Encapsulation of biocides by cyclodextrins: toward synergistic effects against pathogens

A Comparative Study on Cyclodextrin Derivatives in Improving Oral Bioavailability of Etoricoxib as a Model Drug: Formulation and Evaluation of Solid Dispersion-Based Fast-Dissolving Tablets

Etoricoxib, as a model drug, has a poor solubility and dissolution rate. Cyclodextrin derivatives can be used to solve such a problem. A comparative study was run on three cyclodextrin derivatives, namely β-CD, HP β-CD, and SBE β-CD, to solve the drug problem through the formulation of solid dispersions and their preparation into fast-dissolving tablets. Preparations utilized different (1:1, 1:2, and 1:4) drug:carrier ratios. Nine fast-dissolving tablets (containing 1:4 drug: carrier) were formulated using Prosolv ODT® and/or F-melt® type C as super-disintegrants. Optimized formulation was chosen based on a 32 factorial design. The responses chosen were the outcomes of the in vitro evaluation tests. The optimized formulation that had the highest desirability (0.86) was found to be SD-HP3, which was prepared from etoricoxib: HP β-CD at a 1:4 ratio using equal amounts of Prosolv ODT® and F-melt® type C. An in vivo evaluation of SD-HP3 on a rabbit model revealed its superiority over the marketed product Arcoxia®. SD-HP3 showed a significantly lower Tmax (13.3 min) and a significantly higher Cmax (9122.156 μg/mL), as well as a significantly higher AUC, than Arcoxia®. Thus, the solubility, dissolution, and bioavailability of etoricoxib were significantly enhanced.

Preparation of aromatic β-cyclodextrin nano/microcapsules and corresponding aromatic textiles: A review

Fragrance finishing of textiles is receiving substantial interest, with aromatherapy being one of the most popular aspects of personal health care. However, the longevity of aroma on textiles and presence after subsequent launderings are major concerns for aromatic textiles directly loaded with essential oils. These drawbacks can be weakened by incorporating essential oil-complexed β-cyclodextrins (β-CDs) onto various textiles. This article reviews various preparation methods of aromatic β-cyclodextrin nano/microcapsules, as well as a wide variety of methods for the preparation of aromatic textiles based on them before and after forming, proposing future trends in preparation processes. The review also covers the complexation of β-CDs with essential oils, and the application of aromatic textiles based on β-CD nano/microcapsules. Systematic research on the preparation of aromatic textiles facilitates the realization of green and simple industrialized large-scale production, providing needed application potential in the fields of various functional materials.

Antifungal potential of volatiles produced by Bacillus subtilis BS-01 against Alternaria solani in Solanum lycopersicum

Bacterial biocontrol agent/s (BCAs) against plant diseases are eco-friendly and sustainable options for profitable agricultural crop production. Specific beneficial strains of Bacillus subtilis are effective in controlling many fungal diseases including Alternaria blight caused by a notorious pathogen "Alternaria solani". In the present study, the biocontrol attributes of a newfangled strain of B. subtilis (BS-01) have been investigated and its bioactive compounds were also identified against A. solani. The volatile organic compounds (VOCs) produced by BS-01 in organic solvents viz., n-hexane, dichloromethane, and ethyl acetate were extracted and their antifungal efficacy has evaluated against A. solani. Also, the preventive and curative biocontrol method to reduce the fungal load of A. solani was estimated by both foliar and seed applications on infected tomato (Solanum lycopersicum) plants as determined by quantitative PCR assays. Growth chamber bioassay revealed that both foliar and seed application of BS-01 on tomato plants previously or subsequently infected by A. solani significantly reduced the pathogen load on inoculated tomato foliage. Results showed that antifungal bioassays with various concentrations (10-100 mg mL^-1) of extracted metabolites produced by BS-01 in ethyl acetate fraction showed the highest inhibition in fungal biomass (extracellular metabolites: 69-98% and intracellular metabolites: 48-85%) followed by n-hexane (extracellular metabolites: 63-88% and intracellular metabolites: 35-62%) and dichloromethane (extracellular metabolites: 41-74% and intracellular metabolites: 42-70%), respectively. The extracted volatile compounds of BS-01 were identified via GC-MS analysis and were found in great proportions in the organic fractions as major potent antifungal constituents including triphenylphosphine oxide; pyrrolo[1,2-a] pyrazine-1,4-dione, hexahydro-3-(2-methylpropyl); pyrrolo[1,2-a] pyrazine-1,4-dione, hexahydro-3-(phenylmethyl); n-hexadecanoic acid; n-tridecan-1-ol; octadecane; octadecanoic acid; eicosane and dodecyl acrylate. Separate or mixture of these bioactive VOCs had the potential to mitigate the tomato early blight disease severity in the field that would act as a sustainable plant protection strategy to generate profitable tomato production.

