Exploring the 3-piperidin-4-yl-1H-indole scaffold as a novel antimalarial chemotype

Study of antiplasmodial activity, toxicity, pharmacokinetic profiles of n-methyl-isatin (CH3ISACN) derivative

One of the main factors that have made it difficult to control malaria is the large number of parasites that are resistant to the usual antimalarial drugs. Therefore, the development of new drugs that are more effective and with low toxicity for humans is necessary. In this work, we evaluated the adduct 2-(3-hydroxy-1-methyl-2-oxoindolin-3-yl)acrylonitrile, also called CH3ISACN, as a potential antimalarial through in vitro studies, and evaluated its effects in silico and in vivo toxicology. For this, the compound CH3ISACN was exposed to P. falciparum W2 strain in infected human erythrocytes. The results showed that the CH3ISACN adduct showed good antiplasmodial activity, moderate cytotoxicity, and good cell viability. In addition, it has been shown to have good theoretical oral bioavailability and did not pose a risk of toxicity in in-silico studies. Through the in vivo study, acute toxicity was evaluated, in which doses of 300 mg/kg and 2000 mg/kg of the test substance were administered to adult female Wistar rats. CH3ISACN did not cause death in any of the animals, thus presenting a high LD50 and therefore low toxicity. There was no behavioral change in the animals, as well as in the other parameters evaluated; the highest dose tested did not cause any significant change. Only a reduction in urea concentration, but that did not bring relevant clinical significance. Through the histological study, no changes were found that would indicate intoxication in the organs of the animals. Finally, the CH3ISACN adduct presents itself as a promising drug candidate for the treatment of malaria.

Synthetic account on indoles and their analogues as potential anti-plasmodial agents

Malaria caused by P. falciparum, has been recognized as one of the major infectious diseases causing the death of several patients as per the reports from the World Health Organization. In search of effective therapeutic agents against malaria, several research groups have started working on the design and development of novel heterocycles as anti-malarial agents. Heterocycles have been recognized as the pharmacophoric features for the different types of medicinally important activities. Among all these heterocycles, nitrogen containing aza-heterocycles should not be underestimated owing to their wide therapeutic window. Amongst the aza-heterocycles, indoles and fused indoles such as marinoquinolines, isocryptolepines and their regioisomers, manzamines, neocryptolenines, and indolones have been recognized as anti-malarial agents active against P. falciparum. The present work unleashes the synthetic attempts of anti-malarial indoles and fused indoles through cyclocondensation, Fischer-indole synthesis, etc. along with the brief discussions on structure-activity relationships, in vitro or in vivo studies for the broader interest of these medicinal chemists, working on their design and development as potential anti-malarial agents.

Amphiphilic small molecule antimicrobials: From cationic antimicrobial peptides (CAMPs) to mechanism-related, structurally-diverse antimicrobials

Bacterial infections are characterized by their rapid and widespread proliferation, leading to significant morbidity. Despite the availability of a variety of antimicrobial drugs, the resistance exhibited by pathogenic microorganisms towards these drugs demonstrates a consistent upward trajectory year after year. This trend can be attributed to the abuse or misuse of antibiotics. Although antimicrobial peptides can avoid the emergence of drug resistance to a certain extent, their clinical application has been hindered by factors such as their high production cost, poor in vivo stability, and potential cytotoxicity. Consequently, there arises an urgent need for the development of novel antimicrobial drugs. Small-molecule amphiphatic antimicrobials have a good prospect for research and development. These peptides hold the potential to address several issues, including the high cost of antimicrobial peptide production, poor in vivo stability, and cytotoxicity. Moreover, they exhibit the capability to overcome bacterial resistance, thereby considerably satisfying market demands and clinical needs. This paper reviews recent research pertaining to small molecule host-defending amphiphatic antimicrobials with cationic amphiphilic structures. It focuses on the design concepts, inherent relationships, drug-like properties, antimicrobial activities, application prospects, and emerging screening methods for novel antimicrobial. This review assumes paramount importance in mitigating the current shortcomings of antimicrobial agents. It also provides potential new ideas and methodologies for the research and development of antimicrobial agents.

