ABSTRACT
he resistance against antimalarial drugs represents a global challenge in the fight and control of malaria. The Brazilian biodiversity can be an important tool for research and development of new medicinal products. In this context, toxinology is a multidisciplinary approach on the development of new drugs, including the isolation, purification, and evaluation of the pharmacological activities of natural toxins. The present study aimed to evaluate the cytotoxicity, as well as the antimalarial activity in silico and in vitro of four compounds isolated from Rhinella marina venom as potential oral drug prototypes. Methods: Four compounds were challenged against 35 target proteins from P. falciparum and screened to evaluate their physicochemical properties using docking assay in Brazilian Malaria Molecular Targets (BraMMT) software and in silico assay in OCTOPUS® software. The in vitro antimalarial activity of the compounds against the 3D7 Plasmodium falciparum clones were assessed using the SYBR Green I based assay (IC50). For the cytotoxic tests, the LD50 was determined in human pulmonary fibroblast cell line using the [3(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] (MTT) assay. Results: All compounds presented a ligand-receptor interaction with ten Plasmodium falciparum-related protein targets, as well as antimalarial activity against chloroquine resistant strain (IC50 = 3.44 µM to 19.11 µM). Three of them (dehydrobufotenine, marinobufagin, and bufalin) showed adequate conditions for oral drug prototypes, with satisfactory prediction of absorption, permeability, and absence of toxicity. In the cell viability assay, only dehydrobufotenin was selective for the parasite. Conclusions: Dehydrobufotenin revealed to be a potential oral drug prototype presenting adequate antimalarial activity and absence of cytotoxicity, therefore should be subjected to further studies.(AU)
Subject(s)
Bufanolides/administration & dosage , Bufonidae , Biodiversity , Malaria/immunology , Antimalarials , In Vitro Techniques , Computer SimulationABSTRACT
Objective:To examine the efficacy of 1-(N-acetyl-6-aminohexyl)-3-hydroxy-2-methylpyridin-4-one (CM1) iron chelator and green tea extract (GTE) as anti-malarial activity in Plasmodium berghei (P. berghei ) infected mice. Methods:The CM1 (0–100 mg/kg/day) and GTE (0–100 mg (-)-epigallocatechin 3-gallate equivalent/kg/day) were orally administered to P. berghei infected mice for consecutive 4 days. Parasitized red blood cells (PRBC) were enumerated by using Giemsa staining microscopic method. Results: CM1 lowered percentage of PRBC in dose-dependent manner with an ED50 value of 56.91 mg/kg, when compared with pyrimethamine (PYR) (ED50=0.76 mg/kg). GTE treatment did not show any inhibition of the malaria parasite growth. In combined treatment, CM1 along with 0.6 mg/kg PYR significantly inhibited the growth of P. berghei in mice while GTE did not enhance the PYR anti-malarial activity. Conclusions: CM1 would be effective per se and synergize with PYR in inhibiting growth of murine malaria parasites, possibly by limiting iron supply from plasma transferrin and host PRBC cytoplasm, and chelating catalytic iron constitutive in parasites’ mitochondrial cytochromes and cytoplasmic ribonucleotide reductase. CM1 would be a promising adjuvant to enhance PYR anti-malarial activity and minimize the drug resistance.
ABSTRACT
Objective: To examine the efficacy of 1-(N-acetyl-6-aminohexyl)-3-hydroxy-2-methylpyridin-4-one (CM1) iron chelator and green tea extract (GTE) as anti-malarial activity in Plasmodium berghei ( P. berghei) infected mice. Methods: The CM1 (0-100 mg/kg/day) and GTE (0-100 mg (-)-epigallocatechin 3-gallate equivalent/kg/day) were orally administered to P. berghei infected mice for consecutive 4 days. Parasitized red blood cells (PRBC) were enumerated by using Giemsa staining microscopic method. Results: CM1 lowered percentage of PRBC in dose-dependent manner with an ED
ABSTRACT
In the prevention and control of malaria, Prompt and accurate diagnosis is the key to effective disease management. Giemsa microscopy and rapid diagnostic tests (RDTs) are the diagnostic tests each with characteristic strengths and limitations is the best way for accurate diagnosis has a key role for malaria control successfully. Reduction in morbidity and drug resistance intensity of malaria require a parasite based diagnostic methods. A parallel commitment is needed in production of antimalarial drug or malaria vaccine along with improvement in diagnostic tests and their availability to people in endemic areas.endemic areas.
