Structure-activity relationship studies of (E)-3,4-dihydroxystyryl alkyl sulfones as novel neuroprotective agents based on improved antioxidant, anti-inflammatory activities and BBB permeability

The vinyl sulfone motif as a structural unit for novel drug design and discovery

INTRODUCTION

Vinyl sulfones are a special sulfur-containing structural unit that have attracted considerable attention, owing to their important role in serving as key structural motifs of various biologically active compounds as well as serving as versatile building blocks for organic transformations. The synthetic strategy of vinyl sulfone derivatives has been substantially upgraded over the past 30 years, and the wide application of this functional group in drug design and discovery has been promoted.

AREA COVERED

In this review, the authors review the application of vinyl sulfones in drug discovery and select optimized compounds which might have significant impact or potential inspiration for drug design.

EXPERT OPINION

Vinyl sulfones have been reported to target various macromolecular targets via non-covalent or covalent interactions, including multiple kinases, tubulin, cysteine protease, transcription factor, and so on. Thus, it has been significantly applied as a privileged scaffold in the design of anticancer, anti-infective, anti-inflammatory, and neuroprotective agents. However, much work remains to be done to improve the drug-like properties, such as chemical and metabolic stability, ADME, and toxicity. Besides, the chemical space of vinyl sulfones needs to be expanded, including but not limited to the design of constrained endocyclic and exocyclic vinyl sulfones.

One-Pot, Metal-Free Synthesis of Allyl Sulfones in Water

A one-pot dehydration cross-coupling reaction between allyl alcohols and sodium sulfinates that provides allyl sulfones in good to excellent yields is presented. Its broad substrate scope includes symmetrical and asymmetrical α,α-diaryl- and α-aryl-substituted allylic alcohols and aryl and alkyl sodium sulfinates. For asymmetrical allylic substrates, the E isomer predominates with examples of excellent stereoselectivity. Control experiments provide the basis for a proposed radical-mediated mechanism. The metal-free procedure applies cheap and commercially available tetrabutylammonium tribromide as the catalyst and H2O as the solvent. Notable features of this simple, efficient, weakly toxic, and environmentally benign strategy include mild and convenient operating conditions and readily accessible starting materials.

Design, synthesis, and biological evaluation of novel (4-(1,2,4-oxadiazol-5-yl)phenyl)-2-aminoacetamide derivatives as multifunctional agents for the treatment of Alzheimer's disease

On the basis of our previous work, a novel series of (4-(1,2,4-oxadiazol-5-yl)phenyl)-2-aminoacetamide derivatives were synthesized and evaluated as multifunctional ligands for the treatment of Alzheimer's disease (AD). Biological evaluations indicated that the derivatives can be used as anti-AD drugs that have multifunctional properties, inhibit the activity of butyrylcholinesterase (BuChE), inhibit neuroinflammation, have neuroprotective properties, and inhibit the self-aggregation of Aβ. Compound f9 showed good potency in BuChE inhibition (IC₅₀: 1.28 ± 0.18 μM), anti-neuroinflammatory potency (NO, IL-1β, TNF-α; IC₅₀: 0.67 ± 0.14, 1.61 ± 0.21, 4.15 ± 0.44 μM, respectively), and inhibited of Aβ self-aggregation (51.91 ± 3.90%). Preliminary anti-inflammatory mechanism studies indicated that the representative compound f9 blocked the activation of the NF-κB signaling pathway. Moreover, f9 exhibited 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging effect, and an inhibitory effect on the production of intracellular reactive oxygen species (ROS). In the bi-directional transport assay, f9 displayed proper blood-brain barrier (BBB) permeability. In addition, the title compound improved memory and cognitive functions in a mouse model induced by scopolamine. Hence, the compound f9 can be considered as a promising lead compound for further investigation in the treatment of AD.

Small molecule compounds with good anti-inflammatory activity reported in the literature from 01/2009 to 05/2021: a review

Inflammation and disease are closely related. Inflammation can induce various diseases, and diseases can promote inflammatory response, and two possibly induces each other in a bidirectional loop. Inflammation is usually treated using synthetic anti-inflammatory drugs which are associated with several adverse effects hence are not safe for long-term use. Therefore, there is need for anti-inflammatory drugs which are not only effective but also safe. Several researchers have devoted to the research and development of effective anti-inflammatory drugs with little or no side effects. In this review, we studied some small molecules with reported anti-inflammatory activities and hence potential sources of anti-inflammatory agents. The information was retrieved from relevant studies published between January 2019 and May, 2021 for review. This review study was aimed to provide relevant information towards the design and development of effective and safe anti-inflammation agents.

