Design, Synthesis, and Structure–Activity Relationship Study of Novel Indole-2-carboxamide Derivatives as Anti-inflammatory Agents for the Treatment of Sepsis

Protective Effect of a Isothiazolinone Derivative on Acute Lung Injury by Regulating PI3K-AKT Signaling Pathway

Acute lung injury (ALI) is a prevalent organ injury in sepsis, characterized by an inflammatory reactive disorder. Both the incidence and mortality rates of ALI have been steadily increasing. Isothiazolinone derivatives have displayed anti-inflammatory activity and have shown effectiveness in treating pneumonia. The objective of the study is to assess the effects and mechanisms of the isothiazolinone derivative 4-benzoyl-2-butyl-5-(ethylsulfinyl)isothiazol-3(2H)-one (C6) on sepsis-induced ALI.The analysis of biological function and signal pathway enrichment demonstrated that C6 primarily exhibited anti-inflammatory effects. Administration of different doses of C6 through intraperitoneal injection significantly improved the survival rate, body temperature, and body mass of mice with ALI induced by cecal ligation and puncture (CLP). Additionally, it mitigated lung tissue injury, pulmonary edema, lung permeability, inflammatory cell infiltration, apoptosis, and the expression of inflammatory cytokines. Network targeting analysis and experimental validation in mouse leukemia cells of monocyte macrophage (RAW264.7) cells and CLP-induced ALI mice revealed that the anti-inflammatory effect of C6 was mediated by the inhibition of the phosphatidylinositol 3 kinase -protein kinase B (PI3K-AKT) signaling pathway. The research suggest that C6 has protective effects against ALI by inhibiting the PI3K-AKT signaling pathway. This information could be valuable in developing potential treatments for ALI.

Design, synthesis and antiviral activity of indole derivatives containing quinoline moiety

A series of indole derivatives containing quinoline structures were designed and synthesized. The synthesized compounds were characterized by NMR and HRMS. And W14 was performed by single crystal X-ray diffraction experiments. The antiviral activity studies showed that some of the target compounds possessed significant activity against tobacco mosaic virus (TMV). In particular, W20 had significant activity. The results of in vivo anti-TMV activity assay showed that W20 possessed the best curative and protective activities with EC50 values of 84.4 and 65.7 μg/mL, which were better than ningnanmycin (NNM) 205.1 and 162.0 μg/mL, respectively. The results of Microscale thermophoresis (MST) showed that W20 had a strong binding affinity for the tobacco mosaic virus coat protein (TMV-CP) with a dissociation constant (Kd) of 0.00519 μmol/L, which was superior to that of NNM (1. 65320 μmol/L). The molecular docking studies were in accordance with the experimental results. In addition, the determination of malondialdehyde (MDA) content in tobacco leaves showed that W20 improved the disease resistance of tobacco. Overall, this study shows that indole derivatives containing quinoline can be used as new antiviral agents for plant viruses for further research.

Design, synthesis, and anti-inflammatory activity of indole-2-formamide benzimidazole[2,1-b]thiazole derivatives

Molecular hybridization is a widely employed technique in medicinal chemistry for drug modification, aiming to enhance pharmacological activity and minimize side effects. The combination of an indole ring and imidazole[2,1-b]thiazole has shown promising potential as a group that exhibits potent anti-inflammatory effects. In this study, we designed and synthesized a series of derivatives comprising indole-2-formamide benzimidazole[2,1-b]thiazole to evaluate their impact on LPS-induced production of pro-inflammatory cytokines NO, IL-6, and TNF-α release, as well as iron death in RAW264.7 cells. The findings revealed that most compounds effectively inhibited LPS-induced production of pro-inflammatory cytokines NO, IL-6, and TNF-α release in RAW264.7 cells. Compound 13b exhibited the most potent anti-inflammatory activity among the tested compounds. The results of the cytotoxicity assay indicated that compound 13b was nontoxic. Additionally, compound 13b was found to elevate the levels of ROS, MDA, and Fe2+, while reducing GSH content, thereby facilitating the iron death process. Consequently, compound 13b showed promise for future development as an anti-inflammatory drug.

Discovery of the Diphenyl 6-Oxo-1,6-dihydropyridazine-3-carboxylate/carboxamide Analogue J27 for the Treatment of Acute Lung Injury and Sepsis by Targeting JNK2 and Inhibiting the JNK2-NF-κB/MAPK Pathway

Acute lung injury (ALI) and sepsis are both serious and complex conditions associated with high mortality, yet there are no effective treatments. Herein, we designed and synthesized a series of diphenyl 6-oxo-1,6-dihydropyridazine-3-carboxylate/carboxamide analogues exhibiting anti-inflammatory activity. The optimal compound J27 decreased the release of TNF-α and IL-6 in mouse and human cells J774A.1 and THP-1 (IL-6 IC50 = 0.22 μM) through the NF-κB/MAPK pathway. J27 demonstrated remarkable protection against ALI and sepsis in vivo and exhibited good safety in subacute toxicity experiments. Pharmacokinetic study indicated that J27 had good bioavailability (30.74%). To our surprise, J27 could target JNK2 with a totally new molecular skeleton compared with the only few JNK2 inhibitors reported. Moreover, there is no report that JNK2 inhibitors could apply for ALI and sepsis. Therefore, this work provides a new lead structure for the study of JNK2 inhibitors and a new target of JNK2 to treat ALI and sepsis.

