Reproductive and endocrine effects of artemisinin, piperaquine, and artemisinin-piperaquine combination in rats.

BACKGROUND: The WHO recommends artemisinin-based combination regimens for uncomplicated Plasmodium falciparum malaria. One such combination is artemisinin-piperaquine tablets (ATQ). ATQ has outstanding advantages in anti-malarial, such as good efficacy, fewer side effects, easy promotion and application in deprived regions. However, the data about the reproductive and endocrine toxicity of ATQ remains insufficient. Thus, we assessed the potential effects of ATQ and its individual components artemisinin (ART) and piperaquine (PQ) on the reproductive and endocrine systems in Wistar rats. METHODS: The unfertilized female rats were intragastric administrated with ATQ (20, 40, and 80 mg/kg), PQ (15, 30, and 60 mg/kg), ART (2.5, 5, and 10 mg/kg), or water (control) for 14 days, respectively. The estrous cycle and serum levels of estradiol (E2), follicle-stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), prostaglandin (PG), and adrenocorticotropic hormone (ACTH) were determined. The weights of the kidney, adrenal gland, uterus, and ovaries were measured. The histopathological examinations of the adrenal gland, ovary, uterus, and mammary gland were performed. RESULTS: Compared with the control group, there were no significant differences in the examined items of female rats in the ART groups, including general observation, estrous cycle, hormonal level, organ weight, and histopathological examination. The estrous cycle of female rats was disrupted within 4-7 days after ATQ or PQ administration, and then in a persistent dioestrus phase. At the end of administration, ATQ and PQ at three doses induced decreased PG, increased ACTH, increased adrenal weight and size, and pathological lesions in the adrenal gland and ovary, including vasodilation and hyperemia in the adrenal cortex and medulla as well as hyperplasia and vacuolar degeneration, ovarian corpus luteum surface hyperemia, numerous but small corpus luteum, and disordered follicle development. But the serum levels of E2, FSH, LH, and PRL did not change obviously. These adverse effects in ATQ or PQ treated rats could not completely disappear after 21 days of recovery. CONCLUSION: Based on the results of this study, ART had no obvious reproductive and endocrine effects on female rats, while ATQ and PQ caused adrenal hyperplasia, increased ACTH, decreased PG, blocked estrus, corpus luteum surface hyperemia, and disrupted follicle development in female rats. These events suggest that ATQ and PQ may interfere with the female reproductive and endocrine systems, potentially reducing fertility.

Metabolism is not a Major Contributor to the Toxicity of Piperaquine, a Long-acting Antimalarial Agent in Artemisinin-based Combination Therapy.

BACKGROUND: Hepatocellular damage has been reported for the antimalarial piperaquine (PQ) in the clinic after cumulative doses. OBJECTIVES: The role of metabolism in PQ toxicity was evaluated, and the mechanism mediating PQ hepatotoxicity was investigated. METHODS: The toxicity of PQ and its major metabolite (PQ N-oxide; M1) in mice was evaluated in terms of serum biochemical parameters. The role of metabolism in PQ toxicity was investigated in mice pretreated with an inhibitor of CYP450 (ABT) and/or FMO enzyme (MMI). The dose-dependent pharmacokinetics of PQ and M1 were studied in mice. Histopathological examination was performed to reveal the mechanism mediating PQ hepatotoxicity. RESULTS: Serum biochemical levels (ALT and BUN) increased significantly (P < 0.05) in mice after three-day oral doses of PQ (> 200 mg/kg/day), indicating hepatotoxicity and nephrotoxicity of PQ at a high dose. Weaker toxicity was observed for M1. Pretreatment with ABT and/or MMI did not increase PQ toxicity. PQ and M1 showed linear pharmacokinetics in mice after a single oral dose, and multiple oral doses led to their cumulative exposures. Histopathological examination showed that a high dose of PQ (> 200 mg/kg/day for three days) could induce hepatocyte apoptosis. The mRNA levels of targets in NF-κB and p53 pathways could be up-regulated by 2-30-fold in mice by PQ or M1. CONCLUSION: PQ metabolism led to detoxification of PQ, but there was a low possibility of altered toxicity induced by metabolism inhibition. The hepatotoxicity of PQ and its N-oxidation metabolite was partly mediated by NF-κB inflammatory pathway and p53 apoptosis pathway.

