Sahar Kandil

Discovery of a novel HCV helicase inhibitor by a de novo drug design approach.

Herein we report a successful application of a computer-aided design approach to identify a novel HCV helicase inhibitor. A de novo drug design methodology was used to generate an initial set of structures that could potentially bind to a putative binding site. Further structure refinement was carried out through docking a series of focused virtual libraries. The most promising compound was synthesised and it exhibited a submicromolar inhibition of the HCV helicase.

Synthesis and biological evaluation of 2-amino-3-(3′,4′,5′-trimethoxybenzoyl)-6-substituted-4,5,6,7-tetrahydrothieno[2,3-c]pyridine derivatives as antimitotic agents and inhibitors of tubulin polymerization

Microtubules are among the most successful targets of compounds potentially useful for cancer therapy. A new series of inhibitors of tubulin polymerization based on the 2-amino-3-(3,4,5-trimethoxybenzoyl)-4,5,6,7-tetrahydrothieno[b]pyridine molecular skeleton was synthesized and evaluated for antiproliferative activity, inhibition of tubulin polymerization, and cell cycle effects. The most promising compound in this series was 2-amino-3-(3,4,5-trimethoxybenzoyl)-6-methoxycarbonyl-4,5,6,7-tetrahydrothieno[b]pyridine, which inhibits cancer cell growth with IC(50)-values ranging from 25 to 90 nM against a panel of four cancer cell lines, and interacts strongly with tubulin by binding to the colchicine site. In this series of N(6)-carbamate derivatives, any further increase in the length and in the size of the alkyl chain resulted in reduced activity.

Design, synthesis and biological evaluation of phosphorodiamidate prodrugs of antiviral and anticancer nucleosides

Abstract We herein report the application of the phosphorodiamidate phosphate prodrug approach to a series of thirteen nucleoside analogs with antiviral or anticancer activity. Twenty-five symmetrical phosphorodiamidates were synthesized, bearing esterified l-Alanine (and in one case d-Alanine) in the prodrug moiety, each as single stereoisomer. The presence of an achiral phosphorus represents a potential advantage over the phosphoramidate ProTide approach, where diastereoisomeric mixtures are routinely obtained, and different biological profiles may be expected from the diastereoisomers. Optimization of the synthetic pathway allowed us to identify two general methods depending on the particular nucleoside analogs. All the compounds were biologically evaluated in antiviral and anticancer assays and several showed improvement of activity compared to their parent nucleosides, as in the case of ddA, d4T, abacavir and acyclovir against HIV-1 and/or HIV-2. The biological results were supported by metabolism studies with carboxypeptidase Y monitored by 31P NMR to investigate their bioactivation. This work further validates the phosphorodiamidate approach as a monophosphate prodrug motif with broad application in the antiviral and anticancer fields.

Novel cis-selective and non-epimerisable C3 hydroxy azapodophyllotoxins targeting microtubules in cancer cells

Podophyllotoxin (PT) and its clinically used analogues are known to be powerful antitumour agents. These compounds contain a trans fused strained γ-lactone system, a feature that correlates to the process of epimerisation, whereby the trans γ-lactone system of ring D opens and converts to the more thermodynamically stable cis epimer. Since these cis epimers are known to be either less active or lacking antitumour activity, epimerisation is an undesirable feature from a chemotherapeutic point of view. To circumvent this problem, considerable efforts have been reported, amongst which is the synthesis of azapodophyllotoxins where the stereocentres at C2 and C3 are removed in order to preclude epimerisation. Herein we report the identification of a novel C3 hydroxy, cis-selective γ-lactone configuration of ring C in the azapodophyllotoxin scaffold, through an efficient stereoselective multicomponent reaction (MCR) involving fluorinated and non-fluorinated aldehydes. This configuration releases the highly strained trans γ-lactone system in podophyllotoxin analogues into the more thermodynamically stable cis γ-lactone motif and yet retains significantly potent activity. These compounds were evaluated against the human cancer lines MCF-7 and 22Rv1 in vitro. Fourteen out of the seventeen tested compounds exhibited sub-micromolar activity with IC50 values in the range of 0.11–0.91 μM, which is comparable and in some cases better than the activity profile of etoposide in this assay. Interestingly, we obtained strong evidence from spectroscopic and X-ray data analyses that the previously reported structure of similar analogues is not accurate. Molecular modelling performed using the podophyllotoxin binding site on β tubulin revealed a novel binding mode of these analogues. Furthermore, sub-cellular study of our compounds using immunolabelling and confocal microscopy analyses showed strong microtubule disruptive activity, particularly in dividing cells.

