Advances in Liposome-Encapsulated Phthalocyanines for Photodynamic Therapy.

This updated review aims to describe the current status in the development of liposome-based systems for the targeted delivery of phthalocyanines for photodynamic therapy (PDT). Although a number of other drug delivery systems (DDS) can be found in the literature and have been studied for phthalocyanines or similar photosensitizers (PSs), liposomes are by far the closest to clinical practice. PDT itself finds application not only in the selective destruction of tumour tissues or the treatment of microbial infections, but above all in aesthetic medicine. From the point of view of administration, some PSs can advantageously be delivered through the skin, but for phthalocyanines, systemic administration is more suitable. However, systemic administration places higher demands on advanced DDS, active tissue targeting and reduction of side effects. This review focuses on the already described liposomal DDS for phthalocyanines, but also describes examples of DDS used for structurally related PSs, which can be assumed to be applicable to phthalocyanines as well.

mTOR inhibitor improves autistic-like behaviors related to Tsc2 haploinsufficiency but not following developmental status epilepticus.

BACKGROUND: Tuberous sclerosis complex (TSC), a multi-system genetic disorder often associated with autism spectrum disorder (ASD), is caused by mutations of TSC1 or TSC2, which lead to constitutive overactivation of mammalian target of rapamycin (mTOR). In several Tsc1+/- and Tsc2+/- animal models, cognitive and social behavior deficits were reversed by mTOR inhibitors. However, phase II studies have not shown amelioration of ASD and cognitive deficits in individuals with TSC during mTOR inhibitor therapy. We asked here if developmental epilepsy, common in the majority of individuals with TSC but absent in most animal models, could explain the discrepancy. METHODS: At postnatal day P12, developmental status epilepticus (DSE) was induced in male Tsc2+/- (Eker) and wild-type rats, establishing four experimental groups including controls. In adult animals (n = 36), the behavior was assessed in the paradigms of social interaction test, elevated plus-maze, light-dark test, Y-maze, and novel object recognition. The testing was carried out before medication (T1), during a 2-week treatment with the mTOR inhibitor everolimus (T2) and after an 8-week washing-out (T3). Electroencephalographic (EEG) activity was recorded in a separate set of animals (n = 18). RESULTS: Both Tsc2+/- mutation and DSE caused social behavior deficits and epileptiform EEG abnormalities (T1). Everolimus led to a persistent improvement of the social deficit induced by Tsc2+/-, while deficits related to DSE did not respond to everolimus (T2, T3). CONCLUSIONS: These findings may contribute to an explanation why ASD symptoms in individuals with TSC, where comorbid early-onset epilepsy is common, were not reliably ameliorated by mTOR inhibitors in clinical studies.

Drug Delivery Systems for Phthalocyanines for Photodynamic Therapy.

The focus of this review is to describe the state-of-art in the development of innovative drug delivery systems for phthalocyanines as photosensitizers for photodynamic therapy (PDT). PDT is a medical treatment combining photosensitizers (PSs) activated by visible light of a specific wavelength to selectively destroy targeted cells, tumor tissues and its surrounding vasculature. In the last decades, PDT has been under intense investigation, first as a promising alternative approach for improved cancer treatment, later against microbial infection and nowadays, mainly in aesthetic medicine, against age-related degeneration. The success of PDT is restricted because of difficulties with administration and skin permeation of PSs. As PDT importance raises, there is high interest for advanced formulations and delivery systems (DDS) for PS, especially formulations based on nanotechnology. Accordingly, this review deals with the innovations pertaining to DDS for PDT as disclosed in recent patents and literature.

Caffeine-hydrazones as anticancer agents with pronounced selectivity toward T-lymphoblastic leukaemia cells.

We report design and synthesis of set of novel anticancer agents based on caffeine-hydrazones bearing 2-hydroxyaryl- or 2-N-heteroaryl moiety. Anticancer activity evaluation using seven cancer cell lines and two non-malignant cell lines demonstrated that several derivatives display significant anticancer activity and great selectivity index toward T-lymphoblastic leukaemia cells. In general, hydrazones bearing 2-N-heteroaryl moiety are more active and selective than those with 2-hydroxyaryl moiety. Tested compounds exhibit dose-dependent inhibition of both RNA and DNA synthesis, with some exceptions. Antimicrobial activities were tested on set of twelve bacterial and yeast strains, however prepared compounds were not active, suggesting for a molecular target specific for eukaryotic cells.