New indoleacetic acid-functionalized soluble oxidized starch-based nonionic biopolymers as natural antibacterial materials

This study aims to develop a new soluble oxidized starch-based nonionic antibacterial polymer (OCSI) featuring high antibacterial activity and non-leachability by grafting indoleacetic acid monomer (IAA) onto the oxidized corn starch (OCS). The synthesized OCSI was characterized analytically by Nuclear magnetic resonance H-spectrometer (¹H NMR), Fourier transform infrared spectroscopy (FTIR), Ultraviolet-visible spectroscopy (UV-Vis), X-ray diffractometer (XRD), X-ray Photoelectron Spectroscopy (XPS), Scanning Electronic Microscopy (SEM), Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). The results showed that the synthesized OCSI was endowed with high thermal stability and favorable solubility, and the substitution degree reached 0.6. Besides, the disk diffusion test revealed a lowest OCSI inhibitory concentration of 5 μg disk^-1, and showed significant bactericidal activity against Gram-positive bacteria (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli). Moreover, the antibacterial films (OCSI-PCL), featuring their good compatibility, mechanical properties, antibacterial activity, non-leachability, and low water vapor permeability (WVP), were also successfully prepared by blending OCSI with biodegradable polycaprolactone (PCL). Finally, CCK-8 assay results confirmed the excellent biocompatibility of the OCSI-PCL films. Overall, this very study evidenced the applicability of the obtained oxidized starch-based biopolymers as an eco-friendly non-ionic antibacterial material and confirmed their promising applications in areas including biomedical materials, medical devices, and food packaging.

Discovery of 4-oxo-N-phenyl-1,4-dihydroquinoline-3-carboxamide derivatives as novel anti-inflammatory agents for the treatment of acute lung injury and sepsis

Acute lung injury (ALI) and sepsis, characterized by systemic inflammatory response syndrome, remain the major causes of death in severe patients. Inhibiting the release of proinflammatory cytokines is considered to be a promising method for the treatment of inflammation-related diseases. In this study, a total of 28 4-oxo-N-phenyl-1,4-dihydroquinoline-3-carboxamide derivatives were designed and synthesized and their anti-inflammatory activities in J774A.1 were evaluated. Among them, derivative 13a was found to significantly inhibit lipopolysaccharide (LPS)-induced expression of the proinflammatory cytokines interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) on J774A.1, THP-1 and LX-2 cells, and inhibited the activation of the NF-κB pathway. Furthermore, administration of 13ain vivo significantly improved the symptoms in LPS-induced ALI mice, including alleviation of pathological changes in the lung tissue, reduction of pulmonary edema, and inhibition of macrophage infiltration. Moreover, the administration of 13ain vivo significantly promoted survival in LPS-induced sepsis mice. 13a demonstrated favorable pharmacokinetic properties with T_1/2 value of 11.8 h and F value of 36.3%. Therefore, this study has identified a novel 4-oxo-N-phenyl-1,4-dihydroquinoline-3-carboxamide derivative, 13a, which is an effective anti-inflammatory agent. The findings have laid a foundation for the further development of agents to treat ALI and sepsis.

Synthesis, biological activity of newly designed sulfonamide based indole derivative as anti-microbial agent

Background

In medicinal chemistry, indole and its derivative play an important role. Indole is gaining a lot of importance in medicinal chemistry due to its physiological activity which includes anticancer, antitubercular, antimicrobial, antiviral, antimalarial, anti-inflammatory activities, antileishmanial agents, anti-cholinesterase, and enzyme inhibitory. The spread of antimicrobial resistance becomes a threat to both humans and animals. Antimicrobial resistance has been declared in the top 10 global major health risks by WHO including reported data of 2020 of AMR with 3,106,002 confirmed infections in humans across 70 countries.

Result

In this present work some new sulfonamide-based indole derivatives were synthesized by using 1H-indole -2 carboxylic acid as a starting material. The structure of all synthesized sulfonamide-based indole derivatives was confirmed by 1H NMR and LCMS Spectroscopy.

Conclusion

All the synthesized compounds were screened for anti-microbial activity against Gram Positive Staphylococcus aureus, Bacillus megaterium, and Gram Negative Klebsiella pneumonia, Escherichia coli, Salmonellatyphiae, Shigella sp., Enterobacter aerogenes. Among gram-positive Staphylococcus aureus, and Bacillus megaterium. The compound shows activity against Staphylococcus aureus, and among all gram-negative bacteria against Klebsiella pneumonia shows good activity.

