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To design and discover a new compound can used as a COX with TNF-α and IL-6 inhibitors is highly challenge. A series of spiroindolone-bearing benzofuran moieties were resynthesized from the chalcone-based benzo[b]furan with substituted isatin, and amino acids. The requisite spiroindolone analogues were tested for their potential inhibitory activities against lipid metabolizing enzymes such as cyclooxygenase COX-1, COX-2, and the release of pro-inflammatory cytokines interleukin IL-6, and tumor necrosis factor TNF-α. Among the tested compounds, 5a, 5c, 5h, 5i, 5l, and 5p exhibited COX-1 inhibitor selectively with percent of inhibition 40.81–83.4% and IC50 values ranging from 20.42 µM to 38.24 µM. In addition, all the synthesized target compounds possessed lipopolysaccharide-induced TNF-α, and IL-6 expression with a varying degree of COX-1 inhibition. Compounds 5d, 5e, 5f, 5g, and 5k markedly inhibited TNF-α, and IL-6 release in WI-38 fibroblast cells. Molecular docking of the most effective and highly selective compounds were investigated and shown important binding mechanisms which could affect pro-inflammatory enzymes and cytokines via the inhibition of COX-1, COX-2, IL-6, and TNF-α. Keywords: Spirooxindole, Lipid metabolic enzymes, Pro-inflammatory cytokines, COX-1, COX-2, IL-6, TNF-α

Synthetic and natural spiroxindoles are important anti-inflammatory, antibacterial, antileishmanial, and anticancer agents. In this study, we prepared a spiroxindole derivative and evaluated the preliminary results of its biological activity including anti-inflammatory, antileishmanial, and cytotoxic activity against 3T3 and Hela cell lines. By adopting the 1,3-dipolar cycloaddition reaction, we were able to successfully combine olefin, isatin, and an amino acid to form the desired spiroxindole analog 4 (yield, up to 94%). To elucidate the chemical structure of 4, the X-ray single crystal diffraction technique was employed, and the electronic and NMR spectra of 4 were calculated using the B3LYP/6-311G(d,p) method. The calculated 1H and 13C NMR chemical shifts aligned well with the experimental data. Compound 4 was then evaluated for its anti-inflammatory, antileishmanial, and cytotoxic activity against 3T3 and Hela cell lines. This spiroxindole pyrothiazole (IC50 = 65.9 ± 6.6 μM) showed weak anti-inflammatory activity compared to the test standard, ibuprofen (IC50 = 11.2 ± 1.9 μM), and moderate anticancer activity against Hela cell lines compared to doxorubicin (IC50 = 1.2 ± 0.4 μM vs IC50 = 11.2 ± 0.3 μM for 4). Compound 4 also appeared as an effective antileishmanial agent (IC50 = 39.8 ± 0.43 μM) when tested in vitro.

The alpha (α)-amylase is a calcium metalloenzyme that aids digestion by breaking down polysaccharide molecules into smaller ones such as glucose and maltose. In addition, the enzyme causes postprandial hyperglycaemia and blood glucose levels to rise. α-Amylase is a well-known therapeutic target for the treatment and maintenance of postprandial blood glucose elevations. Various enzymatic inhibitors, such as acarbose, miglitol and voglibose, have been found to be effective in targeting this enzyme, prompting researchers to express an interest in developing potent alpha-amylase inhibitor molecules. The review mainly focused on designing different derivatives of drug molecules such as benzofuran hydrazone, indole hydrazone, spiroindolone, benzotriazoles, 1,3-diaryl-3-(arylamino) propan-1-one, oxadiazole and flavonoids along with their target-receptor interactions, IC50 values and other biological activities.

The spiroindolone cipargamin, a new antimalarial compound that inhibits Plasmodium ATP4, is currently in clinical development. This study aimed to characterize the antimalarial activity of cipargamin in healthy volunteers experimentally infected with blood-stage Plasmodium falciparum., The spiroindolone cipargamin, a new antimalarial compound that inhibits Plasmodium ATP4, is currently in clinical development. This study aimed to characterize the antimalarial activity of cipargamin in healthy volunteers experimentally infected with blood-stage Plasmodium falciparum. Eight subjects were intravenously inoculated with parasite-infected erythrocytes and received a single oral dose of 10 mg cipargamin 7 days later. Blood samples were collected to monitor the development and clearance of parasitemia and plasma cipargamin concentrations. Parasite regrowth was treated with piperaquine monotherapy to clear asexual parasites, while allowing gametocyte transmissibility to mosquitoes to be investigated. An initial rapid decrease in parasitemia occurred in all participants following cipargamin dosing, with a parasite clearance half-life of 3.99 h. As anticipated from the dose selected, parasite regrowth occurred in all 8 subjects 3 to 8 days after dosing and allowed the pharmacokinetic/pharmacodynamic relationship to be determined. Based on the limited data from the single subtherapeutic dose cohort, a MIC of 11.6 ng/ml and minimum parasiticidal concentration that achieves 90% of maximum effect of 23.5 ng/ml were estimated, and a single 95-mg dose (95% confidence interval [CI], 50 to 270) was predicted to clear 109 parasites/ml. Low gametocyte densities were detected in all subjects following piperaquine treatment, which did not transmit to mosquitoes. Serious adverse liver function changes were observed in three subjects, which led to premature study termination. The antimalarial activity characterized in this study supports the further clinical development of cipargamin as a new treatment for P. falciparum malaria, although the hepatic safety profile of the compound warrants further evaluation. (This study has been registered at ClinicalTrials.gov under identifier NCT02543086.)

