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An efficient, one-pot approach has been established for synthesizing a wide range of 3-amino-[1,2,4]-triazolo pyridines and related heterocycles from the electrochemically induced desulfurative cyclization of 2-hydrazinopyridines with isothiocyanates. The protocol allows for the formation of C-N bonds under simple conditions without transition metals or external oxidants. The practicability of this strategy is demonstrated by its broad substrate scope, good functional group compatibility, and gram-scale synthesis. The late-stage modification of 3-amino-[1,2,4]-triazolo pyridines enables us to obtain several molecules with potent anticancer activity.

An efficient, sustainable and straightforward method is reported for the synthesis of a series of α,α-difluoromethyl carbinols via K2CO3-triggered Friedel–Crafts reaction of electron-rich arenes using the stable and easily affordable 2,2-difluorovinyl arylsulfonate.

An efficient cathodic carbonyl alkylation of aryl ketones or aldehydes with unactivated alkyl halides has been realized through the electrochemical activation of iron. The protocol is believed to include a radical-radical coupling or nucleophilic addition process, and the formation of ketyl radicals and alkyl radicals has been demonstrated. The protocol provides various tertiary or secondary alcohols by the formation of intermolecular C-C bonds under safe and mild conditions, is scalable, consumes little energy, and exhibits a broad substrate scope.

A practical protocol has been established to access diverse oxazol-2-amine derivatives in one step via the electrochemical desulfurative cyclization of isothiocyanates and α-amino ketones. On the basis of the cycle of in situ generation of iodine/desulfurative cyclization/iodide anion regeneration, the reaction is performed under metal-free and external-oxidant-free electrolytic conditions to achieve the formation of intermolecular C-O and C-N bonds, providing oxazol-2-amines in moderate to excellent yields.

Herein, we have developed a robust Pd-catalyzed haloalkynylation of haloalkynes for the synthesis of dihaloalkenyne derivatives. This cross-haloalkynylation reaction proceeds in a highly chemo- and regioselective manner under mild conditions in the presence of two slightly structurally different haloalkynes and shows strong functional group tolerance under ligand- and base-free conditions.

A straightforward protocol for efficient and highly selective hydrogenation of unsaturated carbon–carbon bonds via electrochemical reduction has been reported. A series of chain alkanes and carbonyl compounds are produced under metal-free and external-reductant-free electrolytic conditions. Scale-up experiments have exhibited the potential applications of this protocol in practical synthesis. Deuterium-labelling experiments demonstrate that both DMSO and H2O in the reaction system can provide hydrogen atoms for the reaction.

An electrochemical protocol for the construction of substituted isoindolinones via reduction/amidation of 2-carboxybenzaldehydes and amines has been realized. Under metal-free and external-reductant-free electrolytic conditions, the reaction achieves the cascade formation of intermolecular C-N bonds and provides a series of isoindolinones in moderate to good yields. The deuterium-labeling experiment proves that the hydrogen in the methylene of the product is mainly provided by H2O in the system.

The low depth of tissue penetration by therapeutic light sources severely restricts photodynamic therapy (PDT) in treating deep-seated tumors. Using a luciferase/d-luciferin bioluminescence system to artificially create internal light sources in cells instead of external light sources is an effective means of solving the above problems. However, high-efficiency bioluminescence requires a higher concentration of luciferase in the cell, which poses a considerable challenge to the existing system of enzyme loading, delivery, activity and retention of drugs, and dramatically increases the cost of treatment. We loaded the substrate D-luciferin, and the photosensitizer hypericin into a polyethyleneimine (PEI)-modified nano-calcium phosphate (CaP) to solve this problem. Subsequently, the plasmid DNA containing the luciferase gene was loaded onto it using the high-density positive charge characteristic of PEI from the nanodrug (denoted DHDC). After the DHDC enters the tumor cell, it collapses and releases the plasmid DNA, which uses the intracellular protein synthesis system to continuously and massively express luciferase. Using endogenous ATP, Mg2+ , and O2 in cells, luciferase oxidizes d-luciferin and produces luminescence. The luminescence triggers hypericin excitation to generate ROS and kill cancer cells. This study provides a new strategy for the application of bioluminescence in PDT treatment.

