranteed the complete inactivation of high concentrations of bacteria, yeasts, and spores at doses between 200 and 2000 J/m2.

Synthesis and Biological Evaluation of 6-O-Sucrose Monoester Glycolipids as Possible New Antifungal Agents.

A small library of 6-O-sucrose monoester surfactants has been synthesized and tested against various microorganisms. The synthetic procedure involved a modified Mitsunobu reaction, which showed improved results compared to those present in the literature (higher yields and larger scope). The antifungal activities of most of these glycolipids were satisfactory. In particular, sucrose palmitoleate (URB1537) showed good activity against Candida albicans ATCC 10231, Fusarium spp., and Aspergillus fumigatus IDRAH01 (MIC value: 16, 32, 64 µg/mL, respectively), and was further characterized through radical scavenging, anti-inflammatory, and biocompatibility tests. URB1537 has been shown to control the inflammatory response and to have a safe profile.

Role of melanin in the black yeast fungi Aureobasidium pullulans and Zalaria obscura in promoting tolerance to environmental stresses and to antimicrobial compounds.

The role of melanin in Aureobasidium pullulans ATCC 15233 and Zalaria obscura LS31012019, under simulated osmotic, oxidative, and high temperature stress conditions, on the susceptibility to essential oils (EOs) or antifungals and on the resistance to UV-C radiation was investigated. 93.6% of melanized A. pullulans and 92% of Z. obscura survived to 40 °C for 1 h compared to 77% and 76% of the non-melanized ones, while both yeasts tolerated a high concentration of NaCl (up to 30%) and H2O2 (up to 400 mM) regardless of melanin production. Higher EOs antifungal efficacy was observed in non-melanized cells (growth inhibition zone >30 mm) compared to the melanized ones (25 mm). Similarly, the lowest Minimum Inhibitory Concentrations (MIC) and Minimum Fungicidal Concentration (MFC) values were evidenced for Fluconazole, Clotrimazole, Bifonazole and Amphotericin in the non-melanized fungi. Increasing UV-C intensity (up to 2004.5 J/m2) caused total death in the non-melanized strains compared to about 30% growth reduction in the melanized ones. The results of this investigation, the first focused on the biological role of melanin in "black-fungi", are novel and encourage a better understanding of the biochemical features of melanin in the environmental adaptive ability of the new species Z. obscura.

A Multidisciplinary Approach in Examining the Susceptibility to Microbial Attack of Polyacrylic and Polyurethane Resins Used in Art Restoration.

The synthetic polymers used to protect artworks from deterioration process can be colonized by the fungi and bacteria responsible for the biodeterioration process. In this study, the susceptibility of synthetic polyacrylics and polyurethane resins to microorganisms (Aspergillus niger ATCC 9642, Aureobasidium pullulans ATCC 15233, Chaetomium globosum ATCC 6205, Cladosporium cladosporioides ATCC 16022, Alternaria alternata BC01, Penicillium citrinum LS1 and Pseudomonas aeruginosa ATCC 9027) was investigated. The microbial attack was simulated alone and with a biocide and the related growth was observed up to 21 days for bacteria and 28 days for fungi. The polyacrylic and polyurethane resins were subjected to microbial attack, regardless of the biocide treatment, with a fungal growth from 60% to the complete coverage of the plate surface. Penicillium citrinum showed the greatest adaptation ability and was found in all the examined resins. P. aeruginosa was visible in all the different resins, regardless of the presence of biocide. An environmental scanning electron microscope (ESEM) revealed the presence of fungal conidia and hyphae in the inoculated resins and the Fourier transform IR spectroscopy (FTIR-ATR) indicated chemical transformations in the IR spectra, particularly the hydrolysis of esters, with some differences between the polyacrylic and polyurethane resins, which were probably due to their different chemical features. Overall, our data stress that the chemical, physical and biological deterioration caused by microorganisms capable of degrading synthetic polymers is still a problem in art restoration and that new strategies must be considered to counteract this phenomenon.

Growth ability, carbon source utilization and biochemical features of the new specie Zalaria obscura.