Background Cipargamin (KAE609) is a novel spiroindolone class drug for the treatment of malaria, currently undergoing phase 2 clinical development. This review provides an overview and interpretation of the pre-clinical and clinical data of this possible next-generation antimalarial drug published to date. Methods We systematically searched the literature for studies on the preclinical and clinical development of cipargamin. PubMed and Google Scholar databases were searched using the terms ‘cipargamin’, ‘KAE609ʹ or ‘NITD609’ in the English language; one additional article was identified during revision. Nineteen of these in total 43 papers identified reported original studies; 13 of those articles were on pre-clinical studies and 6 reported clinical trials. Results A total of 20 studies addressing its preclinical and clinical development have been published on this compound at the time of writing. Cipargamin acts on the PfATP4, which is a P-type Na + ATPase disrupting the Na + homeostasis in the parasite. Cipargamin is a very fast-acting antimalarial, it is active against all intra-erythrocytic stages of the malaria parasite and exerts gametocytocidal activity, with transmission-blocking potential. It is currently undergoing phase 2 clinical trial to assess safety and efficacy, with a special focus on hepatic safety. Conclusion In the search for novel antimalarial drugs, cipargamin exhibits promising properties, exerting activity against multiple intra-erythrocytic stages of plasmodia, including gametocytes. It exhibits a favourable pharmacokinetic profile, possibly allowing for single-dose treatment with a suitable combination partner. According to the clinical results of the first studies in Asian malaria patients, a possible safety concern is hepatotoxicity.

Inhibition of &alpha, amylase and &alpha, glucosidase by specified synthetic compounds during the digestion of starch helps control post-prandial hyperglycemia and could represent a potential therapy for type II diabetes mellitus. A new series of spiroheterocyclic compounds bearing oxindole/benzofuran/pyrrolidine/thiazolidine motifs were synthesized via a 1,3-dipolar cyclo-addition reaction approach. The specific compounds were obtained by reactions of chalcones having a benzo[b]furan scaffold (compounds 2a&ndash, f), with a substituted isatin (compounds 3a&ndash, c) and heterocyclic amino acids (compounds 4a,b). The target spiroindolone analogues 5a&ndash, r were evaluated for their potential inhibitory activities against the enzymes &alpha, glucosidase. Preliminary results indicated that some of the target compounds exhibit promising &alpha, glucosidase inhibitory activity. Among the tested spiroindolone analogues, the cycloadduct 5r was found to be the most active (IC50 = 22.61 &plusmn, 0.54 &mu, M and 14.05 &plusmn, 1.03 &mu, M) as &alpha, glucosidase inhibitors, with selectivity indexes of 0.62 and 1.60, respectively. Docking studies were carried out to confirm the binding interaction between the enzyme active site and the spiroindolone analogues.

In vitro drug treatment with artemisinin derivatives, such as dihydroartemisinin (DHA), results in a temporary growth arrest (i.e., dormancy) at an early ring stage in Plasmodium falciparum . This response has been proposed to play a role in the recrudescence of P. falciparum infections following monotherapy with artesunate and may contribute to the development of artemisinin resistance in P. falciparum malaria. We demonstrate here that artemether does induce dormant rings, a finding which further supports the class effect of artemisinin derivatives in inducing the temporary growth arrest of P. falciparum parasites. In contrast and similarly to lumefantrine, the novel and fast-acting spiroindolone compound KAE609 does not induce growth arrest at the early ring stage of P. falciparum and prevents the recrudescence of DHA-arrested rings at a low concentration (50 nM). Our findings, together with previous clinical data showing that KAE609 is active against artemisinin-resistant K13 mutant parasites, suggest that KAE609 could be an effective partner drug with a broad range of antimalarials, including artemisinin derivatives, in the treatment of multidrug-resistant P. falciparum malaria.

