Undefeated-Changing the phenamacril scaffold is not enough to beat resistant Fusarium.

Filamentous fungi belonging to the genus Fusarium are notorious plant-pathogens that infect, damage and contaminate a wide variety of important crops. Phenamacril is the first member of a novel class of single-site acting cyanoacrylate fungicides which has proven highly effective against important members of the genus Fusarium. However, the recent emergence of field-resistant strains exhibiting qualitative resistance poses a major obstacle for the continued use of phenamacril. In this study, we synthesized novel cyanoacrylate compounds based on the phenamacril-scaffold to test their growth-inhibitory potential against wild-type Fusarium and phenamacril-resistant strains. Our findings show that most chemical modifications to the phenamacril-scaffold are associated with almost complete loss of fungicidal activity and in vitro inhibition of myosin motor domain ATPase activity.

Efficient Grafting of Cyclodextrin to Alginate and Performance of the Hydrogel for Release of Model Drug.

Controlling the rate of release of molecules from a hydrogel is of high interest for various drug delivery systems and medical devices. A strategy to alter the release profiles of soluble and poorly soluble active ingredients from hydrogels can be to combine the hydrogel forming ability of alginate with the inclusion forming ability of cyclodextrins (CyD). Here, ß-CyD was grafted to alginate in a three-step synthesis using periodate oxidation, reductive amination and copper(I)-catalyzed azide-alkyne cycloaddition. A grafting degree of 4.7% mol ß-CyD/mol sugar residues was obtained. The grafting degree was controlled by varying the reaction parameters where the amount of linker used in reductive amination was especially influential. Ca-alginate gel beads grafted with ß-CyD showed increased uptake of the model molecule methyl orange. Release experiments showed that the grafted material had a prolonged release of methyl orange and an increased total amount of released methyl orange. These results show that the ß-CyD grafted alginate is still able to form a hydrogel while the grafted cyclodextrins retain their ability to form inclusion complex with methyl orange. Further testing should be done with this system to investigate capability for drug delivery applications.

Therapeutic efficacy of folate receptor-targeted amphiphilic cyclodextrin nanoparticles as a novel vehicle for paclitaxel delivery in breast cancer.

PURPOSE: The aim of this study is to test folate-conjugated cyclodextrin nanoparticles (FCD-1 and FCD-2) as a vehicle for reducing toxicity and increasing the antitumor efficacy of paclitaxel especially for metastatic breast cancer. METHODS: For the evaluation of PCX-loaded FCD nanoparticles, animal studies were realised in terms of survival rate, tumour size, weight change, metastazis and histopathological examination. RESULTS: FCD-1 displayed significant advantages such as efficient targeting of folate receptor positive breast cancer cells and having considerably lower toxicity compared to that of Cremophor®. When loaded with paclitaxel, FCD-1 nanoparticles, which have smaller particle size, neutral zeta potential, high encapsulation efficiency and better loading capacity for controlled release, emerged as an effective formulation in terms of cytotoxicity and high cellular uptake. In an experimental breast cancer model, anticancer activity of these nanoparticles were compatible with that of paclitaxel in Cremophor® however repeated administrations of FCD-1 nanoparticles were better tolerated by the animals. These nanoparticles were able to localise in tumour site. Both paclitaxel-loaded FCD-1 and FCD-2 significantly reduced tumour burden while FCD-1 significantly improved the survival. CONCLUSIONS: Folate-conjugated amphiphilic cyclodextrin nanoparticles can be considered as promising Cremophor®-free, low-toxicity and efficient active drug delivery systems for paclitaxel.

Host-guest interaction and structural ordering in polymeric nanoassemblies: Influence of molecular design.

Host-guest nanoassemblies made from spontaneous self-association of host and guest polymers in aqueous solutions have been studied. The specific motivation behind this work was to clarify the impact of the molecular design of the polymers on the interactions between them and on the inner structure of the resulting nanoassemblies. The polymers were composed of a dextran backbone, functionalized with either pendant ß-cyclodextrin (CD) or adamantyl (Ada). Those groups were connected to the backbone either directly or with hydrophilic polyethylene glycol (PEG) spacers. To study the impact of those spacers we have proposed a synthetic pathway to new guest polymers. The latter relied on the use of thiol-substituted dextrans as a scaffold, which is subsequently transformed into PEG-Ada grafted guest polymers via nucleophile-mediated thiol-click reaction. Surface plasmon resonance (SPR) studies evidenced strong mutual affinities between the host and guest polymers and showed that the stoichiometry was close to the ideal one (CD/Ada = 1/1) when PEG spacers were introduced. The structure of the nanoassemblies was studied by a combination of dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS). The nature of the individual host or guest polymers has a strong impact on the size and internal structure of the resulting nanoassemblies. The presence of PEG spacers in the polymers led to smaller and less compact nanoassemblies, as evidenced by their large correlation length values (4-20nm compared to 2nm without PEG spacers). At the same time, all types of nanoassemblies appear to have radial density distribution with denser cores and pending polymer chains at the periphery. This study, centered on the influence of the molecular design on the host-guest interactions and structural ordering in polymeric nanoassemblies, will help to tailor host-guest nanoassemblies with attractive drug delivery profiles.

