Isatin Hybrids and Their Pharmacological Investigations

Development of novel melatonin-isatin hybrids as multifunctional agents for Alzheimer's disease

The development of multifunctional agents has been a heated area of research for AD treatment in recent years. In this work, a series of melatonin-isatin hybrids were designed, synthesized, and evaluated as multifunctional agents for treating AD. In vitro studies indicated that most of the synthesized compounds displayed moderate to good MAO-B inhibition activities and good antioxidant activities. In particular, compounds IM-5 and IM-10 exhibited the best inhibitory activities with IC50 value of 12.4 μM and 15.6 μM against MAO-B, and potent antioxidant activities with their ORAC-FL values of 4.6 and 5.2 at 5 μM, respectively. ThT assay revealed compounds IM-5 and IM-10 exhibited the optimal Aβ1-42 self-induced aggregation inhibitory activities with the inhibition ratio of 72.8% and 69.7% at 20 μM. In addition, compounds IM-5 and IM-10 exhibited low cytotoxicities and significant neuroprotective effects on Aβ1-42-induced and H2O2-induced SH-SY5Y cell injury. More importantly, compounds IM-5 and IM-10 could significantly ameliorate the memory impairment and cognition injury in scopolamine-induced mice. The SwissADME program was used to predict drug-like properties of compounds IM-5 and IM-10 which exhibited they had good pharmacokinetics and drug-likeness properties. Molecular docking study further manifested that compounds IM-5 and IM-10 showed high hMAO-B inhibitory potency. In summary, all above results revealed compounds IM-5 and IM-10 might be promising multifunctional agents for AD treatment.

Diastereoselective Three-Component 1,3-Dipolar Cycloaddition to Access Functionalized β-Tetrahydrocarboline- and Tetrahydroisoquinoline-Fused Spirooxindoles

A chemselective catalyst-free three-component 1,3-dipolar cycloaddition has been described. The unique polycyclic THPI and THIQs were creatively employed as dipolarophiles, which led to the formation of functionalized β-tetrahydrocarboline- and tetrahydroisoquinoline-fused spirooxindoles in 60-94% of yields with excellent diastereoselectivities (10: 1->99: 1 dr). This reaction not only realizes a concise THPI- or THIQs-based 1,3-dipolar cycloaddition, but also provides a practical strategy for the construction of two distinctive spirooxindole skeletons.

Discerning of isatin-based monoamine oxidase (MAO) inhibitors for neurodegenerative disorders by exploiting 2D, 3D-QSAR modelling and molecular dynamics simulation

Almost a billion people worldwide suffer from neurological disorders, which pose public health challenges. An important enzyme that is well-known for many neurodegenerative illnesses is monoamine oxidase (MAO). Although several promising drugs for the treatment of MAO inhibition have recently been examined, it is still necessary to identify the precise structural requirements for robust efficacy. Atom-based, field-based, and GA-MLR (genetic algorithm multiple linear regression) models were created for this investigation. All of the models have strong statistical (R2 and Q2) foundations because of both internal and external validation. Our dataset's molecule has a higher docking score than safinamide, a well-known and co-crystallized MAO-B inhibitor, as we also noticed. Using the SwissSimilarity platform, we further inquired which of our docked molecules would be the best for screening. We chose ZINC000016952895 as the screen molecule with the best binding docking score (XP score = -13.3613). Finally, the 100 ns for the ZINC000016952895-MAO-B complex in our MD investigations is stable. For compounds that we hit, also anticipate ADME properties. Our research revealed that the successful compound ZINC000016952895 might pave the way for the future development of MAO inhibitors for the treatment of neurological disease.Communicated by Ramaswamy H. Sarma.