Considerable attention has been focused on the [1,3] dipolar cycloaddition reaction approach of olefin with amino acid (sarcosine), and isatin which underwent smoothly, and afforded a highly functionalized complex molecule. The target spiroindolone analogue 4 was synthesized in excellent yield. The desired compound was elucidated based on X-ray single crystal diffraction technique. Compound 4 was examined against three different cancer cell lines for liver, breast and colorectal cancer (HepG2, MCF-7 and HCT-116, respectively). It showed high selectivity against colon cancer (HCT-116). Hirshfeld molecular packing analysis of 4 showed that the H⋯H, Cl⋯H and C⋯H contacts are the most abundant while the N⋯H and O⋯H hydrogen bonding interactions are the strongest. Molecular and electronic structures as well as the Uv–Vis and NMR spectra of 4 were discussed based on DFT calculations. The longest wavelength band observed at 298 nm was assigned for the HOMO-2/HOMO-1→LUMO excitations. The 1H and 13C NMR chemical shifts of 4 were calculated and compared with the experimental data (0.934–0.954).

The PfATP4 (PF3D7 1211900) multi-drug resistance mutation G223R is found in Africa by genetically analyzing 2640 worldwide Plasmodium falciparum blood stage isolates (the MalariaGen Pf3k resource). This mutation confers an approximate 8 fold [4] increase in the PfATP4 IC50 of Spiroindolones (KAE609 & KAE678) [14],[16],[4],[10] and Aminopyrazoles (GNF-Pf4492) [4]. It is postulated that the G223R mutation may be a consequence of the drug resistant Southeast Asian Dd2 genotype becoming more dominant in Africa [3]. The presence of this mutation has important policy implications for the eventual general deployment of the Spiroindolone KAE609 (Cipargamin) which is currently undergoing stage 2 clinical trials.

KAE609 [(1'R,3'S)-5,7'-dichloro-6'-fluoro-3'-methyl-2',3',4',9'-tetrahydrospiro[indoline-3,1'-pyridol[3,4-b]indol]-2-one] is a potent, fast-acting, schizonticidal agent being developed for the treatment of malaria. After oral dosing of KAE609 to rats and dogs, the major radioactive component in plasma was KAE609. An oxidative metabolite, M18, was the prominent metabolite in rat and dog plasma. KAE609 was well absorbed and extensively metabolized such that low levels of parent compound (≤11% of the dose) were detected in feces. The elimination of KAE609 and metabolites was primarily mediated via biliary pathways (≥93% of the dose) in the feces of rats and dogs. M37 and M23 were the major metabolites in rat and dog feces, respectively. Among the prominent metabolites of KAE609, the isobaric chemical species, M37, was observed, suggesting the involvement of an isomerization or rearrangement during biotransformation. Subsequent structural elucidation of M37 revealed that KAE609, a spiroindolone, undergoes an unusual C-C bond cleavage, followed by a 1,2-acyl shift to form a ring expansion metabolite M37. The in vitro metabolism of KAE609 in hepatocytes was investigated to understand this novel biotransformation. The metabolism of KAE609 was qualitatively similar across the species studied; thus, further investigation was conducted using human recombinant cytochrome P450 enzymes. The ring expansion reaction was found to be primarily catalyzed by cytochrome P450 (CYP) 3A4 yielding M37. M37 was subsequently oxidized to M18 by CYP3A4 and hydroxylated to M23 primarily by CYP1A2. Interestingly, M37 was colorless, whereas M18 and M23 showed orange yellow color. The source of the color of M18 and M23 was attributed to their extended conjugated system of double bonds in the structures.

Malaria is caused by the Plasmodium parasite and is a major health problem leading to many deaths worldwide. Lack of a vaccine and increasing drug resistance highlights the need for new antimalarial drugs with novel targets. Antiplasmodial activity of spiroindolones was discovered through whole-cell, phenotypic screening methods. Optimization of the lead spiroindolone improved both potency and pharmacokinetic properties leading to drug candidate NITD609 which has produced encouraging results in clinical trials. Spiroindolones inhibit PfATP4, a P-type Na+-ATPase in the plasma membrane of the parasite, causing a fatal disruption of its sodium homeostasis. Other diverse compounds from the Malaria Box appear to target PfATP4 warranting further research into its structure and binding with NITD609 and other potential antimalarial drugs.

The intraerythrocytic malaria parasite, Plasmodium falciparum, maintains a low cytosolic Na+ concentration and the plasma membrane P-type cation translocating ATPase ‘PfATP4’ has been implicated as playing a key role in this process. PfATP4 has been the subject of significant attention in recent years as mutations in this protein confer resistance to a growing number of new antimalarial compounds, including the spiroindolones, the pyrazoles, the dihydroisoquinolones, and a number of the antimalarial agents in the Medicines for Malaria Venture's ‘Malaria Box’. On exposure of parasites to these compounds there is a rapid disruption of cytosolic Na+. Whether, and if so how, such chemically distinct compounds interact with PfATP4, and how such interactions lead to parasite death, is not yet clear. The fact that multiple different chemical classes have converged upon PfATP4 highlights its significance as a potential target for new generation antimalarial agents. A spiroindolone (KAE609, now known as cipargamin) has progressed through Phase I and IIa clinical trials with favourable results. In this review we consider the physiological role of PfATP4, summarise the current repertoire of antimalarial compounds for which PfATP4 is implicated in their mechanism of action, and provide an outlook on translation from target identification in the laboratory to patient treatment in the field., Graphical abstract, Highlights • PfATP4 is proposed to function as a Na+/H+-ATPase, regulating parasite Na+. • There is evidence that multiple, unrelated chemical classes target PfATP4. • One such compound, cipargamin, exhibited promising results in Phase II trials. • The precise mechanism by which such compounds kill parasites remains unclear.