Total Synthesis and Antimalarial Activity of 2-(p-Hydroxybenzyl)-prodigiosins, Isoheptylprodigiosin, and Geometric Isomers of Tambjamine MYP1 Isolated from Marine Bacteria.

Highly efficient and straightforward synthetic routes toward the first total synthesis of 2-(p-hydroxybenzyl)-prodigiosins (2-5), isoheptylprodigiosin (6), and geometric isomers of tambjamine MYP1 ((E/Z)-7) have been developed. The crucial steps involved in these synthetic routes are the construction of methoxy-bipyrrole-carboxaldehydes (MBCs) and a 20-membered macrocyclic core and a regioselective demethylation of MBC analogues. These new synthetic routes enabled us to generate several natural prodiginines 24-27 in larger quantity. All of the synthesized natural products exhibited potent asexual blood-stage antiplasmodial activity at low nanomolar concentrations against a panel of Plasmodium falciparum parasites, with a great therapeutic index. Notably, prodiginines 6 and 24-27 provided curative in vivo efficacy against erythrocytic Plasmodium yoelii at 25 mg/kg × 4 days via oral route in a murine model. No overt clinical toxicity or behavioral change was observed in any mice treated with prodiginines and tambjamines.

Evaluation of ethnopharmacologically selected Vitex negundo L. for In vitro antimalarial activity and secondary metabolite profiling.

ETHANOPHARMACOLOGICAL RELEVANCE: Limited drugs, rise in drug resistance against frontline anti-malarial drugs, non-availability of efficacious vaccines and high cost of drug development hinders malaria intervention programs. Search for safe, effective and affordable plant based anti-malarial agents, thus becomes crucial and vital in the current scenario. The Vitex negundo L. is medicinal plant possessing a variety of pharmaceutically important compounds. The plant is used traditionally worldwide for the treatment of malaria including India and Malaysia by the indigenous tribes. In vitro studies have reported the anti-malarial use of the plant in traditional medicinal systems. AIM OF THE STUDY: The aim of the current study is to evaluate the traditionally used medicinal plants for in vitro anti-malarial activity against human malaria parasite Plasmodium falciparum and profiling secondary metabolite using spectroscopic and chromatographic methods. Chemical profiling of active secondary metabolites in the extracts was undertaken using LC-MS. MATERIALS AND METHODS: Based on the ethno-botanical data V. negundo L. was selected for in vitro anti-malarial activity against P. falciparum chloroquine-sensitive (3D7) and multidrug resistant (K1) strains using SYBR Green-I based fluorescence assay. Cytotoxicity of extracts was evaluated in VERO cell line using the MTT assay. Haemolysis assay was performed using human red blood cells. Secondary metabolites profiling was undertaken using chromatographic and spectroscopic analysis. Liquid chromatography analysis was performed using a C18, 150 X 2.1, 2.6 µm column with gradient mobile phase Solvent A: 95% (H2O: ACN), Solvent B: Acetonitrile, Solvent C: Methanol, Solvent D: 5 mM NH4 in 95:5 (H2O: ACN) at a constant flow rate of 0.250 ml/min. The LC-MS spectra were acquired in both positive and negative ion modes with electrospray ionization (ESI) source. RESULTS: The anti-malarial active extract of V. negundo L. leaf exhibited potent anti-malarial activity with IC50 values of 7.21 µg/ml and 7.43 µg/ml against 3D7 and K1 strains, respectively with no evidence of significant cytotoxicity against mammalian cell line (VERO) and no toxicity as observed in haemolysis assay. The HPLC-LC-MS analysis of the extract led to identification of 73 compounds. We report for the first time the presence of Sabinene hydrate acetate, 5-Hydroxyoxindole, 2(3,4-dimethoxyphenyl)-6, 7-dimethoxychromen-4-one, Cyclotetracosa-1, 13-diene and 5, 7-Dimethoxyflavanone in the anti-malarial active extract of V. negundo L. leaf. Agnuside, Behenic acid and Globulol are some of the novel compounds with no reports of anti-malarial activity so far and require further evaluation in pure form for the development of potent anti-malarial compounds. CONCLUSIONS: The result report and scientifically validate the traditional use of V. negundo L. for the treatment of malaria providing new avenues for anti-malarial drug development. Several novel and unknown compounds were identified that need to be further characterized for anti-malarial potential.

