Efficacy and safety of pyrotinib combined with albumin-bound paclitaxel as first-line treatment for HER2-positive metastatic breast cancer in patients previously treated with adjuvant and/or neoadjuvant trastuzumab therapy: The stage 1 results of a single-arm, phase 2 prospective clinical trial.

OBJECTIVE: It has been observed that the prognosis of patients with HER2-positive metastatic breast cancer has improved significantly with HER2-targeted agents. However, there is still a lack of evidence regarding first-line anti-HER2 treatment options for patients who have received adjuvant and/or neoadjuvant trastuzumab for HER2-positive metastatic breast cancer. Besides, there are no reliable markers that can predict the efficacy of anti-HER2 treatment in these patients. METHODS: Patients who have received adjuvant and/or neoadjuvant trastuzumab for HER2-positive metastatic breast cancer were enrolled. Pyrotinib plus albumin-bound paclitaxel were used as first-line treatment. The primary endpoint was the objective response rate (ORR). The safety profile was also assessed. In order to explore predictive biomarkers using Olink technology, blood samples were collected dynamically. RESULTS: From December 2019 to August 2023, the first stage of the study involved 27 eligible patients. It has not yet reached the median PFS despite the median follow-up being 17.8 months. Efficacy evaluation showed that the ORR was 92.6%, and the DCR was 100%. Adverse events of grade 3 or higher included diarrhoea (29.6%), leukopenia (11.1%), neutropenia (25.9%), oral mucositis (3.7%), and hand-foot syndrome (3.7%). Toll-like receptor 3 (TLR3) and Proto-oncogene tyrosine-protein kinase receptor (RET) were proteins with significant relevance to PFS in these patients. CONCLUSIONS: This study demonstrates that pyrotinib plus albumin-bound paclitaxel as a first-line treatment regimen shows good efficacy and manageable safety for patients who have received adjuvant and/or neoadjuvant trastuzumab for HER2-positive metastatic breast cancer. Besides, a significant association was identified between the expression levels of TLR3 and RET and the PFS in patients.

Synthesis and SAR investigation of biphenylaminoquinoline derivatives with benzyloxy substituents as promising anticancer agents.

The biphenyl scaffold represents a prominent privileged structure within the realms of organic chemistry and drug development. Biphenyl derivatives have demonstrated notable biological activities, including antimicrobial, anti-inflammatory, anti-HIV, and the treatment of neuropathic pain. Importantly, their anticancer abilities should not be underestimated. In this context, the present study involves the design and synthesis of a series of biphenyl derivatives featuring an additional privileged structure, namely the quinoline core. We have also diversified the substituents attached to the benzyloxy group at either the meta or para position of the biphenyl ring categorized into two distinct groups: [4,3']biphenylaminoquinoline-substituted and [3,3']biphenylaminoquinoline-substituted compounds. We embarked on an assessment of the cytotoxic activities of these derivatives in colorectal cancer cell line SW480 and prostate cancer cell line DU145 for exploring the structure-activity relationship. Furthermore, we determined the IC50 values of selected compounds that exhibited superior inhibitory effects on cell viability against SW480, DU145 cells, as well as MDA-MB-231 and MiaPaCa-2 cells. Notably, [3,3']biphenylaminoquinoline derivative 7j displayed the most potent cytotoxicity against these four cancer cell lines, SW480, DU145, MDA-MB-231, and MiaPaCa-2, with IC50 values of 1.05 µM, 0.98 µM, 0.38 µM, and 0.17 µM, respectively. This highly promising outcome underscores the potential of [3,3']biphenylaminoquinoline 7j for further investigation as a prospective anticancer agent in future research endeavors.

Extended blood stage sensitivity profiles of Plasmodium cynomolgi to doxycycline and tafenoquine, as a model for Plasmodium vivax.