An asymmetric aza-Diels-Alder reaction of 3-vinylindoles with isatin-derived ketimines has been developed. A series of spiroindolone derivatives were thus obtained in good to excellent yields with excellent enantioselectivity (up to 96 % yield and 99 % ee). Furthermore, the antimalarial compound NITD609 could be obtained in three steps with an overall yield of 40.6 %. Control experiments and operando IR experiments imply a concerted reaction pathway. The regioselectivity and exo selectivity result from π-π interactions between the two indoline rings of the two reactants.

Recent clinical trials revealed a surprisingly rapid clearance of red blood cells (RBCs) infected with malaria parasites by the spiroindolone KAE609. Here, we show that ring-stage parasite-infected RBCs exposed to KAE609 become spherical and rigid, probably through osmotic dysregulation consequent to the disruption of the parasite's sodium efflux pump (adenosine triphosphate 4). We also show that this peculiar drug effect is likely to cause accelerated splenic clearance of the rheologically impaired Plasmodium vivax- and Plasmodium falciparum-infected RBCs.

Limited information is available on the pharmacokinetic (PK) and pharmacodynamic (PD) parameters driving the efficacy of antimalarial drugs. Our objective in this study was to determine dose-response relationships of a panel of related spiroindolone analogs and identify the PK-PD index that correlates best with the efficacy of KAE609, a selected class representative. The dose-response efficacy studies were conducted in the Plasmodium berghei murine malaria model, and the relationship between dose and efficacy (i.e., reduction in parasitemia) was examined. All spiroindolone analogs studied displayed a maximum reduction in parasitemia, with 90% effective dose (ED 90 ) values ranging between 6 and 38 mg/kg of body weight. Further, dose fractionation studies were conducted for KAE609, and the relationship between PK-PD indices and efficacy was analyzed. The PK-PD indices were calculated using the in vitro potency against P. berghei (2× the 99% inhibitory concentration [IC 99 ]) as a threshold (TRE). The percentage of the time in which KAE609 plasma concentrations remained at >2× the IC 99 within 48 h (% T >TRE ) and the area under the concentration-time curve from 0 to 48 h (AUC 0–48 )/TRE ratio correlated well with parasite reduction ( R 2 = 0.97 and 0.95, respectively) but less so for the maximum concentration of drug in serum ( C max )/TRE ratio ( R 2 = 0.88). The present results suggest that for KAE609 and, supposedly, for its analogs, the dosing regimens covering a T >TRE of 100%, AUC 0–48 /TRE ratio of 587, and a C max /TRE ratio of 30 are likely to result in the maximum reduction in parasitemia in the P. berghei malaria mouse model. This information could be used to prioritize analogs within the same class of compounds and contribute to the design of efficacy studies, thereby facilitating early drug discovery and lead optimization programs.

A tandem gold-catalyzed 5-endo-dig/spirocyclization of 2-[(2-aminophenyl)ethynyl]phenylamines with isatins was achieved to produce the corresponding 5′,11′-dihydrospiro[indoline-3,6′-indolo[3,2-c]quinolin]-2-one derivatives in good yields with high regioselectivity. This reaction proceeded well at ambient temperature under mild conditions. Ketones also participated smoothly under similar conditions to produce 6,6-disubstituted-6,11-dihydro-5H-indolo[3,2-c]quinolones.

Here, we show that spiroindolone, an effective treatment for plasmodia, is also active against Toxoplasma gondii tachyzoites. In vitro , spiroindolone NITD609 is cidal for tachyzoites (50% inhibitory concentration [IC 50 ], 1μM) and not toxic to human cells at ≥10μM. Two daily oral doses of 100 mg/kg of body weight reduced the parasite burden in mice by 90% ( P = 0.002), measured 3 days after the last dose. This inhibition of T. gondii tachyzoites in vitro and in vivo indicates that spiroindolone is a promising lead candidate for further medicine development.

