Organoseleno cytostatic derivatives: Autophagic cell death with AMPK and JNK activation.

Selenocyanates and diselenides are potential antitumor agents. Here we report two series of selenium derivatives related to selenocyanates and diselenides containing carboxylic, amide and imide moieties. These compounds were screened for their potency and selectivity against seven tumor cell lines and two non-malignant cell lines. Results showed that MCF-7 cells were especially sensitive to the treatment, with seven compounds presenting GI50 values below 10 µM. Notably, the carboxylic selenocyanate 8b and the cyclic imide 10a also displayed high selectivity for tumor cells. Treatment of MCF-7 cells with these compounds resulted in cell cycle arrest at S phase, increased levels of pJNK and pAMPK and caspase independent cell death. Autophagy inhibitors wortmannin and chloroquine partially prevented 8b and 10a induced cell death. Consistent with autophagy, increased Beclin1 and LC3-IIB and reduced SQSTM1/p62 levels were detected. Our results point to 8b and 10a as autophagic cell death inducers.

Methylselenol release as a cytotoxic tool: a study of the mechanism of the activity achieved by two series of methylselenocarbamate derivatives.

A molecular modeling study has been carried out on two previously reported series of methylselenocarbamate derivatives that show remarkable antiproliferative and cytotoxic in vitro activity, against a panel of human cancer cell lines. These derivatives can be considered as having been constructed by a selenomethyl fragment located over a carbon atom which is decorated with two carbamate moieties, both aliphatic and aromatic, one of them attached by a single bond to the central carbon atom, while the second is connected by a double bond. According to the data obtained, these derivatives can undergo a water-mediated nucleophilic attack on the carbons with marked electrophilic character, which leads to the rupture of C-Se and carbamate C-O bonds. The aliphatic derivatives, series 1, show an early release of methylselenol and a further release of hydroxyl derivatives (alcohols), whereas the aromatic carbamates, series 2, show an early release of phenols followed by the subsequent release of methylselenol. Thus, the activity of the compounds can be related to the progressive release of active fragments. The data that support this connection are related to the overall molecular topology, volume and surface area as well as to quantum parameters such as the relative electrophilic character of the target carbon atoms (measured in terms of positive charge values) or the bond order values, especially concerning the central C-SeCH3 bond and the carbamate ones. Moreover, the data obtained regarding the chromatographic behavior of some representative compounds confirm this proposal.

Combined Acylselenourea-Diselenide Structures: New Potent and Selective Antitumoral Agents as Autophagy Activators.

A series of 16 new diselenide-acylselenourea conjugates have been designed following the fragment-based drug strategy. Compound in vitro cytotoxic potential was evaluated against six human cancer cell lines and two nonmalignant derived cell lines with the aim of determining their potency and selectivity. Nine derivatives exhibited GI50 values under 10 µM in at least four cancer cell lines. A clear gap situated phenyl substitution over heterocyclic moieties in terms of selectivity. Among carbocyclic compounds, derivatives 2 and 7 significantly inhibited cell growth of breast adenocarcinoma cells with GI50 values of 1.30 and 0.15 nM, respectively, with selectivity indexes 12 and 121 times higher than those obtained for doxorubicin. Preliminary mechanistic studies indicated that compounds 2 and 7 induce cell cycle arrest and autophagy-dependent cell death evidenced by the blockage of cell death with pretreatment with wortmannin or chloroquine and confirmed by the upregulation of the markers Beclin1 and LC3B in MCF-7 cells.

Antitumoural Sulphur and Selenium Heteroaryl Compounds: Thermal Characterization and Stability Evaluation.

The physicochemical properties of a compound play a crucial role in the cancer development process. In this context, polymorphism can become an important obstacle for the pharmaceutical industry because it frequently leads to the loss of therapeutic effectiveness of some drugs. Stability under manufacturing conditions is also critical to ensure no undesired degradations or transformations occur. In this study, the thermal behaviour of 40 derivatives of a series of sulphur and selenium heteroaryl compounds with potential antitumoural activity were studied. In addition, the most promising cytotoxic derivatives were analysed by a combination of differential scanning calorimetry, X-ray diffraction and thermogravimetric techniques in order to investigate their polymorphism and thermal stability. Moreover, stability under acid, alkaline and oxidative media was tested. Degradation under stress conditions as well as the presence of polymorphism was found for the compounds VA6E and VA7J, which might present a hurdle to carrying on with formulation. On the contrary, these obstacles were not found for derivative VA4J.