Isatin-tethered halogen-containing acylhydrazone derivatives as monoamine oxidase inhibitor with neuroprotective effect

Sixteen isatin-based hydrazone derivatives (IS1-IS16) were synthesized and assessed for their ability to inhibit monoamine oxidases (MAOs). All the molecules showed improved inhibitory MAO-B activity compared to MAO-A. Compound IS7 most potently inhibited MAO-B with an IC50 value of 0.082 μM, followed by IS13 and IS6 (IC50 = 0.104 and 0.124 μM, respectively). Compound IS15 most potently inhibited MAO-A with an IC50 value of 1.852 μM, followed by IS3 (IC50 = 2.385 μM). Compound IS6 had the highest selectivity index (SI) value of 263.80, followed by IS7 and IS13 (233.85 and 212.57, respectively). In the kinetic study, the Ki values of IS6, IS7, and IS13 for MAO-B were 0.068 ± 0.022, 0.044 ± 0.002, and 0.061 ± 0.001 μM, respectively, and that of IS15 for MAO-A was 1.004 ± 0.171 μM, and the compounds were reversible-type inhibitors. The lead compounds were central nervous system (CNS) permeable, as per parallel artificial membrane permeability assay (PAMPA) test results. The lead compounds were examined for their cytotoxicity and potential neuroprotective benefits in hazardous lipopolysaccharide (LPS)-exposed SH-SY5Y neuroblastoma cells. Pre-treatment with lead compounds enhanced anti-oxidant levels (SOD, CAT, GSH, and GPx) and decreased ROS and pro-inflammatory cytokine (IL-6, TNF-alpha, and NF-kB) production in LPS-intoxicated SH-SY5Y cells. To confirm the promising effects of the compound, molecular docking, dynamics, and MM-GBSA binding energy were used to examine the molecular basis of the IS7-MAO-B interaction. Our findings indicate that lead compounds are potential therapeutic agents to treat neurological illnesses, such as Parkinson's disease.

Exploring novel derivatives of isatin-based Schiff bases as multi-target agents: design, synthesis, in vitro biological evaluation, and in silico ADMET analysis with molecular modeling simulations

Recently, scientists developed a powerful strategy called "one drug-multiple targets" to discover vital and unique therapies to fight the most challenging diseases. Novel derivatives of isatin-based Schiff bases 2-7 have been synthesized by the reaction of 3-hydrazino-isatin (1) with aryl aldehydes, hetero-aryl aldehydes, and dialdehydes. The structure of the synthesized derivatives was proved by physical and spectral analysis. Additionally, in vitro biological studies were performed, including antioxidant, anti-diabetic, anti-Alzheimer, and anti-arthritic activities. The four derivatives 3b, 5a, 5b, and 5c possess the highest activities. Among the four potent derivatives, compound 5a exhibited the highest antioxidant (TAC = 68.02 ± 0.15 mg gallic acid per g; IRP = 50.39 ± 0.11) and scavenging activities (ABTS = 53.98 ± 0.12% and DPPH = 8.65 ± 0.02 μg mL-1). Furthermore, compound 5a exhibited an α-amylase inhibitory percentage of 57.64 ± 0.13% near the acarbose (ACA = 69.11 ± 0.15%) and displayed inhibitor activity of the acetylcholinesterase (AChE) enzyme = 36.38 ± 0.08%. Moreover, our work extended to determining the anti-arthritic effect, and compound 5a revealed good inhibitor activities with very close values for proteinase denaturation (PDI) = 39.59 ± 0.09% and proteinase inhibition (PI) = 36.39 ± 0.08%, compared to diclofenac sodium PDI = 49.33 ± 0.11% and PI = 41.88 ± 0.09%. Additionally, the quantum chemical calculations, including HOMO, LUMO, and energy band gap were determined, and in silico ADMET properties were predicted, and their probability was recorded. Finally, molecular docking simulations were performed inside α-amylase and acetylcholinesterase enzymes.