The resurgence in antimalarial drug discovery research to address the threat of resistance to current therapies has led to a boon in the number of new drugs entering the global malaria pipeline ( www.mmv.org) . Among these potential new therapies are the spiroindolones, a unique class of antimalarials which work through a previously unknown mechanism of action and currently in Phase II clinical trials. The lead compound was identified from the Novartis compound libraries after a high throughput screening campaign on the malaria parasite, Plasmodium falciparum . Its progression from hit to drug candidate in less than four and a half years also resulted in the discovery of a new drug target, Pf ATP4 (P-type ATPase cation transporter).

The measurement of intracellular ion concentrations, and the screening of chemical agents to identify molecules targeting ion transport, has traditionally involved low-throughput techniques. Here we present a novel HPLC method that allows the rapid, high-sensitivity measurement of cell Na+ and K+ content, demonstrating its utility by monitoring the ionic changes induced in the intracellular malaria parasite by the new spiroindolone antimalarial KAE609.

The spiroindolones, a new class of antimalarial medicines discovered in a cellular screen, are rendered less active by mutations in a parasite P-type ATPase, PfATP4. We show here that S. cerevisiae also acquires mutations in a gene encoding a P-type ATPase (ScPMA1) after exposure to spiroindolones and that these mutations are sufficient for resistance. KAE609 resistance mutations in ScPMA1 do not confer resistance to unrelated antimicrobials, but do confer cross sensitivity to the alkyl-lysophospholipid edelfosine, which is known to displace ScPma1p from the plasma membrane. Using an in vitro cell-free assay, we demonstrate that KAE609 directly inhibits ScPma1p ATPase activity. KAE609 also increases cytoplasmic hydrogen ion concentrations in yeast cells. Computer docking into a ScPma1p homology model identifies a binding mode that supports genetic resistance determinants and in vitro experimental structure-activity relationships in both P. falciparum and S. cerevisiae. This model also suggests a shared binding site with the dihydroisoquinolones antimalarials. Our data support a model in which KAE609 exerts its antimalarial activity by directly interfering with P-type ATPase activity.

Among the several new antimalarials discovered over the past decade are at least three clinical candidate drugs, each with a distinct chemical structure, that disrupt Na+ homeostasis resulting in a rapid increase in intracellular Na+ concentration ([Na+]i) within the erythrocytic stages of Plasmodium falciparum. At present, events triggered by Na+ influx that result in parasite demise are not well-understood. Here we report effects of two such drugs, a pyrazoleamide and a spiroindolone, on intraerythrocytic P. falciparum. Within minutes following the exposure to these drugs, the trophozoite stage parasite, which normally contains little cholesterol, was made permeant by cholesterol-dependent detergents, suggesting it acquired a substantial amount of the lipid. Consistently, the merozoite surface protein 1 and 2 (MSP1 and MSP2), glycosylphosphotidylinositol (GPI)-anchored proteins normally uniformly distributed in the parasite plasma membrane, coalesced into clusters. These alterations were not observed following drug treatment of P. falciparum parasites adapted to grow in a low [Na+] growth medium. Both cholesterol acquisition and MSP1 coalescence were reversible upon the removal of the drugs, implicating an active process of cholesterol exclusion from trophozoites that we hypothesize is inhibited by high [Na+]i. Electron microscopy of drug-treated trophozoites revealed substantial morphological changes normally seen at the later schizont stage including the appearance of partial inner membrane complexes, dense organelles that resemble “rhoptries” and apparent nuclear division. Together these results suggest that [Na+]i disruptor drugs by altering levels of cholesterol in the parasite, dysregulate trophozoite to schizont development and cause parasite demise., Author Summary Malaria remains a major public health challenge in the world, especially with the realization that parasites causing the disease are becoming resistant to currently used antimalarial drugs. There are new antimalarial drugs under development, and among these are 3 clinical candidate drugs that have the propensity to cause sodium leakage into parasites growing inside human red blood cells. We have investigated events that lead to parasite death when sodium concentration inside the parasite increases. Our findings suggest that the drug-treated parasite rapidly acquires cholesterol and clusters containing lipid-embedded proteins MSP1 and MSP2 form within the plasma membrane. Because these changes are reversible when the drugs are removed, we suggest that there is an active process that keeps cholesterol out of the parasite. We also observed massive morphological changes resembling premature steps of parasite division following drug treatment. The changes we describe appear to be a direct consequence of increased sodium level in the parasites. We hypothesize that sodium influx constitutes a normal signaling process in malaria parasites and that the new antimalarial drugs initiate this process prematurely, which results in the death of the parasites.

The need for new drugs against tropical parasites such as Plasmodium falciparum and Trypanosoma brucei is persistent since problems with resistance and toxicity are jeopardizing the currently available medicines. Public-private partnerships aiming to develop new medicines for malaria and sleeping sickness have, over the past 12 years, brought forward several drug candidates that have entered clinical trials. These are the synthetic peroxide OZ439 and the spiroindolone NITD609 against P. falciparum, fexinidazole and the oxaborole SCYX-7158 against T. brucei. A further class of high chemotherapeutic potential are the diamidines, novel members of which may serve as back-up compounds against trypanosomes and other parasites. Thus, finally, new therapeutic agents against malaria and sleeping sickness are within reach.