Facile Access to Structurally Diverse Antimalarial Indoles Using a One-Pot A3 Coupling and Domino Cyclization Approach

A multistep and diversity-oriented synthetic route aiming at the A3 coupling/domino cyclization of o-ethynyl anilines, aldehydes and s-amines is described. The preparation of the corresponding precursors included a series of transformations, such as haloperoxidation and Sonogashira cross-coupling reactions, amine protection, desilylation and amine reduction. Some products of the multicomponent reaction underwent further detosylation and Suzuki coupling. The resulting library of structurally diverse compounds was evaluated against blood and liver stage malaria parasites, which revealed a promising lead with sub-micromolar activity against intra-erythrocytic forms of Plasmodium falciparum. The results from this hit-to-lead optimization are hereby reported for the first time.

Synthesis, characterization, antioxidant and antiparasitic activities new naphthyl-thiazole derivatives

In this work, 13 thiosemicarbazones (1a - m) and 16 thiazoles (2a - p) were obtained, which were properly characterized by spectroscopic and spectrometric techniques. The pharmacokinetic properties obtained in silico revealed that the derivatives are in accordance with the parameters established by lipinski and veber, showing that such compounds have good bioavailability or permeability when administered orally. In assays of antioxidant activity, thiosemicarbazones showed moderate to high antioxidant potential when compared to thiazoles. In addition, they were able to interact with albumin and DNA. Screening assays to assess the toxicity of compounds to mammalian cells revealed that thiosemicarbazones were less toxic when compared to thiazoles. In relation to in vitro antiparasitic activity, thiosemicarbazones and thiazoles showed cytotoxic potential against the parasites Leishmania amazonensis and Trypanosoma cruzi. Among the compounds, 1b, 1j and 2l stood out, showing inhibition potential for the amastigote forms of the two parasites. As for the in vitro antimalarial activity, thiosemicarbazones did not inhibit Plasmodium falciparum growth. In contrast, thiazoles promoted growth inhibition. This study shows in a preliminary way that the synthesized compounds have antiparasitic potential in vitro.

Design and synthesis of N-(1-(6-(substituted phenyl)-pyridazin-3-yl)-piperidine-3-yl)-amine derivatives as JMJD6 inhibitors

JMJD6 is a member of the JmjC domain-containing family and has been identified as a promising therapeutic target for treating estrogen-induced and triple-negative breast cancer. To develop novel anti-breast cancer agents, we synthesized a class of N-(1-(6-(substituted phenyl)-pyridazine-3-yl)-piperidine-3-yl)-amine derivatives as potential JMJD6 inhibitors. Among them, the anti-cancer compound A29 was an excellent JMJD6 binder (K_D = 0.75 ± 0.08 μM). It could upregulate the mRNA and protein levels of p53 and its downstream effectors p21 and PUMA by inhibiting JMJD6. Besides, A29 displayed potent anti-proliferative activities against tested breast cancer cells by the induction of cell apoptosis and cell cycle arrest. Significantly, A29 also promoted a remarkable reduction in tumor growth, with a TGI value of 66.6% (50 mg/kg, i.p.). Taken together, our findings suggest that A29 is a potent JMJD6 inhibitor bearing a new scaffold acting as a promising drug candidate for the treatment of breast cancer.

An insight into the recent developments in anti-infective potential of indole and associated hybrids

Prevention, accurate diagnosis, and effective treatment of infections are the main challenges in the overall management of infectious diseases. The best example is the ongoing SARs-COV-2(COVID-19) pandemic; the entire world is extremely worried about at present. Interestingly, heterocyclic moieties provide an ideal scaffold on which suitable pharmacophores can be designed to construct novel drugs. Indoles are amongst the most essential class of heteroaromatics in medicinal chemistry, which are ubiquitous across natural sources. The aforesaid derivatives have become invaluable scaffolds because of their wide spectrum therapeutic applications. Therefore, many researchers are focused on the design and synthesis of indole and associated hybrids of biological relevance. Hence, in the present review, we concisely discuss the indole containing natural sources, marketed drugs, clinical candidates, and their biological activities like antibacterial, antifungal, anti-TB, antiviral, antimalarial, and anti-leishmanial activities. The structure-activity relationships study of indole derivatives is also presented for a better understanding of the identified structures. The literature data presented for the anti-infective agents herein covers largely for the last twelve years.