Synthesis and biological activity evaluation of hydrazone derivatives based on a Tröger's base skeleton.

We report the design and synthesis of novel anticancer agents based on bis-hydrazones separated by a rigid Tröger's base skeleton. This novel approach combines a biologically active moiety (hydrazone) with this scaffold (Tröger's base) to construct DNA intercalators. Evaluation of the anticancer activity of these agents using seven cancer cell lines and two healthy cell lines found that several derivatives had potent anticancer activity and excellent selectivity indexes toward cancer cells. The antimicrobial activities were tested on a set of thirteen bacterial stains, but the prepared compounds were not active. Complexation studies using biologically important metal ions demonstrated that these compounds are able to bind Cu(2+), Fe(3+), Co(2+), Ni(2+) and Zn(2+). DNA intercalation studies showed that the compounds themselves do not interact with DNA, but their metallocomplexes do interact, most likely via intercalation into DNA.

A novel sorbent for chromatographic separations: a silica matrix modified with non-covalently bonded tetrakis(ß-cyclodextrin)-porphyrin conjugates.

We prepared new phases for LC that consisted of silica modified with non-covalently bonded tetrakis(ß-cyclodextrin)-porphyrin (where cyclodextrin is CD) conjugates. The effects of the porphyrin core, type of spacer and ß-CD moieties on the behaviours of the modified phases for the separation of aromatic compounds (benzene, toluene, ethylbenzene, propylbenzene, butylbenzene, pentylbenzene, o-terphenyl, triphenylene, phenol and caffeine) and fluorinated aromatic compounds (pentafluorobenzonitrile, pentafluoronitrobenzene and hexafluorobenzene) were studied using the Tanaka test. The results indicate that the non-covalent substitution of silica with CD-based macromolecules that have a porphyrin core can be a very effective method for preparing novel sorbents with specific chromatographic properties for applications in LC.

On the solubility and lipophilicity of metallacarborane pharmacophores.

Metallacarborane moieties have been identified as promising pharmacophores. The pharmaceutical use of such compounds is, however, complicated by their low solubility and tendency to self-assemble in aqueous solution. In this work, we estimated the solubilities of a vast series of metallacarboranes [cobalt bis(dicarbollide) derivatives] in pure water, saline, and saline with human serum albumin as a model of blood plasma. In addition, we determined the octanol-water partition coefficients (Pow) as a lipophilicity descriptor. Pow weakly correlates with the water solubility of metallacarboranes, whereas the ability of HSA to increase the solubility of metallacarboranes correlates well with their Pow values. Because metallacarboranes are known inhibitors of HIV protease, the possible correlation between Pow and the ability to inhibit HIV protease was investigated. Results from this study indicate that interaction of metallacarborane inhibitors with HIV protease is driven by specific binding rather than by promiscuous lipophilic interactions. The most promising candidates for further drug development were identified by ligand lipophilicity efficiency analysis.

Nitric oxide synthases activation and inhibition by metallacarborane-cluster-based isoform-specific affectors.

A small library of boron-cluster- and metallacarborane-cluster-based ligands was designed, prepared, and tested for isoform-selective activation or inhibition of the three nitric oxide synthase isoforms. On the basis of the concept of creating a hydrophobic analogue of a natural substrate, a stable and nontoxic basic boron cluster system, previously used for boron neutron capture therapy, was modified by the addition of positively charged moieties to its periphery, providing hydrophobic and nonclassical hydrogen bonding interactions with the protein. Several of these compounds show efficacy for inhibition of NO synthesis with differential effects on the various nitric oxide synthase isoforms.

Low-melting salts based on a glycolated cobalt bis(dicarbollide) anion.