ABSTRACT
Chloroplasts offer high-level transgene expression and transgene containment due to maternal inheritance, and are ideal hosts for biopharmaceutical biosynthesis via multigene engineering. To exploit these advantages, we have expressed 12 enzymes in chloroplasts for the biosynthesis of artemisinic acid (precursor of artemisinin, antimalarial drug) in an alternative plant system. Integration of transgenes into the tobacco chloroplast genome via homologous recombination was confirmed by molecular analysis, and biosynthesis of artemisinic acid in plant leaf tissues was detected with the help of 13C NMR and ESI-mass spectrometry. The excess metabolic flux of isopentenyl pyrophosphate generated by an engineered mevalonate pathway was diverted for the biosynthesis of artemisinic acid. However, expression of megatransgenes impacted the growth of the transplastomic plantlets. By combining two exogenous pathways, artemisinic acid was produced in transplastomic plants, which can be improved further using better metabolic engineering strategies for commercially viable yield of desirable isoprenoid products.
ABSTRACT
It has been demonstrated that continuous exposure to amodiaquine (AQ) alone elicits <i>in vitro</i> antischistosomal activities at concentrations of 1 - 10 µg/ml. However, orally administered drugs reach a peak blood concentration within one or two hours and then gradually decrease. The blood concentration does not remain at a constant level over several days as <i>in vitro</i> concentration of continuous drug exposure. <i>In vitro</i> activities by one day exposure to AQ better reflect the actual antischistosomal activities after oral administration than those elicited by continuous exposure.The objective of the present study is to compare the antischistosomal potential of one-day exposure to AQ with that to praziquantel (PZQ), a current antischistosomal drug. <i>Schistosoma mansoni</i> adult worm pairs were incubated with 0 (control), 1, 2, 5 and 10 µg/ml AQ as well as 0.01, 0.02, 0.05 and 0.1 µg/ml PZQ for the first day, and were subsequently incubated in drug-free media for a period of 14 days. The one-day exposure to AQ significantly reduced the daily egg output of the worm pairs at 1 - 10 µg/ml. The inhibitory effect on egg production continued at 5 and 10 µg/ml but proved temporary at 1 and 2 µg/ml. Furthermore, AQ-induced specific morphological alterations (severe swelling and/or localization of hemozoin) were observed in the worms at 5 and 10 µg/ml. The AQ-specific appearance of the male worms gradually faded during subsequent incubation in drug-free media, although the female worms showed elongation. Meanwhile, PZQ inhibited the egg output of adult worm pairs at concentrations of 0.01 - 0.1 µg/ml during exposure. The inhibitory effect on egg production continued at 0.05 and 0.1 µg/ml but proved temporary at 0.01 and 0.02 µg/ml. Furthermore, PZQ induced a visible contraction and shortening of the male and female worms at 0.05 and 0.1 µg/ml during exposure, but the PZQ-specific alterations quickly disappeared during subsequent incubation in drug-free media. To our knowledge, this is the first report showing that one-day exposure to AQ inhibits the egg production of adult worm pairs at 1 - 10 µg/ml and induces specific morphological alterations in the worms at 5 and 10 µg/ml. The present findings have important implications for the evaluation of the therapeutic effects of both AQ monotherapy and combination therapy with artesunate on schistosomiasis in clinical field trials.
ABSTRACT
It has been demonstrated that continuous exposure to amodiaquine (AQ) alone elicits <i>in vitro</i> antischistosomal activities at concentrations of 1–10 μg/ml. However, orally administered drugs reach a peak blood concentration within one or two hours and then gradually decrease. The blood concentration does not remain at a constant level over several days as <i>in vitro</i> concentration of continuous drug exposure. <i>In vitro</i> activities by one day exposure to AQ better reflect the actual antischistosomal activities after oral administration than those elicited by continuous exposure.The objective of the present study is to compare the antischistosomal potential of one-day exposure to AQ with that to praziquantel (PZQ), a current antischistosomal drug. <i>Schistosoma mansoni</i> adult worm pairs were incubated with 0 (control), 1, 2, 5 and 10 μg/ml AQ as well as 0.01, 0.02, 0.05 and 0.1 μg/ml PZQ for the first day, and were subsequently incubated in drug-free media for a period of 14 days. The one-day exposure to AQ significantly reduced the daily egg output of the worm pairs at 1–10 μg/ml. The inhibitory effect on egg production continued at 5 and 10 μg/ml but proved temporary at 1 and 2 μg/ml. Furthermore, AQ-induced specific morphological alterations (severe swelling and/or localization of hemozoin) were observed in the worms at 5 and 10 μg/ml. The AQ-specific appearance of the male worms gradually faded during subsequent incubation in drug-free media, although the female worms showed elongation. Meanwhile, PZQ inhibited the egg output of adult worm pairs at concentrations of 0.01–0.1 μg/ml during exposure. The inhibitory effect on egg production continued at 0.05 and 0.1 μg/ml but proved temporary at 0.01 and 0.02 μg/ml. Furthermore, PZQ induced a visible contraction and shortening of the male and female worms at 0.05 and 0.1 μg/ml during exposure, but the PZQ-specific alterations quickly disappeared during subsequent incubation in drug-free media. To our knowledge, this is the first report showing that one-day exposure to AQ inhibits the egg production of adult worm pairs at 1–10 μg/ml and induces specific morphological alterations in the worms at 5 and 10 μg/ml. The present findings have important implications for the evaluation of the therapeutic effects of both AQ monotherapy and combination therapy with artesunate on schistosomiasis in clinical field trials.