This research investigated the characteristics of Zalaria obscura LS31012019 in terms of growth ability in different media (SDB, YPD and TSB) and temperatures (22, 25 and 37 °C), utilization of several carbon sources (Glucose, Fructose, Lactose, Sucrose, Xylose, Glycerol and Mannitol at 5, 2 and 1%) and several biochemical features (total protein content, Glutathione, pigments), in comparison with those of the phylogenetically related Aureobasidium pullulans ATCC 15233. The best growth of Z. obscura LS31012019 was obtained in YPD at 25 °C with the highest OD value (0.45) after 144 h of incubation, similar to that of A. pullulans ATCC 15233 (0.48). Glucose resulted the preferred carbon source for both the considered yeasts but also sucrose resulted in efficacy supporting the growth of Z. obscura LS31012019 and A. pullulans ATCC 15233, for their ability in converting sucrose to glucose and fructose and the latter into glucose. Interestingly, Z. obscura LS31012019 utilized also glycerol and mannitol. The biochemical analysis showed the similarity of protein profile in Z. obscura LS31012019 and A. pullulans ATCC 15233 (from 90 to 20 kDa) and a reduced GSH content (0.321 and 0.233 µmol/mg). The pigments extraction with hexane generated a yellow oleaginous pellet in both the strains, while a yellow solid matrix more intensely coloured in A. pullulans ATTC 15233 was visible with the following solvent extractions. Overall, our data showed that Z. obscura LS31012019 can grow in different media and temperatures and utilize carbon sources apart from glucose and sucrose, shifting to a non-fermentative metabolism. These results improve the information regarding the characteristics of Z. obscura, opening a new field of investigation for the possible application of new species of black yeasts in human application.

Comparative Analysis of the Antimicrobial Activity of Essential Oils and Their Formulated Microemulsions against Foodborne Pathogens and Spoilage Bacteria.

The antimicrobial activity of several essential oils (EOs) and their related microemulsions (MEs) was investigated. EOs were obtained from Cannabis sativa L. cv CS (C. sativa), Carum carvi L. (C. carvi), Crithmum maritimum L. (C. maritimum), Cuminum cyminum L. (C. cyminum), x Cupressocyparis leylandii A.B. Jacks & Dallim. (C. leylandii), Cupressus arizonica Greene (C. arizonica), Ferula assa-foetida L. (F. assa-foetida)., Ferula gummosa Boiss. (F. gummosa), Juniperus communis L. (J. communis), Juniperus x pfitzeriana (Spath) P.A. Schmidt (J. pfitzeriana), Pimpinella anisum L (P. anisum). Preliminary screening revealed that Cuminum cyminum, Crithmum maritimum, and Pimpinella anisum (10% v/v) were effective against all tested microorganisms (Escherichia coli ATCC 35218, Listeria monocytogenes ATCC 7644, Staphylococcus aureus ATCC 29213, Pseudomonas fluorescens DSM 4358, and Candida albicans ATCC 10231), with growth inhibition diameter from 10 to 25 mm. These EOs were used to formulate the MEs with an average size < 50 nm and a good stability over 30 days. EOs' antimicrobial activity was further enhanced in the MEs, with a generalized lowering of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values. C. cyminum-ME reached, in most cases, MIC two times lower (0.312%) than the corresponding EO (0.625%) and even eight times lower against S. aureus (0.156 vs. 1.25%). A more remarkable microbicide effect was noted for C. cyminum-ME, with MBC values eight times lower (from 0.312 to 0.625%) than the corresponding EO (from 2.5 to 5%). Overall, MEs resulted in an efficient system for EOs encapsulation, enhancing solubility and lowering concentration to exert antimicrobial efficacy.

Synthesis and Biological Characterization of the New Glycolipid Lactose Undecylenate (URB1418).

As a follow-up to our previous studies on glycolipid surfactants, a new molecule, that is lactose 6'-O-undecylenate (URB1418), was investigated. To this end, a practical synthesis and studies aimed at exploring its specific properties were carried out. URB1418 showed antifungal activities against Trichophyton rubrum F2 and Candida albicans ATCC 10231 (MIC 512 µg/mL) and no significant antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa. At the same time, it presented anti-inflammatory properties, as documented by the dose-dependent reduction in LPS-induced NO release in RAW 264.7 cells, while a low antioxidant capacity in the range of concentrations tested (EC50 > 200 µM) was also observed. Moreover, URB1418 offers the advantage of being more stable than the reference polyunsaturated lactose esters and of being synthesized using a "green" procedure, involving an enzymatic method, high yield and low manufacturing cost. For all these reasons and the absence of toxicity (HaCaT cells), the new glycolipid presented herein could be considered an interesting compound for applications in various fields.