A hypometabolic defense strategy against malaria

Hypoglycemia is a clinical hallmark of severe malaria, the often-lethal outcome of Plasmodium falciparum infection. Here, we report that malaria-associated hypoglycemia emerges from a non-canonical resistance mechanism, whereby the infected host reduces glycemia to starve Plasmodium. This hypometabolic response is elicited by labile heme, a byproduct of hemolysis that induces illness-induced anorexia and represses hepatic glucose production. While transient repression of hepatic glucose production prevents unfettered immune-mediated inflammation, organ damage, and anemia, when sustained over time it leads to hypoglycemia, compromising host energy expenditure and adaptive thermoregulation. The latter arrests the development of asexual stages of Plasmodium via a mechanism associated with parasite mitochondrial dysfunction. In response, Plasmodium activates a transcriptional program associated with the reduction of virulence and sexual differentiation toward the generation of transmissible gametocytes. In conclusion, malaria-associated hypoglycemia represents a trade-off of a hypometabolic-based defense strategy that balances parasite virulence versus transmission.

Synthetic Red Blood Cell-Specific Glycolytic Intermediate 2,3-Diphosphoglycerate (2,3-DPG) Inhibits Plasmodium falciparum Development In Vitro

Mechanisms of malaria parasite interaction with its host red blood cell may provide potential targets for new antimalarial approaches. Pyruvate kinase deficiency has been associated with resistance to malaria in both experimental models and population studies. Two of the major pyruvate kinase deficient-cell disorders are the decrease in ATP and the increase in 2,3-biphosphoglycerate (2,3-BPG) concentration. High levels of this metabolite, only present in mammalian red blood cell, has an inhibitory effect on glycolysis and we hypothesized that its accumulation may also be harmful to the parasite and be involved in the mechanism of protection provided by that enzymopathy. We examined the effect of a synthetic form, 2,3-DPG, on the Plasmodium falciparum intraerythrocytic developmental cycle in vitro. Results showed an impairment of parasite growth with a direct effect on parasite maturation as significant lower progeny emerged from parasites that were submitted to 2,3-DPG. Further, adding the compound to the culture medium did not result in any effect on the host cell, but instead the metabolic profile of an infected cell became closer to that of a non-infected cell.

Synthesis, α-glucosidase inhibition, α-amylase inhibition, and molecular docking studies of 3,3-di(indolyl)indolin-2-ones

The synthesized 3,3-di(indolyl)indolin-2-ones 1a-p showed desired higher α-glucosidase inhibitory activities and lower α-amylase inhibitory activities than standard drug acarbose. Particularly, compound 1i showed favorable higher α-glucosidase % inhibition of 67 ± 13 and lower α-amylase % inhibition of 51 ± 4 in comparison to acarbose with % inhibition activities of 19 ± 5 and 90 ± 2, respectively. Docking studies of selected 3,3-di(indolyl)indolin-2-ones revealed key interactions with the active sites of both α-glucosidase and α-amylase, further supporting the observed % inhibitory activities. Furthermore, the binding energies are consistent with the % inhibition values. The results suggest that 3,3-di(indolyl)indolin-2-ones may be developed as suitable Alpha Glucosidase Inhibitors (AGIs) and the lower α-amylase activities should be advantageous to reduce the side effects exhibited by commercial AGIs.

Recent Progress in the Development of Indole-Based Compounds Active against Malaria, Trypanosomiasis and Leishmaniasis

Human protozoan diseases represent a serious health problem worldwide, affecting mainly people in social and economic vulnerability. These diseases have attracted little investment in drug discovery, which is reflected in the limited available therapeutic arsenal. Authorized drugs present problems such as low efficacy in some stages of the disease or toxicity, which result in undesirable side effects and treatment abandonment. Moreover, the emergence of drug-resistant parasite strains makes necessary an even greater effort to develop safe and effective antiparasitic agents. Among the chemotypes investigated for parasitic diseases, the indole nucleus has emerged as a privileged molecular scaffold for the generation of new drug candidates. In this review, the authors provide an overview of the indole-based compounds developed against important parasitic diseases, namely malaria, trypanosomiasis and leishmaniasis, by focusing on the design, optimization and synthesis of the most relevant synthetic indole scaffolds recently reported.

