Design, Synthesis, and Biological Evaluation of Novel 1,3-Oxazole Sulfonamides as Tubulin Polymerization Inhibitors

Novel sulfonamides unveiled as potent anti-lung cancer agents via tumor pyruvate kinase M2 activation

This rational pursuit led to the identification of a novel sulfonamide derivative as a potent anti-lung cancer (LC) compound. Considering these results, we synthesized 38 novel sulfonamide derivatives with diverse skeletal structures. In vitro cytotoxicity assays revealed a potent and selective antiproliferative effect against A549 cells after evaluating a panel of cancer cell lines. Compound 9b has emerged as a potent activator of tumor pyruvate kinase M2 (PKM2), a protein known to play a critical role in LC. Apoptosis assays and cell cycle analysis demonstrated early apoptosis and G2 phase arrest. In silico studies demonstrated interactions between compound 9b and the activator binding site of PKM2. Surface plasmon resonance (SPR) experiments strongly indicated that 9b has a high affinity (K d of 1.378 nM) for PKM2. Furthermore, the increase in reactive oxygen species and decrease in lactate concentration suggested that compound 9b has significant anticancer effects. Notably, the increase in particle size following treatment with 9b suggested the tetramerization of PKM2. This work provides insights that might advance efforts to develop effective non-platinum anticancer agents.

Development of Potent Microtubule Targeting Agent by Structural Simplification of Natural Diazonamide

The marine metabolite diazonamide A exerts low nanomolar cytotoxicity against a range of tumor cell lines; however, its highly complex molecular architecture undermines the therapeutic potential of the natural product. We demonstrate that truncation of heteroaromatic macrocycle in natural diazonamide A, combined with the replacement of the challenging-to-synthesize tetracyclic hemiaminal subunit by oxindole moiety leads to considerably less complex analogues with improved drug-like properties and nanomolar antiproliferative potency. The structurally simplified macrocycles are accessible in 12 steps from readily available indolin-2-one and tert-leucine with excellent diastereoselectivity (99:1 dr) in the key macrocyclization step. The most potent macrocycle acts as a tubulin assembly inhibitor and exerts similar effects on A2058 cell cycle progression and induction of apoptosis as does marketed microtubule-targeting agent vinorelbine.

Recent development of azole-sulfonamide hybrids with the anticancer potential

Cancer exhibits heterogeneity that enables adaptability and remains grand challenges for effective treatment. Chemotherapy is a validated and critically important strategy for the treatment of cancer, but the emergence of multidrug resistance which may lead to recurrence of disease or even death is a major hurdle for successful chemotherapy. Azoles and sulfonamides are important anticancer pharmacophores, and azole-sulfonamide hybrids have the potential to simultaneously act on dual/multiple targets in cancer cells, holding great promise to overcome drug resistance. This review outlines the current scenario of azole-sulfonamide hybrids with the anticancer potential, and the structure-activity relationships as well as mechanisms of action are also discussed, covering articles published from 2020 onward.

Photoinduced [3+2] Cycloaddition of Carbenes and Nitriles: A Versatile Approach to Oxazole Synthesis

We have developed a photoinduced protocol for the synthesis of pharmaceutically important oxazole molecules using diazo- and nitrile-containing reactants. The process involves the initial photolysis of the diazo compound to afford singlet carbenes, which are tapped by nitriles in a [3+2] cycloaddition fashion to give substituted oxazoles. With di-nitrile compounds, useful bis-oxazoles were obtained. The applicability of the transformation is showcased through the expedient synthesis of small-molecule drugs and biologically relevant molecules such as felbinac, pimprinine, texamine, ugnenenazole etc. The protocol is also useful for the generation of 2 H and 13 C isotope labelled oxazoles. Merging photolysis with continuous-flow chemistry was demonstrated for scaling up the reaction. The non-requirement of metal catalysis or photosensitizers to harness the light energy with blue light sufficing the execution of the reaction makes it a versatile and general protocol for the synthesis of structurally diverse oxazoles.