A new series of low-melting quaternary ammonium salts based on a glycolated cobalt bis(dicarbollide) anion structure have been synthesized and characterized, and their spectroscopic and physicochemical properties have been studied. The lowest melting point was obtained for 1-butyl-3-methylimidazolium (∼50 °C) followed by 1-butyl-1-methylpiperidinium (∼80 °C), 1-butyl-1-methylpyrrolidinium (∼95 °C), and 1-butyl-4-methylpyridinium salts (∼115 °C). The salts were thermally stable up to 180 °C [decomposition of an oligo(ethylene glycol) chain] and contained variable amounts of water. The flexible oligo(ethylene glycol) chains contributed to the waxy state of salts. The solubility of the salts was determined for 76 solvents that are commonly used in organic chemistry. Generally, the solubility increased with the dipole moment and relative polarity of the solvent. Salts exhibited good solubility in ketones and esters; moderate solubility was observed in alcohols, aromates, and chlorinated solvents, and poor solubility was obtained in ethers. The salts were practically insoluble in higher hydrocarbons and water. Salts are dissolved in the form of ion pairs or separated ions, depending on the nature of the solvent.

Interaction of ionic liquids ions with natural cyclodextrins.

The interaction of natural α-, ß-, and γ-cyclodextrins (CDs) with 14 hydrophobic ionic moieties of ionic liquids (ILs) was systematically examined in dilute aqueous solutions using isothermal titration microcalorimetry (ITC) and NMR spectroscopy. The studied cationic and anionic moieties involved some recently developed heavily fluorinated structures, as well as some others of common use. To isolate the effect of a given ion, the measurements were performed on salts containing the hydrophobic IL ion in question and a complexation-inactive counterion. Additional ITC experiments on ILs whose both cation and anion can interact appreciably with the CD cavity demonstrated that to resolve the effect of individual ions from such data is generally a tricky task and confirmed the superiority of the isolation strategy adopted for the purpose throughout this work. The binding constant, enthalpy and entropy determined at 298.15 K for the 1:1 (ion:CD) inclusion complex formation range in broad limits, being 0 < K < 2 × 10(5), 0 < -Δ(r)H°/(kJ·mol(-1)) < 44, and -28 < TΔ(r)S°/(kJ·mol(-1)) < 14, respectively. The stabilities of complexes of perfluorohexyl bearing ions with ß-CD belong to the highest ever observed with natural CDs in water. The established binding affinity scales were discussed in both thermodynamic and molecular terms. The concepts of hydrophobic interaction and guest-host size matching supported by simple molecular modeling proved useful to rationalize the observed widely different binding affinities and suggest possible binding modes. Enthalpy and entropy contributions to the stability of the ion-CD complexes were found to compensate each other considerably obeying more or less the linear compensation relationship marked by existing literature data on binding other guests to natural CDs. As outliers to this pattern, the most stable complexes of -C(6)F(13) bearing ions with ß-CD were found to receive an enhanced inherent entropy stabilization due to extraordinarily high extent of desolvation occurring in the course of binding.

Cobalt bis(dicarbollide) derivatives: solubilization and self-assembly suppression.

Cobalt bis(dicarbollide) derivatives are promising therapeutic agents however their utilization is complicated due to their low solubility and self-assembling in water. Earlier we have shown that their solubility can be increased by using of suitable biocompatible excipients--carriers of pharmaceutically active compounds. Expected mechanism of solubilization was disassembling of self-assemblies and complexation of unimers. Newly our results of time-dependent light scattering study correct this presumption. Poor solubility of all derivatives can be easily improved by using various excipients, however only heptakis(2,6-di-O-methyl)-ß-cyclodextrin displays ability to disassemble self-assemblies of all derivatives and suppress their self-assembling. Surprisingly, the other excipients participate on formation of mixed assemblies of derivative/excipient complex or cover assemblies to make them more soluble without decreasing their size.

Solubilization and deaggregation of cobalt bis(dicarbollide) derivatives in water by biocompatible excipients.

In the field of medicinal chemistry, cobalt bis(dicarbollide) derivatives are promising therapeutic agents. The potential pharmaceutical utilization of metallacarboranes is complicated due to spontaneous self-assembling in water. This problem can be solved by using suitable deaggregating agent. We present here the comprehensive screen of substituted cobalt bis(dicarbollide) derivatives with cyclodextrin derivatives, classical surfactants and amphiphilic copolymers to find general biocompatible excipients. Preliminary results are obtained by using UV/Vis spectroscopy as the technique with the best ratio of applicable information to time and source dependence.