N-alkyl triphenylvinylpyridinium conjugated dihydroartemisinin perturbs mitochondrial functions resulting in enhanced cancer versus normal cell toxicity.

Dihydroartemisinin (DHA) is an FDA-approved antimalarial drug that has been repurposed for cancer therapy because of its preferential antiproliferative effects on cancer versus normal cells. Mitochondria represent an attractive target for cancer therapy based on their regulatory role in proliferation and cell death. This study investigates whether DHA conjugated to innately fluorescent N-alkyl triphenylvinylpyridinium (TPVP) perturbs mitochondrial functions resulting in a differential toxicity of cancer versus normal cells. TPVP-DHA treatments resulted in a dose-dependent toxicity of human melanoma and pancreatic cancer cells, whereas normal human fibroblasts were resistant to this treatment. TPVP-DHA treatments resulted in a G1-delay of the cancer cell cycle, which was also associated with a significant inhibition of the mTOR-metabolic and ERK1/2-proliferative signaling pathways. TPVP-DHA treatments perturbed mitochondrial functions, which correlated with increases in mitochondrial fission. In summary, TPVP mediated mitochondrial targeting of DHA enhanced cancer cell toxicity by perturbing mitochondrial functions and morphology.

TNFα enhances trovafloxacin-induced in vitro hepatotoxicity by inhibiting protective autophagy.

Trovafloxacin (TVX) is associated with idiosyncratic drug-induced liver injury (iDILI) and inflammation-mediated hepatotoxicity. However, the inflammatory stress-regulated mechanisms in iDILI remain unclear. Herein, we elucidated the novel role of tumor-necrosis factor alpha (TNFα), an inflammatory stress factor, in TVX-induced in vitro hepatotoxicity and synergistic toxicity. TVX specifically induced synergistic toxicity in HepG2 cells with TNFα, which inhibits autophagy. TVX-treated HepG2 cells induced protective autophagy by inhibiting the expression of mTOR signaling proteins, while ATG5 knockdown in HepG2 cells, responsible for the impairment of autophagy, enhanced TVX-induced toxicity due to the increase in cytochrome C release and JNK pathway activation. Interestingly, the expression of mTOR signal proteins, which were suppressed by TVX, disrupted the negative feedback of the PI3K/AKT pathway and TNFα rebounded p70S6K phosphorylation. Co-treatment with TVX and TNFα inhibited protective autophagy by maintaining p70S6K activity, which enhanced TVX-induced cytotoxicity. Phosphorylation of p70S6K was inhibited by siRNA knockdown and rapamycin to restore TNFα-inhibited autophagy, which prevented the synergistic effect on TVX-induced cytotoxicity. These results indicate that TVX activates protective autophagy in HepG2 cells exposed to toxicity and an imbalance in negative feedback regulation of autophagy by TNFα synergistically enhanced the toxicity. The finding from this study may contribute to a better understanding of the mechanisms underlying iDILI associated with inflammatory stress.

Repurposing of existing therapeutics to combat drug-resistant malaria.

In the era of drug repurposing, speedy discovery of new therapeutic options for the drug-resistant malaria is the best available tactic to reduce the financial load and time in the drug discovery process. Six anticancer drugs, three immunomodulators and four antibiotics were selected for the repositioning against experimental malaria owing to their mode of action and published literature. The efficacy of existing therapeutics was evaluated against chloroquine-resistant in vitro and in vivo strains of Plasmodium falciparum and P. yoelii, respectively. All the pre-existing FDA-approved drugs along with leptin were primarily screened against chloroquine-resistant (PfK1) and drug-sensitive (Pf3D7) strains of P. falciparum using SYBR green-based antiplasmodial assay. Cytotoxic profiling of these therapeutics was achieved on Vero and HepG2 cell lines, and human erythrocytes. Percent blood parasitemia and host survival was determined in chloroquine-resistant P. yoelii N67-infected Swiss mice using appropriate doses of these drugs/immunomodulators. Antimalarial screening together with cytotoxicity data revealed that anticancer drugs, idelalisib and 5-fluorouracil acquired superiority over their counterparts, regorafenib, and tamoxifen, respectively. ROS-inducer anticancer drugs, epirubicin and bleomycin were found toxic for the host. Immunomodulators (imiquimod, lenalidomide and leptin) were safest but less active in in vitro system, however, in P. yoelii-infected mice, they exhibited modest parasite suppression at their respective doses. Among antibiotics, moxifloxacin exhibited better antimalarial prospective than levofloxacin, roxithromycin and erythromycin. 5-Fluorouracil, imiquimod and moxifloxacin displayed 97.64, 81.18 and 91.77 % parasite inhibition in treated animals and attained superiority in their respective groups thus could be exploited further in combination with suitable antimalarials.