Exploring Pyrrolo-Fused Heterocycles as Promising Anticancer Agents: An Integrated Synthetic, Biological, and Computational Approach

Five new series of pyrrolo-fused heterocycles were designed through a scaffold hybridization strategy as analogs of the well-known microtubule inhibitor phenstatin. Compounds were synthesized using the 1,3-dipolar cycloaddition of cycloimmonium N-ylides to ethyl propiolate as a key step. Selected compounds were then evaluated for anticancer activity and ability to inhibit tubulin polymerization in vitro. Notably, pyrrolo[1,2-a]quinoline 10a was active on most tested cell lines, performing better than control phenstatin in several cases, most notably on renal cancer cell line A498 (GI₅₀ 27 nM), while inhibiting tubulin polymerization in vitro. In addition, this compound was predicted to have a promising ADMET profile. The molecular details of the interaction between compound 10a and tubulin were investigated through in silico docking experiments, followed by molecular dynamics simulations and configurational entropy calculations. Of note, we found that some of the initially predicted interactions from docking experiments were not stable during molecular dynamics simulations, but that configurational entropy loss was similar in all three cases. Our results suggest that for compound 10a, docking experiments alone are not sufficient for the adequate description of interaction details in terms of target binding, which makes subsequent scaffold optimization more difficult and ultimately hinders drug design. Taken together, these results could help shape novel potent antiproliferative compounds with pyrrolo-fused heterocyclic cores, especially from an in silico methodological perspective.

Design, synthesis, structure-activity relationship studies, and evaluation of novel GLS1 inhibitors

Glutaminase converts glutamine into glutamic acid and has two isoforms: glutaminase 1 (GLS1) and glutaminase 2 (GLS2). GLS1 is overexpressed in several tumors, and research to develop glutaminase inhibitors as antitumor drugs is currently underway. The present study examined candidate GLS1 inhibitors using in silico screening and attempted to synthesize novel GLS1 inhibitors and assess their GLS1 inhibitory activities in a mouse kidney extract and against recombinant mouse and human GLS1. Novel compounds were synthesized using compound C as the lead compound, and their GLS1 inhibitory activities were evaluated using the mouse kidney extract. Among the derivatives tested, the trans-4-hydroxycyclohexylamide derivative 2j exhibited the strongest inhibitory activity. We also assessed the GLS1 inhibitory activities of the derivatives 2j, 5i, and 8a against recombinant mouse and human GLS1. The derivatives 5i and 8a significantly decreased the production of glutamic acid at 10 mM. In conclusion, we herein identified two compounds that exhibited GLS1 inhibitory activities with equal potencies as known GLS1 inhibitors. These results will contribute to the development of effective novel GLS1 inhibitors with more potent inhibitory activity.

It's ok to be outnumbered - sub-stoichiometric modulation of homomeric protein complexes

An arsenal of molecular tools with increasingly diversified mechanisms of action is being developed by the scientific community to enable biological interrogation and pharmaceutical modulation of targets and pathways of ever increasing complexity. While most small molecules interact with the target of interest in a 1 : 1 relationship, a noteworthy number of recent examples were reported to bind in a sub-stoichiometric manner to a homomeric protein complex. This approach requires molecular understanding of the physiologically relevant protein assemblies and in-depth characterization of the compound's mechanism of action. The recent literature examples summarized here were selected to illustrate methods used to identify and characterize molecules with such mechanisms. The concept of one small molecule targeting a homomeric protein assembly is not new but the subject deserves renewed inspection in light of emerging technologies and increasingly diverse target biology, to ensure relevant in vitro systems are used and valuable compounds with potentially novel sub-stoichiometric mechanisms of action aren't overlooked.

An umpolung strategy for intermolecular [2 + 2 + 1] cycloaddition of aryl aldehydes and nitriles: a facile access to 2,4,5-trisubstituted oxazoles

We have described the first example of an umpolung strategy for intermolecular [2 + 2 + 1] cycloaddition between two aryl aldehydes and a nitrile under the influence of TMSOTf that proceeds through the formation of N–C, O–C and C–C bonds providing a simple synthetic protocol for obtaining 2,4,5-trisubstituted oxazoles.

An unprecedented intermolecular [2 + 2 + 1] cycloaddition strategy between two aryl aldehydes and a nitrile, wherein one of the aryl aldehydes serves as a carbanion (or equivalent) in the presence of TMSOTf for obtaining oxazole framework is presented.