Design, Synthesis, and Biological Evaluation of New Type of Gemini Analogues with a Cyclopropane Moiety in Their Side Chain.

We synthesized two new gemini analogues, UG-480 and UG-481, that incorporate a modified longer side chain containing a cyclopropane group. The evaluation of the bioactivities of the two gemini analogues indicated that the 17,20 threo (20S) compound, UG-480, is the most active one and is as active as 1,25(OH)2D3. Docking and molecular dynamics (MD) data showed that the compounds bind efficiently to vitamin D receptor (VDR) with UG-480 to form an energetically more favorable interaction with His397. Structural analysis indicated that whereas the UG-480 compound efficiently stabilizes the active VDR conformation, it induces conformational changes in the H6-H7 VDR region that are greater than those induced by the parental Gemini and that this is due to the occupancy of the secondary channel by its modified side chain.

Structural analysis and biological activities of C25-amino and C25-nitro vitamin D analogs.

Intense synthetic efforts have been directed towards the development of noncalcemic analogs of 1,25-dihydroxyvitamin D3. We describe here the structural analysis and biological evaluation of two derivatives of 1,25-dihydroxyvitamin D3 with modifications limited to the replacement of the 25-hydroxyl group by a 25-amino or 25-nitro groups. Both compounds are agonists of the vitamin D receptor. They mediate biological effects similar to 1,25-dihydroxyvitamin D3, the 25-amino derivative being the most potent one while being less calcemic than 1,25-dihydroxyvitamin D3. The in vivo properties of the compounds make them of potential therapeutic value.

On the mechanism of the dyotropic expansion of hydrindanes into decalins.

A combined computational/experimental approach has revealed key mechanistic aspects in a recently reported dyotropic expansion of hydrindanes into decalins. While computer simulations had already anticipated the need for acid catalysis for making this reaction feasible under the mild conditions used in the laboratory, this work places the dyotropic step not into the reaction flask but at a later step, during the work up instead. With this information in hand the reaction has been optimized by exploring the performance of different activating agents and shown to be versatile, particularly in steroid related chemistry due to the two scaffolds that this reaction connects. Finally, the scope of the reaction has been significantly broadened by showing that this protocol can also operate in the absence of the fused six-member ring.

Easy Access to Polyfunctionalized Chiral Decalins.

An unexpected ring expansion that converts hydrindanes into decalins via an unprecedented dyotropic reaction involving a mesylate group has been observed, and this paved the way for easy access to polyfunctionalized chiral decalins. These polyfunctionalized chiral decalins can be very useful building blocks for the synthesis of the thia analogues of many natural compounds. They can also be used in asymmetric catalysis and also in the synthesis of the new analogues of vitamin D with a modified D ring and side chain. The use of chiral sulfoxide ligands for asymmetric catalysis or asymmetric sulfur ylide-mediated epoxidation of carbonyl compounds is a very important topic in the field of organic chemistry, hence our results could be useful to the scientific community.

Access to a Library of 1,3-disubstituted-1,2,3-triazenes and Evaluation of their Antimicrobial Properties.

BACKGROUND: Due to the rapid development of microbial resistance, finding new molecules became urgent to counteract this problem. OBJECTIVE: The objective of this work is to access 1,2,3-triazene-1,3-disubstituted, a class of molecule with high therapeutic potential. METHODS: Here we describe the access to 17 new triazene including six with an imidazole-1,2,3-triazene moiety and eleven with an alkyl-1,2,3-triazene moiety and their evaluation against five strains: two gram (-): Escherichia coli ATCC 25921 and Pseudomonas aeruginosa ATCC 27253; two gram (+) : Staphylococcus aureus ATCC 38213 and Enterococcus faecalis ATCC 29212; and one fungi: Candida albicans ATCC 24433. RESULTS: All strains were sensitive and the best MIC, 0.28 µM, is observed for 4c against Escherichia coli ATCC 25921. Compound 9, 3-isopropynyltriazene, appears to be the most interesting since it is active on the five evaluated strains with satisfactory MIC 0.32 µM against Escherichia coli and Pseudomonas aeruginosa and 0.64 µM against Enterococcus faecalis and Pseudomonas aeruginosa. CONCLUSION: Comparing the structure activity relationship, electron withdrawing groups appear to increase antimicrobial activity.

Novel calcitriol analogue with an oxolane group: In vitro, in vivo, and in silico studies.