Pentafluoro-3-hydroxy-pent-2-en-1-ones Potently Inhibit FNT-Type Lactate Transporters from all Five Human-Pathogenic Plasmodium Species.

The protozoan parasite Plasmodium falciparum causes the most severe and prevailing form of malaria in sub-Saharan Africa. Previously, we identified the plasmodial lactate transporter, PfFNT, a member of the microbial formate-nitrite transporter family, as a novel antimalarial drug target. With the pentafluoro-3-hydroxy-pent-2-en-1-ones, we discovered PfFNT inhibitors that potently kill P. falciparum parasites in vitro. Four additional human-pathogenic Plasmodium species require attention, that is, P. vivax, most prevalent outside of Africa, and the regional P. malariae, P. ovale and P. knowlesi. Herein, we show that the plasmodial FNT variants are highly similar in terms of protein sequence and functionality. The FNTs from all human-pathogenic plasmodia and the rodent malaria parasite were efficiently inhibited by pentafluoro-3-hydroxy-pent-2-en-1-ones. We further established a phenotypic yeast-based FNT inhibitor screen, and found very low compound cytotoxicity and monocarboxylate transporter 1 off-target activity on human cells, particularly of the most potent FNT inhibitor BH267.meta, allowing these compounds to proceed towards animal model malaria studies.

A new look at 9-substituted acridines with various biological activities.

Heterocycles have long been the focus of intensive study in attempts to develop novel therapeutic compounds, and acridine, a polynuclear nitrogen molecule containing a heterocycle, has attracted a considerable amount of scientific attention. Acridine derivatives have been studied in detail and have been found to possess multitarget properties, which inhibit topoisomerase enzymes that regulate topological changes in DNA and interfere with the essential biological function of DNA. This article describes some recent advancements in the field of new 9-substituted acridine heterocyclic agents and describes both the structure and the structure-activity relationship of the most promising molecules. The article will also present the IC50 values of the novel derivatives against various human cancer cell lines. The mini review also investigates the topoisomerase inhibition and antibacterial and antimalarial activity of these polycyclic aromatic derivatives.

Nonclassical Phenyl Bioisosteres as Effective Replacements in a Series of Novel Open-Source Antimalarials.

The replacement of one chemical motif with another that is broadly similar is a common method in medicinal chemistry to modulate the physical and biological properties of a molecule (i.e., bioisosterism). In recent years, bioisosteres such as cubane and bicyclo[1.1.1]pentane (BCP) have been used as highly effective phenyl mimics. Herein, we show the successful incorporation of a range of phenyl bioisosteres during the open-source optimization of an antimalarial series. Cubane (19) and closo-carborane (23) analogues exhibited improved in vitro potency against Plasmodium falciparum compared to the parent phenyl compound; however, these changes resulted in a reduction in metabolic stability; unusually, enzyme-mediated oxidation was found to take place on the cubane core. A BCP analogue (22) was found to be equipotent to its parent phenyl compound and showed significantly improved metabolic properties. While these results demonstrate the utility of these atypical bioisosteres when used in a medicinal chemistry program, the search to find a suitable bioisostere may well require the preparation of many candidates, in our case, 32 compounds.

Antimalarial agent artesunate induces G0/G1 cell cycle arrest and apoptosis via increasing intracellular ROS levels in normal liver cells.

