Reverse-Design toward Optimized Labeled Chemical Probes – Examples from the Endocannabinoid System

Labeled chemical probes are of utmost importance to bring drugs from the laboratory through the clinic and ultimately to market. They support and impact all research and discovery phases: target verification and validation; assay development; lead optimization; and biomarker engagement in the context of preclinical studies and human trials. Probes should display high potency and selectivity as well as fulfill specific criteria in connection with absorption, distribution, metabolism, excretion and toxicology (ADMET) profile. Progress in fields such as imaging and proteomics increased the need for specialized probes to support drug discovery. Labeled probes carrying an additional reporter group are valuable tools to meet specific application requirements, but pose significant challenges in design and construction. In the reverse-design approach, small molecules previously optimized in medicinal chemistry programs form the basis for the generation of such high-quality probes. We discuss the reverse design concept for the generation of labeled probes targeting the endocannabinoid system (ECS), a complex lipid signaling network that plays a key role in many human health and disease conditions. The examples highlighted include diverse reporter units for a range of applications. In several cases the reported probes were the product of mutually rewarding and highly cross-fertilizing collaborations among academic and industry research programs, a strategy that can serve as a blueprint for future probe generation efforts

Detection of cannabinoid receptor type 2 in native cells and zebrafish with a highly potent, cell-permeable fluorescent probe.

Despite its essential role in the (patho)physiology of several diseases, CB2R tissue expression profiles and signaling mechanisms are not yet fully understood. We report the development of a highly potent, fluorescent CB2R agonist probe employing structure-based reverse design. It commences with a highly potent, preclinically validated ligand, which is conjugated to a silicon-rhodamine fluorophore, enabling cell permeability. The probe is the first to preserve interspecies affinity and selectivity for both mouse and human CB2R. Extensive cross-validation (FACS, TR-FRET and confocal microscopy) set the stage for CB2R detection in endogenously expressing living cells along with zebrafish larvae. Together, these findings will benefit clinical translatability of CB2R based drugs

The global abundance of tree palms

Aim Palms are an iconic, diverse and often abundant component of tropical ecosystems that provide many ecosystem services. Being monocots, tree palms are evolutionarily, morphologically and physiologically distinct from other trees, and these differences have important consequences for ecosystem services (e.g., carbon sequestration and storage) and in terms of responses to climate change. We quantified global patterns of tree palm relative abundance to help improve understanding of tropical forests and reduce uncertainty about these ecosystems under climate change. Location Tropical and subtropical moist forests. Time period Current. Major taxa studied Palms (Arecaceae). Methods We assembled a pantropical dataset of 2,548 forest plots (covering 1,191 ha) and quantified tree palm (i.e., ≥10 cm diameter at breast height) abundance relative to co‐occurring non‐palm trees. We compared the relative abundance of tree palms across biogeographical realms and tested for associations with palaeoclimate stability, current climate, edaphic conditions and metrics of forest structure. Results On average, the relative abundance of tree palms was more than five times larger between Neotropical locations and other biogeographical realms. Tree palms were absent in most locations outside the Neotropics but present in >80% of Neotropical locations. The relative abundance of tree palms was more strongly associated with local conditions (e.g., higher mean annual precipitation, lower soil fertility, shallower water table and lower plot mean wood density) than metrics of long‐term climate stability. Life‐form diversity also influenced the patterns; palm assemblages outside the Neotropics comprise many non‐tree (e.g., climbing) palms. Finally, we show that tree palms can influence estimates of above‐ground biomass, but the magnitude and direction of the effect require additional work. Conclusions Tree palms are not only quintessentially tropical, but they are also overwhelmingly Neotropical. Future work to understand the contributions of tree palms to biomass estimates and carbon cycling will be particularly crucial in Neotropical forests

O Largo da Banana e a presença negra em São Paulo

The Largo da Banana relates to the history of the black population in São Paulo. Acknowledged as one of São Paulo’s “cradle” of samba, samba musicians are its main spokespersons. Largo da Banana used to be located near the former Barra Funda Railway Station. From the first decades to around half the Twentieth century, informal laborers in the railway logistics used to gather together in that space. Within a precarious and unsteady daily life, they used to play samba and tiririca. In the fifties, the municipality built the Pacaembu Viaduct in that area, aiming to extend the homonym avenue beyond the railway road. In the sixties, samba musician Geraldo Filme wrote two songs in which he paid homage to Largo da Banana and regrettedits disappearance after the viaduct’s inauguration. In these and other of his songs, the artist recorded his perceptions on the life conditions of São Paulo’s blacks and samba musicians, their sociabilities, and also the urban changes he witnessed. Considering that his artistic work contributes to enlighten aspects of social reality, I analyze some of his songs to interpret the sociabilities at Largo da Banana, as well as the urban intervention in that location.O Largo da Banana está associado à história da população negra em São Paulo. Reconhecido como um dos “berços” do samba paulista, é sobretudo através dos próprios sambistas que essa história pode hoje ser conhecida. Localizado junto à antiga estação da Barra Funda, desde as primeiras décadas até meados do século passado, aquele espaço concentrou trabalhadores informais vinculados às atividades da ferrovia. Em meio a um cotidiano precário e instável, essa população realizava rodas de samba e de tiririca. Nos anos 1950, foi construído naquele local o Viaduto Pacaembu, que prolongava a avenida homônima para além davia férrea. A partir da década de 1960, o sambista negro Geraldo Filme compôs duas canções em que homenageava o Largo da Banana e lamentava seu desaparecimento após a inauguração do viaduto. Nessas e em outras composições, o artista registrou suas percepções sobre as condições de vida da população negra e sambista na cidade, suas sociabilidades, bem como sobre as transformações urbanas que testemunhou. Considerando que sua obra artística contribui para iluminar aspectos da realidade social, ela é adotada como fonte para analisar as formas de sociabilidade no Largo da Banana e a intervenção urbanística naquele local