Synthesis and evaluation of ursolic acid-based 1,2,4-triazolo[1,5-a]pyrimidines derivatives as anti-inflammatory agents

Here, two series of novel ursolic acid-based 1,2,4-triazolo[1,5-a]pyrimidines derivatives were synthesized and screened for their anti-inflammatory activity by evaluating their inhibition effect of using LPS-induced inflammatory response in RAW 264.7 macrophages in vitro; the effects of different concentrations of the compounds on the secretion of nitric oxide (NO) and inflammatory cytokines including TNF-α and IL-6 were evaluated. Their toxicity was also assessed in vitro. Results showed that the most prominent compound 3 could significantly decrease production of the above inflammatory factors. Docking study was performed for the representative compounds 3, UA, and Celecoxib to explain their interaction with cyclooxygenase-2 (COX-2) receptor active site. In vitro enzyme study implied that compound 3 exerted its anti-inflammatory activity through COX-2 inhibition.

Synthesis and biological evaluation of indole-based peptidomimetics as antibacterial agents against Gram-positive bacteria

The emergence of bacterial multidrug resistance and the lack of new antimicrobial agents urgently demand the discovery and development of novel antibacterials that avoid bacterial resistance. Antimicrobial peptidomimetics represent a promising approach for overcoming antibiotic resistance. Herein we report the synthesis and evaluation of indole-based amphiphilic antimicrobial peptidomimetics, bearing hydrophobic side chains and hydrophilic cationic moieties. Among these derivatives, compound 28 demonstrated potent antimicrobial activity against Gram-positive bacteria, low hemolytic activity and low toxicity towards mammalian cells, as well as good stability in salt conditions. Moreover, compound 28 showed the rapid killing of bacteria via membrane-targeting action without developing bacterial resistance. More importantly, compound 28 displayed high antimicrobial potency against Gram-positive bacteria in a murine model of bacterial keratitis, and was found to be more efficient than vancomycin. Thus, compound 28 had great potential as a promising lead compound for the treatment of Gram-positive bacterial infection.

4-(Indol-3-yl)thiazole-2-amines and 4-ιndol-3-yl)thiazole Acylamines as Νovel Antimicrobial Agents: Synthesis, In Silico and In Vitro Evaluation

This manuscript deals with the synthesis and computational and experimental evaluation of the antimicrobial activity of twenty-nine 4-(indol-3-yl)thiazole-2-amines and 4-ιndol-3-yl)thiazole acylamines. An evaluation of antibacterial activity against Gram (+) and Gram (-) bacteria revealed that the MIC of indole derivatives is in the range of 0.06-1.88 mg/mL, while among fourteen methylindole derivatives, only six were active, with an MIC in the range of of 0.47-1.88 mg/mL. S. aureus appeared to be the most resistant strain, while S. Typhimurium was the most sensitive. Compound 5x was the most promising, with an MIC in the range of 0.06-0.12 mg/mL, followed by 5d and 5m. An evaluation of these three compounds against resistant strains, namely MRSA P. aeruginosa and E. coli, revealed that they were more potent against MRSA than ampicillin. Furthermore, compounds 5m and 5x were superior inhibitors of biofilm formation, compared to ampicillin and streptomycin, in terms Compounds 5d, 5m, and 5x interact with streptomycin in additive manner. The antifungal activity of some compounds exceeded or was equipotent to those of the reference antifungal agents bifonazole and ketoconazole. The most potent antifungal agent was found to be compound 5g. Drug likeness scores of compounds was in a range of -0.63 to 0.29, which is moderate to good. According to docking studies, E. coli MurB inhibition is probably responsible for the antibacterial activity of compounds, whereas CYP51 inhibition was implicated in antifungal activity. Compounds appeared to be non-toxic, according to the cytotoxicity assessment in MRC-5 cells.

Discovery of Novel Pterostilbene Derivatives That Might Treat Sepsis by Attenuating Oxidative Stress and Inflammation through Modulation of MAPKs/NF-κB Signaling Pathways

Sepsis remains one of the most common life-threatening illnesses that is characterized by a systemic inflammatory response syndrome (SIRS) and usually arises following severe trauma and various septic infections. It is still in urgent need of new effective therapeutic agents, and chances are great that some candidates can be identified that can attenuate oxidative stress and inflammatory responses. Pterostilbene, which exerts attractive anti-oxidative and anti-inflammatory activities, is a homologue of natural polyphenolic derivative of resveratrol. Starting from it, we have made several rounds of rational optimizations. Firstly, based on the strategy of pharmacophore combination, indanone moiety was introduced onto the pterostilbene skeleton to generate a novel series of pterostilbene derivatives (PIF_1–PIF_16) which could possess both anti-oxidative and anti-inflammatory activities for sepsis treatment. Then, all target compounds were subjected to their structure–activity relationships (SAR) screening of anti-inflammatory activity in mouse mononuclear macrophage RAW264.7 cell line, and their cytotoxicities were determined after. Finally, an optimal compound, PIF_9, was identified. It decreased the mRNA levels of lipopolysaccharide (LPS)-induced interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), inducible nitric oxide synthase (iNOS), and cyclooxygenase 2 (COX2). We also found that the anti-inflammatory effects might be contributed by its suppression on the nuclear factor-κB (NF-κB) and MAPKs signaling pathway. Moreover, PIF_9 also demonstrated potent anti-oxidative activity in RAW264.7 macrophages and the sepsis mouse model. Not surprisingly, with the benefits mentioned above, it ameliorated LPS-induced sepsis in C57BL/6J mice and reduced multi-organ toxicity. Taken together, PIF_9 was identified as a potential sepsis solution, targeting inflammation and oxidative stress through modulating MAPKs/NF-κB.