Real-time imaging of the growth-inhibitory effect of JS399-19 on Fusarium.

Real-time imaging was used to study the effects of a novel Fusarium-specific cyanoacrylate fungicide (JS399-19) on growth and morphology of four Fusarium sp. This fungicide targets the motor domain of type I myosin. Fusarium graminearum PH-1, Fusarium solani f. sp. pisi 77-13-4, Fusarium avenaceum IBT8464, and Fusarium avenaceum 05001, which has a K216Q amino-acid substitution at the resistance-implicated site in its myosin type I motor domain, were analyzed. Real-time imaging shows that JS399-19 inhibits fungal growth but not to the extent previously reported. The fungicide causes the hypha to become entangled and unable to extend vertically. This implies that type I myosin in Fusarium is essential for hyphal and mycelia propagation. The K216Q substitution correlates with reduced susceptibility in F. avenaceum.

Design and optimization of novel paclitaxel-loaded folate-conjugated amphiphilic cyclodextrin nanoparticles.

As nanomedicines are gaining momentum in the therapy of cancer, new biomaterials emerge as alternative platforms for the delivery of anticancer drugs with bioavailability problems. In this study, two novel amphiphilic cyclodextrins (FCD-1 and FCD-2) conjugated with folate group to enable active targeting to folate positive breast tumors were introduced. The objective of this study was to develop and characterize new folated-CD nanoparticles via 3(2) factorial design for optimal final parameters. Full physicochemical characterization studies were performed. Blank and paclitaxel loaded FCD-1 and FCD-2 nanoparticles remained within the range of 70-275nm and 125-185nm, respectively. Zeta potential values were neutral and -20mV for FCD-1 and FCD-2 nanoparticles, respectively. Drug release studies showed initial burst release followed by a longer sustained release. Blank nanoparticles had no cytotoxicity against L929 cells. T-47D and ZR-75-1 human breast cancer cells with different levels of folate receptor expression were used to assess anti-cancer efficacy. Through targeting the folate receptor, these nanoparticles were efficiently engulfed by the breast cancer cells. Additionally, breast cancer cells became more sensitive to cytotoxic and/or cytostatic effects of PCX delivered by FCD-1 and FCD-2. In conclusion, these novel folate-conjugated cyclodextrin nanoparticles can therefore be considered as promising alternative systems for safe and effective delivery of paclitaxel with a folate-dependent mechanism.

Bifunctionalized dextrans for surface PEGylation via multivalent host-guest interactions.

The main goal of this work was to develop a supramolecular chemistry strategy to decorate interfaces with polyethylene glycol (PEG) grafts. A series of novel bifunctionalized dextrans, bearing 40-60 PEG pending chains and 12-24 hydrophobic adamantyl groups, have been prepared by copper(I)-catalyzed azide-alkyne cycloaddition. Their binding properties toward native ßCD and ßCD polymers were characterized both in solution and at interface using isothermal titration microcalorimetry and surface plasmon resonance. The polymers were found to form stable layers onto neutral and positively charged ßCD-polymer films pre-adsorbed on gold surfaces, due to multivalent interpolymer host-guest interactions. The thickness and stability of the layers could be tuned by varying the ratio between the degrees of substitution by PEG and adamantyl groups.

Synthesis and surface grafting of a ß-cyclodextrin dimer facilitating cooperative inclusion of 2,6-ANS.

A novel ß-cyclodextrin (ß-CD) dimer was synthesized and surface-grafted by click chemistry onto azide-functionalized quartz surfaces in order to introduce the cooperative features of the ß-CD dimer to solid surfaces. Using NMR and fluorescence spectroscopy, it is shown that the free ß-CD dimer forms a 1:1 complex with the fluorescent guest molecule, 2-anilinonaphthalene-6-sulfonic acid (otherwise known not to form 1:2 complexes with parent ß-CD), with an apparent association constant of 7300 M(-1). Further, it is shown using total internal reflection fluorescence spectroscopy that the inclusion of the fluorescent guest into both cavities of the ß-CD dimer is maintained when grafted onto a solid surface.