A combination of sugar esters and chitosan to promote in vivo wound care.

In recent years, researchers are exploring innovative green materials fabricated from renewable natural substances to meet formulation needs. Among them, biopolymers like chitosans and biosurfactants such as sugar fatty acid esters are of potential interest due to their biocompatibility, biodegradability, functionality, and cost-effectiveness. Both classes of biocompounds possess the ability to be efficiently employed in wound dressing to help physiological wound healing, which is a bioprocess involving uncontrolled oxidative damage and inflammation, with an associated high risk of infection. In this work, we synthesized two different sugar esters (i.e., lactose linoleate and lactose linolenate) that, in combination with chitosan and sucrose laurate, were evaluated in vitro for their cytocompatibility, anti-inflammatory, antioxidant, and antibacterial activities and in vivo as wound care agents. Emphasis on Wnt/ß-catenin associated machineries was also set. The newly designed lactose esters, sucrose ester, and chitosan possessed sole biological attributes, entailing considerable blending for convenient formulation of wound care products. In particular, the mixture composed of sucrose laurate (200 µM), lactose linoleate (100 µM), and chitosan (1%) assured its superiority in terms of efficient wound healing prospects in vivo together with the restoring of the Wnt/ß-catenin signaling pathway, compared with the marketed wound healing product (Healosol®), and single components as well. This innovative combination of biomaterials applied as wound dressing could effectively break new ground in skin wound care.

Extracellular Vesicles from Campylobacter jejuni CDT-Treated Caco-2 Cells Inhibit Proliferation of Tumour Intestinal Caco-2 Cells and Myeloid U937 Cells: Detailing the Global Cell Response for Potential Application in Anti-Tumour Strategies.

Cytolethal distending toxin (CDT) is produced by a range of Gram-negative pathogenic bacteria such as Campylobacter jejuni. CDT represents an important virulence factor that is a heterotrimeric complex composed of CdtA, CdtB, and CdtC. CdtA and CdtC constitute regulatory subunits whilst CdtB acts as the catalytic subunit exhibiting phosphatase and DNase activities, resulting in cell cycle arrest and cell death. Extracellular vesicle (EV) secretion is an evolutionarily conserved process that is present throughout all kingdoms. Mammalian EVs play important roles in regular cell-to-cell communications but can also spread pathogen- and host-derived molecules during infections to alter immune responses. Here, we demonstrate that CDT targets the endo-lysosomal compartment, partially evading lysosomal degradation and exploiting unconventional secretion (EV release), which is largely involved in bacterial infections. CDT-like effects are transferred by Caco-2 cells to uninfected heterologous U937 and homologous Caco-2 cells. The journey of EVs derived from CDT-treated Caco-2 cells is associated with both intestinal and myeloid tumour cells. EV release represents the primary route of CDT dissemination, revealing an active toxin as part of the cargo. We demonstrated that bacterial toxins could represent suitable tools in cancer therapy, highlighting both the benefits and limitations. The global cell response involves a moderate induction of apoptosis and autophagic features may play a protective role against toxin-induced cell death. EVs from CDT-treated Caco-2 cells represent reliable CDT carriers, potentially suitable in colorectal cancer treatments. Our data present a potential bacterial-related biotherapeutic supporting a multidrug anticancer protocol.

3D printed clotrimazole intravaginal ring for the treatment of recurrent vaginal candidiasis.