Discovery of novel and potent safinamide-based derivatives as highly selective hMAO-B inhibitors for treatment of Parkinson's disease (PD): Design, synthesis, in vitro, in vivo and in silico biological studies

Up to date, the current clinical practice employs only symptomatic treatments for management of Parkinson's disease (PD) but unable to stop disease progression. The discovery of new chemical entities endowed with potent and selective human monoamine oxidase B (hMAO-B) inhibitory activity is a clinically relevant subject. Herein, a structural optimization strategy for safinamide (a well-known second generation hMAO-B inhibitor) afforded a series of thirty-six safinamide-derived new analogs (4aa-bj). Most compounds showed promising inhibitory activities against hMAO-B (>70% inhibition at a single dose concentration of 10 µM), with no apparent effect on hMAO-A at 100 μM. Moreover, while six compounds (4ak, 4as, 4az, 4be, 4bg, and 4bi) exhibited potent double-digit nanomolar activities over hMAO-B with IC₅₀ values of 29.5, 42.2, 22.3, 18.8, 42.2, and 33.9 nM, respectively, three derivatives (4aq, 4at, and 4bf), possessing the same carboxamide moiety (2-pyrazinyl), showed the most potent single-digit nanomolar activities (IC₅₀ = 9.7, 5.1, and 3.9 nM, respectively). Compound 4bf revealed an excellent selectivity index (SI > 25641) with a 29-fold increase compared to safinamide (SI > 892). A structure activity relationship along with molecular docking simulations provided insights into enzyme - inhibitor interactions and a rational for the observed activity. In an in vivo MPTP-induced mouse model of PD, oral administration of compound 4bf significantly protected nigrostriatal dopaminergic neurons as revealed by tyrosine hydroxylase staining and prevented MPTP-induced Parkinsonism as revealed by motor behavioral assays. Accordingly, we present compound 4bf as a novel, highly potent, and selective hMAO-B inhibitor with an effective therapeutic profile for relieving PD.

An Indole-2-Carboxamide Derivative, LG4, Alleviates Diabetic Kidney Disease Through Inhibiting MAPK-Mediated Inflammatory Responses

Aim

Elevated inflammatory signaling has been shown to play an important role in diabetic kidney disease (DKD). We previously developed a new anti-inflammatory compound LG4. In the present study, we have tested the hypothesis that LG4 could prevent DKD by suppressing inflammation and identified the underlying mechanism.

Methods

Streptozotocin-induced type 1 diabetic mice were used to develop DKD and evaluate the effects of LG4 against DKD. To identify the potential targets of LG4, biotin-linked LG4 was synthesized and subjected to proteome microarray screening. The cellular mechanism of LG4 was investigated in HG-challenged SV40MES13 cells.

Results

Although LG4 treatment had no effect on the body weight and blood glucose levels, it remarkably reversed the hyperglycemia-induced pathological changes and fibrosis in the kidneys of T1DM mice. Importantly, hyperglycemia-induced renal inflammation evidenced by NF-κB activation and TNFα and IL-6 overexpression was greatly ameliorated with LG4 treatment. Proteosome microarray screening revealed that JNK and ERK were the direct binding proteins of LG4. LG4 significantly reduced HG-induced JNK and ERK phosphorylation and subsequent NF-κB activation in vivo and in vitro. In addition, LG4 did not show further anti-inflammatory effect in HG-challenged mesangial cells with the presence of JNK or ERK inhibitor.

Conclusion

LG4 showed renoprotective activity through inhibiting ERK/JNK-mediated inflammation in diabetic mice, indicating that LG4 may be a therapeutic agent for DKD.

Enantioselective synthesis of indole derivatives by Rh/Pd relay catalysis and their anti-inflammatory evaluation

An efficient Rh/Pd relay catalyzed intermolecular and cascade intramolecular hydroamination for the synthesis of exclusive trans 1-indolyl dihydronaphthalenols (up to 88% yield, 99% ee) is described under mild conditions. Moreover, the in silico and in vitro screening showed that the novel 1-indolyl dihydronaphthalenol products are potent lead compounds for treating inflammation disease.

Regioselectivity of aminomethylation in 3-acetyl-7-hydroxycoumarins: Mannich bases and Betti bases

The atomic electron density distribution in 3-acetyl-7-hydroxycoumarin was analysed to elucidate the regioselectivity of aminomethylation.