Rational design and synthesis of novel anti-prostate cancer agents bearing a 3,5-bis-trifluoromethylphenyl moiety

Prostate cancer is a major cause of male death worldwide and the identification of new and improved treatments is constantly required. Among the available options, different non-steroidal androgen receptor (AR) antagonists are approved also to treat castration-resistant forms. Most of these drugs show limited application due to the development of resistant mutants of their biological target. Following docking-based studies on a homology model for the AR open antagonist conformation, a series of novel 3,5-bis-trifluoromethylphenyl compounds was designed with the aim to improve the antiproliferative activity of anti-androgen drugs bicalutamide and enzalutamide. The new structural modifications might impede the receptor to adopt its closed agonist conformation also in the presence of adaptive mutations. Among the novel compounds synthesised, several displayed significantly improved in vitro activity in comparison with the parent structures, with IC50 values in the low micromolar range against four different prostate cancer cell lines (LNCaP, VCaP, DU-145, 22Rv1). Selected hits demonstrated full AR antagonistic behaviour and promising candidates for further development were identified.

7-Substituted umbelliferone derivatives as androgen receptor antagonists for the potential treatment of prostate and breast cancer

The clinically used androgen receptor (AR) antagonists (bicalutamide, flutamide and nilutamide) bind with low affinity to AR and can induce escape mechanisms. Furthermore, under AR gene amplification or mutation conditions they demonstrate agonist activity and fail to inhibit AR, causing relapse into castration resistant prostate cancer (CRPC). Discovery of new scaffolds distinct from the 4-cyano/nitro-3-(trifluoromethyl)phenyl group common to currently used antiandrogens is urgently needed to avoid cross-resistance with these compounds. In this study, a series of twenty-nine 7-substituted umbelliferone derivatives was prepared and their antiproliferative activities were evaluated. The most active compound 7a demonstrated submicromolar inhibitory activity in the human prostate cancer cell line (22Rv1); IC50=0.93 μM which represents a 50 fold improvement over the clinical antiandrogen bicalutamide (IC50=46 μM) and a more than 30 fold improvement over enzalutamide (IC50=32 μM). Interestingly, this compound showed even better activity against the human breast cancer cell line (MCF-7); IC50=0.47 μM. Molecular modelling studies provided a plausible theoretical explanation for our findings.

ProTides of BVdU as potential anticancer agents upon efficient intracellular delivery of their activated metabolites

Graphical abstract

Novel Trifluoromethylated Enobosarm Analogues with Potent Antiandrogenic Activity In Vitro and Tissue Selectivity In Vivo

Prostate cancer often develops antiandrogen resistance, possibly via androgen receptor (AR) mutations, which change antagonists to agonists. Novel therapies with increased anticancer activity, while overcoming current drug resistance are urgently needed. Enobosarm has anabolic effects on muscle and bone while having no effect on the prostate. Here, we describe the activity of novel chemically modified enobosarm analogues. The rational addition of bis‐trifluoromethyl groups into ring B of enobosarm, profoundly modified their activity, pharmacokinetic and tissue distribution profiles. These chemical structural modifications resulted in an improved AR binding affinity—by increasing the molecular occupational volume near helix 12 of AR. In vitro, the analogues SK33 and SK51 showed very potent antiandrogenic activity, monitored using LNCaP/AR‐Luciferase cells where growth, PSA and luciferase activity were used as AR activity measurements. These compounds were 10-fold more potent than bicalutamide and 100-fold more potent than enobosarm within the LNCaP model. These compounds were also active in LNCaP/BicR cells with acquired bicalutamide resistance. In vivo, using the AR‐Luc reporter mice, these drugs showed potent AR inhibitory activity in the prostate and other AR‐expressing tissues, e.g., testes, seminal vesicles, and brain. These compounds do not inhibit AR activity in the skeletal muscle, and spleen, thus indicating a selective tissue inhibitory profile. These compounds were also active in vivo in the Pb-Pten deletion model. SK33 and SK51 have significantly different and enhanced activity profiles compared with enobosarm and are ideal candidates for further development for prostate cancer therapy with potentially fewer side effects. Mol Cancer Ther; 17(9); 1846–58. ©2018 AACR.

The discovery of new and more potent chloropyramine (C4) analogues for the potential treatment of invasive breast cancer

Breast cancer is the second most common cancer worldwide, accounting for 25% of all female cancers. Although the survival rate has increased significantly in the past few decades, patients who develop secondary site metastasis as well as those diagnosed with triple negative breast cancer still represent a real unmet medical challenge. Previous studies have shown that chloropyramine (C4) inhibits FAK‐VEGFR3 signalling. More recently, C4 is reported to have SASH1 inducing properties. However, C4 exerts its antitumour and antiangiogenic effects at high micromolar concentrations (>100 μm) that would not be compatible with further drug development against invasive breast cancer driven by FAK signalling. In this study, molecular modelling guided structural modifications have been introduced to the chloropyramine C4 scaffold to improve its activity in breast cancer cell lines. Seventeen compounds were designed and synthesized, and their antiproliferative activity was evaluated against three human breast cancer lines (MDA‐MB‐231, BT474 and T47D). Compound 5c was identified to display an average activity of IC50 = 23.5–31.3 μm, which represents a significant improvement of C4 activity in the same assay model. Molecular modelling and pharmacokinetic studies provided more promising insights into the mechanistic features of this new series.