In an era of emerging and reemerging infectious diseases, and increasing multidrug resistance, the need to identify novel therapy is imperative. Unfortunately, the recent shift of the drug discovery paradigm from cellular screening to target-based approaches has not delivered the anticipated benefits. A recent renaissance of the traditional cell-based approach, on the other hand, has yielded several clinical candidates. Three successful examples are illustrated in this review, namely spiroindolone, thiazolidinone, and diarylquinoline for the treatment of malaria, hepatitis C virus, and tuberculosis, respectively. We describe in detail their identification, mechanism of action (MoA), and common features in the chemical structures. The challenges of the cell-based approach for anti-infective drug discovery are also discussed. We propose a shift from standard libraries to synthetic natural-product-like compound collections to improve the success of phenotypic lead finding and to facilitate the validation of hits.

The antiplasmodial activity of a series of spirotetrahydro beta-carbolines is described. Racemic spiroazepineindole (1) was identified from a phenotypic screen on wild type Plasmodium falciparum with an in vitro IC(50) of 90 nM. Structure-activity relationships for the optimization of 1 to compound 20a (IC(50) = 0.2 nM) including the identification of the active 1R,3S enantiomer and elimination of metabolic liabilities is presented. Improvement of the pharmacokinetic profile of the series translated to exceptional oral efficacy in the P. berghei infected malaria mouse model where full cure was achieved in four of five mice with three daily doses of 30 mg/kg.

The title reaction with isatin-derived ketimines opens the access to various functionalized polycyclic N-heterocycles which include a spirooxindolone unit.

Background Malaria remains a challenging and fatal infectious disease in developing nations and the urgency for the development of new drugs is even greater due to the rapid spread of anti-malarial drug resistance. While numerous parasite genetic, protein and metabolite biomarkers have been proposed for testing emerging anti-malarial compounds, they do not universally correspond with drug efficacy. The biophysical character of parasitized cells is a compelling alternative to these conventional biomarkers because parasitized erythrocytes become specifically rigidified and this effect is potentiated by anti-malarial compounds, such as chloroquine and artesunate. This biophysical biomarker is particularly relevant because of the mechanistic link between cell deformability and enhanced splenic clearance of parasitized erythrocytes. Methods Recently a microfluidic mechanism, called the multiplexed fluidic plunger that provides sensitive and rapid measurement of single red blood cell deformability was developed. Here it was systematically used to evaluate the deformability changes of late-stage trophozoite-infected red blood cells (iRBCs) after treatment with established clinical and pre-clinical anti-malarial compounds. Results It was found that rapid and specific iRBC rigidification was a universal outcome of all but one of these drug treatments. The greatest change in iRBC rigidity was observed for (+)-SJ733 and NITD246 spiroindolone compounds, which target the Plasmodium falciparum cation-transporting ATPase ATP4. As a proof-of-principle, compounds of the bisindole alkaloid class were screened, where cladoniamide A was identified based on rigidification of iRBCs and was found to have previously unreported anti-malarial activity with an IC50 lower than chloroquine. Conclusion These results demonstrate that rigidification of iRBCs may be used as a biomarker for anti-malarial drug efficacy, as well as for new drug screening. The novel anti-malarial properties of cladoniamide A were revealed in a proof-of-principle drug screen. Electronic supplementary material The online version of this article (doi:10.1186/s12936-015-0957-z) contains supplementary material, which is available to authorized users.

International audience; The chemical investigations of Dicorynia guianensis heartwood led to the isolation of four new indole alkaloids for the first time in this plant. Compound (1) identified as spiroindolone 2',3',4',9'-tetrahydrospiro [indoline-3,1'pyrido[3,4-b]-indol]-2-one, and compound (3) described as nitrone 1-methyl-4,9-dihydro-3H-pyrido [3,4-b] indole 2-oxide and were isolated for the first time as natural products. ABTS antioxidant activity guided their isolation. (C) 2015 Phytochemical Society of Europe.

A tandem gold-catalyzed 5-endo-dig/spirocyclization of 2-[(2-aminophenyl)ethynyl]phenylamines with isatins was achieved to produce the corresponding 5′,11′-dihydrospiro[indoline-3,6′-indolo[3,2-c]quinolin]-2-one derivatives in good yields with high regioselectivity. This reaction proceeded well at ambient temperature under mild conditions. Ketones also participated smoothly under similar conditions to produce 6,6-disubstituted-6,11-dihydro-5H-indolo[3,2-c]quinolones.