Ethyl 1H-indole-2-carboxyl-ate

Our work in the area of synthesis of tris indole compounds as a potential chelator led to the synthesis and crystallization of ethyl 1H-indole-2-carboxyl-ate, C11H11NO2, an indole that was synthesized by the thionyl chloride reaction of 1H-indole-2-carb-oxy-lic acid, followed by dissolution in ethanol. The mol-ecular packing exhibits a herringbone pattern with the zigzag running along the b-axis direction; the compound crystallizes as a hydrogen-bonded dimer resulting from O⋯H-N hydrogen bonds, between the indole N-H group and the keto oxygen atom, which build centrosymmetric R 2 2(10) ring motifs in the crystal.

3-Amino-5-(indol-3-yl)methylene-4-oxo-2-thioxothiazolidine Derivatives as Antimicrobial Agents: Synthesis, Computational and Biological Evaluation

Herein we report the design, synthesis, computational, and experimental evaluation of the antimicrobial activity of fourteen new 3-amino-5-(indol-3-yl) methylene-4-oxo-2-thioxothiazolidine derivatives. The structures were designed, and their antimicrobial activity and toxicity were predicted in silico. All synthesized compounds exhibited antibacterial activity against eight Gram-positive and Gram-negative bacteria. Their activity exceeded those of ampicillin and (for the majority of compounds) streptomycin. The most sensitive bacterium was S. aureus (American Type Culture Collection ATCC 6538), while L. monocytogenes (NCTC 7973) was the most resistant. The best antibacterial activity was observed for compound 5d (Z)-N-(5-((1H-indol-3-yl)methylene)-4-oxo-2-thioxothiazolidin-3-yl)-4-hydroxybenzamide (Minimal inhibitory concentration, MIC at 37.9–113.8 μM, and Minimal bactericidal concentration MBC at 57.8–118.3 μM). Three most active compounds 5d, 5g, and 5k being evaluated against three resistant strains, Methicillin resistant Staphilococcus aureus (MRSA), P. aeruginosa, and E. coli, were more potent against MRSA than ampicillin (MIC at 248–372 μM, MBC at 372–1240 μM). At the same time, streptomycin (MIC at 43–172 μM, MBC at 86–344 μM) did not show bactericidal activity at all. The compound 5d was also more active than ampicillin towards resistant P. aeruginosa strain. Antifungal activity of all compounds exceeded those of the reference antifungal agents bifonazole (MIC at 480–640 μM, and MFC at 640–800 μM) and ketoconazole (MIC 285–475 μM and MFC 380–950 μM). The best activity was exhibited by compound 5g. The most sensitive fungal was T. viride (IAM 5061), while A. fumigatus (human isolate) was the most resistant. Low cytotoxicity against HEK-293 human embryonic kidney cell line and reasonable selectivity indices were shown for the most active compounds 5d, 5g, 5k, 7c using thiazolyl blue tetrazolium bromide MTT assay. The docking studies indicated a probable involvement of E. coli Mur B inhibition in the antibacterial action, while CYP51 inhibition is likely responsible for the antifungal activity of the tested compounds.

Uncommon terpenoids with anti-inflammatory activity from the Hainan soft coral Sinularia tumulosa

One novel sesquiterpenoid containing an unprecedented eight-membered cyclic peroxide motif, sinulatumolin A (1), along with four new related terpenoids, namely sinulatumolins B-E (2-4 and 6), were isolated from South China Sea soft coral Sinularia tumulosa. The structures of all the isolates were elucidated by detailed spectroscopic analysis, chemical transformations, and single X-ray diffraction analysis. Compound 1 represents the first example of sesquiterpene bearing an eight-membered cyclic peroxide ring from soft coral. All the new compounds isolated were evaluated for their anti-inflammatory activity. Compounds 1, 3, 4 and 6 displayed significant TNF-α inhibitory activity being comparable with that of the positive control dexamethasone (IC₅₀ = 8.7 μM), with IC₅₀ values of 7.5, 2.6, 5.5, and 3.6 μM, respectively.

Novel phthalide derivatives: Synthesis and anti-inflammatory activity in vitro and in vivo

Phthalide is a promising chemical scaffold and has been proved to show potent anti-inflammatory efficacy. In this study, three series, total of 31 novel phthalide derivatives were designed and synthesized, their anti-inflammatory activities were screened in vitro and in vivo. The anti-inflammatory activity of all the compounds were screened on LPS induced NO production to evaluating their inhibitory effects. Structure-activity relationship has been concluded, and finally 3-((4-((4-fluorobenzyl)oxy)phenyl)(hydroxy)methyl)-5,7-dimethoxyisobenzofuran-1 (3H)-one (compound 9o) was found to be the active one with low toxicity, which showed 95.23% inhibitory rate at 10 μM with IC₅₀ value of 0.76 μM against LPS-induced NO over expression. Preliminary mechanism studies indicated that compound 9o activated Nrf2/HO-1 signaling pathway via accumulation ROS and blocks the NF-κB/MAPK signaling pathway. The in vivo anti-inflammatory activity shown that compound 9o had obvious therapeutic effect against the adjuvant-induced rat arthritis model.