Topical treatment of L. major infected BALB/c mice with a novel diselenide chitosan hydrogel formulation.

Topical therapy is the ideal outpatient treatment of cutaneous leishmaniasis (CL) because of the ease of administration and lower cost. It could be suitable as monotherapy for localized cutaneous leishmaniasis (LCL) or in combination with systemic therapies for more severe forms of the disease. Although paromomycin (PM) ointment can be recommended for the treatment of LCL caused by Leishmaniamajor, a more effective topical treatment should be achieved regarding the physicochemical properties of this aminoglucoside and its rather poor intrinsic antileishmanial activity, that hampers the accumulation of enough amount of drug in the dermis (where the infected macrophages home) to exert its activity. In this work, we determined a 50% effective dose of 5.6 µM for a novel compound, bis-4-aminophenyldiselenide, against L. major intracellular amastigotes. This compound and PM were formulated in chitosan hydrogels and ex vivo permeation and retention studies in the different skin layers were performed with pig ear skin in Franz diffusion cells. The results showed that less than 2-4% of the diselenide drug penetrated and permeated through the skin. In contrast, the percentage of PM penetration was about 25-60% without important retention in the skin. When topically applied to lesions of L. major infected BALB/c mice, the novel diselenide chitosan formulation was unable to slow lesion progression and reduce parasite burden. Considerations during the process of novel drug development and formulation discovery algorithm for CL are discussed.

Structural variations on antitumour agents derived from bisacylimidoselenocarbamate. A proposal for structure-activity relationships based on the analysis of conformational behaviour.

A molecular modelling study has been carried out on a previously reported series of symmetrically substituted bisacylimidoselenocarbamate (BSeC) derivatives that show remarkable antitumour activity in vitro against a panel of human tumour cell lines. These derivatives can be considered as a central scaffold constructed around a methyl carbamimidoselenoate nucleus in which two heteroarylacyl fragments are located on the scaffold nitrogen atoms, thus forming the different BSeCs. The results reveal that the nature of the selected heteroaryl ring has a marked influence on the antiproliferative activity of the compounds and this can be related, as a first approximation, to the ability to release methylselenol (MeSeH), a compound that, according to our initial hypothesis, is ultimately responsible for the antitumour activity of the compounds under investigation. The release of MeSeH from the active BSeCs has been confirmed by means of Head Space Gas Chromatography Mass Spectrometry techniques. The data that support this connection include the topography of the molecules, the conformational behaviour of the compounds, which influences the accessibility of the hydrolysis point, the interaction map obtained for an O2H type probe, and the location and energy of the HOMO/LUMO orbitals.

Structural characteristics of phosphoramide derivatives as urease inhibitors. Requirements for activity.

Taking as a reference the structural characteristics of a set of compounds that act as jack bean ( Canavalia ensiformis) urease inhibitors, namely, phenylphosphorodiamidate (PPD), N- n-butylthiophosphorictriamide (NBPT), and N- n-butylphosphorictriamide (NBPTO), we have studied the structure-activity relationships of a series of phosphoramide derivatives for which the activity as urease inhibitors in both in vitro and in vivo assays is known. Molecular modeling studies were carried out, and the results highlighted the relevance of characteristics such as the presence of intramolecular hydrogen bonds, the volume of the fragment involved in the enzyme interaction, and the degree of conformational freedom as well as the HOMO orbital and atomic orbital contributions to the HOMO orbital, electron density, and PEM distributions on the activity of these compounds as urease inhibitors. These data, along with the preliminary docking study carried out, allow us to propose a union mode to the active site of the enzyme for these compounds.

Design, synthesis, and biological evaluation of phosphoramide derivatives as urease inhibitors.

The design, synthesis, and biological evaluation of phosphoramide derivatives as urease inhibitors to reduce the loss of ammonia has been carried out. Forty phosphorus derivatives were synthesized and their inhibitory activities evaluated against that of jack bean urease. In addition, in vivo assays have been carried out. All of the compounds were characterized by IR, (1)H NMR, MS, and elemental microanalysis. In some cases, detailed molecular modeling studies were carried out, and these highlighted the interaction between the enzyme active center and the compounds and also the characteristics related to their activity as urease inhibitors. According to the IC(50) values for in vitro inhibitory activity, 12 compounds showed values below 1 microM and 8 of them represent improvements of activity in comparison to the commercial urease inhibitor N-n-butylthiophosphorictriamide (NBPT) (100 nM) (AGROTAIN). On the basis of the activity results and the conclusions of the molecular modeling study, a structural model for new potential inhibitors has been defined.