Aminopyrazoles are a new class of antimalarial compounds identified in a cellular antiparasitic screen with potent activity against Plasmodium falciparum asexual and sexual stage parasites. To investigate their unknown mechanism of action and thus identify their target, we cultured parasites in the presence of a representative member of the aminopyrazole series, GNF-Pf4492, to select for resistance. Whole genome sequencing of three resistant lines showed that each had acquired independent mutations in a P-type cation-transporter ATPase, PfATP4 (PF3D7_1211900), a protein implicated as the novel Plasmodium spp. target of another, structurally unrelated, class of antimalarials called the spiroindolones and characterized as an important sodium transporter of the cell. Similarly to the spiroindolones, GNF-Pf4492 blocks parasite transmission to mosquitoes and disrupts intracellular sodium homeostasis. Our data demonstrate that PfATP4 plays a critical role in cellular processes, can be inhibited by two distinct antimalarial pharmacophores, and supports the recent observations that PfATP4 is a critical antimalarial target.

The ultimate aim of malaria chemotherapy is not only to treat symptomatic infection but also to reduce transmission potential. With the absence of clinically proven vaccines, drug-mediated blocking of malaria transmission gains growing interest in the research agenda for malaria control and elimination. In addition to the limited arsenal of antimalarials available, the situation is further complicated by the fact that most commonly used antimalarials are being extensively resisted by the parasite and do not assist in blocking its transmission to vectors. Most antimalarials do not exhibit gametocytocidal and/ or sporontocidal activity against the sexual stages of Plasmodium falciparum but may even enhance gametocytogenesis and gametocyte transmissibility. Artemisinin derivatives and 8-aminoquinolines are useful transmission-blocking antimalarials whose optimal actions are on different stages of gametocytes. Transmission control interventions that include gametocytocides covering the spectrum of gametocyte development should be used to reduce and, if possible, stop transmission and infectivity of gametocytes to mosquitoes. Potent gametocytocidal drugs could also help deter the spread of antimalarial drug resistance. Novel proof-of-concept compounds with gametocytocidal activity, such as trioxaquines, synthetic endoperoxides, and spiroindolone, should be further tested for possible clinical utility before investigating the possibility of integrating them in transmission-reducing interventions. Strategic use of potent gametocytocides at appropriate timing with artemisinin-based combination therapies should be given attention, at least, in the short run. This review highlights the role that antimalarials could play in blocking gametocyte transmission and infectivity to mosquitoes and, hence, in reducing the potential of falciparum malaria transmissibility and drug resistance spread.

BACKGROUND: KAE609 (cipargamin; formerly NITD609, Novartis Institute for Tropical Diseases) is a new synthetic antimalarial spiroindolone analogue with potent, dose-dependent antimalarial activity against asexual and sexual stages of Plasmodium falciparum. METHODS: We conducted a phase 2, open-label study at three centers in Thailand to assess the antimalarial efficacy, safety, and adverse-event profile of KAE609, at a dose of 30 mg per day for 3 days, in two sequential cohorts of adults with uncomplicated P. vivax malaria (10 patients) or P. falciparum malaria (11). The primary end point was the parasite clearance time. RESULTS: The median parasite clearance time was 12 hours in each cohort (interquartile range, 8 to 16 hours in patients with P. vivax malaria and 10 to 16 hours in those with P. falciparum malaria). The median half-lives for parasite clearance were 0.95 hours (range, 0.68 to 2.01; interquartile range, 0.85 to 1.14) in the patients with P. vivax malaria and 0.90 hours (range, 0.68 to 1.64; interquartile range, 0.78 to 1.07) in those with P. falciparum malaria. By comparison, only 19 of 5076 patients with P. falciparum malaria (

A steady increase in the number of antimalarial drug candidates since 2007 follows a call to eradicate malaria from the World Health Organization (WHO), the Bill and Melinda Gates Foundation and others. Four new fixed dose combination medicines have been approved by stringent authorities or the WHO in as many years. OZ439, a synthetic endoperoxide currently in Phase II, could reduce treatment to a single dose. Significant challenges remain: while drugs to treat patients suffering from malaria are essential, drugs focused on breaking the lifecycle between human and mosquito host are needed. Effective medicines that are easy to take in the field are needed, together with treatments for infants and for women in the first trimester of pregnancy. Research has concentrated on Plasmodium falciparum infection but there is a need for medicines that prevent relapses of P. vivax infection. In addition, the evolution of pathogen resistance against established drugs poses a threat to existing medicines. Direct testing of compounds against whole parasites as well as target approaches has accelerated the process of drug discovery, and identified new classes of compounds. The most advanced of these, spiroindolone, already in clinical development, kills the blood stages of both P. falciparum and P. vivax by a mechanism unrelated to any current antimalarial. The collaborative model of drug discovery between the Medicines for Malaria Venture, pharmaceutical companies and academic institutions has resulted in the construction of a promising pipeline of new classes of compounds, focused on the needs of the patient.