The active form of vitamin D3 , calcitriol, is a potent antiproliferative compound. However, when effective antitumor doses of calcitriol are used, hypercalcemic effects are observed, thus blocking its therapeutic application. To overcome this problem, structural analogues have been designed with the aim of retaining or even increasing the antitumor effects while decreasing its calcemic activity. This report aims at gaining insights into the structure-activity relationships of the novel oxolane-containing analogue, AM-27, recently synthesized. We herein demonstrate that this compound has antiproliferative and antimigratory effects in squamous cell carcinoma, glioblastoma, and breast cancer cell lines. Analyses of the mechanisms underlying the AM-27 effects on cell viability revealed induction of apoptosis by the analogue. Importantly, nonmalignant cell lines were little or not affected by the compound. In addition, the analogue did not produce hypercalcemia in mice. Also, in silico studies involving docking and molecular dynamics techniques showed that AM-27 is able to bind to the human vitamin D receptor with a higher affinity than the natural ligand calcitriol, a feature that is mostly derived from an electrostatic interaction pattern. Altogether, the proapoptotic effect observed in cancer cells, the lack of calcemic activity in mice, and the differential effects in normal cells suggest the potential of AM-27 as a therapeutic compound for cancer treatment.

Synthesis of a novel analog of calcitriol and its biological evaluation as antitumor agent.

Calcitriol analogs have shown promising potential as compounds to be used in cancer chemotherapy. This report presents the synthesis of a novel vitamin D3 derivative with an amide and a carboxyl group in its side chain, called ML-344. In addition, we report its in vitro antitumor activity and its in vivo calcemic effects. We demonstrate that the analog decreases cell viability and retards cell migration of different breast, glioblastoma and head and neck cancer cell lines. Additionally, unlike calcitriol, ML-344 does not display citotoxicity to the murine non-malignant mammary cells and human astrocytes. In concordance with the antimigratory effects found in breast cancer cells, ML-344 decreased the invasive capacity and induced a rearrangement of the actin cytoskeleton in the LM3 breast cancer cell line. In relation to the in vivo studies, the analog did not cause hypercalcemic effects in CF1 mice administered daily at 5 µg/Kg of body weight during a period of 264 h. Finally, computational studies were performed to evaluate the potential binding of the analog to the vitamin D receptor and the in silico assays showed that ML-344 is able to bind to VDR with interesting particularities and greater affinity than calcitriol. Altogether, these results suggest that ML-344 has a promising potential as an antitumor agent with a differential effect between tumor and non-malignant cells.

From Hydrindane to Decalin: A Mild Transformation through a Dyotropic Ring Expansion.

An unexpected ring expansion converting hydrindane cores into decalins has been observed. The process occurs under very mild conditions and with exquisite transfer of chiral information. The ring expansion provides access to decorated decalins with complete stereocontrol. The reaction mechanism is studied in order to gain insight into the underlying causes for the low thermal requirements in this reaction and the nature of the chirality transfer process. Interestingly, both result from an unprecedented dyotropic reaction involving a mesylate group.

Structure-activity relationship study of vitamin D analogs with oxolane group in their side chain.

Synthetic analogs of 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3) have been developed with the goal of improving the biological profile of the natural hormone for therapeutic applications. Derivatives of 1,25(OH)2D3 with the oxolane moiety branched in the side chain at carbon C20, act as Vitamin D nuclear Receptor (VDR) superagonists being several orders of magnitude more active than the natural ligand. Here, we describe the synthesis and biological evaluation of three diastereoisomers of (1S, 3R)-Dihydroxy-(20S)-[(2″-hydroxy-2″-propyl)-tetrahydrofuryl]-22,23,24,25,26,27-hexanor-1α-hydroxyvitamin D3, with different stereochemistry at positions C2 and C5 of the oxolane ring branched at carbon C22 (1, C2RC5S; 2, C2SC5R; 3, C2SC5S). These compounds act as weak VDR agonist in transcriptional assays with compound 3 being the most active. X-ray crystallographic analysis of the VDR ligand-binding domain accommodating the three compounds indicates that the oxolane group branched at carbon C22 is not constrained as in case of compound with oxolane group branched at C20 leading to the loss of interactions of the triene group and increased flexibility of the C/D-rings and of the side chain.

Use of surface plasmon resonance in the binding study of vitamin D, metabolites and analogues with vitamin D binding protein.