A novel electrochemical synthesis protocol has been achieved for reductive amination between aldehydes and amines in undivided cells at room temperature. Under metal-free and external-reductant-free electrolysis conditions, various important secondary amine products are obtained in moderate-to-high yields. Deuterium-labeling experiments have demonstrated that low-toxicity DMSO acts both as a solvent and a H-donor in the reaction. On this basis, various deuterium-labeled products with good-to-excellent D-incorporation have been synthesized by using DMSO-d6 as a solvent. Furthermore, a molecule with GR-antagonistic activity has been synthesized through further sulfonylation.

A series of hybrids containing the pharmacophores of the histone deacetylase (HDAC) inhibitor, SAHA, and the antioxidant ebselen were designed and synthesized as multi-target-directed ligands against Alzheimer’s disease. An in vitro assay indicated that some of these molecules exhibit potent HDAC inhibitory activity and ebselen-related pharmacological effects. Specifically, the optimal compound 7f was found to be a potent HDAC inhibitor (IC50 = 0.037 μM), possessing rapid hydrogen peroxide scavenging activity and glutathione peroxidase-like activity (ν0 = 150.0 μM min−1) and good free oxygen radical absorbance capacity (value of ORAC: 2.2). Furthermore, compound 7f showed significant protective effects against damage induced by H2O2 and the ability to prevent ROS accumulation in PC12 cells.

A novel series of boron-containing compounds were designed, synthesized and evaluated as multi-target-directed ligands against Alzheimer's disease. The biological activity results demonstrated that these compounds possessed a significant ability to inhibit self-induced Aβ aggregation (20.5–82.8%, 20 μM) and to act as potential antioxidants (oxygen radical absorbance capacity assay using fluorescein (ORAC-FL) values of 2.70–5.87). In particular, compound 17h is a potential lead compound for AD therapy (IC(50) = 3.41 μM for self-induced Aβ aggregation; ORAC-FL value = 4.55). Compound 17h also functions as a metal chelator. These results indicated that boron-containing compounds could be new structural scaffolds for the treatment of AD.

Inhibition of tubulin polymerization is one of the significant strategies in the treatment of cancer. Inspired by the excellent antitumor activity of EP128495 and the beneficial biological activities of selenium compounds, a series of new selenium-containing 4-anilinoquinazoline hybrids were synthesized and evaluated as tubulin polymerization inhibitors. An anti-proliferative activity assay showed that most of the compounds inhibited human sensitive cancer cells at low nanomolar concentrations. A mechanism study revealed that the optimal compound 5a disrupted microtubule dynamics, decreased the mitochondrial membrane potential and arrested HeLa cells in the G2/M phase, finally resulting in cellular apoptosis.

By fusing donepezil and curcumin, a novel series of compounds were obtained as multitarget-directed ligands against Alzheimer's disease. Among them, compound 11b displayed potent acetylcholinesterase (AChE) inhibition (IC50=187nM) and the highest BuChE/AChE selectivity (66.3). Compound 11b also inhibited 45.3% Aβ1-42 self-aggregation at 20μM and displayed remarkable antioxidant effects. The metal-chelating property of compound 11b was elucidated by determining the 1:1 stoichiometry for the 11b-Cu(II) complex. The excellent blood-brain barrier permeability of 11b also indicated the potential for the compound to penetrate the central nervous system.

Sixteen new selenium-containing indole chalcone and diarylketone derivatives were synthesized and evaluated as tubulin polymerization inhibitors. Among them, compound 25b exhibited the most potent antiproliferative activities against six human cancer cell lines with IC50 values of 0.004-0.022 μM. A microtubule dynamics assay and an immunofluorescence assay confirmed that 25b could effectively inhibit tubulin polymerization (IC50 = 2.1 ± 0.27 μM). Further cellular mechanism studies revealed that 25b induced G2/M phase arrest, which was further evidenced by the decrease in the mitochondrial membrane potential (MMP).