ABSTRACT
Studies on mechanisms of antimalarial action of artemisinin and its derivatives had been reviewed after artemisinin as an antimalarial drug was developed in 1972. The research work, which was mainly done by Chinese scholars, was introduced in the paper, and comprised 4 aspects:histopathology on the ultrastructure by electro-microscopy, the metabolism including the pigment clumping of the malarial parasite by biochemical pharmacology, and oxidation and Fe iron’s effect that were discussed in details based on studies from both domestic and international labs.
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Aims: To assess the pattern of antimalarial drug use among the patients attending the teaching hospital in Jos North local Government of Nigeria. Study Design: Cross-sectional study. Place and Duration of Study: Tertiary hospital in Jos North Local Government of Plateau state of Nigeria, between July and September, 2012. Methodology: A sample size of 441 male and female patients was selected into this study using a universal sampling. Information on the knowledge, attitudes and practices with respect to antimalarial drug use were obtained with the aid of a pre-tested interviewer-administered questionnaire. Data was analyzed using the SPSS software. Results: Four hundred and forty one (441) patients completed the questionnaire. Respondent knowledge of malaria with respect to description of malaria decreased (42.7% to 0.2%). Almost all the patients were able to describe the causes and symptoms of malaria. One hundred and sixty nine (38.3%) frequently treated their malaria with Sulphadoxine-Pyrimethamine (SP) combination, Three hundred and eighty two (86.6%) reported to have used oral preparation, almost half of the respondents (47.6%) obtained these medications from many sources apart from hospitals, only two hundred and forty eight reported to comply to treatment. Majority of the participants always used some methods for the prevention of malaria Conclusion: Concerted effort should be made to educate the population on malaria as well as the importance of drug adherence.
ABSTRACT
In this study, the in vitro effects of amodiaquine (AQ) monotherapy on the egg output of paired adult Schistosoma mansoni worms and their survival during in vitro culture were assessed. In addition, the gross morphological alterations of male and female worms caused by AQ were visually observed under a dissecting microscope. AQ significantly reduced the daily egg output of paired adult S. mansoni worms following incubation for 14 days at 1-5 µg/mL, but not at 0.5 µg/mL, compared with the control group. AQ also reduced the survival of male and female worms at concentrations of 2 and 5 µg/mL, respectively. Moreover, exposure to 5 µg/mL AQ caused severe swelling and/or localisation of black content in the body of all male and female worms within one or two days of incubation; subsequently, shrinkage in the male worms and elongation in the female worms were observed. The initial morphological alterations caused by AQ occurred along the intestinal tract of the male and female worms. To our knowledge, this is the first study to report not only the efficacy of AQ at concentrations lower than 5 µg/mL on paired adult S. mansoni worms, but also the effects of AQ on the intestinal tracts of worms in in vitro culture.
