Benzothiazole Derivatives as Multifunctional Antioxidant Agents for Skin Damage: Structure-Activity Relationship of a Scaffold Bearing a Five-Membered Ring System.

Skin diseases often give multifactorial damages; therefore, the development of multifunctional compounds represents a suitable approach especially against disorders that are induced by oxidative stress. Thus, taking into account the successful results we achieved on benzimidazoles, we have devised a new series of isosteric benzothiazoles and investigated their antioxidant, photoprotective, antifungal and antiproliferative activity. Particular attention has been paid to synergistic antioxidant and photoprotective properties. For compounds 9a and 10a, a multifunctional profile was outlined, supported by an excellent filtering capacity, mainly UVB, which has higher capacities than those of the reference PBSA which is currently in the market as a UV sunscreen filter. The two compounds were also the best in terms of growth inhibition of dermatophytes and Candida albicans, and 10a also showed good antioxidant activity. Furthermore, 9a was also effective on melanoma tumor cells (SK-Mel 5), making these compounds good candidates in the development of new skin protective and preventive agents.

Design, Synthesis, Spectroscopic Characterisation and In Vitro Cytostatic Evaluation of Novel Bis(coumarin-1,2,3-triazolyl)benzenes and Hybrid Coumarin-1,2,3-triazolyl-aryl Derivatives.

In this work, a series of novel 1,2,3-triazolyl-coumarin hybrid systems were designed as potential antitumour agents. The structural modification of the coumarin ring was carried out by Cu(I)-catalysed Huisgen 1,3-dipolar cycloaddition of 7-azido-4-methylcoumarin and terminal aromatic alkynes to obtain 1,4-disubstituted 1,2,3-triazolyl-coumarin conjugates 2a-g, bis(1,2,3-triazolyl-coumarin)benzenes 2h-i and coumarin-1,2,3-triazolyl-benzazole hybrids 4a-b. The newly synthesised hybrid molecules were investigated for in vitro antitumour activity against five human cancer cell lines, colon carcinoma HCT116, breast carcinoma MCF-7, lung carcinoma H 460, human T-lymphocyte cells CEM, cervix carcinoma cells HeLa, as well as human dermal microvascular endothelial cells (HMEC-1). Most of these compounds showed moderate to pronounced cytotoxic activity, especially towards MCF-7 cell lines with IC50 = 0.3-32 µM. In addition, compounds 2a-i and 4a-b were studied by UV-Vis absorption and fluorescence spectroscopy and their basic photophysical parameters were determined.

Transition metal-catalyzed synthesis of new 3-substituted coumarin derivatives as antibacterial and cytostatic agents.

Aim: The aim of this study was to synthesize new coumarin-based compounds and evaluate their antibacterial and antitumor potential. Results: Using transition metal-catalyzed reactions, a series of 7-hydroxycoumarin derivatives were synthesized with aliphatic and aryl moiety attached directly at C-3 of the coumarin ring and through the ethynyl or 1,2,3-triazole linker. The 3-substituted coumarin derivative bearing bistrifluoromethylphenyl at the C-4 position of 1,2,3-triazole (33) showed strong and selective antiproliferative activity against cervical carcinoma cells. The 7-hydroxy-4-methylcoumarin with a phenyl ring directly attached to coumarin at C-3 (10) showed good potency against the methicillin-resistant Staphylococcus aureus and vancomycin-resistant strains. Conclusion: The most active coumarin derivatives owe their antiproliferative potential to the 3,5-ditrifluoromethylphenyl substituent (in 33) and antibacterial activity to the aromatic moiety (in 10); their structure can be optimized further for improved effect.

N-alpha-Aminoacyl Colchicines as Promising Anticancer Agents.