Artesunate (ARS) has been shown to be highly effective against chloroquine-resistant malaria. In vitro studies reported that ARS has anticancer effects; however, its detrimental action on cancer cells may also play a role in its toxicity toward normal cells and its potential toxicity has not been sufficiently researched. In this study, we investigated the possible cytotoxic effects using normal BRL-3A and AML12 liver cells. The results showed that ARS dose-dependently inhibited cell proliferation and arrested the G0/G1 phase cell cycle in both BRL-3A and AML12 liver cells. Western blotting demonstrated that ARS induced a significant downregulation of cyclin-dependent kinase-2 (CDK2), CDK4, cyclin D1, and cyclin E1 in various levels and then caused apoptosis when the Bcl-2/Bax ratio decreased. Conversely, the levels of intracellular reactive oxygen species (ROS) were increased. The ROS scavenger N-acetylcysteine can significantly inhibit cell cycle arrest and apoptosis induced by ARS. Thus, the data confirmed that ARS exposure impairs normal liver cell proliferation by inducing G0/G1 cell cycle arrest and apoptosis, and this detrimental action may be associated with intracellular ROS accumulation. Collectively, the possible side effects of ARS on healthy normal cells cannot be neglected when developing therapies.

Old drug repurposing for neglected disease: Pyronaridine as a promising candidate for the treatment of Echinococcus granulosus infections.

BACKGROUND: Cystic echinococcosis (CE), a condition caused by the larval stage of the dog tapeworm Echinococcus granulosus sensu stricto, is a globally distributed zoonotic disease. Current treatment options for CE are limited, and an effective and safe anti-echinococcal drug is urgently required. METHODS: Drug repurposing strategy was employed to identify new therapeutic agents against echinococcal cysts. An in vitro protoscolicidal assay along with in vivo murine models was applied in the drug screening. A microinjection procedure was employed to mimic the clinical PAIR (puncture, aspiration, injection and reaspiration) technique to evaluate the potential application of the candidate drug in clinical practice. FINDINGS: We repurposed pyronaridine, an approved antimalarial drug, for the treatment of CE. Following a three-dose intraperitoneal regimen (57 mg/kg, q.d. for 3 days), pyronaridine caused 100% cyst mortality. Oral administration of pyronaridine at 57 mg/kg, q.d. for 30 days significantly reduced the parasitic burden in the pre-infected mice compared with albendazole group (p < 0.001). Using a microinjection of drug into cysts, pyronaridine (200 µM) showed highly effective in term of inhibition of cyst growth (p < 0.05, compared with saline group). Pharmacokinetic analysis revealed that pyronaridine was highly distributed in the liver and lungs, the most affected organs of CE. Function analysis showed that pyronaridine inhibited the activity of topoisomerase I (IC50 = 209.7 ± 1.1 µM). In addition, classical apoptotic hallmarks, including DNA fragmentation and caspase activation, were triggered. INTERPRETATION: Given its approved clinical safety, the repurposing of pyronaridine offers a rapidly translational option for treating CE including PAIR. FUND: National Natural Science Foundation of China and International Cooperation Project of the Qinghai Science and Technology Department.

Protective effect of dietary vitamin E (alpha; Tocopherol) on artemisinin induced oxidative liver tissue damage in rats / Efecto protector de la vitamina E en la dieta (alfa; tocoferol) sobre el daño oxidativo del tejido hepático inducido por artemisinina en ratas

This experiment was designed to study the effects of oral administration of artemether which is the most rapid-acting class of antimalarial drugs and the possible protective effect of vitamin E taken with it on the liver of albino rats. A total of twenty-four adult male albino rats were used in this study and were divided into four groups. Group one served as a control and rats in group two exposed to oral intake of artemether daily for fifteen days. The third and fourth groups treated with artemether plus low and high doses of vitamin E respectively. At the end of the experiment, the rats were sacrificed, and the livers were obtained and processed for histological, biochemical and statistical studies. Histological study of the hepatocytes of rats exposed to artemether showed nearly complete disintegration of most cellular contents except few numbers of mitochondria and rough endoplasmic reticulum. Also, the cytoplasm of these cells had few lysosomes, many vacuoles and irregular nuclei with abnormal distribution of chromatin and were shown. The hepatic sinusoids were dilated and filled with blood and vacuoles and bile ductules were abnormal in its structure. Treatment with low and high doses of vitamin E in concomitant with artemether ameliorated the hepatic histopathological lesions and its parenchyma attained nearly normal structure. As far as biochemical changes, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in rats treated with artemether were significantly elevated as compared to the control. Superoxide dismutase (SOD) and malondialdehyde (MDA) levels were significantly increased in the liver in rats treated with artemether. However, vitamin E ameliorated the rise in ALT and AST with decreased MDA concentration and levels of SOD as compared to the corresponding artemether group values. Results of the present suggest that artemether has a harmful and stressful effect on hepatic tissue and the treatment with vitamin E may alleviate this toxicity.