Testing Plasmodium vivax antimicrobial sensitivity is limited to ex vivo schizont maturation assays, which preclude determining the IC50s of delayed action antimalarials such as doxycycline. Using Plasmodium cynomolgi as a model for P. vivax, we determined the physiologically significant delayed death effect induced by doxycycline [IC50(96 h), 1,401 ± 607 nM]. As expected, IC50(96 h) to chloroquine (20.4 nM), piperaquine (12.6 µM), and tafenoquine (1,424 nM) were not affected by extended exposure.

Involvement of nucleus accumbens SERCA2b in methamphetamine-induced conditioned place preference.

Methamphetamine (METH) is a highly addictive psycho-stimulant that induces addictive behaviour by stimulating increased dopamine release in the nucleus accumbens (NAc). The sarco/endoplasmic reticulum calcium ion transport ATPases (SERCA or ATP2A) is a calcium ion (Ca2+) pump in the endoplasmic reticulum (ER) membrane. SERCA2b is a SERCA subtype mainly distributed in the central nervous system. This study used conditioned place preference (CPP), a translational drug reward model, to observe the effects of SERCA and SERCA2b on METH-CPP in mice. Result suggested that the activity of SERCA was significantly decreased in NAc after METH-CPP. Intraperitoneal SERCA agonist CDN1163 injection or bilateral CDN1163 microinjection in the NAc inhibited METH-CPP formation. SERCA2b overexpression by the Adeno-associated virus can reduce the DA release of NAc and inhibit METH-CPP formation. Although microinjection of SERCA inhibitor thapsigargin in the bilateral NAc did not significantly aggravate METH-CPP, interference with SERCA2b expression in NAc by adeno-associated virus increased DA release and promoted METH-CPP formation. METH reduced the SERCA ability to transport Ca2+ into the ER in SHSY5Y cells in vitro, which was reversed by CDN1163. This study revealed that METH dysregulates intracellular calcium balance by downregulating SERCA2b function, increasing DA release in NAc and inducing METH-CPP formation. Drugs that target SERCA2b may have the potential to treat METH addiction.

Aminoquinoline-based Re(I) tricarbonyl complexes: Insights into their antiproliferative activity and mechanisms of action.

In an effort to develop new potent anticancer agents, two Schiff base rhenium(I) tricarbonyl complexes, containing the ubiquitous aminoquinoline scaffold, were synthesized. Both aminoquinoline ligands and Re(I) complexes showed adequate stability over a 48-h incubation period. Furthermore, the cytotoxic activity of the precursor ligands and rhenium(I) complexes were evaluated against the hormone-dependent MCF-7 and hormone-independent triple negative MDA-MB-231 breast cancer cell lines. Inclusion of the [Re(CO)3Cl]+ entity significantly enhanced the cytotoxicity of the aminoquinoline Schiff base ligands against the tested cancer cell lines. Remarkably, the incorporation of the Schiff-base iminoquinolyl entity notably enhanced the cytotoxic activity of the Re(I) complexes, in comparison with the iminopyridyl entity. Notably, the quinolyl-substituted complex showed up to three-fold higher activity than cisplatin against breast cancer cell lines, underpinning the significance of the quinoline pharmacophore in rational drug design. In addition, the most active Re(I) complex showed better selectivity towards the breast cancer cells over non-tumorigenic FG-0 cells. Western blotting revealed that the complexes increased levels of γH2AX, a key DNA damage response protein. Moreover, apoptosis was confirmed in both cell lines due to the detection of cleaved PARP. The complexes show favourable binding affinities towards both calf thymus DNA (CT-DNA), and bovine serum albumin (BSA), and the order of their interactions align with their cytotoxic effects. The in silico molecular simulations of the complexes were also performed with CT-DNA and BSA targets.

Exploring diverse frontiers: Advancements of bioactive 4-aminoquinoline-based molecular hybrids in targeted therapeutics and beyond.