Vulvovaginal candidiasis is a vaginal infection caused by the fungal pathogen Candida albicans that, most commonly, affects women of reproductive age. Its first-line treatment consists in topical applications of conventional drug formulations (e.g., creams, gels, tablets) containing imidazole drugs. The treatment involves single or multiple daily applications and, in the case of recurrences, daily administration of oral antifungal drugs for up to one month. Intravaginal rings are flexible, biocompatible medical devices that, compared to conventional drug formulations, offer the possibility of a controlled vaginal drug delivery over a determined period with a single application, thus increasing patient compliance. Among innovative manufacturing techniques, in recent years, fused deposition modeling 3D printing has emerged in the pharmaceutical field to produce different therapeutics combining drugs and polymers. This technique allows to print objects layer by layer with many different thermoplastic materials after a computer-assisted design. Thermoplastic polyurethanes are flexible and biocompatible materials that can be efficiently employed for the manufacturing of drug release systems, already utilized to prepare vaginal devices. In this work, we produced a clotrimazole-loaded intravaginal ring by fused deposition modeling 3D printing combining the drug with thermoplastic polyurethane using hot melt extrusion. The rings were computer-designed and then printed with two different drug concentrations (i.e., 2% and 10% w/w). The intravaginal rings were first tested in an agar-diffusion test to evaluate their effectiveness against C. albicans; and the 10% loaded ring was selected for further studies. Drug release was evaluated in two different media (i.e., 50% ethanol and vaginal fluid simulant) showing a sustained release over a period of seven days. Next, in vitro time-kill analysis against C. albicans in simulated vaginal fluid was performed and displayed a complete growth inhibition after 5 days, compared to the control. These results suggest a potential application of these 3D printed intravaginal rings for the treatment of vulvovaginal candidiasis and for the long-time treatment of recurrences.

A Fluorinated Analogue of Marine Bisindole Alkaloid 2,2-Bis(6-bromo-1H-indol-3-yl)ethanamine as Potential Anti-Biofilm Agent and Antibiotic Adjuvant Against Staphylococcus aureus.

Methicillin resistant Staphylococcus aureus (MRSA) infections represent a major global healthcare problem. Therapeutic options are often limited by the ability of MRSA strains to grow as biofilms on medical devices, where antibiotic persistence and resistance is positively selected, leading to recurrent and chronic implant-associated infections. One strategy to circumvent these problems is the co-administration of adjuvants, which may prolong the efficacy of antibiotic treatments, by broadening their spectrum and lowering the required dosage. The marine bisindole alkaloid 2,2-bis(6-bromo-1H-indol-3-yl)ethanamine (1) and its fluorinated analogue (2) were tested for their potential use as antibiotic adjuvants and antibiofilm agents against S. aureus CH 10850 (MRSA) and S. aureus ATCC 29213 (MSSA). Both compounds showed antimicrobial activity and bisindole 2 enabled 256-fold reduction (ΣFICs = 0.5) in the minimum inhibitory concentration (MIC) of oxacillin for the clinical MRSA strain. In addition, these molecules inhibited biofilm formation of S. aureus strains, and compound 2 showed greater eradicating activity on preformed biofilm compared to 1. None of the tested molecules exerted a viable but non-culturable cells (VBNC) inducing effect at their MIC values. Moreover, both compounds exhibited no hemolytic activity and a good stability in plasma, indicating a non-toxic profile, hence, in particular compound 2, a potential for in vivo applications to restore antibiotic treatment against MRSA infections.

Intracellular Survival and Translocation Ability of Human and Avian Campylobacter jejuni and Campylobacter coli Strains.

Campylobacter acts using complex strategies to establish and promote intestinal infections. After ingestion via contaminated foods, this bacterium invades and can survive within the intestinal cells, also inducing epithelial translocation of non-invasive intestinal bacteria. In this investigation, the ability of human and avian C. jejuni and C. coli isolates to survive within two different intestinal epithelial cells lines, Caco-2 and INT 407, as well as the intestinal translocation phenomenon, was assessed. Our data demonstrated that both C. jejuni and C. coli strains survived in Caco-2 (81.8% and 100% respectively) and INT 407 monolayers (72.7% and 100% respectively) within the first 24 h post-infection period, with a progressive reduction in the prolonged period of 48 h and 72 h post-infection. The translocation of the non-invasive E. coli 60/06 FB was remarkably increased in C. jejuni treated Caco-2 monolayers (2.36 ± 0.42 log cfu/mL) (P < 0.01) and less in those treated with C. coli (1.2 ± 0.34 log cfu/mL), compared to E. coli 60/06 FB alone (0.37 ± 0.14 log cfu/mL). Our results evidenced the ability of both human and avian strains of C. jejuni and C. coli to efficiently survive within intestinal cells and induce the translocation of a non-invasive pathogen. Overall, these findings stress how this pathogen can interact with host cells and support the hypothesis that defects in the intestinal barrier function induced by Campylobacter spp. could have potentially negative implications for human health.