Nonfouling tunable ßCD dextran polymer films for protein applications.

Polymeric ß-cyclodextrin (ßCD) films tunable with respect to thickness and ßCD content were prepared in order to develop a suitable platform, allowing for inclusion of nonpolar guest molecules in the ßCD cavity, while suppressing nonspecific protein adsorption. The ßCD films were synthesized from linear ßCD dextran polymers, and grafted onto silicon oxide surfaces by "click" chemistry. Topographic and morphological characteristics are controllable by reaction conditions and polymer type, with average film heights from 2.5 to 12.5 nm. Reversible introduction of electrostatic charges in the ßCD dextran by complex formation with 1-adamantanecarboxylic acid prior to surface grafting resulted in a thinner and denser film, presumably by decompaction of the polymers. Total internal reflection fluorescence spectroscopy (TIRF) was employed to evaluate the accessibility of ßCD cavities to the fluorescent probe 2-anilinonaphthalene-6-sulfonic acid. Only a minor fraction of the ßCD cavities was accessible in the thicker and less dense films; however, accessibility was largely improved with increased ionic strength using NaCl up to 1 M. Antifouling properties of the ßCD dextran polymer films were assessed by TIRF real-time monitoring, using bovine serum albumin as a model protein, and showed a 5- to 10-fold reduction in nonspecific adsorption as compared to a bare quartz surface with the degree of reduction reflecting film thickness and interfacial polymer density.

Removal of volatile organic compounds using amphiphilic cyclodextrin-coated polypropylene.

Polypropylene nonwovens were functionalised using a self-assembled, amphiphilic cyclodextrin coating and the potential for water purification by removal of pollutants was studied. As benzene is one of the problematic compounds in the Water Framework Directive, six volatile organic compounds (benzene and five benzene-based substances) were chosen as model compounds. The compounds were tested as a mixture in order to provide a more realistic situation since the wastewater will be a complex mixture containing multiple pollutants. The volatile organic compounds are known to form stable inclusion complexes with cyclodextrins. Six different amphiphilic cyclodextrin derivatives were synthesised in order to elucidate whether or not the uptake abilities of the coating depend on the structure of the derivative. Headspace gas chromatography was used for quantification of the uptake exploiting the volatile nature of benzene and its derivatives. The capacity was shown to increase beyond the expected stoichiometries of guest-host complexes with ratios of up to 16:1.

Dextran-based cyclodextrin polymers: their solubilizing effect and self-association.

Cyclodextrins and their water-soluble derivatives are excellent solubilizers and stabilizers and widely used as enabling pharmaceutical excipients. However, still new cyclodextrin derivatives are being designed and synthesized in an effort to improve their physicochemical properties. In this study physicochemical and self-associating characteristics of dextran-based cyclodextrin polymers, with ether or ester linkage between the ß-cyclodextrin and the dextran backbone, were investigated. Methods applied include phase-solubility studies, permeation studies and dynamic light scattering. Results with a model drug, hydrocortisone, showed that the solubilization and binding efficiency slowly declined with increasing molecular weight. The degree of substitution had significant effect on the properties, making the polymers with ether linkage more favorable. Self-association of the drug-polymer complexes was observed, although the instability can hamper their utilization.

Impact of curcumin supersaturation in antibacterial photodynamic therapy--effect of cyclodextrin type and amount: studies on curcumin and curcuminoides XLV.

Curcumin has been investigated as a potential photosensitizer (PS) in antimicrobial photodynamic therapy (aPDT). The phototoxic effect of curcumin is dependent on proper formulations of the compound because of the lipophilic nature of the molecule and the extremely low water solubility at physiological conditions. In the present study, the combination of curcumin with either a methylated ß-cyclodextrin (CD) or polyethylene glycol-based ß-CD or γ-CD polymers was investigated in aPDT using Escherichia coli (E. coli) and Enterococcus faecalis as model bacteria. Solutions with various supersaturation ratios of curcumin were prepared with the selected CD or CD polymers. The concept of supersaturation was then investigated as a mean to enhance the phototoxic effect of curcumin, especially toward the gram-negative bacteria E. coli. A high supersaturation ratio corresponded with high phototoxicity of E. coli. Depending on the curcumin preparation, the bacterial survival ranged from 0.01% to no significant effect after irradiation with blue light (29 J/cm(2) ). Temporal stabilization of the supersaturated state is necessary in order to retain high and predictable photoreactivity of the PS. Further studies will be needed in order to formulate curcumin preparations with acceptable hydrolytic and photolytic stability and a temporal stabilization of a supersaturated state.