Development of a ternary cyclodextrin–arginine–ciprofloxacin antimicrobial complex with enhanced stability

Designing useful functionalities in clinically validated, old antibiotics holds promise to provide the most economical solution for the global lack of effective antibiotics, as undoubtedly a serious health threat. Here we show that using the surface chemistry of the cyclodextrin (βCD) cycle and arginine (arg) as a linker, provides more stable ternary antibiotic complex (βCD-arg-cpx). In contrast to classical less stable inclusion complexes, which only modify antibiotic solubility, here-presented ternary complex is more stable and controls drug release. The components of the complex intensify interactions with bacterial membranes and increase the drug’s availability inside bacterial cells, thereby improving its antimicrobial efficacy and safety profile. Multifunctional antibiotics, formulated as drug delivery systems per se, that take the drug to the site of action, maximize its efficacy, and provide optical detectability are envisaged as the future in fighting against infections. Their role as a tool against multiresistant strains remains as interesting challenge open for further research.

Fabrication of Encapsulated Gemini Surfactants

(1) Background: Encapsulation of surfactants is an innovative approach that allows not only protection of the active substance, but also its controlled and gradual release. This is primarily used to protect metallic surfaces against corrosion or to create biologically active surfaces. Gemini surfactants are known for their excellent anticorrosion, antimicrobial and surface properties; (2) Methods: In this study, we present an efficient methods of preparation of encapsulated gemini surfactants in form of alginate and gelatin capsules; (3) Results: The analysis of infrared spectra and images of the scanning electron microscope confirm the effectiveness of encapsulation; (4) Conclusions: Gemini surfactants in encapsulated form are promising candidates for corrosion inhibitors and antimicrobials with the possibility of protecting the active substance against environmental factors and the possibility of controlled outflow.

Host-Guest Inclusion Complexes of Natural Products and Nanosystems: Applications in the Development of Repellents

Repellents are compounds that prevent direct contact between the hosts and the arthropods that are vectors of diseases. Several studies have described the repellent activities of natural compounds obtained from essential oils. In addition, these chemical constituents have been pointed out as alternatives to conventional synthetic repellents due to their interesting residual protection and low toxicity to the environment. However, these compounds have been reported with short shelf life, in part, due to their volatile nature. Nanoencapsulation provides protection, stability, conservation, and controlled release for several compounds. Here, we review the most commonly used polymeric/lipid nanosystems applied in the encapsulation of small organic molecules obtained from essential oils that possess repellent activity, and we also explore the theoretical aspects related to the intermolecular interactions, thermal stability, and controlled release of the nanoencapsulated bioactive compounds.

Biomedical applications of polysaccharide nanoparticles for chronic inflammatory disorders: Focus on rheumatoid arthritis, diabetes and organ fibrosis

Polysaccharides are biopolymers distinguished by their complex secondary structures executing various roles in microorganisms, plants, and animals. They are made up of long monomers of similar type or as a combination of other monomeric chains. Polysaccharides are considered superior as compared to other polymers due to their diversity in charge and size, biodegradability, abundance, bio-compatibility, and less toxicity. These natural polymers are widely used in designing of nanoparticles (NPs) which possess wide applications in therapeutics, diagnostics, delivery and protection of bioactive compounds or drugs. The side chain reactive groups of polysaccharides are advantageous for functionalization with nanoparticle-based conjugates or therapeutic agents such as small molecules, proteins, peptides and nucleic acids. Polysaccharide NPs show excellent pharmacokinetic and drug delivery properties, facilitate improved oral absorption, control the release of drugs, increases in vivo retention capability, targeted delivery, and exert synergistic effects. This review updates the usage of polysaccharides based NPs particularly cellulose, chitosan, hyaluronic acid, alginate, dextran, starch, cyclodextrins, pullulan, and their combinations with promising applications in diabetes, organ fibrosis and arthritis.

Cyclodextrin-enabled green environmental biotechnologies

Most of the organic compounds contaminating the environment can form inclusion complexes with cyclodextrins resulting in enhanced solubility (a benefit in soil remediation) or just the opposite: reduced mobility by sorption (a benefit in wastewater treatment). Combining biotechnologies with cyclodextrin, a renewable and biodegradable material, green environmental technologies of high efficiency were developed. For instance, the cyclodextrin-enabled soil washing/flushing technologies combined with bioremediation have been demonstrated in full-scale field experiments. The efficiency of tertiary wastewater treatment by sorption of non-biodegradable xenobiotics, such as residual pharmaceutics, was proved. The biofilm formation in fouling processes can be prevented or reduced either by applying cyclodextrin-based coatings or by manipulation of quorum sensing (bacterial communication) via capturing signal molecules.