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.

Synthetically-tailored and nature-derived dual COX-2/5-LOX inhibitors: Structural aspects and SAR

Inflammation is a most complex pathological process that gives birth to different diseases. Different inflammatory mediators are released during an inflammation responsible for acute pain and chronic inflammatory diseases like cancer, asthma, rheumatoid arthritis, osteoarthritis, neurodegenerative diseases, metabolic and cardiovascular disorders. The arachidonic acid pathway, which results in the production of inflammatory mediators, provides several targets for anti-inflammatory intervention. The most popularly used medications for inflammation are non-steroidal anti-inflammatory agents (NSAIDs) but it has some limitations, in particular traditional NSAIDs which inhibit the COX pathway non-selectively, producing gastrointestinal side effects, and other adverse effects like stroke and renal failure. On the other hand, selective COX-2 inhibitors commonly known as 'coxibs' produce cardiovascular side effects. Frequent inhibition of either cyclooxygenase or lipoxygenase enzyme switches the metabolism of arachidonic acid from one to another which could lead to serious consequences. Therefore, a need to develop novel, effective and safe anti-inflammatory agents which can inhibit the release of both prostaglandins and leukotrienes from the respective cyclooxygenase and lipoxygenase pathways has emerged. This resulted in the discovery of new anti-inflammatory agents derived from natural and synthetic sources as dual COX-2/5-LOX inhibitors. To further contribute towards the discovery in this field, we have attempted to summarize structural features and pharmacological activities of heterocyclic scaffolds and natural products explored as dual COX-2/5-LOX inhibitors. We have emphasized the designing of the dual inhibitors inspired by the previously reported COX-2 and 5-LOX inhibitors. This outline could render us to identify the best pharmacophores catering to dual COX-2/5-LOX inhibitory activity while improving their efficiency as anti-inflammatory agents.

Discovery of novel tubulin inhibitors targeting taxanes site by virtual screening, molecular dynamic simulation, and biological evaluation

Microtubules play crucial role in process of mitosis and cell proliferation, which have been considered as attractive drug targets for anticancer therapy. The aim of this study was to discover novel and chemically diverse tubulin inhibitors for treatment of cancer. In this investigation, the multilayer virtual screening methods, including common feature pharmacophore model, structure-based pharmacophore model and molecular docking, were developed to screen BioDiversity database with 30,000 compounds. A total of 102 compounds were obtained by the virtual screening, and further filtered by diverse chemical clusters with desired properties and PAINS analysis. Finally, 50 compounds were selected and submitted to the biological evaluation. Among these hits, hits 8 and 30 with novel scaffolds displayed stronger antiproliferative activity on four human tumor cells including Hela, A549, MCF-7, and HepG2. Moreover, the two hits were subsequently submitted to molecular dynamic simulations of 90 ns with the aim of exploring the stability of ligand-protein interactions into the binding pocket, and further probing the mechanism of the interaction between tubulin and hits. The molecular dynamic simulation results revealed there had stronger interactions between tubulin and hits in equilibrium state. Therefore, the hits 8 and 30 have been well characterized as lead compounds for developing new tubulin inhibitors with potential anticancer activity.

Diversity-oriented synthesis derived indole based spiro and fused small molecules kills artemisinin-resistant Plasmodium falciparum

BACKGROUND

Despite numerous efforts to eradicate the disease, malaria continues to remain one of the most dangerous infectious diseases plaguing the world. In the absence of any effective vaccines and with emerging drug resistance in the parasite against the majority of anti-malarial drugs, the search for new drugs is urgently needed for effective malaria treatment.

METHODS

The goal of the present study was to examine the compound library, based on indoles generated through diversity-oriented synthesis belonging to four different architecture, i.e., 1-aryltetrahydro/dihydro-β-carbolines and piperidine/pyrrolidine-fused indole derivatives, for their in vitro anti-plasmodial activity. Trifluoroacetic acid catalyzed transformation involving tryptamine and various aldehydes/ketones provided the library.