Vitamin D3 and its metabolites are lipophilic molecules with low aqueous solubility and must be transported bound to plasma carrier proteins, primarily to vitamin D binding protein (DBP). The biological functions of vitamin D3 metabolites are intimately dependent on the protein, hence the importance of determining their affinity for DBP. In this study, we developed a novel procedure for measuring the kinetic and equilibrium constants of human-DBP with vitamin D3 and three metabolites: 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], 25-hydroxyvitamin D3 (25OHD3) and 24,25-dihydroxyvitamin D3 [24,25(OH)2D3] by surface plasmon resonance (SPR). At the same time, five different analogues, synthetized in our laboratory, were evaluated in order to compare the affinity values with the metabolites. Real-time SPR measurements showed that 25OHD3 and 24,25(OH)2D3 had higher affinity (0.3 µM) than 1,25(OH)2D3 (5 µM), with the higher affinity of 25OHD3 and 24,25(OH)2D3 due to dissociation constants 1 order of magnitude slower. In the case of the analogues, the affinity values were lower, with 1-hydroxy-25-nitro-vitamin D3 (NO2-446), structurally closer to 1,25(OH)2D3, showing the highest value with a K D of 50 µM. (24R)-1,25-dihydroxyvitamin-24-buthyl-28-norvitamin D2 (Bu-471) and (24R)-1,25-dihydroxyvitamin-24-phenyl-28-norvitamin D2 (Ph-491), structurally similar, had affinities of 180 and 170 µM, respectively. (22R,23E)-1-hydroxy-22-ethenyl-25-methoxy-23-dehydrovitamin D3 (MeO-455) and 1-hydroxy-20(R)-[5(S)-(2,2-dimethyltetrahydropyran-5-yl)]-22,23-dinor vitamin D3 (Oxan-429) had affinities of 310 and 100 µM, respectively. The binding of the metabolites and analogues was reversible allowing the rapid capture of data for replicates. The kinetic and equilibrium data for both the metabolites and the analogues fitted to the Langmuir model describing a 1:1 interaction. Graphical Abstract Label-free, real time binding study between vitamin D binding protein immmobilized on the surface of a SPR sensor chip and the vitamin D, metabolites and analogues passed over it as analytes.

The UVB1 Vitamin D analogue inhibits colorectal carcinoma progression.

Vitamin D has been shown to display a wide variety of antitumour effects, but their therapeutic use is limited by its severe side effects. We have designed and synthesized a Gemini vitamin D analogue of calcitriol (UVB1) which has shown to display antineoplastic effects on different cancer cell lines without causing hypercalcemia. The aim of this work has been to investigate, by employing in silico, in vitro, and in vivo assays, whether UVB1 inhibits human colorectal carcinoma progression. We demonstrated that UVB1 induces apoptotic cell death and retards cellular migration and invasion of HCT116 colorectal carcinoma cells. Moreover, the analogue reduced the tumour volume in vivo, and modulated the expression of Bax, E-cadherin and nuclear ß-catenin in tumour animal tissues without producing toxic effects. In silico analysis showed that UVB1 exhibits greater affinity for the ligand binding domain of vitamin D receptor than calcitriol, and that several characteristics in the three-dimensional conformation of VDR may influence the biological effects. These results demonstrate that the Gemini vitamin D analogue affects the growth of the colorectal cancer and suggest that UVB1 is a potential chemotherapeutic agent for treatment of this disease.

Vitamin D analogue: potent antiproliferative effects on cancer cell lines and lack of hypercalcemic activity.

The active form of vitamin D3, 1α,25(OH)2D3, plays a major role in maintaining calcium/phosphate homeostasis. In addition, it is a potent antiproliferative and pro-differentiating agent. Unfortunately, it usually causes hypercalcemia in vivo when effective antitumour doses are used. It has therefore been found necessary to synthesise new analogues that retain or even increase the antitumour effects but preclude hypercalcemia. This report presents the synthesis of a novel Gemini vitamin D analogue (UVB1) and its biological evaluation. We demonstrate that this compound has potent antitumoural effects over a wide panel of tumour cell lines while showing lack of hypercalcemic activity and toxicity effects in in vivo assays.

Synthesis and biological evaluation of a new vitamin D2 analogue.

A new vitamin D(2) analogue was synthesized using the Julia-Kocienski olefination. It has antiproliferative effects on cell lines from squamous cell carcinomas of colon and head and neck, but is also as hypercalcaemic as calcitriol in vivo.

Review of synthesis, biological assay, and QSAR studies of HMGR inhibitors.

Effective as statin drugs or acids are inhibitors mevinic limiting enzyme in cholesterol biosynthesis, 3-hydroxy- 3-methyl-glutaryl coenzyme A-3-hydroxy-3-reductase (HMGR), an enzyme responsible for the reduction the double methyl-glutaryl coenzyme A. These compounds promoted the synthesis and evaluation of new inhibitors of HMGR, called HMGRIs. The high number of potential candidates need to create models of quantitative structure-activity relationship in order to guide the HMGRI (3-hydroxy-3-methyl-glutarylcoenzyme A inhibitor) synthesis. In this work, we revised different computational studies for a very large and heterogeneous series of HMGRIs. First, we revised QSAR studies with conceptual parameters how flexibility of rotation, probability of availability, etc; Next, using method of regression analysis; and QSAR studies in order to understand the essential structural requirement for binding with receptor. Next, we review 3D QSAR, CoMFA and CoMSIA with different compound to find out the structural requirements for 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) inhibitory activity.