Synthetic strategies, SAR studies, and computer modeling of indole 2 and 3-carboxamides as the strong enzyme inhibitors: a review

Abstract

Indole derivatives have been the focus of many researchers in the study of pharmaceutical compounds for many years. Researchers have investigated the effect of carboxamide moiety at positions 2 and 3, giving unique inhibitory properties to these compounds. The presence of carboxamide moiety in indole derivatives causes hydrogen bonds with a variety of enzymes and proteins, which in many cases, inhibits their activity. In this review, synthetic strategies of indole 2 and 3-carboxamide derivatives, the type, and mode of interaction of these derivatives against HLGP, HIV-1, renin enzyme, and structure–activity studies of these compounds were investigated. It is hoped that indole scaffolds will be tested in the future for maximum activity in pharmacological compounds.

Graphic abstract

Synthesis and Evaluation of Antimicrobial Activities of Novel N-Substituted Indole Derivatives

Indole motifs are one of the most significant scaffolds in the discovery of new drugs. We have described a synthesis of new N-substituted indole derivatives (1-3), and their in vitro antimicrobial activities were investigated. The synthesis of titled compounds has been demonstrated by utilizing commercially available starting materials. The antibacterial and antifungal activities were performed using new strains of bacteria Staphylococcus aureus, Escherichia coli, and Candida albicans using the disc diffusion method. Notably, the compound 4-(1-(2-(1H-indol-1-yl) ethoxy) pentyl)-N,N-dimethyl aniline (1) was found to be most potent than the other analogues (2 and 3), which has shown higher inhibition than the standard drug chloramphenicol.

3,4-seco-Dammarane Triterpenoid Saponins with Anti-Inflammatory Activity Isolated from the Leaves of Cyclocarya paliurus

Cyclocarya paliurus is commonly used for the prevention and treatment of hypertension, diabetes, and inflammation in South China. Although research on the anti-inflammatory effects of C. paliurus leaves has been reported, no active anti-inflammatory compounds have been identified. In the present study, RAW 264.7 cells were used to establish a bioactivity-guided identification model to verify the inhibitory effects of C. paliurus leaves on inflammation and identify the anti-inflammatory constituents. The active fraction was isolated to yield 18 dammarane triterpenoid saponins, including 11 new 3,4-seco-dammarane triterpenoid saponins (1-11), the structures of which were identified on the basis of analyses of nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS) and comparison with literature data. Compounds 7, 8, 10, and 11 showed strong inhibition on nitric oxide (NO) productions, with IC50 values ranging from 8.23 to 11.23 μM. These four compounds significantly decreased the secretion of tumor necrosis factor-alpha (TNF-α), prostaglandin E2 (PGE2), and interleukin 6 (IL-6) in lipopolysaccharide-activated RAW 264.7 cells. Furthermore, compound 7 decreased the expression of the proteins cyclooxygenase-2 (COX-2), inducible nitric-oxide synthase (iNOS), and nuclear factor kappa-B (NF-κB/p65). In addition, the structure-activity relationships of the isolates were investigated. The results suggest that 3,4-seco-dammarane triterpenoid saponins may be used as potential anti-inflammatory drugs and warrant further investigation.

Indole-2-Carboxamide Derivative LG25 Inhibits Triple-Negative Breast Cancer Growth By Suppressing Akt/mTOR/NF-κB Signalling Pathway

Background

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer which is associated with poor patient outcome and lack of targeted therapy. Our laboratory has synthesized a series of indole-2-carboxamide derivatives. Among this series, compound LG25 showed a favorable pharmacological profile against sepsis and inflammatory diseases. In the present study, we investigated the chemotherapeutic potential of LG25 against TNBC utilizing in vitro and in vivo models.

Methods

Changes in cell viability, cell cycle phases and apoptosis were analyzed using MTT, clonogenic assay, FACS and Western blotting assays. The anti-cancer effects of LG25 were further determined in a xenograft mouse model.

Results

Our findings reveal that LG25 reduced TNBC viability in a dose-dependent manner. Flow cytometric and Western blot analyses showed that LG25 enhances G2/M cell cycle arrest and induced cell apoptosis. In addition, LG25 treatment significantly inhibited Akt/mTOR phosphorylation and nuclear translocation of nuclear factor-κB (NF-κB). These inhibitory activities of LG25 were confirmed in mice implanted MDA-MB-231 TNBC cells.

Conclusion

Our studies provide experimental evidence that indole-2-carboxamide derivative LG25 effectively targeted TNBC in preclinical models by inducing cell cycle arrest and apoptosis, through suppressing Akt/mTOR/NF-κB signaling pathway.

Design and synthesis of novel pyrazolo[4,3-d]pyrimidines as potential therapeutic agents for acute lung injury

Four series of total 35 new pyrazolo[4,3-d]pyrimidine compounds were designed, synthesized and evaluated for their inhibitory activity against LPS-induced NO production in RAW264.7 macrophages. Among them, compound 4e was found to be the most potent inhibitor, which decreased the production of cytokines in vitro, such as NO, IL-6 and TNF-α, with IC₅₀ values of 2.64, 4.38 and 5.63 μM, respectively. Further studies showed that compound 4e inhibited cytokines secretion of macrophages through suppressing TLR4/p38 signaling pathway. Additionally, compound 4e showed in vivo anti-inflammatory activity in LPS-induced model of acute lung injury. These data suggested that compound 4e may be a promising lead structure for the treatment of ALI.