RESULTS

Among all the compounds screened, 1-aryltetrahydro-β-carbolines 2 and 3 displayed significant anti-plasmodial activity against both the artemisinin-sensitive and artemisinin-resistant strain of Plasmodium falciparum. It was observed that these compounds inhibited the overall parasite growth in intra-erythrocytic developmental cycle (IDC) via reactive oxygen species-mediated parasitic death and thus could be potential anti-malarial compounds.

CONCLUSION

Overall the compounds 2 and 3 identified in this study shows promising anti-plasmodial activity that can kill both artemisinin-sensitive and artemisinin-resistant strains of P. falciparum.

Indole: The After Next Scaffold of Antiplasmodial Agents?

Malaria remains a global public health problem due to the uphill fight against the causative Plasmodium parasites that are relentless in developing resistance. Indole-based antiplasmodial compounds are endowed with multiple modes of action, of which inhibition of hemozoin formation is the major mechanism of action reported for compounds such as cryptolepine, flinderoles, and isosungucine. Indole-based compounds exert their potent activity against chloroquine-resistant Plasmodium strains by inhibiting hemozoin formation in a mode of action different from that of chloroquine or through a novel mechanism of action. For example, dysregulating the sodium and osmotic homeostasis of Plasmodium through inhibition of PfATP4 is the novel mechanism of cipargamin. The potential of developing multi-targeted compounds through molecular hybridization ensures the existence of indole-based compounds in the antimalarial pipeline.

Synthesis and Antimalarial Activity of 1,4-Disubstituted Piperidine Derivatives

In order to prepare, at low cost, new compounds active against Plasmodium falciparum, and with a less side-effects, we have designed and synthesized a library of 1,4-disubstituted piperidine derivatives from 4-aminopiperidine derivatives 6. The resulting compound library has been evaluated against chloroquine-sensitive (3D7) and chloroquine-resistant (W2) strains of P. falciparum. The most active molecules—compounds 12d (13.64 nM (3D7)), 13b (4.19 nM (3D7) and 13.30 nM (W2)), and 12a (11.6 nM (W2))—were comparable to chloroquine (22.38 nM (3D7) and 134.12 nM (W2)).

Hybrid molecules with potential in vitro antiplasmodial and in vivo antimalarial activity against drug-resistant Plasmodium falciparum

Malaria is a tropical disease, leading to around half a million deaths annually. Antimalarials such as quinolines are crucial to fight against malaria, but malaria control is extremely challenged by the limited pipeline of effective pharmaceuticals against drug-resistant strains of Plasmodium falciparum which are resistant toward almost all currently accessible antimalarials. To tackle the growing resistance, new antimalarial drugs are needed urgently. Hybrid molecules which contain two or more pharmacophores have the potential to overcome the drug resistance, and hybridization of quinoline privileged antimalarial building block with other antimalarial pharmacophores may provide novel molecules with enhanced in vitro and in vivo activity against drug-resistant (including multidrug-resistant) P falciparum. In recent years, numerous of quinoline hybrids were developed, and their activities against a panel of drug-resistant P falciparum strains were screened. Some of quinoline hybrids were found to possess promising in vitro and in vivo potency. This review emphasized quinoline hybrid molecules with potential in vitro antiplasmodial and in vivo antimalarial activity against drug-resistant P falciparum, covering articles published between 2010 and 2019.

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, Structural and Thermal Studies of 3-(1-Benzyl-1,2,3,6-tetrahydropyridin-4-yl)-5-ethoxy-1H-indole (D2AAK1_3) as Dopamine D₂ Receptor Ligand

Compound D2AAK1_3 was designed as a modification of the lead structure D2AAK1 (an in vivo active multi-target compound with nanomolar affinity to a number of aminergic GPCRs) and synthesized in the reaction of 5-ethoxyindole and 1-benzyl-4-piperidone. This compound has an affinity to the human dopamine D₂ receptor with K_i of 151 nM. The aim of these studies was the structural and thermal characterization of the compound D2AAK1_3. In particular; X-ray studies; molecular docking and molecular dynamics as well as thermal analysis were performed. The studied compound crystallizes in orthorhombic system; in chiral space group P2₁2₁2₁. The compound has a non-planar conformation. The studied compound was docked to the novel X-ray structure of the human dopamine D₂ receptor in the inactive state (PDB ID: 6CM4) and established the main contact between its protonatable nitrogen atom and Asp (3.32) of the receptor. The obtained binding pose was stable in molecular dynamics simulations. Thermal stability of the compound was investigated using the TG-DSC technique in the air atmosphere, while TG-FTIR analyses in air and nitrogen atmospheres were also performed. The studied compound is characterized by good thermal stability. The main volatile products of combustion are the following gases: CO₂; H₂O toluene and CO while in the case of pyrolysis process in the FTIR spectra; the characteristic bands of NH₃; piperidine and indole are additionally observed.

