Design and synthesis of some thieno[2,3-c]pyridazine derivatives of expected anticancer activity

Ligand-based designing of DPP-4 inhibitors via hybridization; synthesis, docking, and biological evaluation of pyridazine-acetohydrazides

A series of novel pyridazine-acetohydrazide hybrids were designed, synthesized, and evaluated for their in vitro and in vivo antihyperglycemic activity. In this context, pyridazine-acetohydrazides (6a-6p) were synthesized by coupling substituted aldehyde with 2-(5-cyano-6-oxo-3,4-diphenylpyridazine-1-6H-yl) acetohydrazide, which was prepared via the reaction of pyridazine ester with hydrazine hydrate. The molecular docking study was carried out to examine the binding affinities and interaction of designed compounds against the DPP-4 enzyme. Compounds 6e, 6f, 6l, and 6n exhibited interaction with active residue. In silico ADMET properties, and toxicity studies corroborated that compounds were found to have good bioavailability and less toxic. The synthesized compounds were further estimated for in vitro DPP-4 activity. Compounds 6e and 6l were found as the most effective DPP-4 inhibitor in this series with IC50 values (6.48, 8.22 nM) when compared with sitagliptin (13.02 nM). According to the toxicity assay compound, 6l showed very less toxicity at a higher concentration so further selected for the in vivo antihyperglycemic activity.

SABRE hyperpolarized anticancer agents for use in 1 H MRI

Purpose

Enabling drug tracking (distribution/specific pathways) with magnetic resonance spectroscopy requires manipulation (via hyperpolarization) of spin state populations and targets with sufficiently long magnetic lifetimes to give the largest possible window of observation. Here, we demonstrate how the proton resonances of a group of thienopyridazines (with known anticancer properties), can be amplified using the para‐hydrogen (p‐H₂) based signal amplification by reversible exchange (SABRE) hyperpolarization technique.

Methods

Thienopyridazine isomers, including a ²H version, were synthesized in house. Iridium‐based catalysts dissolved in a methanol‐d₄ solvent facilitated polarization transfer from p‐H₂ gas to the target thienopyridazines. Subsequent SABRE ¹H responses of hyperpolarized thienopyridazines were completed (400 MHz NMR). Pseudo‐singlet state approaches were deployed to extend magnetic state lifetimes. Proof of principle spectral‐spatial images were acquired across a range of field strengths (7T‐9.4T MRI).

Results

¹H‐NMR signal enhancements of −10,130‐fold at 9.4T (~33% polarization) were achieved on thieno[2,3‐d]pyridazine (T[2,3‐d]P), using SABRE under optimal mixing/field transfer conditions. ¹H T₁ lifetimes for the thienopyridazines were ~18‐50 s. Long‐lived state approaches extended the magnetic lifetime of target proton sites in T[2,3‐d]P from an average of 25‐40 seconds. Enhanced in vitro imaging (spatial and chemical shift based) of target T[2,3‐d]P was demonstrated.

Conclusion

Here, we demonstrate the power of SABRE to deliver a fast and cost‐effective route to hyperpolarization of important chemical motifs of anticancer agents. The SABRE approach outlined here lays the foundations for realizing continuous flow, hyperpolarized tracking of drug delivery/pathways.

Design, synthesis and evaluation of novel thienopyridazine derivatives as Chk1/2 inhibitors

In order to search for novel checkpoint kinase 1/2 (Chk1) inhibitors, we have designed and synthesized a series of new compounds incorporating thienopyridazine core. Bioevaluation showed that compounds 10j, 10i, 13e and 10o exhibited relatively good inhibitory activity. Notably, compound 10o displayed high selectivity against a panel of kinases and inhibited Chk1/2 signaling pathway stimulated by DNA damage drugs in cellular level. Molecular docking of 10o to the ATP-binding site of Chk1 kinase domain indicated the existence of polar interactions between 10o and the ATP-ribose-binding residues of Chk1. In mouse HT-29 xenografts, a synergistic effect was observed. Co-treatment by CPT-11 and 10o significantly diminished the tumor volume, indicating the great potential of 10o as a candidate of Chk1/2 inhibitor.

A robust photoluminescence screening assay identifies uracil-DNA glycosylase inhibitors against prostate cancer

Many cancers have developed resistance to 5-FU, due to removal by the enzyme uracil-DNA glycosylase (UDG), a type of base excision repair enzyme (BER) that can excise uracil and 5-fluorouracil (5-FU) from DNA. However, the development of UDG inhibitor screening methods, especially for the rapid and efficient screening of natural product/natural product-like compounds, is still limited so far. We developed herein a robust time-resolved photoluminescence method for screening UDG inhibitors, which could significantly improve sensitivity over the screening method based on the conventional steady-state spectroscopy, reducing the substantial fluorescence background interference. As a proof-of-concept, two potential UDG inhibitors were identified from a database of natural products and approved drugs. Co-treatment of these two compounds with 5-FU showed synergistic cytotoxicity, providing the basis for treating drug-resistant cancers. Overall, this method provides an avenue for the rapid screening of small molecule regulators of other BER enzyme activities that can avoid false negatives arising from the background fluorescence.

The discovery of UDG inhibitors against prostate cancer by using a robust photoluminescence screening assay that can avoid false negatives arising from the background fluorescence.