Quantification of 2- and 3-isopropylmalic acids in forty Italian wines by UHPLC-MS/MS triple quadrupole and evaluation of their antimicrobial, antioxidant activities and biocompatibility.

2-Isopropylmalic acid (2-IPMA) and 3-isopropylmalic acid (3-IPMA), recently discovered in wines, were simultaneously quantified in forty wines by UHPLC-MS/MS triple quadrupole. Principal component analysis displayed that red wines were more correlated with high amounts of 2-IPMA (average content 31.60 mg/L); white wines were mostly characterized by low levels of both organic acids. No correlation of theirs levels to other wine features (wine ageing or alcoholic content) were found. 2-IPMA and 3-IPMA showed MICs values of 4096 mg/L and MBCs values of 8192 mg/L or higher against several food borne pathogens. In association, an interesting lower MIC and MBC values (2048 mg/L and 4096 mg/L respectively) were observed against Y. enterocolitica. Interestingly, 3-IPMA showed a mild antioxidant activity by DPPH assay (EC50 = 3940 mg/L), higher than that of 2-IPMA (EC50 > 4800 mg/L). No toxicity of these compounds against human colorectal and liver cells (TB assay) was observed.

Rapamycin Re-Directs Lysosome Network, Stimulates ER-Remodeling, Involving Membrane CD317 and Affecting Exocytosis, in Campylobacter Jejuni-Lysate-Infected U937 Cells.

The Gram-negative Campylobacter jejuni is a major cause of foodborne gastroenteritis in humans worldwide. The cytotoxic effects of Campylobacter have been mainly ascribed to the actions of the cytolethal distending toxin (CDT): it is mandatory to put in evidence risk factors for sequela development, such as reactive arthritis (ReA) and Guillain-Barré syndrome (GBS). Several researches are directed to managing symptom severity and the possible onset of sequelae. We found for the first time that rapamycin (RM) is able to largely inhibit the action of C. jejuni lysate CDT in U937 cells, and to partially avoid the activation of specific sub-lethal effects. In fact, we observed that the ability of this drug to redirect lysosomal compartment, stimulate ER-remodeling (highlighted by ER-lysosome and ER-mitochondria contacts), protect mitochondria network, and downregulate CD317/tetherin, is an important component of membrane microdomains. In particular, lysosomes are involved in the process of the reduction of intoxication, until the final step of lysosome exocytosis. Our results indicate that rapamycin confers protection against C. jejuni bacterial lysate insults to myeloid cells.

Isolation and molecular identification of a strain belonging to the new species Zalaria obscura from a deteriorated wooden artwork.

We report the case of an outdoor deteriorated wooden sculpture of Madonna, completely blackened in the face, and thus suspected of fungal attack. A multi-disciplinary approach, including microbiological analysis, molecular biology, and Fourier transform infrared (FT-IR) spectroscopy, was applied to understand the real nature of the observed alteration. FT-IR showed that the blackening was due to the application of a natural terpene resin subjected to alteration over time. The microbiological assay allowed to isolate a particular black fungus that has been recovered in the vegetative phase, growing as the only species adapted to the examined substrate. Basic Local Alignment Search Tool (BLAST) analysis of the ITS (internal transcribed spacer) region sequence identified the fungus (LS31012019) as Zalaria obscura, a black yeast belonging to the new genus Zalaria, family Dothideales. Overall, this study evidenced the importance of a multi-disciplinary approach to understand the real causes of observed deterioration of artworks. More interestingly, the recovery of a strain identified as Z. obscura from this type of substrate is never reported in the literature and this finding could offer the possibility to investigate the role of this microorganism in the deterioration process of cultural heritage.

Moulds on cementitious building materials-problems, prevention and future perspectives.

Materials rich in organic and inorganic compounds, such as building materials or paints, represent an excellent substrate for the development of moulds. Several conditions affect mould's growth on cementitious materials, such as nutrient and water availability, temperature, pH and moisture. Microorganisms, and especially moulds, attack these surfaces and contribute to their erosion, thereby reducing the life of the structure itself and negatively affecting human health through inhalation, ingestion and dermal contact with spores. Interventions are based on The European Communities Council Directive 89/106/EEC, that obliges the use of materials, products and building elements that are resistant to fungi and other forms of degradation, and that do not constitute a health risk for users and the environment. This mini-review summarises the current state of problems related to mould growth on cementitious building materials, emphasising new innovative approaches for limiting or contrasting their growth. In particular, the use of nanoparticles and the related nanomaterials as well as the potential use of new "biocides" from natural sources is discussed.

