RESUMO
Prized for their ability to rapidly generate chemical complexity by building new ring systems and stereocentres1, cycloaddition reactions have featured in numerous total syntheses2 and are a key component in the education of chemistry students3. Similarly, carbon-carbon (C-C) cross-coupling methods are integral to synthesis because of their programmability, modularity and reliability4. Within the area of drug discovery, an overreliance on cross-coupling has led to a disproportionate representation of flat architectures that are rich in carbon atoms with orbitals hybridized in an sp2 manner5. Despite the ability of cycloadditions to introduce multiple carbon sp3 centres in a single step, they are less used6. This is probably because of their lack of modularity, stemming from the idiosyncratic steric and electronic rules for each specific type of cycloaddition. Here we demonstrate a strategy for combining the optimal features of these two chemical transformations into one simple sequence, to enable the modular, enantioselective, scalable and programmable preparation of useful building blocks, natural products and lead scaffolds for drug discovery.
Assuntos
Carbono/química , Técnicas de Química Sintética , Reação de Cicloadição , Produtos Biológicos/síntese química , Produtos Biológicos/química , Descoberta de DrogasRESUMO
Syntheses of a crystalline polycyclic halichondrin C1-C14 building block starting from a d-gulono-1,4-lactone-derived intermediate in the current Halaven manufacturing process are described. Key features of the syntheses include an acid-catalyzed tandem intermolecular oxy-Michael/intramolecular trans-ketalization reaction and stereoselective Kishi reductions.
RESUMO
Crystallization-induced diastereoselective transformation (CIDT) of an α-methyl nitrile completes an entirely non-chromatographic synthesis of the halichondrinâ B C14-C26 stereochemical array. The requisite α-methyl nitrile substrate is derived from D-quinic acid through a series of substrate-controlled stereoselective reactions via a number of crystalline intermediates that benefit from a rigid polycyclic template. Therefore, all four stereogenic centers in the Halaven C14-C26 fragment were derived from the single chiral source D-quinic acid.
RESUMO
Stimulator of interferon genes (STING) is an innate immune receptor activated by natural or synthetic agonists to elicit antitumoral immune response via type I IFNs and other inflammatory cytokines. Bacillus Calmette-Guerin (BCG) is the standard of care as intravesical therapy for patients with high-risk non-muscle invasive bladder cancer (NMIBC). There are limited options available for patients with NMIBC who developed BCG unresponsiveness. In this study, we characterized in vitro and in vivo antitumor effects of E7766, a macrocyle-bridged STING agonist, via intravesical instillation in two syngeneic orthotopic murine NMIBC tumor models resistant to therapeutic doses of BCG and anti-PD-1 agents. E7766 bound to recombinant STING protein with a Kd value of 40 nmol/L and induced IFNß expression in primary human peripheral blood mononuclear cells harboring any of seven major STING genotypes with EC50 values of 0.15 to 0.79 µmol/L. Intravesical E7766 was efficacious in both NMIBC models with induction of effective immunologic memory in the treated animals. Pharmacologic activation of the STING pathway in the bladder resulted in IFN pathway activation, infiltration of T cells and natural killer (NK) cells, dendritic cell activation, and antigen presentation in bladder epithelium, leading to the antitumor activity and immunity. In addition, measurements of the pharmacodynamic markers, Ifnß1 and CXCL10, in bladder, urine, and plasma, and of STING pathway intactness in cancer cells, supported this mode of action. Taken together, our studies reveal an antitumor immune effect of pharmacologic activation of the STING pathway in bladder epithelium and thus provide a rationale for subsequent clinical studies in patients with NMIBC.