Este experimento fue diseñado para estudiar los efectos de la administración oral de arteméter, la clase de medicamentos antipalúdicos de acción rápida, y el posible efecto protector de la vitamina E en el hígado de ratas albinas. Se utilizaron un total de 24 ratas albinas machos adultas y se dividieron en cuatro grupos. El grupo uno sirvió como control y las ratas en el grupo dos recibieron la dosis oral de arteméter diariamente durante 15 días. Los grupos tres y cuatro fueron tratados con arteméter, más dosis bajas y altas de vitamina E, respectivamente. Al final del experimento, se sacrificaron las ratas y se obtuvieron y procesaron los hígados para estudios histológicos, bioquímicos y estadísticos. El estudio histológico de los hepatocitos de ratas expuestas a arteméter mostró una desintegración casi completa de la mayoría de los contenidos celulares, excepto algunos mitocondrias y retículo endoplásmico rugoso. Además, el citoplasma de estas células tenía pocos lisosomas, muchas vacuolas y núcleos irregulares con distribución anormal de cromatina. Los sinusoides hepáticos estaban dilatados y llenos de sangre y vacuolas, y los conductos biliares tenían una estructura anormal. El tratamiento con dosis bajas y altas de vitamina E en forma concomitante con arteméter mejoró las lesiones histopatológicas hepáticas y su parénquima alcanzó una estructura casi normal. En cuanto a los cambios bioquímicos, la alanina aminotransferasa (ALT) y la aspartato aminotransferasa (AST) en ratas tratadas con arteméter se elevaron significativamente en comparación con el control. Los niveles de superóxido dismutasa (SOD) y malondialdehído (MDA) aumentaron significativamente en el hígado en ratas tratadas con arteméter. Sin embargo, la vitamina E mejoró el aumento de ALT y AST con una disminución de la concentración de MDA y los niveles de SOD en comparación con los valores correspondientes del grupo de arteméter. Los resultados del presente estudio sugieren que el arteméter tiene un efecto dañino y estresante sobre el tejido hepático y el tratamiento con vitamina E puede aliviar esta toxicidad.

Ameliorative effect of vitamin E on biochemical and ultrastructural changes in artemether-induced renal toxicity in rats / Efecto paliativo de la vitamina E sobre los cambios bioquímicos y ultraestructurales en la toxicidad renal inducida por arteméter en ratas

This experiment was designed to study the administration of normal doses of one of recent antimalarial drug and coadministration of vitamin E on the kidney tissue. A total twenty-four adult male albino rats were used and divided into four groups: the first one served as a control, the second received artemether orally for three days consecutively. The rats of the third and fourth groups received the same dose of artemether concomitantly with 50 and 100 mg/kg vitamin E orally daily for 2 weeks. After the last dose, the rats were sacrificed and the kidney tissues with blood samples obtained and processed for light, electron microscopic and biochemical analysis. Histologically, artemether treated kidneys showed atrophied glomeruli with widened urinary space and kidney tubules were degenerated with disturbed contour and some vacuoles inside it. Ultrastructurally, the glomeruli of this group showed hypertrophic endothelial cells, irregularity of its basement membrane, disrupted foot processes and filtration slits. The kidney tubule cells showed loss of basal infoldings, cytoplasmic vacuolation, polymorphic damaged swollen mitochondria a loss of its microvilli towards its capillary lumen. Artemether plus vitamin E of the rat kidney groups showed improvement of morphological changes compared to the changes seen in artemether alone. These data were confirmed by biochemical findings with marked improvement of blood urea and creatinine levels and increase of anti-oxidant enzyme activities of glutathione peroxidase and superoxide dismutase in the vitamin E treated groups. The results of this study revealed that vitamins E can improve the adverse changes of artemether of rat renal tissue.