Amongst heterocyclic compounds, quinoline and its derivatives are advantaged scaffolds that appear as a significant assembly motif for developing new drug entities. Aminoquinoline moiety has gained significant attention among researchers in the 21stcentury. Considering the biological and pharmaceutical importance of aminoquinoline derivatives, herein, we review the recent developments (since 2019) in various biological activities of the 4-aminoquinoline scaffold hybridized with diverse heterocyclic moieties such as quinoline, pyridine, pyrimidine, triazine, dioxine, piperazine, pyrazoline, piperidine, imidazole, indole, oxadiazole, carbazole, dioxole, thiazole, benzothiazole, pyrazole, phthalimide, adamantane, benzochromene, and pyridinone. Moreover, by gaining knowledge about SARs, structural insights, and molecular targets, this review may help medicinal chemists design cost-effective, selective, safe, and more potent 4-aminoquinoline hybrids for diverse biological activities.

Novel 4-aminoquinoline analogs targeting the HIF-1α signaling pathway.

Background: The aminoquinoline core exhibits versatile pharmacological properties, particularly in the area of anticancer activity. This study was designed to investigate the potential of the 4-aminoquinoline scaffold in the development of anticancer agents by targeting the HIF-1α signaling pathway. Methodology: The authors synthesized multiple derivatives of 4-aminoquinoline containing heterocyclic rings by a microwave reactor and assessed the cytotoxicity and inhibitory effects of these derivatives on the HIF-1α signaling pathway. Conclusion: Compound 3s was identified as the most promising HIF-1α inhibitor due to its exceptional antiproliferative effects, with IC50 values of 0.6 and 53.3 nM observed in MiaPaCa-2 and MDA-MB-231 cells, respectively. Furthermore, compound 3s was found to inhibit HIF-1α expression by decreasing the level of HIF-1α mRNA.

G-quadruplex in hepatitis B virus pregenomic RNA promotes its translation.

Hepatitis B virus (HBV) is a hepatotropic DNA virus that has a very compact genome. Due to this genomic density, several distinct mechanisms are used to facilitate the viral life cycle. Recently, accumulating evidence show that G-quadruplex (G4) in different viruses play essential regulatory roles in key steps of the viral life cycle. Although G4 structures in the HBV genome have been reported, their function in HBV replication remains elusive. In this study, we treated an HBV replication-competent cell line and HBV-infected cells with the G4 structure stabilizer pyridostatin (PDS) and evaluated different HBV replication markers to better understand the role played by the G4. In both models, we found PDS had no effect on viral precore RNA (pcRNA) or pre-genomic RNA (pgRNA), but treatment did increase HBeAg/HBc ELISA reads and intracellular levels of viral core/capsid protein (HBc) in a dose-dependent manner, suggesting post-transcriptional regulation. To further dissect the mechanism of G4 involvement, we used in vitro-synthesized HBV pcRNA and pgRNA. Interestingly, we found PDS treatment only enhanced HBc expression from pgRNA but not HBeAg expression from pcRNA. Our bioinformatic analysis and CD spectroscopy revealed that pgRNA harbors a conserved G4 structure. Finally, we introduced point mutations in pgRNA to disrupt its G4 structure and observed the resulting mutant failed to respond to PDS treatment and decreased HBc level in in vitro translation assay. Taken together, our data demonstrate that HBV pgRNA contains a G4 structure that plays a vital role in the regulation of viral mRNA translation.

Evaluation of 4-aminoquinoline derivatives with an n-octylamino spacer as potential multi-targeting ligands for the treatment of Alzheimer's disease.