A review on diverse heterocyclic compounds as the privileged scaffolds in antimalarial drug discovery

The upward extend of malaria collectively with the emergence of resistance against predictable drugs has put enormous pressure on public health systems to introduce new malaria treatments. Heterocycles play an important role in the design and discovery of new malaria active compounds. Heterocyclic compounds have attracted significant attention for malaria treatment because of simplicity of parallelization and the examining power with regard to chemical space. Introduction of a variety of heterocyclic compounds have enabled to maintain the high levels of antimalarial potency observed for other more lipophilic analogues whilst improving the solubility and the oral bioavailability in pre-clinical species. In this review, we present an overview of recent literature to provide imminent into the applications of different heterocyclic scaffolds in fighting against malaria.

New endoperoxides highly active in vivo and in vitro against artemisinin-resistant Plasmodium falciparum

BACKGROUND

The emergence and spread of Plasmodium falciparum resistance to artemisinin-based combination therapy in Southeast Asia prompted the need to develop new endoperoxide-type drugs.

METHODS

A chemically diverse library of endoperoxides was designed and synthesized. The compounds were screened for in vitro and in vivo anti-malarial activity using, respectively, the SYBR Green I assay and a mouse model. Ring survival and mature stage survival assays were performed against artemisinin-resistant and artemisinin-sensitive P. falciparum strains. Cytotoxicity was evaluated against mammalian cell lines V79 and HepG2, using the MTT assay.

RESULTS

The synthesis and anti-malarial activity of 21 new endoperoxide-derived compounds is reported, where the peroxide pharmacophore is part of a trioxolane (ozonide) or a tetraoxane moiety, flanked by adamantane and a substituted cyclohexyl ring. Eight compounds exhibited sub-micromolar anti-malarial activity (IC₅₀ 0.3-71.1 nM), no cross-resistance with artemisinin or quinolone derivatives and negligible cytotoxicity towards mammalian cells. From these, six produced ring stage survival < 1% against the resistant strain IPC5202 and three of them totally suppressed Plasmodium berghei parasitaemia in mice after oral administration.

CONCLUSION

The investigated, trioxolane-tetrazole conjugates LC131 and LC136 emerged as potential anti-malarial candidates; they show negligible toxicity towards mammalian cells, ability to kill intra-erythrocytic asexual stages of artemisinin-resistant P. falciparum and capacity to totally suppress P. berghei parasitaemia in mice.

Synthesis and antiplasmodial activity of novel indoleamide derivatives bearing sulfonamide and triazole pharmacophores

Due to the recent reports of growing parasite resistance to artemisinins and other antimalarial drugs, development of new antimalarial chemotypes is an urgent priority. Here in, we report a novel series of adamantyl/cycloheptyl indoleamide derivatives bearing sulfonamide and triazole pharmacophores adopting different chemical modifications and evaluated them for antiplasmodial activity in vitro. Among all the indoleamides, compounds 22, 24, 26 and 30 with sulfonamide pharmacophore showed promising activity with IC₅₀ of 1.87, 1.93, 2.00, 2.17 μM against CQ sensitive Pf3D7 strain and 1.69, 2.12, 1.60, 2.19 μM against CQ resistant PfK1 strain, respectively.

1-[(4-Methoxyphenyl)sulfonyl]-1H-indole-3-carbaldehyde

In the molecule of the title compound, C16H13NO4S, the mean plane of the indole ring system and that of the methoxyphenyl ring, which are bridged by a sulfonyl group, are inclined at a dihedral angle of 88.98 (9)°. The crystal structure is stabilized by intermolecular C—H...O hydrogen bonds.