BACKGROUND: In the last years, many efforts have been made to find colchicine derivatives with reduced toxicity. Additionally, the deregulation of amino acid uptake by cancer cells provides an opportunity to improve anticancer drug effectiveness. OBJECTIVE: To design new colchicine derivatives with reduced cytotoxicity and enhanced selectivity by means of introducing aminoacyl groups. METHODS: 34 colchicine analogues bearing L- and D-amino acid pendants were synthetized and characterized by NMR, IR and MS techniques. Cytotoxicity and antimitotic properties were assessed by spectrophotometry and cell cycle assays. Oncogene downregulation was studied by RTqPCR whereas in vivo studies were performed in SCID mice. RESULTS: Compounds exhibit high antiproliferative activities at the nanomolar level while being, in general, less cytotoxic than colchicine. Most compounds inhibit the polymerization of tubulin in a way similar to colchicine itself, with L-amino acid derivatives being the most active in the inhibition of tubulin polymerization. All selected compounds caused cell cycle arrest at the G2/M phase when tested at 1 µM. More specifically, Boc-L-proline derivative 6 arrested half of the population and showed one of the highest Selectivity Indexes. Derivatives 1 (Boc-glycine), 27 (D-leucine) and 31 (Boc-glycine-glycine) proved fairly active in downregulating the expression of the c-Myc, hTERT and VEGF oncogenes, with compound 6 (Boc-L-proline) having the highest activity. This compound was shown to exert a potent anti-tumor effect when administered intraperitoneally (LD50 > 100 mg/kg for 6, compared with 2.5 mg/kg for colchicine). CONCLUSION: Compound 6 offers an opportunity to be used in cancer therapy with less toxicity problems than colchicine.

Benzazole Substituted Iminocoumarins as Potential Antioxidants with Antiproliferative Activity.

BACKGROUND: Benzazole and coumarin derivatives are one of the most privileged heterocyclic substructures in the medicinal chemistry with well-known biological features, which include a wide range of versatile biological activities as well as excellent spectroscopic characteristics thus offering their potential application in many research fields. OBJECTIVE: The prepared iminocoumarins were synthesized to evaluate their antioxidative potential by using ABTS and FRAP assays and in vitro antiproliferative activity. METHODS: A series of coumarin derivatives containing a 2-benzazole motif were synthesized and evaluated for their antioxidative capacity and antiproliferative activity. Their molecular structure incorporates a push-pull functionality: an electron donor donating group at the 7-position with an electron-withdrawing group, such as benzimidazole, benzothiazole and imidazopyridine fragment at the 3-position. RESULTS: The iminocoumarins bearing different substituents on 7-position were evaluated for their antiproliferative activity on tree cancer cells with only 4 compounds showing the antiproliferative activity. The most active derivative was N,N-diethylamino substituted benzimidazole derivative 4d and imidazo[4,5-b]pyridine analogue 6b, both also displayed selective activity toward CEM with submicromolar inhibitory concentration (0.059 µM; 0.17 ± 0.09, respectively). The inhibitory effect of 4d and 6b derivatives on the cell-cycle progression of HeLa cells was studied. A flow cytometric analysis of the HeLa cells indicated an appreciable cell-cycle arrest in a dose-dependent manner. Antioxidant properties were studied by ABTS and FRAP assays and obtained results revealed that the most promising antioxidant has proven to be compound 3b while other compounds, in general, showed moderate to very low antioxidative capacity in both assays. CONCLUSION: Unsubstituted benzimidazole derivatives bearing hydroxyl group on iminocoumarin nuclei exhibited the most prominent antioxidant potential in ABTS assay (3b; 40.5 ± 0.01). The most significant and selective antiproliferative activity was displayed by compounds 4d and 6b (0.059 µM; 0.17 ± 0.09, respectively), which were chosen as lead compounds for further optimization and rational design to obtain more active and selective antiproliferative agents.

Skin Damages-Structure Activity Relationship of Benzimidazole Derivatives Bearing a 5-Membered Ring System.

In the search for scaffolds for multifunctional compounds we investigated the structure activity relationship of a class of benzimidazole derivatives bearing 5-membered ring. The newly synthesized and the already known compounds were divided into three classes that present different substituent at 5 position of the benzimidazole ring (-H, -COOH or -SO3H) and different heterocycle at position 2 (thiophene, furan or pyrrole). All the derivatives were synthesized and tested to determine their photoprotective profile against UV rays, in vitro antioxidant capacity against different radicals (DPPH and FRAP test), antifungal inhibitory activity (dermatophytes and Candida albicans), antiviral and antiproliferative activity. A Structure-Activity Relationship study indicated compound 10, bearing a pyrrole heterocycle on the benzimidazole ring, as the best multifunctional derivative of the series and as potential candidate for the development of drugs especially in case of melanoma.