Preclinical lead optimization of a 1,2,4-triazole based tankyrase inhibitor

Abstract Tankyrases 1 and 2 are central biotargets in the WNT/β-catenin signaling and Hippo signaling pathways. We have previously developed tankyrase inhibitors bearing a 1,2,4-triazole moiety and binding predominantly to the adenosine binding site of the tankyrase catalytic domain. Here we describe a systematic structure-guided lead optimization approach of these tankyrase inhibitors. The central 1,2,4-triazole template and trans-cyclobutyl linker of the lead compound 1 were left unchanged, while side-group East, West, and South moieties were altered by introducing different building blocks defined as point mutations. The systematic study provided a novel series of compounds reaching picomolar IC₃₀ inhibition in WNT/β-catenin signaling cellular reporter assay. The novel optimized lead 13 resolves previous atropisomerism, solubility, and Caco-2 efflux liabilities. 13 shows a favorable ADME profile, including improved Caco-2 permeability and oral bioavailability in mice, and exhibits antiproliferative efficacy in the colon cancer cell line COLO 320DM in vitro

Discovery of a novel series of tankyrase inhibitors by a hybridization approach

Abstract A structure-guided hybridization approach using two privileged substructures gave instant access to a new series of tankyrase inhibitors. The identified inhibitor 16 displays high target affinity on tankyrase 1 and 2 with biochemical and cellular IC₅₀ values of 29 nM, 6.3 nM and 19 nM, respectively, and high selectivity toward other poly (ADP-ribose) polymerase enzymes. The identified inhibitor shows a favorable in vitro ADME profile as well as good oral bioavailability in mice, rats, and dogs. Critical for the approach was the utilization of an appropriate linker between 1,2,4-triazole and benzimidazolone moieties, whereby a cyclobutyl linker displayed superior affinity compared to a cyclohexane and phenyl linker

Development of a 1,2,4-triazole-based lead tankyrase inhibitor:part II

Abstract Tankyrase 1 and 2 (TNKS1/2) catalyze post-translational modification by poly-ADP-ribosylation of a plethora of target proteins. In this function, TNKS1/2 also impact the WNT/β-catenin and Hippo signaling pathways that are involved in numerous human disease conditions including cancer. Targeting TNKS1/2 with small-molecule inhibitors shows promising potential to modulate the involved pathways, thereby potentiating disease intervention. Based on our 1,2,4-triazole-based lead compound 1 (OM-1700), further structure–activity relationship analyses of East-, South- and West-single-point alterations and hybrids identified compound 24 (OM-153). Compound 24 showed picomolar IC₅₉ inhibition in a cellular (HEK293) WNT/β-catenin signaling reporter assay, no off-target liabilities, overall favorable absorption, distribution, metabolism, and excretion (ADME) properties, and an improved pharmacokinetic profile in mice. Moreover, treatment with compound 24 induced dose-dependent biomarker engagement and reduced cell growth in the colon cancer cell line COLO 320DM

EU-OPENSCREEN:a novel collaborative approach to facilitate chemical biology

Abstract Compound screening in biological assays and subsequent optimization of hits is indispensable for the development of new molecular research tools and drug candidates. To facilitate such discoveries, the European Research Infrastructure EU-OPENSCREEN was founded recently with the support of its member countries and the European Commission. Its distributed character harnesses complementary knowledge, expertise, and instrumentation in the discipline of chemical biology from 20 European partners, and its open working model ensures that academia and industry can readily access EU-OPENSCREEN’s compound collection, equipment, and generated data. To demonstrate the power of this collaborative approach, this perspective article highlights recent projects from EU-OPENSCREEN partner institutions. These studies yielded (1) 2-aminoquinazolin-4(3H)-ones as potential lead structures for new antimalarial drugs, (2) a novel lipodepsipeptide specifically inducing apoptosis in cells deficient for the pVHL tumor suppressor, (3) small-molecule-based ROCK inhibitors that induce definitive endoderm formation and can potentially be used for regenerative medicine, (4) potential pharmacological chaperones for inborn errors of metabolism and a familiar form of acute myeloid leukemia (AML), and (5) novel tankyrase inhibitors that entered a lead-to-candidate program. Collectively, these findings highlight the benefits of small-molecule screening, the plethora of assay designs, and the close connection between screening and medicinal chemistry within EU-OPENSCREEN