Design, synthesis, and biological evaluation of diosgenin-indole derivatives as dual-functional agents for the treatment of Alzheimer's disease

The complex pathogenesis of Alzheimer's disease (AD) has become a major obstacle in its treatment. An effective approach is to develop multifunctional agents that simultaneously target multiple pathological processes. Here, a series of diosgenin-indole compounds were designed, synthesized and evaluated for their neuroprotective effects against H₂O₂ (hydrogen peroxide), 6-OHDA (6-hydroxydopamine) and Aβ (beta amyloid) damages. Preliminary structure-activities relationship revealed that the introduction of indole fragment and electron-donating group at C-5 on ring indole could be beneficial for neuroprotective activities. Results indicated that compound 5b was the most promising candidate against cellular damage induced by H₂O₂ (52.9 ± 1.9%), 6-OHDA (38.4 ± 2.4%) and Aβ_1-42 (54.4 ± 2.7%). Molecular docking study suggested the affinity for 5b bound to Aβ_1-42 was -40.59 kcal/mol, which revealed the strong binding affinity of 5b to Aβ_1-42. The predicted values of brain/blood partition coefficient (-0.733) and polar surface area (85.118 Å²) indicated the favorable abilities of BBB permeation and absorption of 5b. In addition, 5b significantly decreased ROS (reactive oxygen species) production induced by H₂O₂. In the following in vivo experiment, 5b obviously attenuated memory and learning impairments of Aβ-injected mice. In summary, compound 5b could be considered as a promising dual-functional neuroprotective agent against AD.

Synthesis, characterization and pharmacological evaluation of quinoline derivatives and their complexes with copper(ΙΙ) in in vitro cell models of Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disorder of the central nervous system. The main pathophysiological mechanisms involve cholinergic neurotransmission, beta-amyloid (Αβ) and Tau proteins, several metal ions and oxidative stress, among others. Current drugs offer only relief of symptoms and not a cure of AD. Accumulating evidence suggests that multifunctional compounds, targeting multiple pathophysiological mechanisms, may have a great potential for the treatment of AD. In this study, we report on the synthesis and physicochemical characterization of four quinoline-based metal chelators and their respective copper(II) complexes. Most compounds were non-toxic at concentrations ≤5 μM. In neuroprotection studies employing undifferentiated and differentiated SH-SY5Y cells, the metal chelator N²,N⁶-di(quinolin-8-yl)pyridine-2,6-dicarboxamide (H₂dqpyca) appeared to exert significant neuroprotection against both, Aβ peptide- and H₂O₂-induced toxicities. The copper(II) complex [Cu^II(H₂bqch)Cl₂]^.3H₂O (H₂bqch = N,N'-Bis(8-quinolyl)cyclohexane-1,2-diamine) also protected against H₂O₂-induced toxicity, with a half-maximal effective concentration of 80 nM. Molecular docking simulations, using the crystal structure of the acetylcholinesterase (AChE)-rivastigmine complex as a template, indicated a strong interaction of the metal chelator H₂dqpyca, followed by H₂bqch, with both the peripheral anionic site and the catalytic active site of AChE. In conclusion, the sufficient neuroprotection provided by the metal chelator H₂dqpyca and the copper(II) complex [Cu^II(H₂bqch)Cl₂]^.3H₂O along with the evidence for interaction between H₂dqpyca and AChE, indicate that these compounds have the potential and should be further investigated in the framework of preclinical studies employing animal models of AD as candidate multifunctional lead compounds for the treatment of the disease.

Synthesis of Novel 2-(Isopropylamino)thiazol-4(5H)-one Derivatives and Their Inhibitory Activity of 11β-HSD1 and 11β-HSD2 in Aspect of Carcinogenesis Prevention

Glucocorticoid metabolism at the tissue level is regulated by two isoenzymes 11β-hydroxysteroid dehydrogenase (11β-HSD), which mutually convert biologically active cortisol and inactive cortisone. Recent research is focused on the role of 11β-HSD1 and 11β-HSD2 as autocrine factors of tumor cell proliferation and differentiation. Herein, we report the synthesis of novel 2-(isopropylamino)thiazol-4(5H)-one derivatives and their inhibitory activity for 11β-HSD1 and 11β-HSD2. The derivative containing the spiro system of thiazole and cyclohexane rings shows the highest degree of 11β-HSD1 inhibition (54.53% at 10 µM) and is the most selective inhibitor of this enzyme among the tested compounds. In turn, derivatives containing ethyl and n-propyl group at C-5 of thiazole ring inhibit the activity of 11β-HSD2 to a high degree (47.08 and 54.59% at 10 µM respectively) and are completely selective. Inhibition of the activity of these enzymes may have a significant impact on the process of formation and course of tumors. Therefore, these compounds can be considered as potential pharmaceuticals supporting anti-cancer therapy.