Synthesis and Biological Evaluation of Analogs of Didehydroepiandrosterone as Potential New Anticancer Agents.

The synthesis, cytotoxicity and inhibition of CDK8 by thirteen analogs of cortistatin A are reported. These efforts revealed that the analogs with either a 6- or 7-isoquinoline or 5-indole side chain in the 17-position are the most promising anti-proliferative agents. These compounds showed potent cytotoxic effects in CEM, HeLa and HMEC-1 cells. All three compounds exhibited IC50 values < 10µM. The most interesting 10l analog exhibited an IC50 value of 0.59 µM towards the human dermal microvascular endothelial cell line (HMEC-1), significantly lower than the reference standard 2-methoxyestradiol. At a concentration at 50 nM the most potent 10h compound reduced the activity of CDK8 to 35%.

Design, synthesis and evaluation of benzothiazole derivatives as multifunctional agents.

Oxidative stress is the product or aetiology of various multifactorial diseases; on the other hand, the development of multifunctional compounds is a recognized strategy for the control of complex diseases. To this end, a series of benzothiazole derivatives was synthesized and evaluated for their multifunctional effectiveness as antioxidant, sunscreen (filter), antifungal and antiproliferative agents. Compounds were easily synthesized via condensation reaction between 2-aminothiophenols and different benzaldehydes. SAR study, particularly in position 2 and 6 of benzothiazoles, led to the identification of 4g and 4k as very interesting potential compounds for the design of multifunctional drugs. In particular, compound 4g is the best blocker of hERG potassium channels expressed in HEK 293 cells exhibiting 60.32% inhibition with IC50 = 4.79 µM.

Substituted adamantylphthalimides: Synthesis, antiviral and antiproliferative activity.

In this study, three groups of adamantylphthalimides, bearing different substituents at the phthalimide moiety, N-(4'-R2 )phthalimidoadamantanes (1-7), 3-[N-(4'-R2 )phthalimido]-1-adamantanols (8-10), and 3-[N-(4'-R2 )phthalimido]adamantane-1-carboxylic acids (11-15), were synthesized and screened against tumor cells and viruses. The most potent compounds are not substituted at the adamantane and bear an OH or NH2 substituent at the phthalimide (compounds 3 and 5). The antiproliferative activities of compounds 3 and 5 are in the micromolar range, much higher than the one of thalidomide. A minor antiviral activity against cytomegalovirus and varicella-zoster virus was found for compounds 3 and 5, but these compounds lacked selectivity. The results presented are important for the rational design of the next-generation compounds with anticancer and antiviral activities.

Synthesis and Biological Evaluation of New Antitubulin Agents Containing 2-(3',4',5'-trimethoxyanilino)-3,6-disubstituted-4,5,6,7-tetrahydrothieno[2,3-c]pyridine Scaffold.

Two novel series of compounds based on the 4,5,6,7-tetrahydrothieno[2,3-c]pyridine and 4,5,6,7-tetrahydrobenzo[b]thiophene molecular skeleton, characterized by the presence of a 3',4',5'-trimethoxyanilino moiety and a cyano or an alkoxycarbonyl group at its 2- or 3-position, respectively, were designed, synthesized, and evaluated for antiproliferative activity on a panel of cancer cell lines and for selected highly active compounds, inhibition of tubulin polymerization, and cell cycle effects. We have identified the 2-(3',4',5'-trimethoxyanilino)-3-cyano-6-methoxycarbonyl-4,5,6,7-tetrahydrothieno[2,3-c]pyridine derivative 3a and its 6-ethoxycarbonyl homologue 3b as new antiproliferative agents that inhibit cancer cell growth with IC50 values ranging from 1.1 to 4.7 µM against a panel of three cancer cell lines. Their interaction with tubulin at micromolar levels leads to the accumulation of cells in the G2/M phase of the cell cycle and to an apoptotic cell death. The cell apoptosis study found that compounds 3a and 3b were very effective in the induction of apoptosis in a dose-dependent manner. These two derivatives did not induce cell death in normal human peripheral blood mononuclear cells, suggesting that they may be selective against cancer cells. Molecular docking studies confirmed that the inhibitory activity of these molecules on tubulin polymerization derived from binding to the colchicine site.