Synergistic combinations of antimicrobial peptides against biofilms of methicillin-resistant Staphylococcus aureus (MRSA) on polystyrene and medical devices.

OBJECTIVES: Antimicrobial research is being focused to look for more effective therapeutics against antibiotic-resistant infections such as those caused by methicillin-resistant Staphylococcus aureus (MRSA). In this regard, antimicrobial peptides (AMPs) appear to be a promising solution. The aim of the present study was to investigate the potential activity of temporin A, citropin 1.1, CA(1-7)M(2-9)NH2 and Pal-KGK-NH2 in synergistic activity against MRSA biofilms developed on polystyrene surface (PSS) and central venous catheter (CVC). METHODS: The study was subdivided into distinct phases to assess the ability of AMPs to inhibit biofilm formation, to identify possible synergy between AMPs, and to eradicate preformed biofilms on PSS and CVC using AMPs alone or in combination. RESULTS: Activity of the AMPs was particularly evident in the inhibition of biofilm formation on PSS and CVC, whilst the eradication of preformed biofilms was more difficult and was reached only after 24h of contact. The synergistic activity of AMP combinations, selected by their fractional inhibitory concentration index (FICI), led to an improvement in the performance of all of the molecules in the removal of different biofilms. CONCLUSION: Overall, AMPs could represent the next generation of antimicrobial agents for a prophylactic or therapeutic tool to control biofilms of antibiotic-resistant bacteria and/or biofilm-associated infections on different medical devices.

Synthesis and Evaluation of Saccharide-Based Aliphatic and Aromatic Esters as Antimicrobial and Antibiofilm Agents.

A small library of sugar-based (i.e., glucose, mannose and lactose) monoesters containing hydrophobic aliphatic or aromatic tails were synthesized and tested. The antimicrobial activity of the compounds against a target panel of Gram-positive, Gram-negative and fungi was assessed. Based on this preliminary screening, the antibiofilm activity of the most promising molecules was evaluated at different development times of selected food-borne pathogens (E. coli, L. monocytogenes, S. aureus, S. enteritidis). The antibiofilm activity during biofilm formation resulted in the following: mannose C10 > lactose biphenylacetate > glucose C10 > lactose C10. Among them, mannose C10 and lactose biphenylacetate showed an inhibition for E. coli 97% and 92%, respectively. At MICs values, no toxicity was observed on Caco-2 cell line for all the examined compounds. Overall, based on these results, all the sugar-based monoesters showed an interesting profile as safe antimicrobial agents. In particular, mannose C10 and lactose biphenylacetate are the most promising as possible biocompatible and safe preservatives for pharmaceutical and food applications.

Lactobacillus spp. inhibit the growth of Cronobacter sakazakii ATCC 29544 by altering its membrane integrity.

The effect of the cell-free culture supernatants (CFCSs) from different Lacobacillus spp. on growth ability of Cronobacter sakazakii ATCC 29544 was investigated by time-killing studies. The antimicrobial effect was evaluated using crude and 2.5 × concentrated CFCSs. Most of the CFCSs showed a dose-dependent antimicrobial activity, with the greatest C. sakazakii growth inhibition exerted by the CFCS 2.5 × of Lactobacillus casei rhamnosus ATCC 7469. Indeed, C. sakazakii growth was completely inhibited after 4 h of incubation with the crude CFCSs of L. casei rhamnosus and Lactobacillus acidophilus and after only 2 h using the related 2.5 × CFCSs. The flow cytometric analysis revealed that CFCSs altered the permeability of C. sakazakii cell membrane, showing 55% of live cells after 30 min of treatment with 2.5 × CFCSs of L. casei rhamnosus and L. acidophilus, reaching 1% of live cells after 2 h of exposure. The CFCSs of L. casei rhamnosus and L. acidophilus have showed anti-Cronobacter activity, determining a progressively inhibition of C. sakazakii growth as result of alterations in its membrane permeability.