Multi-Armed 1,2,3-Selenadiazole and 1,2,3-Thiadiazole Benzene Derivatives as Novel Glyoxalase-I Inhibitors

First Exclusive Stereo- and Regioselective Preparation of 5-Arylimino-1,3,4-Selenadiazole Derivatives: Synthesis, NMR analysis, and Computational Studies

Isoselenocyanates are valuable coupling partners required for preparing key chemical intermediates and biologically active molecules in an accelerated and effective way. Likewise, (Z)-2-oxo-N-phenylpropanehydrazonoyl chlorides have been employed in numerous one-step heteroannulation reactions to assemble the structural core of several various kinds of heterocyclic compounds. Here, we describe the inverse electron demand 1,3-dipolar cycloaddition reaction of isoselenocyanates with a variety of substituted (Z)-2-oxo-N-phenylpropanehydrazonoyl chlorides to generate, regioselectively and stereoselectively, a series of 5-arylimino-1,3,4-selenadiazole derivatives comprising a multitude of functional groups on both aryl rings. The synthetic method features gentle room-temperature conditions, wide substrate scope, and good to high reaction yields. The selenadiazoles were separated by gravity filtration in all instances and chemical structures were validated by multinuclear NMR spectroscopy and high accuracy mass spectral measurements. First conclusive molecular structure elucidation of the observed 5-arylimino-selenadiazole regioisomer was verified by single-crystal X-ray diffraction analysis. Crystal-structure measurement was successfully carried out on (Z)-1-(4-(4-iodophenyl)-5-(p-tolylimino)-4,5-dihydro-1,3,4-selenadiazol-2-yl)ethan-1-one and (Z)-1-(5-((4-methoxyphenyl)imino)-4-(4-(methylthio)phenyl)-4,5-dihydro-1,3,4-selenadiazol-2-yl)ethan-1-one. Likewise, the (Z)-geometry of the hydrazonoyl chloride reactant was proven by X-ray diffraction studies. As representative examples, crystal-structure determination was carried out on (Z)-2-oxo-N-phenylpropanehydrazonoyl chloride and (Z)-N-(3,5-bis(trifluoromethyl)phenyl)-2-oxopropanehydrazonoyl chloride. Density functional theory calculations at the B3LYP-D4/def2-TZVP level were conducted to support the noted experimental findings and suggested mechanism.

Design, Synthesis and Biological Evaluation of 1,4-Benzenesulfonamide Derivatives as Glyoxalase I Inhibitors

Background

Glyoxalase system is one of the defense cellular mechanisms that protect cells against endogenous harmful metabolites, mainly methylglyoxal (MG), through conversion of cytotoxic methylglyoxal into the non-toxic lactic acid. Glyoxalase system comprises of two enzymes glyoxalase I, glyoxalase II, and a catalytic amount of reduced glutathione. Cancerous cells overexpress glyoxalase I, making it a target for cancer therapy. Many studies have been conducted to identify potent Glx-I inhibitors.

Methods

Aiming to discover and develop novel Glx-I inhibitors, a series of 1,4-benzenesulfonamide derivatives were designed, synthesized, and biologically evaluated in vitro against human Glx-I enzyme. Seventeen compounds were designed based on the hit compound that was obtained from searching the National Cancer Institute (NCI) database. The synthesis of the target compounds (13-29) was accomplished utilizing an azo coupling reaction of aniline derivatives and activated substituted aromatic compounds. To understand the binding mode of the active compounds at the active site of Glx-I, docking studies were performed.

Results

Structure activity relationship (SAR) studies were accomplished which led to the identification of several compounds that showed potent inhibitory activity with IC50 values below 10 μM. Among the compounds tested, compounds (E)-2-hydroxy-5-((4-sulfamoylphenyl)diazenyl)benzoic acid (26) and (E)-4-((8-hydroxyquinolin-5-yl)diazenyl) benzenesulfonamide (28) displayed potent Glx-I inhibitory activity with IC50 values of 0.39 μM and 1.36 µM, respectively. Docking studies of compounds 26 and 28 were carried out to illustrate the binding mode of the molecules into the Glx-I active site.

Conclusion

Our results show that compounds 26 and 28 displayed potent Glx-I inhibitory activity and can bind the Glx-I well. These findings should lead us to discover new classes of compounds with better Glx-I inhibition.

Selenium-driven enhancement of synergistic cancer chemo-/radiotherapy by targeting nanotherapeutics

To overcome drug resistance in hypoxic tumors and the limitations of radiation impedance and radiation dose, we developed a nano-radiosensitizer to improve the efficacy of cancer radiotherapy. We used multifunctional mesoporous silica nanoparticles (MSNs) as the carriers for a novel anticancer selenadiazole derivative (SeD) and modified its surface with folic acid (FA) to enhance its cervical cancer-targeting effects, forming the nanosystem named SeD@MSNs-FA. Upon radiation, SeD@MSNs-FA inhibits the growth of cervical cancer cells by inducing apoptosis through the death receptor-mediated apoptosis pathway and S phase arrest, significantly improving the sensitivity of cervical cancer cells to X-ray radiation. The combined activity of SeD@MSN-FA and radiation can promote excessive production of intracellular reactive oxygen species (ROS) and induce cell apoptosis by affecting p53, protein kinase B (AKT), and mitogen-activated protein kinase (MAPK) pathways. Furthermore, SeD@MSNs-FA can effectively inhibit tumor growth of xenografted HeLa tumors in nude mice. The toxicity analysis of SeD@MSNs-FA nanoparticles in vivo and the histological analysis performed in the mouse model showed that under the current experimental conditions, the nanoparticles induced no significant damage to the heart, liver, spleen, lungs, kidneys, or other major organs. Taken together, this study provides a translational nanomedicine-based strategy for the simultaneous chemo- and radiotherapy of cervical cancer and sheds light on potential mechanisms that can be used to overcome radiotherapeutic resistance.