Anti-influenza virus activity of benzo[d]thiazoles that target heat shock protein 90.

Seasonal or pandemic influenza virus infections are a worldwide health problem requiring antiviral therapy. Since virus resistance to the established neuraminidase inhibitors and novel polymerase inhibitors is growing, new drug targets are needed. Heat shock protein 90 (Hsp90) is associated with several aspects of the influenza virus life cycle, and is considered a relevant host cell target. We report here on a series of benzo[d]thiazole and 4,5,6,7-tetrahydrobenzo[d]thiazole derivatives with robust and selective activities against influenza A (H1N1, H3N2) and influenza B viruses. Two compounds, 1 and 4, have low micromolar EC50 values and show high binding affinities for Hsp90, which suggests that inhibition of Hsp90 is the mechanism underlying their antiviral effects. These compounds represent suitable scaffolds for designing novel Hsp90 inhibitors with favourable activities against influenza virus.

Design, synthesis and biological evaluation of 2-alkoxycarbonyl-3-anilinoindoles as a new class of potent inhibitors of tubulin polymerization.

A new class of inhibitors of tubulin polymerization based on the 2-alkoxycarbonyl-3-(3',4',5'-trimethoxyanilino)indole molecular skeleton was synthesized and evaluated for antiproliferative activity, inhibition of tubulin polymerization and cell cycle effects. The results presented show that the methoxy substitution and location on the indole nucleus plays an important role in inhibition of cell growth, and the most favorable position for the substituent was at C-6. In addition, a small-size ester function (methoxy/ethoxycarbonyl) at the 2-position of the indole core was desirable. Also, analogues that were alkylated with methyl, ethyl or n-propyl groups or had a benzyl moiety on the N-1 indolic nitrogen retained activity equivalent to those observed in the parent N-1H analogues. The most promising compounds of the series were 2-methoxycarbonyl-3-(3',4'.5'-trimethoxyanilino)-5-methoxyindole 3f and 1-methyl-2-methoxycarbonyl-3-(3',4'.5'-trimethoxyanilino)-6-methoxy-indole 3w, both of which target tubulin at the colchicine site with antitubulin activities comparable to that of the reference compound combretastatin A-4.

Gelatinase B/matrix metalloproteinase-9 and other neutrophil proteases switch off interleukin-2 activity.

Interleukin 2 (IL-2) is critical for T cell development and homeostasis, being a key regulator of adaptive immune responses in autoimmunity, hypersensitivity reactions and cancer. Therefore, its abundance in serum and peripheral tissues needs tight control. Here, we described a new mechanism contributing to the immunobiology of IL-2. We demonstrated, both in biochemical and cell-based assays, that IL-2 is subject to proteolytic processing by neutrophil matrix metalloproteinase-9 (MMP-9). IL-2 fragments produced after cleavage by MMP-9 remained linked by a disulfide bond and displayed a reduced affinity for all IL-2 receptor subunits and a distinct pattern and timing of signal transduction. Stimulation of IL-2-dependent cells, including murine CTLL-2 and primary human regulatory T cells, with cleaved IL-2 resulted in significantly decreased proliferation. The concerted action of neutrophil proteases destroyed IL-2. Our data suggest that in neutrophil-rich inflammatory conditions in vivo, neutrophil MMP-9 may reduce the abundance of signaling-competent IL-2 and generate a fragment that competes with IL-2 for receptor binding, whereas the combined activity of granulocyte proteases has the potential to degrade and thus eliminate bioavailable IL-2.

Potent antiviral activity of carbohydrate-specific algal and leguminous lectins from the Brazilian biodiversity.