The most successful therapeutic strategy in the treatment of Alzheimer's disease (AD) is directed toward increasing levels of the neurotransmitter acetylcholine (ACh) by inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), the enzymes responsible for its hydrolysis. In this paper, we extended our study on 4-aminoquinolines as human cholinesterase inhibitors on twenty-six new 4-aminoquinolines containing an n-octylamino spacer on C(4) and different substituents on the terminal amino group. We evaluated the potency of new derivatives to act as multi-targeted ligands by determining their inhibition potency towards human AChE and BChE, ability to chelate biometals Fe, Cu and Zn, ability to inhibit the action of ß-secretase 1 (BACE1) and their antioxidant capacity. All of the tested derivatives were very potent inhibitors of human AChE and BChE with inhibition constants (Ki) ranging from 0.0023 to 1.6 µM. Most of the compounds were estimated to be able to cross the blood-brain barrier (BBB) by passive transport and were nontoxic to human neuronal, kidney and liver cells in concentrations in which they inhibit cholinesterases. Generally, newly synthesised compounds were weak reductants compared to standard antioxidants, but all possessed a certain amount of antioxidant activity compared to tacrine. Of the eleven most potent cholinesterase inhibitors, eight compounds also inhibited BACE1 activity at 10-18%. Based on our overall results, compounds 8 with 3-fluorobenzyl, 11 with 3-chlorobenzyl and 17 with 3-metoxy benzyl substituents on the terminal amino group stood out as the most promising for the treatment of AD; they strongly inhibited AChE and BChE, were non-toxic on HepG2, HEK293 and SH-SY5Y cells, had the potential to cross the BBB and possessed the ability to chelate biometals and/or inhibit the activity of BACE1 within a range close to the therapeutically desired degree of inhibition.

CDN1163, a SERCA activator, causes intracellular Ca2+ leak, mitochondrial hyperpolarization and cell cycle arrest in mouse neuronal N2A cells.

OBJECTIVE: Activity or expression of sarcoplasmic/endoplasmic reticulum Ca2+ ATPase (SERCA) is diminished in some disease states such as cardiac failure and diabetes mellitus. A newly developed activator of SERCA, CDN1163, reportedly rescued or alleviated pathological conditions attributed to dysfunctional SERCA. We examined whether CDN1163 could relieve mouse neuronal N2A cell growth inhibition caused by cyclopiazonic acid (CPA, SERCA inhibitor). We also examined how CDN1163 affected cytosolic Ca2+, mitochondrial Ca2+ and mitochondrial membrane potential. METHODS: Cell viability was measured by MTT assay and trypan blue exclusion test. Cytosolic Ca2+, mitochondrial Ca2+ and mitochondrial membrane potential were measured using fura 2, Rhod-2 and JC-1, respectively, as fluorescent probes. RESULTS: CDN1163 (10 µM) itself suppressed cell proliferation, and did not alleviate CPA's inhibitory effect (and vice versa). Cell cycle was arrested at the G1 phase after CDN1163 treatment. CDN1163 treatment caused a slow yet persistent cytosolic [Ca2+] elevation partly due to Ca2+ release from an internal store other than the CPA-sensitive endoplasmic reticulum (ER). Treatment with CDN1163 for 3 h raised mitochondrial Ca2+ level and such increase was suppressed by MCU-i4 (an inhibitor of mitochondria Ca2+ uniporter, MCU), suggesting Ca2+ entered the mitochondrial matrix through MCU. Treatment of cells with CDN1163 up to 2 days resulted in mitochondrial hyperpolarization. CONCLUSION: CDN1163 caused internal Ca2+ leak, cytosolic Ca2+ overload, mitochondrial Ca2+ elevation and hyperpolarization, cell cycle arrest and cell growth inhibition.

Imiquimod as Local Immunotherapy in the Management of Premalignant Cutaneous Conditions and Skin Cancer.

Cutaneous cancers are, by far, the most common malignant neoplasms of the human being. Due to the great array of clinical conditions, their worldwide increasing incidence and the steady ageing of the population, non-invasive treatments modalities that show a good clinical response, a proper benefit-risk ratio and cosmetic results are becoming increasingly important in the clinical setting. Imiquimod is a topically applied immunomodulator which is often used in the management of several premalignant and malignant cutaneous disorders. This article is a review of the current literature on its mechanism of action, pharmacokinetics, and therapeutical effects.