The intraerythrocytic malaria parasite has, on its plasma membrane, a H(+)-extruding V-type H(+)-ATPase that plays a central role in maintaining the resting cytosolic pH at around 7.3. Previous studies have demonstrated the presence in the parasite of an unknown acidification mechanism that is revealed on inhibition of the V-type H(+)-ATPase. Here we show that this acidification is dependent on the presence of extracellular Na(+), and is associated with the activity of a plasma membrane Na(+)-ATPase that is inhibited by the novel antimalarial spiroindolone NITD246 and is postulated to export Na(+) ions in counter-transport with H(+) ions. The proposed import of H(+) by the Na(+)-extruding Na(+)-ATPase necessitates "abundant H(+) pumping" by the V-type H(+)-ATPase (Ginsburg H. Abundant proton pumping in Plasmodium falciparum, but why? Trends in Parasitology 2002;18:483-6) and has significant implications for the energy budget of the parasite.

Summary The malaria parasite Plasmodium falciparum establishes in the host erythrocyte plasma membrane new permeability pathways that mediate nutrient uptake into the infected cell. These pathways simultaneously allow Na+ influx, causing [Na+] in the infected erythrocyte cytosol to increase to high levels. The intraerythrocytic parasite itself maintains a low cytosolic [Na+] via unknown mechanisms. Here we present evidence that the intraerythrocytic parasite actively extrudes Na+ against an inward gradient via PfATP4, a parasite plasma membrane protein with sequence similarities to Na+-ATPases of lower eukaryotes. Mutations in PfATP4 confer resistance to a potent class of antimalarials, the spiroindolones. Consistent with this, the spiroindolones cause a profound disruption in parasite Na+ homeostasis, which is attenuated in parasites bearing resistance-conferring mutations in PfATP4. The mutant parasites also show some impairment of Na+ regulation. Taken together, our results are consistent with PfATP4 being a Na+ efflux ATPase and a target of the spiroindolones., Graphical Abstract Highlights ► The intraerythrocytic malaria parasite extrudes Na+ via a Na+-ATPase ► Parasite Na+ homeostasis is disrupted by the antimalarial spiroindolones ► Mutations in PfATP4 confer resistance to Na+ disruption by the spiroindolones ► PfATP4 is postulated to be a Na+ efflux ATPase and a target of the spiroindolones

The global malaria agenda has undergone a reorientation from control of clinical cases to entirely eradicating malaria. For that purpose, a key objective is blocking transmission of malaria parasites from humans to mosquito vectors. The new antimalarial drug candidate NITD609 was evaluated for its transmission-reducing potential and compared to a few established antimalarials (lumefantrine, artemether, primaquine), using a suite of in vitro assays. By the use of a microscopic readout, NITD609 was found to inhibit the early and late development of Plasmodium falciparum gametocytes in vitro in a dose-dependent fashion over a range of 5 to 500 nM. In addition, using the standard membrane feeding assay, NITD609 was also found to be a very effective drug in reducing transmission to the Anopheles stephensi mosquito vector. Collectively, our data suggest a strong transmission-reducing effect of NITD609 acting against different P. falciparum transmission stages.

The condensation cyclization between isatins and 5-methoxy tryptamine catalyzed by chiral phosphoric acids provides spirooxindole tetrahydro-β-carboline products in excellent yields (up to 99%) and enantioselectivity (up to 98:2 er). A comparison of catalysts provides insight for the substrate scope and factors responsible for efficient catalytic activity and selectivity in the spirocyclization. Chiral phosphoric acids with different 3,3′-substitution on the binaphthyl system and opposite axial chirality afford the spiroindolone product with the same absolute configuration.

Antimalarial Drug Candidate Spiroindolones were discovered as promising antimalarial drug candidates through a high-throughput screening approach that should be applicable to a range of neglected infectious diseases. Rottmann et al. (p. 1175 ; see the Perspective by Wells ) present the preclinical profile for an optimized spiroindolone drug candidate, NITD609. They obtained evidence for a decrease in drug sensitivity in strains of the malaria parasite Plasmodium falciparum bearing amino acid mutations in the P-type ATPase, indicating possible mechanisms of action and/or resistance.

Spiroindolones were discovered as promising antimalarial drug candidates through a high-throughput screening approach that should be applicable to a range of neglected infectious diseases. Rottmann et al. (p. [1175][1]; see the Perspective by [Wells][2] ) present the preclinical profile for an optimized spiroindolone drug candidate, NITD609. They obtained evidence for a decrease in drug sensitivity in strains of the malaria parasite Plasmodium falciparum bearing amino acid mutations in the P-type ATPase, indicating possible mechanisms of action and/or resistance. [1]: /lookup/doi/10.1126/science.1193225 [2]: /lookup/doi/10.1126/science.1194923