Brazil has one of the largest biodiversities in the world. The search for new natural products extracted from the Brazilian flora may lead to the discovery of novel drugs with potential to treat infectious and other diseases. Here, we have investigated 9 lectins extracted and purified from the Northeastern Brazilian flora, from both leguminous species: Canavalia brasiliensis (ConBr), C. maritima (ConM), Dioclea lasiocarpa (DLasiL) and D. sclerocarpa (DSclerL), and algae Amansia multifida (AML), Bryothamniom seaforthii (BSL), Hypnea musciformis (HML), Meristiella echinocarpa (MEL) and Solieria filiformis (SfL). They were exposed to a panel of 18 different viruses, including HIV and influenza viruses. Several lectins showed highly potent antiviral activity, often within the low nanomolar range. DSclerL and DLasiL exhibited EC50 values (effective concentration of lectin required to inhibit virus-induced cytopathicity by 50%) of 9 nM to 46 nM for HIV-1 and respiratory syncytial virus (RSV), respectively, DLasiL also inhibited feline corona virus at an EC50 of 5 nM, and DSclerL, ConBr and ConM showed remarkably low EC50 values ranging from 0.4 to 6 nM against influenza A virus strain H3N2 and influenza B virus. For HIV, evidence pointed to the blockage of entry of the virus into its target cells as the underlying mechanism of antiviral action of these lectins. Overall, the most promising lectins based on their EC50 values were DLasiL, DSclerL, ConBr, ConM, SfL and HML. These novel findings indicate that lectins from the Brazilian flora may provide novel antiviral compounds with therapeutic potential.

Diphenyl ether derivatives occupy the expanded binding site of cyclohexanedione compounds at the colchicine site in tubulin by movement of the αT5 loop.

Microtubule targeting agents represent a very active arena in the development of anticancer agents. In particular, compounds binding at the colchicine site in tubulin are being deeply studied, and the structural information recently available on this binding site allows structure-directed design of new ligands. Structural comparison of our recently reported high resolution X-Ray structure of the cyclohexanedione derivative TUB075 bound to tubulin and the tubulin-DAMA-colchicine complex has revealed a conformational change in the αT5 loop. By a grid-based computational analysis of the tubulin-DAMA-colchicine binding site, we have identified a new favourable binding area in the colchicine-site that was unexplored by our lead TUB075. Thus, based on a structure-guided design, new cyclohexanedione derivatives have been synthesized and tested for tubulin binding and in cellular assays. As a result, we have identified diphenyl ether derivatives with IC50 values around 10-40 nM against three different tumor cell lines and affinity constants for tubulin similar to that of colchicine around 107 M-1. As expected, they halted the cell cycle progression at G2/M phase at concentrations as low as 0.08 µM.

Influenza virus entry via the GM3 ganglioside-mediated platelet-derived growth factor receptor ß signalling pathway.

The possible resistance of influenza virus against existing antiviral drugs calls for new therapeutic concepts. One appealing strategy is to inhibit virus entry, in particular at the stage of internalization. This requires a better understanding of virus-host interactions during the entry process, including the role of receptor tyrosine kinases (RTKs). To search for cellular targets, we evaluated a panel of 276 protein kinase inhibitors in a multicycle antiviral assay in Madin-Darby canine kidney cells. The RTK inhibitor Ki8751 displayed robust anti-influenza A and B virus activity and was selected for mechanistic investigations. Ki8751 efficiently disrupted the endocytic process of influenza virus in different cell lines carrying platelet-derived growth factor receptor ß (PDGFRß), an RTK that is known to act at GM3 ganglioside-positive lipid rafts. The more efficient virus entry in CHO-K1 cells compared to the wild-type ancestor (CHO-wt) cells indicated a positive effect of GM3, which is abundant in CHO-K1 but not in CHO-wt cells. Entering virus localized to GM3-positive lipid rafts and the PDGFRß-containing endosomal compartment. PDGFRß/GM3-dependent virus internalization involved PDGFRß phosphorylation, which was potently inhibited by Ki8751, and desialylation of activated PDGFRß by the viral neuraminidase. Virus uptake coincided with strong activation of the Raf/MEK/Erk cascade, but not of PI3K/Akt or phospholipase C-γ. We conclude that influenza virus efficiently hijacks the GM3-enhanced PDGFRß signalling pathway for cell penetration, providing an opportunity for host cell-targeting antiviral intervention.