Bioprospecting Phenols as Inhibitors of Trichothecene-Producing Fusarium: Sustainable Approaches to the Management of Wheat Pathogens

Fusarium spp. are ubiquitous fungi able to cause Fusarium head blight and Fusarium foot and root rot on wheat. Among relevant pathogenic species, Fusarium graminearum and Fusarium culmorum cause significant yield and quality loss and result in contamination of the grain with mycotoxins, mainly type B trichothecenes, which are a major health concern for humans and animals. Phenolic compounds of natural origin are being increasingly explored as fungicides on those pathogens. This review summarizes recent research activities related to the antifungal and anti-mycotoxigenic activity of natural phenolic compounds against Fusarium, including studies into the mechanisms of action of major exogenous phenolic inhibitors, their structure-activity interaction, and the combined effect of these compounds with other natural products or with conventional fungicides in mycotoxin modulation. The role of high-throughput analysis tools to decipher key signaling molecules able to modulate the production of mycotoxins and the development of sustainable formulations enhancing potential inhibitors’ efficacy are also discussed.

Development of an enzymatic encapsulation process for a cycloamylose inclusion complex with resveratrol

Cyclodextrin glucanotransferase (CGTase; EC 2.4.1.19) produces cycloamyloses (CAs), which are large cyclic glucans, and subsequently transforms them to α-, β-, and γ-cyclodextrins. We developed a novel encapsulation process based on the cyclization activity of CGTase and applied it to the formation of CA inclusion complexes with resveratrol (RVT), which has limited bioavailability due to its low water solubility. The encapsulated RVT (CA-RVT) was purified using preparative high-performance liquid chromatography. The water solubility of CA-RVT was 6,000-fold higher than that of RVT. CA-RVT in water demonstrated 98% stability for 1 week at 4 °C. According to radical scavenging activity and anti-inflammatory assays, CA-RVT in aqueous solution exhibited similar activities as an equal amount of RVT in dimethyl sulfoxide, suggesting the limited solubility of RVT can be overcome through CA encapsulation by CGTase, thus enhancing its nutraceutical value as a functional ingredient in the food industry.

The Role of β-Cyclodextrin in the Textile Industry-Review

β-Cyclodextrin (β-CD) is an oligosaccharide composed of seven units of D-(+)-glucopyranose joined by α-1,4 bonds, which is obtained from starch. Its singular trunk conical shape organization, with a well-defined cavity, provides an adequate environment for several types of molecules to be included. Complexation changes the properties of the guest molecules and can increase their stability and bioavailability, protecting against degradation, and reducing their volatility. Thanks to its versatility, biocompatibility, and biodegradability, β-CD is widespread in many research and industrial applications. In this review, we summarize the role of β-CD and its derivatives in the textile industry. First, we present some general physicochemical characteristics, followed by its application in the areas of dyeing, finishing, and wastewater treatment. The review covers the role of β-CD as an auxiliary agent in dyeing, and as a matrix for dye adsorption until chemical modifications are applied as a finishing agent. Finally, new perspectives about its use in textiles, such as in smart materials for microbial control, are presented.

Combining Cellulose and Cyclodextrins: Fascinating Designs for Materials and Pharmaceutics

Cellulose and cyclodextrins possess unique properties that can be tailored, combined, and used in a considerable number of applications, including textiles, coatings, sensors, and drug delivery systems. Successfully structuring and applying cellulose and cyclodextrins conjugates requires a deep understanding of the relation between structural, and soft matter behavior, materials, energy, and function. This review focuses on the key advances in developing materials based on these conjugates. Relevant aspects regarding structural variations, methods of synthesis, processing and functionalization, and corresponding supramolecular properties are presented. The use of cellulose/cyclodextrin conjugates as intelligent platforms for applications in materials science and pharmaceutical technology is also outlined, focusing on drug delivery, textiles, and sensors.

Host-guest complexes of imazalil with cucurbit[8]uril and β-cyclodextrin and their effect on plant pathogenic fungi

We report the control of imazalil (IMZ) antifungal activity utilizing its non-covalent assembly with β-cyclodextrins (β-CD) and cucurbit[8]uril (CB8) macrocycles, as well as its stimuli-responsive disassembly with cadaverine. The NMR results are consistent with inclusion of a single IMZ molecule inside the cavities of either CB8 from its aromatic site or β-CD from its aliphatic end. Efficient complex formation with both host molecules and controlled released upon the addition of cadaverine is supported by NMR measurements. The stimuli-responsiveness of the same host-guest assemblies with cadaverine was validated against seven economically important plant pathogenic fungi which cause agriculturally important plant diseases across the globe. While loading the drug into macrocycles cavities suppressed its activity, subsequent adding of cadaverine efficiently restored it up. The results in the present paper enable researchers working in the area of mycology and plant pathology to inhibit or reduce the fungal growth on demand in order to control these economically important plant pathogenic fungi.