Este proyecto fue diseñado para estudiar la administración de dosis normales de uno de los medicamentos antipalúdicos y de la administración de vitamina E en el tejido renal. Se utilizaron 24 ratas albinas machos adultas divididas en cuatro grupos: el primero sirvió como control, el segundo recibió arteméter por vía oral durante tres días consecutivos. Las ratas del tercer y cuarto grupos recibieron la misma dosis de arteméter concomitantemente con 50 y 100 mg / kg de vitamina E por vía oral diariamente durante 2 semanas. Después de la última dosis, las ratas fueron sacrificadas y se obtuvo el tejido renal de cada muestra los cuales fueron procesados para análisis con microscopías de luz y electrónica, además de exámenes bioquímicos. Histológicamente, los riñones tratados con arteméter mostraron atrofia glomerular con espacio urinario ensanchado y túbulos renales degenerados con contorno alterado y algunas vacuolas en su interior. Ultraestructuralmente, los glomérulos de este grupo mostraron células endoteliales hipertróficas, irregularidad de su membrana basal, procesos alterados del pie y hendiduras de filtración. Las células del túbulo renal mostraron pérdida de inflexiones basales, vacuolación citoplasmática, mitocondrias dañadas y pérdida de sus microvellosidades hacia la luz capilar. Arteméter más vitamina E en los grupos de riñón de rata mostraron una mejora de los cambios morfológicos, en comparación con los cambios observados en arteméter solamente. Estos datos fueron confirmados por hallazgos bioquímicos con una marcada mejoría de los niveles de urea y creatinina en sangre y un aumento de las actividades enzimáticas antioxidantes de la glutatión peroxidasa y la superóxido dismutasa en los grupos tratados con vitamina E. Los resultados de este estudio revelaron que la vitamina E puede mejorar los cambios adversos del arteméter del tejido renal de la rata.

Mefloquine binding to human acyl-CoA binding protein leads to redox stress-mediated apoptotic death of human neuroblastoma cells.

Malaria is an infectious disease that is caused by different species of Plasmodium. Several antimalarial drugs are used to counter the spread and infectivity of Plasmodium species. However, humans are also vulnerable to many of the antimalarial drugs, including the quinoline-based drugs. In particular, the antimalarial mefloquine has been reported to show adverse neuropsychiatric effects in humans. Though mefloquine is known to be neurotoxic, the molecular mechanisms associated with this phenomenon are still obscure. In this study, we show that mefloquine binds to and inactivates the human acyl-CoA binding protein (hACBP), potentially inducing redox stress in human neuroblastoma cells (IMR-32). Mefloquine occupies the acyl-CoA binding pocket of hACBP by interacting with several of the critical acyl-CoA binding amino acids. This leads to the competitive inhibition of acyl-CoA(s) binding to hACBP and to the accumulation of lipid droplets inside the IMR-32 cells. The accumulation of cytosolic lipid globules and oxidative stress finally correlates with the apoptotic death of cells. Taken together, our study deciphers a mechanistic detail of how mefloquine leads to the death of human cells by perturbing the activity of hACBP and lipid homeostasis.

Phytochemistry and antiplasmodial activity of Xylopia sericea leaves.

Aiming to investigate the antiplasmodial activity and the phytochemical composition of Xylopia sericea leaves, the essential oil and dichloromethane extract were analyzed by gas and liquid chromatography, respectively, both of them coupled to mass spectrometry, and were evaluated against the chloroquine-resistant Plasmodium falciparum strain (W2) and for cytotoxicity to HepG2 cells. Low growth inhibition of P. falciparum as well as low cytotoxicity to HepG2 cells were observed for the essential oil. The leaves dichloromethane extract showed moderate growth inhibition of P. falciparum and low cytotoxicity to HepG2 cells. Bioguided chromatographic fractionation of this extract led to fractions with increased antiplasmodial activity from which liriodenine (IC50 6.1 ± 0.1 µg/mL, CC50 > 1000.0 µg/mL, SI > 164), an aporphine alkaloid, and an acetogenin-rich fraction containing mainly isomers of annomontacin and 4-deoxy-annomontacin (IC50 22.7 ± 1.9 µg/mL, CC50 336.1 ± 15.5 µg/mL, SI = 15) might be highlighted for their antiplasmodial activity.

Identification of Plasmodium dipeptidyl aminopeptidase allosteric inhibitors by high throughput screening.