Medicinal chemistry of indole derivatives: Current to future therapeutic prospectives

Indole is a versatile pharmacophore, a privileged scaffold and an outstanding heterocyclic compound with wide ranges of pharmacological activities due to different mechanisms of action. It is an superlative moiety in drug discovery with the sole property of resembling different structures of the protein. Plenty of research has been taking place in recent years to synthesize and explore the various therapeutic prospectives of this moiety. This review summarizes some of the recent effective chemical synthesis (2014-2018) for indole ring. This review also emphasized on the structure-activity relationship (SAR) to reveal the active pharmacophores of various indole analogues accountable for anticancer, anticonvulsant, antimicrobial, antitubercular, antimalarial, antiviral, antidiabetic and other miscellaneous activities which have been investigated in the last five years. The precise features with motives and framework of each research topic is introduced for helping the medicinal chemists to understand the perspective of the context in a better way. This review will definitely offer the platform for researchers to strategically design diverse novel indole derivatives having different promising pharmacological activities with reduced toxicity and side effects.

Synthesis and Anti-inflammatory Evaluation of ( R)-, ( S)-, and (±)-Sanjuanolide Isolated from Dalea frutescens

The known chalcone (±)-sanjuanolide (1) can be isolated from Dalea frutescens. This study presents a convergent strategy for the first total synthesis of ( R)-, ( S)-, and (±)-sanjuanolide (1). The key step for synthesizing ( R)- and ( S)-1 was a Corey-Bakshi-Shibata enantioselective carbonyl reduction to construct the C-2″ configuration. ( R)-1 efficiently inhibited the lipopolysaccharides (LPS)-induced expression of tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6), while ( S)-1 produced no significant anti-inflammatory effect. ( R)-1 also effectively inhibited the mRNA expression of several inflammatory cytokines after the LPS challenge in vitro. The synthesis and biological properties of these compounds have confirmed ( R)-sanjuanolide and (±)-sanjuanolide as promising new leads for developing anti-inflammatory agents.

Synthesis, structure and antiproliferative and optical activities of two new biphenyl-derived Schiff bases

Two novel Schiff bases derived from indole and biphenyl have been designed and synthesized, namely 3-((E)-{(E)-[1-(biphenyl-4-yl)ethylidene]hydrazinylidene}methyl)-1-methyl-1H-indole (3-BEHMI) acetonitrile monosolvate, C₂₄H₂₁N₃·CH₃CN, and 3-((E)-{(E)-[1-(biphenyl-4-yl)ethylidene]hydrazinylidene}methyl)-1-methyl-1H-indole (3-BEHEI) acetonitrile monosolvate, C₂₄H₂₁N₃·CH₃CN. Their structures were characterized by elemental analysis, quadrupole time-of-flight MS, NMR and UV-Vis spectroscopy. The single-crystal packing structure of 3-BEHMI is largely dominated by C-H...π interactions and weak van der Waals interactions. The in vitro cytotoxicity of the two title compounds have been evaluated against two tumour cell lines (A549 human lung cancer and 4T₁ mouse breast cancer) and two normal cell lines (MRC-5 normal lung cells and NIH 3T3 fibroblasts) by MTT assay. The results indicate that 3-BEHEI exhibits a slightly weaker antiproliferative capability (IC₅₀ = ∼50 µM) than the previously reported similar Schiff base 3-BEHI (IC₅₀ = ∼20 µM). This is in line with docking results. 3-BEHMI demonstrates a weak cytotoxic activity, with IC₅₀ values around 110 µM, which disagrees with its docking results. Overall, the tested compounds manifest relevant cytotoxicities on the selected cancer cell lines and normal cell lines. The UV-Vis and fluorescence spectra were recorded and reproduced through the TD-DFT method with four types of hybrid density functionals, including B3LYP, M062X, PBE1PBE and WB97XD.

5-Bromo-1-(4-chlorobenzyl)-1H-indole-2-carboxamides as new potent antibacterial agents

Ten 5-bromoindole-2-carboxamides were synthesized, characterized and evaluated for antibacterial activity against pathogenic Gram-negative bacteria Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa and Salmonella Typhi using gentamicin and ciprofloxacin as internal standards. Compounds 7a–c, 7g and 7h exhibit high antibacterial activity with a minimum inhibitory concentration (MIC) of 0.35–1.25 μg/mL. Compounds 7a–c exhibit antibacterial activities that are higher than those of the standards against E. coli and P. aeruginosa.