Recent developments in antimalarial activities of 4-aminoquinoline derivatives.

Malaria is the fifth most lethal parasitic infection in the world. Antimalarial medications have played a crucial role in preventing and eradicating malaria. Numerous heterocyclic moieties have been incorporated into the creation of effective antimalarial drugs. The 4-aminoquinoline moiety is favoured in antimalarial drug discovery due to the diverse biological applications of its derivative. Since the 1960s, 4-aminoquinoline has been an important antimalarial drug due to its low toxicity, high tolerability, and rapid absorption after administration. This review focused on the antimalarial efficacy of the 4-aminoquinoline moiety hybridised with various heterocyclic scaffolds developed by scientists since 2018 against diverse Plasmodium clones. It could aid in the future development of more effective antimalarial agents.

P2X7 receptor antagonism by AZ10606120 significantly reduced in vitro tumour growth in human glioblastoma.

Glioblastomas are highly aggressive and deadly brain tumours, with a median survival time of 14-18 months post-diagnosis. Current treatment modalities are limited and only modestly increase survival time. Effective therapeutic alternatives are urgently needed. The purinergic P2X7 receptor (P2X7R) is activated within the glioblastoma microenvironment and evidence suggests it contributes to tumour growth. Studies have implicated P2X7R involvement in a range of neoplasms, including glioblastomas, although the roles of P2X7R in the tumour milieu remain unclear. Here, we report a trophic, tumour-promoting role of P2X7R activation in both patient-derived primary glioblastoma cultures and the U251 human glioblastoma cell line, and demonstrate its inhibition reduces tumour growth in vitro. Primary glioblastoma and U251 cell cultures were treated with the specific P2X7R antagonist, AZ10606120 (AZ), for 72 h. The effects of AZ treatment were also compared to cells treated with the current first-line chemotherapeutic drug, temozolomide (TMZ), and a combination of both AZ and TMZ. P2X7R antagonism by AZ significantly depleted glioblastoma cell numbers compared to untreated cells, in both primary glioblastoma and U251 cultures. Notably, AZ treatment was more effective at tumour cell killing than TMZ. No synergistic effect between AZ and TMZ was observed. AZ treatment also significantly increased lactate dehydrogenase release in primary glioblastoma cultures, suggesting AZ-induced cellular cytotoxicity. Our results reveal a trophic role of P2X7R in glioblastoma. Importantly, these data highlight the potential for P2X7R inhibition as a novel and effective alternative therapeutic approach for patients with lethal glioblastomas.

In silico and in vitro assessment of anti-Trypanosoma cruzi efficacy, genotoxicity and pharmacokinetics of pentasubstituted pyrrolic Atorvastatin-aminoquinoline hybrid compounds.

Atorvastatin (AVA) is a third-generation statin with several pleiotropic effects, considered the last synthetic pharmaceutical blockbuster. Recently, our group described the effects of AVA on DNA damage prevention and against Trypanosoma cruzi infection. In this study, our aim was to evaluate the efficacy, safety, and in silico pharmacokinetic profile of four hybrids of aminoquinolines with AVA 4a-d against T. cruzi using in vitro and in silico models. These synthetic compounds were designed by hybridization of the pentapyrrolic moiety of AVA with the aminoquinolinic unit of chloroquine or primaquine. Pharmacokinetics (ADME) and toxicity parameters were predicted by SwissADME, admetSAR and LAZAR in silico algorithms. The trypanocidal activity of AVA-quinoline hybrids were evaluated in vitro against amastigotes and trypomastigotes of T. cruzi, from Y (Tc II) and Tulahuen (Tc VI) strains. In vitro cardiocytotoxicity was assessed using primary cultures of mouse embryonic cardiac cells and in vitro hepatocytotoxicity on bidimensional and 3D-cultured HepG2 cells. Genotoxicity was evaluated by Ames test and micronucleus assay. Despite the overall good in silico ADMET profile, all tested compounds were predicted to be hepatotoxic. All hybrid derivatives presented high trypanocidal activity, against both trypomastigote and intracellular forms of T. cruzi, presenting EC50's lower than 1 µM besides superior selectivity than the reference drug, without evidences of cardiotoxicity in vitro. The compounds 4a and 4b presented a time-dependent toxicity in monolayer culture of HepG2 but no detectable toxic effects in their spheroids, opposing to the in silico prediction. We can conclude that the AVA-aminoquinoline hybrids presented a hit profile as antiparasitic agents in synthetic pharmaceutical innovation platforms.