Novel Azine Linked Hybrids of 2-Indolinone and Thiazolodinone Scaffolds as CDK2 Inhibitors with Potential Anticancer Activity: In Silico Design, Synthesis, Biological, Molecular Dynamics and Binding Free Energy Studies

Molecular hybrid of 2-indolinone-thiazolidinone is a well known scaffold for variable biological activities including anticancer activity. Accordingly, in the current work aided with structure-based molecular modeling studies, a library of novel twenty-six hybrids, 4(a-z), was designed and synthesized. Docking studies in the active site of CDK2, one of the key checkpoints enzymes, revealed that the binding scores of the designed molecules are comparable to the reference enzyme's inhibitors Sunitinib, Nintedanib, and Semaxanib. Variable antiproliferative activities are shown for these molecules against human liver (HepG2), breast (MCF7), and colon (HCT-29) cell lines considering Doxrubacin as a refrence drug. Compared to cytotoxic activities on the normal fibroblasts (WI-38), the tested molecules had better selectivity against the cancerous cells, expressed by their selectivity index (SI), than Doxrubacin and compound 4i was the safest compound. CDK2 inhibitory results of compounds 4f, 4g, 4h, and 4w showed IC50 at 59.43, 143.6, 27.42, and 61.63 nM respectively, while that of Sunitinib was 23.8 nM. To clarify the obtained biological activities of these molecules, broad docking and molecular dynamic simulations studies were undertaken and confirmed the consistency between the computational and the in vitro CDK2 inhibitory activities. Furthermore, in silico ADME/Tox profiles were done for the most active molecules using SwissADME and pkCSM-pharmacokinetics web-based methods predicted good pharmacokinetics, bioavailability, and toxicity profiles for the tested compounds.

The antibacterial potential of ciprofloxacin hybrids against Staphylococcus aureus

Staphylococcus aureus (S. aureus), an important pathogen of both humans and animals, is able to cause a variety of infections at any site of the body. The evolution of S. aureus resistance is notorious, and the widespread of drug-resistant S. aureus, especially methicillin-resistant S. aureus (MRSA), has made the treatment difficult in recent decades. Nowadays, S. aureus is among the leading causes of bacterial infections, creating an urgent need for the development of novel antibacterial agents. Ciprofloxacin, characterized by high clinical efficacy, is a broad-spectrum antibacterial agent with frequency of prescription for various Gram-positive and Gram-negative pathogens, many of which are resistant to a wide range of antibiotics. However, the long-term and widespread use of this antibiotic has led to the emergence of ciprofloxacin-resistant pathogens, and ciprofloxacin-resistant S. aureus has been noted in clinical practice. Ciprofloxacin hybrids have been recognized as advanced chemical entities to simultaneously modulate multiple drug targets in bacteria, so ciprofloxacin hybrids have the potential to overcome drug resistance. The present review provides an overview of ciprofloxacin hybrids with anti-S. aureus potential that have been reported in the last decade with emphasis on their structure-activity relationships and mechanisms of action.

Design, Synthesis and Anti-Lung Cancer Evaluation of 1, 2, 3-Triazole Tethered Dihydroartemisinin-Isatin Hybrids

A series of 1,2,3-triazole tethered dihydroartemisinin-isatin hybrids 8a-c and 9a-k were designed and synthesized. Their antiproliferative activity against A549, doxorubicin-resistant A549 (A549/DOX) as well as cisplatin-resistant A549 (A549/DDP) lung cancer cell lines was also investigated in this study. All hybrids (half maximal inhibitory concentration/IC₅₀: 7.54–73.8 μM) were more potent than the parent drug dihydroartemisinin (IC₅₀: 69.4–88.0 μM) and also non-cytotoxic towards mouse embryonic fibroblast cells NIH/3T3 (IC₅₀: >100 μM). The structure-activity relationships illustrated that the substituents on C-3 and C-5 position of isatin moiety influenced the activity significantly. Imine at C-3 position decreased the activity, whereas fluoro at C-5 position enhanced the activity. In particular, hybrids 8a,c (IC₅₀: 7.54–12.1 μM) and 9i (IC₅₀: 9.10–15.9 μM) were comparable to cisplatin (IC₅₀: 7.54–15.9 μM vs 9.38–19.7 μM) against A549 and A549/DOX, but 4.6–7.6 folds more potent than that of cisplatin (IC₅₀: 8.77–14.3 μM vs 66.9 μM) against A549/DDP cells. Moreover, hybrids 8a,c exhibited excellent stability (liver microsomes: 68–83%) in mouse/human microsomes and good pharmacokinetic properties, demonstrating their potential as a novel anti-lung cancer chemotherapeutic candidates.