Two indole-2-carboxamide derivatives attenuate lipopolysaccharide-induced acute lung injury by inhibiting inflammatory response

Acute lung injury (ALI) is the leading cause of mortality in the intensive care unit. Currently, there is no effective pharmacological treatment for ALI. In our previous study, we reported that Lg25 and Lg26, two indole-2-carboxamide derivatives, inhibited the lipopolysaccharide (LPS)-induced inflammatory cytokines in vitro and attenuated LPS-induced sepsis in vivo. In the present study, we confirmed data from previous studies that LPS significantly induced pulmonary edema and pathological changes in lung tissue, increased protein concentration and number of inflammatory cells in bronchoalveolar lavage fluids (BALF), and increased inflammatory cytokine TNF-α expression in serum and BALF, pro-inflammatory genes expression, and macrophages infiltration in lung tissue. However, pretreatment with Lg25 and Lg26 significantly attenuated the LPS-induced changes in mice. Taken together, these data indicate that the newly discovered indole-2-carboxamide derivatives could be particularly useful in the treatment of inflammatory diseases such as ALI.

A New Compound Isolated from the Reduced Ribose-Tryptophan Maillard Reaction Products Exhibits Distinct Anti-inflammatory Activity

In this study, a compound of 532.24 Da named BF-4 was separated from the ribose-tryptophan Maillard reaction products by solvent extraction and purified through reverse phase high performance liquid chromatography. The purified compound BF-4 was identified as 3-((1 H-indol-3-yl)methyl)-8-(5-((1 H-indol-3-yl)methyl)-6-oxomorpholin-2-yl)-9-hydroxy-1,7,4-dioxazecan-2-one in accordance with 1D- and 2D-NMR spectra and LC-ESI-MS/MS analysis. BF-4 significantly reduced the production of nitric oxide (NO), interleukin-6 (IL-6), and tumor necrosis factor α (TNF-α) in lipopolysaccharide-stimulated RAW 264.7 cells. It inhibited nuclear factor κB (NF-κB) activation and mitogen-activated protein kinase (MAPK) phosphorylation through suppressing phosphorylation of IκBα, P65, P38 and c-Jun N-terminal kinase (JNK). The anti-inflammatory activity of BF-4 was comparable to dexamethasone, and more importantly, BF-4 showed less cytotoxicity than dexamethasone on the normal human liver cell LO2. The results indicate that BF-4 is a promising anti-inflammatory agent with pharmaceutical potential.

Design, synthesis, and structure-activity relationships of 2-benzylidene-1-indanone derivatives as anti-inflammatory agents for treatment of acute lung injury

Purpose

The purpose of this study was to design and synthesize novel 2-benzylidene-1-indanone derivatives for treatment of acute lung injury.

Methods

A series of 39 novel 2-benzylidene-indanone structural derivatives were synthesized and evaluated for anti-inflammatory activity in lipopolysaccharide (LPS)-stimulated murine primary macrophages.

Results

Most of the obtained compounds effectively inhibited the LPS-induced expression of IL-6 and TNF-α. The most active compound, 8f, was found to significantly reduce LPS-induced pulmonary inflammation, as reflected by reductions in the concentration of total protein, inflammatory cell count, as well as the lung wet/dry ratio in bronchoalveolar lavage (BAL) fluid. Furthermore, 8f effectively inhibited mRNA expression of several inflammatory cytokines after LPS challenge in vitro and in vivo. Administration of 8f also blocked LPS-induced activation of the proinflammatory NF-κB/MAPK signaling pathway.

Conclusion

The simple synthetic preparation and biological properties of these derivatives make these 2-benzylidene-indanone scaffolds promising new entities for the development of anti-inflammatory therapeutics for the treatment of acute lung injury.

Design, synthesis, crystal structure and in vitro cytotoxic properties of a novel Schiff base derived from indole and biphenyl

A novel and potentially active dihydroorotate dehydrogenase (DHODH) inhibitor, namely 3-({(E)-[(E)-1-(biphenyl-4-yl)ethylidene]hydrazinylidene}methyl)-1H-indole (BEHI) acetonitrile disolvate, C23H19N3·2CH3CN, has been designed and synthesized. The structure of BEHI was characterized by elemental analysis, Q-TOF (quadrupole time-of-flight) MS, NMR, UV–Vis and single-crystal X-ray diffraction. The antitumour activity of the target molecule was evaluated by the MTT method. Results indicated that BEHI exhibited rather potent cytotoxic activity against human A549 (IC50 = 20.5 µM) and mouse breast 4T1 (IC50 = 18.5 µM) cancer cell lines. Meanwhile, to rationalize its potencies in the target, BEHI was docked into DHODH and the interactions with the active site residues were analyzed. Single-crystal structure analysis indicated that hydrogen bonds are present only between BEHI and acetonitrile solvent molecules in the asymmetric unit. The interplay of weak π–π stacking and weak C(N)—H...π interactions between neighbouring BEHI molecules play crucial roles in the formation of the final supramolecular frameworks.

Palladium-catalyzed tandem addition/cyclization in aqueous medium: synthesis of 2-arylindoles

Pd-catalyzed tandem reaction of potassium aryltrifluoroborates with nitriles for the synthesis of 2-arylindoles in aqueous medium.