4-Aminoquinolines modulate RNA structure and function: Pharmacophore implications of a conformationally restricted polyamine.

RNA structure plays an important role in regulating cellular function and there is a significant emerging interest in targeting RNA for drug discovery. Here we report the identification of 4-aminoquinolines as modulators of RNA structure and function. Aminoquinolines have a broad range of pharmacological activities, but their specific mechanism of action is often not fully understood. Using electrophoretic mobility shift assays and enzymatic probing we identified 4-aminoquinolines that bind the stem-loop II motif (s2m) of SARS-CoV-2 RNA site-specifically and induce dimerization. Using fluorescence-based RNA binding and T-box riboswitch functional assays we identified that hydroxychloroquine binds the T-box riboswitch antiterminator RNA element and inhibits riboswitch function. Based on its structure and riboswitch dose-response activity we identified that the antagonist activity of hydroxychloroquine is consistent with it being a conformationally restricted analog of the polyamine spermidine. Given the known role that polyamines play in RNA function, the identification of an RNA binding ligand with the pharmacophore of a conformationally restricted polyamine has significant implications for further elucidation of RNA structure-function relationships and RNA-targeted drug discovery.

Multi-target Polypharmacology of 4-aminoquinoline Compounds against Malaria, Tuberculosis and Cancer.

BACKGROUND: Polypharmacology means drugs having interactions with multiple targets of a unique disease or many disease pathways. This concept has been greatly appreciated against complex diseases, such as oncology, CNS disorders, and anti-infectives. METHODS: The integration of diverse compounds available on public databases initiates polypharmacological drug discovery research. Immunocompromised patients may suffer from complex diseases. Multiple-component drug formulations may produce side effects and resistance issues due to unintended drug-target interactions. RESULTS: Polypharmacology remains a novel avenue to propose a more effective and less toxic treatment. The 4-amino quinoline scaffold has become an important construction motif for the development of new drugs against lifestyle diseases like cancer and infectious diseases like tuberculosis and malaria. CONCLUSION: The present study is an attempt to explore the polypharmacological effects of 4- aminoquinoline drugs to combat malaria, cancer, and tuberculosis.

Design, synthesis and biological evaluation of 4-aminoquinoline derivatives as receptor-interacting protein kinase 2 (RIPK2) inhibitors.

Receptor-interacting protein kinase 2 (RIPK2) is an essential protein kinase mediating signal transduction by NOD1 and NOD2, which play an important role in regulating immune signalling. In this study, we designed and synthesised a novel series of 4-aminoquinoline-based derivatives as RIPK2 inhibitors. In vitro, compound 14 exhibited high affinity (IC50 = 5.1 ± 1.6 nM) and excellent selectivity to RIPK2 showing in a dendrogram view of the human kinome phylogenetic tree. Bearing favourable lipophilicity and eligible lipophilic ligand efficiency (LipE), compound 14 was selected to investigate cellular anti-inflammatory effect and was identified as a potent inhibitor to reduce the secretion of MDP-induced TNF-α with a dose-dependent manner. Moreover, compound 14 showed moderate stability in human liver microsome. Given these promising results, compound 14 could serve as a favourable inhibitor of RIPK2 for further physiological and biochemical research so as to be used in therapeutic treatment.