Assuntos
Fosfatidilinositol 3-Quinases , Neoplasias da Bexiga Urinária , Animais , Vacina BCG/farmacologia , Linhagem Celular Tumoral , Proliferação de Células , Humanos , Leucócitos Mononucleares/metabolismo , Camundongos , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais , Serina-Treonina Quinases TOR/metabolismo , Bexiga Urinária/metabolismo , Bexiga Urinária/patologia , Neoplasias da Bexiga Urinária/tratamento farmacológico , Neoplasias da Bexiga Urinária/patologiaRESUMO
The inhibition of Plasmodium cytosolic phenylalanine tRNA-synthetase (cFRS) by a novel series of bicyclic azetidines has shown the potential to prevent malaria transmission, provide prophylaxis, and offer single-dose cure in animal models of malaria. To date, however, the molecular basis of Plasmodium cFRS inhibition by bicyclic azetidines has remained unknown. Here, we present structural and biochemical evidence that bicyclic azetidines are competitive inhibitors of L-Phe, one of three substrates required for the cFRS-catalyzed aminoacylation reaction that underpins protein synthesis in the parasite. Critically, our co-crystal structure of a PvcFRS-BRD1389 complex shows that the bicyclic azetidine ligand binds to two distinct sub-sites within the PvcFRS catalytic site. The ligand occupies the L-Phe site along with an auxiliary cavity and traverses past the ATP binding site. Given that BRD1389 recognition residues are conserved amongst apicomplexan FRSs, this work lays a structural framework for the development of drugs against both Plasmodium and related apicomplexans.
Assuntos
Azetidinas/farmacologia , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Malária/enzimologia , Parasitos/enzimologia , Fenilalanina-tRNA Ligase/antagonistas & inibidores , Fenilalanina-tRNA Ligase/química , Plasmodium falciparum/enzimologia , Sequência de Aminoácidos , Aminoacilação , Animais , Domínio Catalítico , Citosol/enzimologia , Resistência a Medicamentos/genética , Modelos Moleculares , Mutação/genética , Fenilalanina/metabolismo , Fenilalanina-tRNA Ligase/metabolismo , Plasmodium falciparum/efeitos dos fármacosRESUMO
A strategy for creating potent and pan-genotypic stimulator of interferon genes (STING) agonists is described. Locking a bioactive U-shaped conformation of cyclic dinucleotides by introducing a transannular macrocyclic bridge between the nucleic acid bases leads to a topologically novel macrocycle-bridged STING agonist (MBSA). In addition to substantially enhanced potency, the newly designed MBSAs, exemplified by clinical candidate E7766, exhibit broad pan-genotypic activity in all major human STING variants. E7766 is shown to have potent antitumor activity with long lasting immune memory response in a mouse liver metastatic tumor model. Two complementary stereoselective synthetic routes to E7766 are also described.
Assuntos
Antineoplásicos/farmacologia , Interferons/agonistas , Compostos Macrocíclicos/farmacologia , Animais , Antineoplásicos/síntese química , Antineoplásicos/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Compostos Macrocíclicos/síntese química , Compostos Macrocíclicos/química , Camundongos , Modelos Moleculares , Estrutura Molecular , Neoplasias Experimentais/tratamento farmacológico , Neoplasias Experimentais/patologiaRESUMO
A byproduct from a Halaven C27-C35 manufacturing process was transformed into a crystalline halichondrin C1-C15 building block by employing a stereospecific intramolecular Kishi reduction as the key step.
RESUMO
Laulimalide is a cytotoxic natural product isolated from marine sponges. It is structurally distinct from taxanes. However, like paclitaxel, laulimalide binds to tubulin and enhances microtubule assembly and stabilization. It exhibits potent inhibition of cellular proliferation with IC50 values in the low nM range against numerous cancer cell lines. In contrast to paclitaxel, however, laulimalide is also very potent against multidrug-resistant (MDR) cancer cell lines which overexpress P-glycoprotein (PgP). It has unique structural and biological properties, and attempts at synthesis have attracted considerable effort in recent years, resulting in more than ten published total syntheses. Despite this extensive attention, there have been no reported in vivo evaluations of laulimalide to date, probably due to the structural complexity of laulimalide and the scarcity of natural material. In our studies to explore the therapeutic potential of laulimalide, a total synthesis capable of producing gram quantities of laulimalide was designed, which enabled both in vitro and in vivo evaluation. Our in vitro results with synthetic material confirmed the previous reports that laulimalide is a mitotic blocker that can inhibit the growth of a variety of both non-MDR and MDR human cancer cell lines. However, despite demonstrating promise in cell-based and pharmacokinetic studies, laulimalide exhibited only minimal tumor growth inhibition in vivo and was accompanied by severe toxicity and mortality. The unfavorable efficacy to toxicity ratio in vivo suggests that laulimalide may have limited value for development as a new anticancer therapeutic agent.