This study revealed a new attractive cyclic-indole scaffold for the discovery of mitosis-targeting anti-tumour agents. Among all of the synthesized derivatives, compound 20 displayed the most potent anti-proliferative activity (with IC50 values of 22–56 nM against seven cancer cell lines) and tubulin polymerization inhibition (IC50 = 0.15 ± 0.07 μM), which were much better than those of the reference compound Combretastain A-4 (CA-4). High selectivity ratios (9.68–7.61) of compound 20 toward human normal cells and cancer cells were also observed. Immunofluorescence assay elucidated that compound 20 disrupted the intracellular microtubule network and interfered with cell mitosis. Cellular mechanism studies demonstrated that compound 20 arrested the cell cycle at the G2/M phase and induced apoptosis in a time- and dose-dependent manner. In summary, compound 20 deserves consideration for in vivo anti-tumour evaluation in further studies.

A series of tacrine-pyrazolo[3,4-b]pyridine hybrids were synthesised and evaluated as dual cholinesterase (ChE) and phosphodiesterase 4D (PDE4D) inhibitors for the treatment of Alzheimer’s disease (AD). Compound 10j, which is tacrine linked with pyrazolo[3,4-b]pyridine moiety by a six-carbon spacer, was the most potent acetylcholinesterase (AChE) with IC50 value of 0.125 μM. Moreover, compound 10j provided a desired balance of AChE and butylcholinesterase (BuChE) and PDE4D inhibition activities, with IC50 value of 0.449 and 0.271 μM, respectively. The above results indicated that this hybrid was a promising dual functional agent for the treatment of AD.

Considering the importance of PDE4D inhibition and the modulation of biometals in Alzheimer's disease (AD) therapeutics, we have designed, synthesized and evaluated a series of new clioquinol-rolipram/roflumilast hybrids as multitarget-directed ligands for the treatment of AD. In vitro studies demonstrated that some of the molecules processed remarkable inhibitory activity against phosphodiesterase 4D (PDE4D), strong intracellular antioxidant capacity, potent inhibition of metal-induced aggregation of Aβ, and potential blood-brain barrier permeability. Compound 7a demonstrated significant improvement in cognitive and spatial memory in an Aβ25-35-induce mouse model in Morris water-maze test (MWM). These results indicate that compound 7a is a promising multifunctional candidate that is worthy of further study.

A series of new benzylideneindanone derivatives were designed, synthesized and evaluated as antitumor agents. Structure–activity relationship (SAR) studies showed that derivatives with 4,5,6-trimethoxyl on an indanone moiety displayed good anti-proliferative activities. Especially, compound 5a demonstrated the most potent inhibitory activity, with GI50 values from 0.172 to 0.57 μM for five kinds of cancer cell lines. Further investigation showed that 5a could inhibit microtubule polymerization and thus induce G2/M phase arrest and apoptosis in A549 cells. Our findings revealed the benzylideneindanone moiety as a new attractive scaffold for mitosis-targeting drug discovery.

The reaction of 5,5'-(pyridine-2,6-diyl)bis(4-amino-3-mercapto-1,2,4-triazole) with various aromatic aldehydes in acetic acid yielded the corresponding 5,5'-(pyridine-2,6-diyl)bis(4-arylideneamino-3-mercapto-1,2,4-triazole) derivatives. The structures of the synthesized compounds as well as their intermediates were confirmed by elemental analysis, infrared spectra, (1)H NMR spectra and mass spectra studies. All the synthesized title compounds were screened for their antibacterial activities, and the preliminary results revealed that some of them showed good activities against Escherichia coli and Pseudomonas aeruginosa.

The reaction of 5,5′-(pyridine-2,6-diyl)bis(4-amino-3-mercapto-1,2,4-triazole) with various carboxylic acid in phosphorus oxychloride yielded the corresponding 2,6-bis(6-substituted-1,2,4-triazolo[3,4-b][1,3,4]thiadiazol-3-yl)pyridine derivatives 6a–l. The structures of the newly synthesized compounds were confirmed by elemental analysis, 1H NMR and 13C NMR spectral, mass spectral, and Infrared spectral studies. All the synthesized target compounds have been investigated for their in vitro antibacterial activity, and the preliminary results revealed that the compounds 6b and 6k exhibited very promising activity against Escherichia coli and Pseudomonas aeruginosa.