Exploration of carbamide derived pyrimidine-thioindole conjugates as potential VEGFR-2 inhibitors with anti-angiogenesis effect

The development of new small molecules from known structural motifs through molecular hybridization is one of the trends in drug discovery. In this connection, we have combined the two pharmacophoric units (pyrimidine and thioindole) in a single entity via molecular hybridization strategy along with introduction of urea functionality at C2 position of pyrimidine to increase the efficiency of H-bonding interactions. Among the synthesized conjugates 12a-aa, compound 12k was found to exhibit significant IC₅₀ values 5.85, 7.87, 6.41 and 10.43 μM against MDA-MB-231 (breast), HepG2 (liver), A549 (lung) and PC-3 (prostate) cancer cell lines, respectively. All these compounds were further evaluated for their inhibitory activities against VEGFR-2 protein. The results specified that among the tested compounds, 12d, 12e, 12k, 12l, 12p, 12q, 12t and 12u prominently suppressed VEGFR-2, with IC₅₀ values of 310-920 nM in association to the positive control (210 nM). Angiogenesis inhibition was evident by tube formation assay in HUVECs and cell-invasion by transwell assay. The mechanism of cellular toxicity on MDA-MB-231 was found through depolarisation of mitochondrial membrane potential, increased ROS production and subsequent DNA damage resulting in apoptosis induction. Moreover, clonogenic and wound healing assays designated the inhibition of colony formation and cell migration by 12k in a dose-dependent manner. Molecular docking studies also shown that compound 12k capably intermingled with catalytically active residues GLU-885, ASP-1046 of the VEGFR-2 through hydrogen-bonding interactions.

Exploiting Chemical Toolboxes for the Expedited Generation of Tetracyclic Quinolines as a Novel Class of PXR Agonists

The discovery of lead compounds relies on the iterative generation of structure-activity relationship data resulting from the synthesis and biological evaluation of hit analogues. Using traditional approaches, a significant time delay may occur from compound design to results, leading to slow and expensive hit-to-lead explorations. Herein, we have exploited the use of chemical toolboxes to expedite lead discovery and optimization. In particular, the integration of flow synthesizers, automation, process analytical technologies, and computational chemistry has provided a prototype system enabling the multicomponent flow synthesis, in-line analysis, and characterization of chiral tetracyclic quinolines as a novel class of PXR agonists. Within 29 compounds, a novel template 19b (3aS,11R,11aS) was identified with an EC₅₀ of 1.2 μM (efficacy 119%) at the PXR receptor.

Propargylamine as functional moiety in the design of multifunctional drugs for neurodegenerative disorders: MAO inhibition and beyond

Much progress has been made in designing analogues that can potentially confer neuroprotection against debilitating neurodegenerative disorders, yet the multifactorial pathogenesis of this cluster of diseases remains a stumbling block for the successful design of an 'ultimate' drug. However, with the growing popularity of the "one drug, multiple targets" paradigm, many researchers have successfully synthesized and evaluated drug-like molecules incorporating a propargylamine function that shows potential to serve as multifunctional drugs or multitarget-directed ligands. It is the aim of this review to highlight the reported activities of these propargylamine derivatives and their prospect to serve as drug candidates for the treatment of neurodegenerative disorders.

Studies toward bivalent κ opioids derived from salvinorin A: heteromethylation of the furan ring reduces affinity

The recent crystal structure of the κ-opioid receptor (κ-OR) revealed, unexpectedly, that the antagonist JDTic is a bivalent ligand: in addition to the orthosteric pocket occupied by morphinans, JDTic also occupies a distinct (allotopic) pocket. Mutagenesis data suggest that salvinorin A (1) also binds to this allotopic pocket, adjacent to the aspartate residue that anchors the basic nitrogen atom of classical opiates (Asp138). It has been suggested that an H-bond donor appended to 1 might interact with Asp138, increasing affinity. Such a bivalent ligand might also possess altered functional selectivity. Based on modeling and known N-furanylmethyl opioid antagonists, we appended H-bond donors to the furan ring of 1. (Dimethylamino)methyl groups at C-15 or C-16 abolished affinity for κ-OR. Hydroxymethylation at C-16 was tolerated, but 15,16-bis-hydroxymethylation was not. Since allosteric modulators may go undetected in binding assays, we also tested these and other low-affinity derivatives of 1 for allosteric modulation of dynorphin A in the [³⁵S]GTPγS assay. No modulation was detected. As an alternative attachment point for bivalent derivatives, we prepared the 2-(hydroxyethoxy)methyl ether, which retained high affinity for κ-OR. We discuss alternative design strategies for linked, fused or merged bivalent derivatives of 1.