Novel 4-aminoquinolines: Synthesis, inhibition of the Mycobacterium tuberculosis enoyl-acyl carrier protein reductase, antitubercular activity, SAR, and preclinical evaluation.

Herein a series of 4-aminoquinolines were synthesized in an attempt to optimize and study the structural features related to LABIO-17 biological activity, a Mycobacterium tuberculosis NADH-dependent enoyl-acyl carrier protein reductase (MtInhA) inhibitor previously identified by a virtual-ligand-screening approach. Structure-activity relationships led to novel submicromolar inhibitors of MtInhA and potent antitubercular agents. The lead compound is 87-fold more potent as enzymatic inhibitors and 32-fold more potent against M. tuberculosis H37Rv strain in comparison with LABIO-17. These molecules were also active against multidrug-resistant strains, devoid of apparent toxicity to mammalian cells and showed favorable in vitro ADME profiles. Additionally, these compounds were active in an intracellular model of tuberculosis (TB) infection, showed no genotoxicity signals, satisfactory absorption parameters and absence of in vivo acute toxicity. Finally, treatment with selected 4-aminoquinoline for two weeks produced bacteriostatic effect in a murine model of TB. Taken together, these findings indicate that this chemical class may furnish candidates for the future development of drug-sensitive and drug-resistant tuberculosis treatments.

Novel Morpholine-Bearing Quinoline Derivatives as Potential Cholinesterase Inhibitors: The Influence of Amine, Carbon Linkers and Phenylamino Groups.

A series of novel 4-N-phenylaminoquinoline derivatives containing a morpholine group were designed and synthesized, and their anti-cholinesterase activities and ABTS radical-scavenging activities were tested. Among them, compounds 11a, 11g, 11h, 11j, 11l, and 12a had comparable inhibition activities to reference galantamine in AChE. Especially, compound 11g revealed the most potent inhibition on AChE and BChE with IC50 values of 1.94 ± 0.13 µM and 28.37 ± 1.85 µM, respectively. The kinetic analysis demonstrated that both the compounds 11a and 11g acted as mixed-type AChE inhibitors. A further docking comparison between the 11a- and 12a-AChE complexes agreed with the different inhibitory potency observed in experiments. Besides, compounds 11f and 11l showed excellent ABTS radical-scavenging activities, with IC50 values of 9.07 ± 1.34 µM and 6.05 ± 1.17 µM, respectively, which were superior to the control, Trolox (IC50 = 11.03 ± 0.76 µM). It is worth noting that 3-aminoquinoline derivatives 12a-12d exhibited better drug-like properties.

Antimalarial Pyrido[1,2-a]benzimidazoles Exert Strong Parasiticidal Effects by Achieving High Cellular Uptake and Suppressing Heme Detoxification.

Pyrido[1,2-a]benzimidazoles (PBIs) are synthetic antiplasmodium agents with potent activity and are structurally differentiated from benchmark antimalarials. To study the cellular uptake of PBIs and understand the underlying phenotype of their antiplasmodium activity, their antiparasitic activities were examined in chloroquine (CQ)-susceptible and CQ-resistant Plasmodium falciparumin vitro. Moreover, drug uptake and heme detoxification suppression were examined in Plasmodium berghei-infected mice. The in vitro potency of PBIs is comparable to most 4-aminoquinolines. They have a speed of action in vitro that is superior to that of atovaquone and an ability to kill rings and trophozoites. The antiparasitic effects observed for the PBIs in cell culture and in infected mice are similar in terms of potency and efficacy and are comparable to CQ but with the added advantage of demonstrating equipotency against both CQ susceptible and resistant parasite strains. PBIs have a high rate of uptake by parasite cells and, conversely, a limited rate of uptake by host cells. The mechanism of cellular uptake of the PBIs differs from the ion-trap mechanism typically observed for 4-aminoquinolines, although they share key structural features. The high cellular uptake, attractive parasiticidal profile, and susceptibility of resistant strains to PBIs are desirable characteristics for new antimalarial agents.