Assuntos
Antineoplásicos/farmacologia , Resistência a Múltiplos Medicamentos , Resistencia a Medicamentos Antineoplásicos , Microtúbulos/efeitos dos fármacos , Taxoides/farmacologia , Subfamília B de Transportador de Cassetes de Ligação de ATP/genética , Subfamília B de Transportador de Cassetes de Ligação de ATP/metabolismo , Animais , Antineoplásicos/farmacocinética , Antineoplásicos/toxicidade , Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Humanos , Macrolídeos , Biologia Marinha , Camundongos , Taxoides/farmacocinética , Taxoides/toxicidade , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Prins reaction of homoallenyl alcohols with aldehyde dimethylacetals in the presence of methoxyacetic acid directly affords tetrasubstituted pyrans relevant to halichondrins with complete control of the C27 stereogenic center. Regioselective Tsuji reduction of the resultant allylic acetates stereoselectively establishes the C25 stereogenic center and C26 exocyclic olefin. Building upon these findings, we achieved concise access to the halichondrin C14-C38 and eribulin C14-C35 fragments.
RESUMO
E7974 is a synthetic analogue of the marine sponge natural product hemiasterlin. Here, we show that E7974, such as parental hemiasterlin, acts via a tubulin-based antimitotic mechanism. E7974 inhibits polymerization of purified tubulin in vitro with IC(50) values similar to those of vinblastine. In cultured human cancer cells, E7974 induces G(2)-M arrest and marked disruption of mitotic spindle formation characteristic of tubulin-targeted anticancer drugs. Extensive hypodiploid cell populations are seen in E7974-treated cells, indicating initiation of apoptosis after prolonged G(2)-M blockage. Consistent with this observation, E7974 induces caspase-3 activation and poly ADP ribose polymerase cleavage, typical biochemical markers of apoptosis. Only a short cellular exposure to E7974 is sufficient to induce maximum mitotic arrest, suggesting that E7974's antitumor effects in vivo may persist even after blood levels of the drug decrease after drug administration. Interactions of E7974 with purified tubulin were investigated using two synthetic tritiated photoaffinity analogues incorporating a benzophenone photoaffinity moiety at two different positions of the E7974 scaffold. Both analogues preferentially photolabeled alpha-tubulin, although minor binding to beta-tubulin was also detected. E7974 thus seems to share a unique, predominantly alpha-tubulin-targeted mechanism with other hemiasterlin-based compounds, suggesting that, unlike many tubulin-targeted natural products and related drugs, the hemiasterlins evolved to mainly target alpha-tubulin, not beta-tubulin subunits.
Assuntos
Antimitóticos/farmacologia , Antineoplásicos/farmacologia , Produtos Biológicos/química , Oligopeptídeos/química , Oligopeptídeos/farmacologia , Piperidinas/farmacologia , Poríferos/química , Água do Mar , Tubulina (Proteína)/metabolismo , Animais , Antimitóticos/química , Antineoplásicos/química , Apoptose/efeitos dos fármacos , Produtos Biológicos/farmacologia , Bovinos , Linhagem Celular Tumoral , Fase G2/efeitos dos fármacos , Humanos , Microtúbulos/efeitos dos fármacos , Microtúbulos/metabolismo , Mitose/efeitos dos fármacos , Marcadores de Fotoafinidade , Piperidinas/química , Fuso Acromático/efeitos dos fármacos , Fuso Acromático/metabolismo , Vimblastina/farmacologiaRESUMO
Analogues of the marine natural product (-)-laulimalide were prepared by total synthesis and evaluated in vitro for anticancer activity.