CCL20, a direct-acting pro-angiogenic chemokine induced by hepatitis C virus (HCV): Potential role in HCV-related liver cancer.

The CCL20/CCR6 chemokine/receptor axis has previously been shown to contribute to the initiation and progression of hepatocellular carcinoma (HCC) through the recruitment of CCR6-positive leukocytes to the tumor microenvironment. In particular, high serum levels of CCL20 are reported in patients with HCC induced by the hepatitis C virus (HCV). A potential non-immune role for the CCL20/CCR6 axis in HCC development has not yet been investigated. Microarray analysis (Benkheil et al., paper submitted for publication), revealed that CCL20 is highly upregulated in hepatoma cells infected with HCV compared with non-infected hepatoma cells. To determine the role of the CCL20/CCR6 axis in HCV-related HCC, we first explored which cell populations express CCR6 in human liver tissue with chronic disease or HCC. Immunohistochemical (IHC) analysis revealed that CCR6 is present on endothelial cells (ECs) of portal blood vessels in livers with chronic HCV infection and in HCV- and alcoholic-HCC tissue. In addition, we found CCR6 to be expressed on primary macrovascular (HUVECs) and microvascular ECs (HMVEC-ds) where it co-expressed with the endothelial marker CD31. In vitro angiogenesis experiments revealed that CCL20 is a direct pro-angiogenic molecule that induces EC invasion, sprouting and migration through CCR6. Moreover, using the angiogenesis matrigel plug assay in immunodeficient NMRI-nu mice, we clearly showed that CCL20 induces blood vessel formation, by attracting CCR6-positive ECs. Finally, we demonstrated that HCV-induced CCL20 protein expression and secretion in hepatoma cells could be abolished by antiviral treatment, indicating that CCL20 expression is dependent on HCV replication. In contrast to HCV, HBV-infection resulted in a decreased expression of CCL20, implying a virus-specific effect. Taken together, we identified HCV-induced CCL20 as a direct pro-angiogenic factor that acts on endothelial CCR6. These results suggest that the CCL20/CCR6 axis contributes to hepatic angiogenesis, promoting the hypervascular state of HCV-HCC.

Peroxynitrite Exposure of CXCL12 Impairs Monocyte, Lymphocyte and Endothelial Cell Chemotaxis, Lymphocyte Extravasation in vivo and Anti-HIV-1 Activity.

CXCL12 is a chemotactic cytokine that attracts many different cell types for homeostasis and during inflammation. Under stress conditions, macrophages and granulocytes produce factors such as peroxynitrite as a consequence of their oxidative response. After short incubations of CXCL12 with peroxynitrite, the gradual nitration of Tyr7, Tyr61, or both Tyr7 and Tyr61 was demonstrated with the use of mass spectrometry, whereas longer incubations caused CXCL12 degradation. Native CXCL12 and the nitrated forms, [3-NT61]CXCL12 and [3-NT7/61]CXCL12, were chemically synthesized to evaluate the effects of Tyr nitration on the biological activity of CXCL12. All CXCL12 forms had a similar binding affinity for heparin, the G protein-coupled chemokine receptor CXCR4 and the atypical chemokine receptor ACKR3. However, nitration significantly enhanced the affinity of CXCL12 for chondroitin sulfate. Internalization of CXCR4 and ß-arrestin 2 recruitment to CXCR4 was significantly reduced for [3-NT7/61]CXCL12 compared to CXCL12, whereas ß-arrestin 2 recruitment to ACKR3 was similar for all CXCL12 variants. [3-NT7/61]CXCL12 was weaker in calcium signaling assays and in in vitro chemotaxis assays with monocytes, lymphocytes and endothelial cells. Surprisingly, nitration of Tyr61, but not Tyr7, partially protected CXCL12 against cleavage by the specific serine protease CD26. In vivo, the effects were more pronounced compared to native CXCL12. Nitration of any Tyr residue drastically lowered lymphocyte extravasation to joints compared to native CXCL12. Finally, the anti-HIV-1 activity of [3-NT7]CXCL12 and [3-NT7/61]CXCL12 was reduced, whereas CXCL12 and [3-NT61]CXCL12 were equally potent. In conclusion, nitration of CXCL12 occurs readily upon contact with peroxynitrite and specifically nitration of Tyr7 fully reduces its in vitro and in vivo biological activities.