The effect of cyclodextrin complexation on the solubility and photostability of nerolidol as pure compound and as main constituent of cabreuva essential oil

Nerolidol (Ner), a major component of many plant essential oils, is known for its various biological properties. However, the low solubility of Ner in water and its susceptibility to degradation limit its application. The aim of our study was to improve the solubility and photostability of Ner through its encapsulation in different cyclodextrins (CDs). The formation constants of cis-, trans-Ner and their commercial mixture with various CDs (α-CD, β-CD, γ-CD, HP-β-CD, RAMEB, CRYSMEB and SBE-β-CD) were determined by phase solubility studies and confirmed by the spectral displacement UV-visible method. The solubility of cabreuva essential oil (EO) rich in trans-Ner was also evaluated by total organic carbon (TOC) analysis. The encapsulation efficiency (EE %) of Ner in HP-β-CD solid complexes was assessed by HPLC. The structural characterization of CD/trans-Ner inclusion complex was then conducted by NMR spectroscopy followed by molecular modelling studies. The effect of encapsulation on the Ner photostability was also carried out over time under UVB irradiation. A_L-type phase-solubility diagrams were obtained, suggesting the formation of 1:1 CD/Ner inclusion complexes. The solubility of Ner was enhanced by approximately 70-fold in the presence of 10 mM HP-β-CD. Moreover, high EE % values were obtained for 5:1 and 10:1 HP-β-CD:Ner molar ratios. NMR and molecular modelling studies revealed the most stable structure for trans-Ner inside the CD cavity with the OH group oriented towards the wider rim of the CD. Finally, CD encapsulation of Ner as pure compound or as main component of the cabreuva EO, protected it from degradation. This effect was more pronounced as the concentration of CD increased. These findings suggested that CDs are promising encapsulating carriers for Ner by enhancing its solubility and stability and thereby its application in food industry.

Supramolecular assistance between cyclodextrins and didecyldimethylammonium chloride against enveloped viruses: Toward eco-biocidal formulations

Nosocomial infections have emerged as important causes of morbidity and mortality in immunocompromised individuals. In this respect, biocides are widely used in hospitals leading to resistant microorganisms. We show here that cyclodextrins can remarkably boost the virucidal activity of di-n-decyldimethylammonium chloride. These oligosaccharides synergistically work with the biocide affording a noticeable reduction of the active virucide concentration between 40 and 85%. Partial replacement of a significant amount of the biocide by eco- and bio-compatible cyclodextrins whilst maintaining the same activity is of great interest as it allows the reduction of the toxicological drawbacks of classical biocide mixtures.

Preparation of alginate-chitosan-cyclodextrin micro- and nanoparticles loaded with anti-tuberculosis compounds

This paper describes the synthesis and application of alginate-chitosan-cyclodextrin micro- and nanoparticulate systems loaded with isoniazid (INH) and isoconazole nitrate (ISN) as antimycobacterial compounds. Preparation and morphology of the obtained particles, as well as antimycobacterial activity data of the obtained systems are presented. Docking of isoconazole into the active site of enoyl-acyl carrier protein reductase (InhA) of Mycobacetrium tuberculosis was carried out in order to predict the binding affinity and non-covalent interactions stabilizing the InhA-isoconazole complex. To assess these interactions, frontier molecular orbital calculations were performed for the active site of InhA and isoconazole obtained from docking. Isoconazole was predicted to be an active inhibitor of InhA with the analysis of the molecular docking and electron density distribution. It has been detected that alginate-chitosan-cyclodextrin microparticulate systems loaded with INH and ISN are as effective as pure INH applied in higher dosages.