Dipeptidyl aminopeptidases (DPAPs) are cysteine proteases that cleave dipeptides from the N-terminus of protein substrates and have been shown to play important roles in many pathologies including parasitic diseases such as malaria, toxoplasmosis and Chagas's disease. Inhibitors of the mammalian homologue cathepsin C have been used in clinical trials as potential drugs to treat chronic inflammatory disorders, thus proving that these enzymes are druggable. In Plasmodium species, DPAPs play important functions at different stages of parasite development, thus making them potential antimalarial targets. Most DPAP inhibitors developed to date are peptide-based or peptidomimetic competitive inhibitors. Here, we used a high throughput screening approach to identify novel inhibitor scaffolds that block the activity of Plasmodium falciparum DPAP1. Most of the hits identified in this screen also inhibit Plasmodium falciparum DPAP3, cathepsin C, and to a lesser extent other malarial clan CA proteases, indicating that these might be general DPAP inhibitors. Interestingly, our mechanism of inhibition studies indicate that most hits are allosteric inhibitors, which opens a completely new strategy to inhibit these enzymes, study their biological function, and potentially develop new inhibitors as starting points for drug development.

Pharmacophore Modeling, Synthesis, Scaffold Hopping and Biological ß- Hematin Inhibition Interaction Studies for Anti-malaria Compounds.

Backgound: Exploring potent compounds is critical to generating multi-target drug discovery. Hematin crystallization is an important mechanism of malaria. METHODS: A series of chloroquine analogues were designed using a repositioning approach to develop new anticancer compounds. Protein-ligand interaction fingerprints and ADMET descriptors were used to assess docking performance in virtual screenings to design chloroquine hybrid ß-hematin inhibitors. A PLS algorithm was applied to correlate the molecular descriptors to IC50 values. The modeling presented excellent predictive power with correlation coefficients for calibration and cross-validation of r2 = 0.93 and q2 = 0.72. Using the model, a series of 4-aminoquinlin hybrids were synthesized and evaluated for their biological activity as an external test series. These compounds were evaluated for cytotoxic cell lines and ß-hematin inhibition. RESULTS: The target compounds exhibited high ß-hematin inhibition activity and were 3-9 times more active than the positive control. Furthermore, all the compounds exhibited moderate to high cytotoxic activity. The most potent compound in the dataset was docked with hemoglobin and its pharmacophore features were generated. These features were used as input to the Pharmit server for screening of six databases. CONCLUSION: The compound with the best score from ChEMBL was 2016904, previously reported as a VEGFR-2 inhibitor. The 11 compounds selected presented the best Gold scores with drug-like properties and can be used for drug development.

Ferrocene-Based Compounds with Antimalaria/Anticancer Activity.

Malaria and cancer are chronic diseases. The challenge with drugs available for the treatment of these diseases is drug toxicity and resistance. Ferrocene is a potent organometallic which have been hybridized with other compounds resulting in compounds with enhanced biological activity such as antimalarial and anticancer. Drugs such as ferroquine were developed from ferrocene and chloroquine. It was tested in the 1990s as an antimalarial and is still an effective antimalarial. Many researchers have reported ferrocene compounds as potent compounds useful as anticancer and antimalarial agents when hybridized with other pharmaceutical scaffolds. This review will be focused on compounds with ferrocene moieties that exhibit either an anticancer or antimalarial activity.

Synthesis of thiazolyl hydrazonothiazolamines and 1,3,4-thiadiazinyl hydrazonothiazolamines as a class of antimalarial agents.

Novel thiazolyl hydrazonothiazolamines and 1,3,4-thiadiazinyl hydrazonothiazolamines were synthesized by a facile one-pot multicomponent approach by the reaction of 2-amino-4-methyl-5-acetylthiazole, thiosemicarbazide or thiocarbohydrazide and phenacyl bromides or 3-(2-bromoacetyl)-2H-chromen-2-ones in acetic acid with good to excellent yields. These new compounds were screened in vitro for their antimalarial activity; among them, four compounds, 4h, 4i, 4k, 4l, showed moderate activity with half-maximal inhibitory concentration (IC50 ) values of 3.2, 2.7, 2.7, and 2.8 and 3.2, 3.2, 3.1, and 3.5 µM against chloroquine-sensitive and -resistant strains of Plasmodium falciparum, respectively. Compound 4l inhibited the ring stage growth of P. falciparum 3D7 at an IC90 concentration of 12.5 µM in a stage-specific assay method, where the culture is incubated with specific stages of P. falciparum for 12 hr, and no activity was found against the trophozoite and schizont stages, confirming that 4l may have potent action against the ring stage of P. falciparum.