Synthesis of a 3'-C-ethynyl-ß-d-ribofuranose purine nucleoside library: Discovery of C7-deazapurine analogs as potent antiproliferative nucleosides.

A focused nucleoside library was constructed around a 3'-C-ethynyl-d-ribofuranose sugar scaffold, which was coupled to variously modified purine nucleobases. The resulting nucleosides were probed for their ability to inhibit tumor cell proliferation, as well as for their activity against a panel of relevant human viruses. While C6-aryl substituted purine nucleosides were found to be weakly active, several C7-substituted 7-deazapurine nucleosides elicited potent antiproliferative activity. Their activity spectrum was evaluated in the NCI-60 tumor cell line panel indicating activity against several solid tumor derived cell lines. Analog 32, equipped with a 7-deaza 7-chloro-6-amino-purin-9-yl base was evaluated in a metastatic breast tumor (MDA-MB-231-LM2) xenograft model. It inhibited both tumor growth and reduced the formation of lung metastases as revealed by BLI analysis. The dideazanucleoside analog 66 showed interesting activity against hCMV. These results highlight the potential advantages of recombining known sugar and nucleobase motifs as a library design strategy to discover novel antiviral or antitumor agents.

Design, synthesis, in vitro antiproliferative activity and apoptosis-inducing studies of 1-(3',4',5'-trimethoxyphenyl)-3-(2'-alkoxycarbonylindolyl)-2-propen-1-one derivatives obtained by a molecular hybridisation approach.

Inhibition of microtubule function using tubulin targeting agents has received growing attention in the last several decades. The indole scaffold has been recognized as an important scaffold in the design of novel compounds acting as antimitotic agents. Indole-based chalcones, in which one of the aryl rings was replaced by an indole, have been explored in the last few years for their anticancer potential in different cancer cell lines. Eighteen novel (3',4',5'-trimethoxyphenyl)-indolyl-propenone derivatives with general structure 9 were synthesized and evaluated for their antiproliferative activity against a panel of four different human cancer cell lines. The highest IC50 values were obtained against the human promyelocytic leukemia HL-60 cell line. This series of chalcone derivatives was characterized by the presence of a 2-alkoxycarbonyl indole ring as the second aryl system attached at the carbonyl of the 3-position of the 1-(3',4',5'-trimethoxyphenyl)-2-propen-1-one framework. The structure-activity relationship (SAR) of the indole-based chalcone derivatives was investigated by varying the position of the methoxy group, by the introduction of different substituents (hydrogen, methyl, ethyl or benzyl) at the N-1 position and by the activity differences between methoxycarbonyl and ethoxycarbonyl moieties at the 2-position of the indole nucleus. The antiproliferative activity data of the novel synthesized compounds revealed that generally N-substituted indole analogues exhibited considerably reduced potency as compared with their parent N-unsubstituted counterparts, demonstrating that the presence of a hydrogen on the indole nitrogen plays a decisive role in increasing antiproliferative activity. The results also revealed that the position of the methoxy group on the indole ring is a critical determinant of biological activity. Among the synthesized derivatives, compound 9e, containing the 2-methoxycarbonyl-6-methoxy-N-1H-indole moiety exhibited the highest antiproliferative activity, with IC50 values of 0.37, 0.16 and 0.17 µM against HeLa, HT29 and MCF-7 cancer cell lines, respectively, and with considerably lower activity against HL-60 cells (IC50: 18 µM). This derivative also displayed cytotoxic properties (IC50 values ∼1 µM) in the human myeloid leukemia U-937 cell line overexpressing human Bcl-2 (U-937/Bcl-2) via cell cycle progression arrest at the G2-M phase and induction of apoptosis. The results obtained also demonstrated that the antiproliferative activity of this molecule is related to inhibition of tubulin polymerisation. The presence of a methoxy group at the C5- or C6-position of the indole nucleus, as well as the absence of substituents at the N-1-indole position, contributed to the optimal activity of the indole-propenone-3',4',5'-trimethoxyphenyl scaffold.