Aqueous solutions of didecyldimethylammonium chloride and octaethylene glycol monododecyl ether: Toward synergistic formulations against enveloped viruses

Micellization of di-n-decyldimethylammonium chloride, [DiC10][Cl], and octaethylene glycol monododecyl ether, C12E8, mixtures have been investigated by surface tension and conductivity measurements. From these results, various physicochemical and thermodynamic key parameters (e.g. micellar mole fraction of [DiC10][Cl], interaction parameter, free energy of micellization, etc.) have been evaluated and discussed in detail. The results prove high synergistic effect between the two surfactants. Based on these results, the virucidal activity of an equimolar mixture of [DiC10][Cl] and C12E8 has been investigated. A marked synergism was observed on lipid-containing deoxyribonucleic and ribonucleic acid viruses, such as herpes virus, respiratory syncytial virus, and vaccinia viruses. In contrast, Coxsackievirus (non-enveloped virus) was not inactivated. These results support that the mechanism is based on the extraction of lipids and/or proteins from the envelope inside the mixed micelles. This extraction creates "holes" the size of which increases with concentration up to a specific value which triggers the virus inactivation. Such a mixture could be used to extend the spectrum of virucidal activity of the amphiphiles virucides commonly employed in numerous disinfectant solutions.

Bioactive ZnO Coatings Deposited by MAPLE-An Appropriate Strategy to Produce Efficient Anti-Biofilm Surfaces

Deposition of bioactive coatings composed of zinc oxide, cyclodextrin and cefepime (ZnO/CD/Cfp) was performed by the Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique. The obtained nanostructures were characterized by X-ray diffraction, IR microscopy and scanning electron microscopy. The efficient release of cefepime was correlated with an increased anti-biofilm activity of ZnO/CD/Cfp composites. In vitro and in vivo tests have revealed a good biocompatibility of ZnO/CD/Cfp coatings, which recommend them as competitive candidates for the development of antimicrobial surfaces with biomedical applications. The release of the fourth generation cephalosporin Cfp in a biologically active form from the ZnO matrix could help preventing the bacterial adhesion and the subsequent colonization and biofilm development on various surfaces, and thus decreasing the risk of biofilm-related infections.

Inclusion complexes of propiconazole nitrate with substituted β-cyclodextrins: the synthesis and in silico and in vitro assessment of their antifungal properties

Inclusion complexes with sulfobutylether-β-cyclodextrin, β-cyclodextrin sulphated sodium salt and monochlorotriazinyl-β-cyclodextrin were characterized and assessed for antifungal activity and cytotoxicity.

Encapsulation of rhodamine-6G within p-sulfonatocalix[n]arenes: NMR, photophysical behaviour and biological activities

Partial inclusion of rhodamine-6G within sulfonatocalixarene macrocycles engenders fluorescence quenching and demonstrates remarkable antiproliferative activities.

Pickering emulsions based on cyclodextrins: A smart solution for antifungal azole derivatives topical delivery

Surfactants are usually used for the preparation of emulsions. Potential drawbacks on the human body or on the environment can be observed for some of them(e.g. skin irritation, hemolysis, protein denaturation, etc.). However, it is possible to use biocompatible emulsifiers such as native cyclodextrins (CDs). The mixture of oil (paraffin oil or isopropyl myristate), water and native CDs results in the formation of Pickering emulsions. The emulsion properties were investigated by ternary phase diagrams elaboration, multiple light scattering, optical and transmission microscopies. The results prove that these Pickering emulsions were very stable against coalescence due to the dense film format the oil/water interface. The rheological behavior has shown that these emulsions remain compatible for topical applications. This kind of emulsions (biocompatibility, stability and surfactant free) has been used to obtain sustainable formulations for antifungal econazole derivatives delivery. Our results prove that these new formulations are at least as active as commercially available formulations.

Antifungal activity improved by coproduction of cyclodextrins and anabaenolysins in Cyanobacteria

Cyclodextrins are cyclic oligosaccharides widely used in the pharmaceutical industry to improve drug delivery and to increase the solubility of hydrophobic compounds. Anabaenolysins are lipopeptides produced by cyanobacteria with potent lytic activity in cholesterol-containing membranes. Here, we identified the 23- to 24-kb gene clusters responsible for the production of the lipopeptide anabaenolysin. The hybrid nonribosomal peptide synthetase and polyketide synthase biosynthetic gene cluster is encoded in the genomes of three anabaenolysin-producing strains of Anabaena. We detected previously unidentified strains producing known anabaenolysins A and B and discovered the production of new variants of anabaenolysins C and D. Bioassays demonstrated that anabaenolysins have weak antifungal activity against Candida albicans. Surprisingly, addition of the hydrophilic fraction of the whole-cell extracts increased the antifungal activity of the hydrophobic anabaenolysins. The fraction contained compounds identified by NMR as α-, β-, and γ-cyclodextrins, which undergo acetylation. Cyclodextrins have been used for decades to improve the solubility and bioavailability of many drugs including antifungal compounds. This study shows a natural example of cyclodextrins improving the solubility and efficacy of an antifungal compound in an ancient lineage of photosynthetic bacteria.