Review of QSAR for DNA polymerase inhibitors and new models for heterogeneous series of compounds.

DNA polymerases are essential enzymes for DNA replication, repair and recombination. The high number of possible candidates creates the necessity of Quantitative Structure-Activity Relationship models in order to guide the DNA polymerase inhibitors. In this work, we revised different computational studies for a very large and heterogeneous series of DNA polymerase inhibitors. First, we reviewed QSAR methods with different compounds to find out the structural requirements for DNA polymerase inhibitory activity. Last, we report a new LDA analysis with the different molecular descriptors calculated with DRAGON software.

An application of two MIFs-based tools (Volsurf+ and Pentacle) to binary QSAR: the case of a palinurin-related data set of non-ATP competitive glycogen synthase kinase 3ß (GSK-3ß) inhibitors.

VolSurf+ and GRIND descriptors extract the information present in MIFs calculated by GRID: the first are simpler to interpret and generally applied to ADME-Tox topics, whereas the latter are more sophisticated and thus more suited for pharmacodynamics events. Here we present a study which compares binary QSAR models obtained with VolSurf+ descriptors and GRIND for a data set of non-ATP competitive GSK-3ß inhibitors chemically related to palinurin for which the biological activity is expressed in binary format. Results suggest not only that the simpler Volsurf+ descriptors are good enough to predict and chemically interpret the investigated phenomenon but also a bioactive conformation of palinurin which may guide future design of ATP non-competitive GSK-3 inhibitors.

First computational chemistry multi-target model for anti-Alzheimer, anti-parasitic, anti-fungi, and anti-bacterial activity of GSK-3 inhibitors in vitro, in vivo, and in different cellular lines.

In the work described here, we developed the first multi-target quantitative structure-activity relationship (QSAR) model able to predict the results of 42 different experimental tests for GSK-3 inhibitors with heterogeneous structural patterns. GSK-3ß inhibitors are interesting candidates for developing anti-Alzheimer compounds. GSK-3ß are also of interest as anti-parasitic compounds active against Plasmodium falciparum, Trypanosoma brucei, and Leishmania donovani; the causative agents for Malaria, African Trypanosomiasis and Leishmaniosis. The MARCH-INSIDE technique was used to quickly calculate total and local polarizability, n-octanol/water partition coefficients, refractivity, van der Waals area and electronegativity values to 4,508 active/non-active compounds as well as the average values of these indexes for active compounds in 42 different biological assays. Both the individual molecular descriptors and the average values for each test were used as input for a linear discriminant analysis (LDA). We discovered a classification function which used in training series correctly classifies 873 out of 1,218 GSK-3 cases of inhibitors (97.4%) and 2,140 out of 2,163 cases of non-active compounds (86.1%) in the 42 different tests. In addition, the model correctly classifies 285 out of 406 GSK-3 inhibitors (96.3%) and 710 out of 721 cases of non-active compounds (85.4%) in external validation series. The result is important because, for the first time, we can use a single equation to predict the results of heterogeneous series of organic compounds in 42 different experimental tests instead of developing, validating, and using 42 different QSAR models. Lastly, a double ordinate Cartesian plot of cross-validated residuals (first ordinate), standard residuals (second ordinate), and leverages (abscissa) defined the domain of applicability of the model as a squared area within ± 2 band for residuals and a leverage threshold of h = 0.0044.

Using topological indices to predict anti-Alzheimer and anti-parasitic GSK-3 inhibitors by multi-target QSAR in silico screening.

Plasmodium falciparum, Leishmania, Trypanosomes, are the causers of diseases such as malaria, leishmaniasis and African trypanosomiasis that nowadays are the most serious parasitic health problems worldwide. The great number of deaths and the few drugs available against these parasites, make necessary the search for new drugs. Some of these antiparasitic drugs also are GSK-3 inhibitors. GSKI-3 are candidates to develop drugs for the treatment of Alzheimer's disease. In this work topological descriptors for a large series of 3,370 active/non-active compounds were initially calculated with the ModesLab software. Linear Discriminant Analysis was used to fit the classification function and it predicts heterogeneous series of compounds like paullones, indirubins, meridians, etc. This study thus provided a general evaluation of these types of molecules.