Subject(s)
Animals , Female , Male , Amodiaquine/pharmacology , Schistosoma mansoni/drug effects , Schistosomicides/pharmacology , Dose-Response Relationship, Drug , Time FactorsABSTRACT
<p><b>OBJECTIVE</b>To compare the applicability of the SYBR Green-I assay with the standard schizont maturation assay, for determination of sensitivity of Plasmodium vivax (P. vivax) to chloroquine and a new antifolate WR 99210.</p><p><b>METHODS</b>The study was conducted at Mae Tao Clinic for migrant workers, Tak Province during April 2009 to July 2010. A total of 64 blood samples (1 mL blood collected into sodium heparinized plastic tube) were collected from patients with mono-infection with P. vivax malaria prior to treatment with standard regimen of a 3-day chloroquine. In vitro sensitivity of P. vivax isolates was evaluated by schizont maturation inhibition and SYBR Green-I assays.</p><p><b>RESULTS</b>A total of 30 out of 64 blood samples collected from patients with P. vivax malaria were successfully analyzed using both the microscopic schizont maturation inhibition and SYBR Green-I assays. The failure rates of the schizont maturation inhibition assay (50%) and the SYBR Green-I assay (54%) were similar (P=0.51). The median IC10s, IC50s and IC90s of both chloroquine and WR99210 were not significantly different from the clinical isolates of P. vivax tested. Based on the cut-off of 100 nM, the prevalences of chloroquine resistance determined by schizont maturation inhibition and SYBR Green-I assays were 19 and 11 isolates, respectively. The strength of agreement between the two methods was very poor for both chloroquine and WR99210.</p><p><b>CONCLUSIONS</b>On the basis of this condition and its superior sensitivity, the microscopic method appears better than the SYBR Green-I Green assay for assessing in vitro sensitivity of fresh P. vivax isolates to antimalarial drugs.</p>
Subject(s)
Humans , Antimalarials , Pharmacology , Chloroquine , Pharmacology , Inhibitory Concentration 50 , Malaria, Vivax , Parasitology , Organic Chemicals , Parasitemia , Parasitology , Parasitic Sensitivity Tests , Plasmodium vivax , SchizontsABSTRACT
The plasmepsins are the aspartic proteases of malaria parasites. Treatment of aspartic protease inhibitor inhibits hemoglobin hydrolysis and blocks the parasite development in vitro suggesting that these proteases might be exploited their potentials as antimalarial drug targets. In this study, we determined the genetic variations of the aspartic proteases of Plasmodium vivax (PvPMs) of wild isolates. Two plasmepsins (PvPM4 and PvPM5) were cloned and sequenced from 20 P. vivax Korean isolates and two imported isolates. The sequences of the enzymes were highly conserved except a small number of amino acid substitutions did not modify key residues for the function or the structure of the enzymes. The high sequence conservations between the plasmepsins from the isolates support the notion that the enzymes could be reliable targets for new antimalarial chemotherapeutics.
Subject(s)
Animals , Humans , Amino Acid Sequence , Aspartic Acid Endopeptidases/genetics , Base Sequence , Cloning, Molecular , Conserved Sequence , DNA, Protozoan/chemistry , Molecular Sequence Data , Plasmodium vivax/enzymology , Polymerase Chain Reaction , Sequence Alignment , Sequence Analysis, DNAABSTRACT
Antimalarial drug samples were collected from different parts of the country for quality investigation in 2004. A total of 129 samples of different batches were collected at three rounds and cross-checked at local, central level and abroad. At the round one, three out of 49 collected samples were found substandard. One of 40 samples of the second round was determined counterfeit (2.5%). The re-analysis of 51 samples at NIDQC revealed two from the first round were substandard and one from the second round was counterfeit
Subject(s)
Malaria , Therapeutics , Pharmaceutical PreparationsABSTRACT
Background: Monitoring antimalarial drug quality should be conducted regularly in locals to enhance the effect of treatment for malaria \r\n', u'Objective: to study and analyze antimalarial drug quality\r\n', u'Subjects and methods: The study was carried out in 2007 for 5 provinces supported by the Global Fund: Ha Giang, Dien Bien, Thanh Hoa, Quang Tri and Gia Lai. Material were malaria drugs: artesunat, chloroquin, quinine, mefloquin, fansidar\u2026etc\r\n', u'Results and conclusion: The strict supervision on the anti-malarial drug quality by the National Malaria Control Program was very good and no substandard antimalarial drugs were detected. Evaluation of antimalarial drug quality and control was made for finding out the counterfeit drugs through sentinel sites in both private and public sectors. A total of 268 samples were collected, of which 13 samples were found substandard drugs (8 samples collected in private and 5 samples in public sectors). No counterfeit drugs were found. \r\n', u'
Subject(s)
Antimalarials , Environmental MonitoringABSTRACT
Background: Dihydroartemisinin 40mg and piperaquine phosphate 320mg (DHA-PQP) drug combination and piperaquin phosphate (PQP) material was first successfully produced in Vietnam \r\n', u'Objective: to study influences of the fixed combination antimalaria drug dihydroartemisinin plus piperaquine in reproductive progress of mice\r\n', u"Subjects and methods: This study was carried out at the Department of Malaria treatment and research, National Institute of Malariology, Parasitology and Entomology (NIMPE), between September, 2006 and March, 2007. The influences of the fixed combination antimalarial drug 40 mg dihydroartemisinin (DHA) plus 320 mg piperaquine phosphate (PQP), with PQP produced firstly in Vietnam, in mice's reproductive progresses were investigated in three generations (including the parent and FI, F2 child generations). \r\n", u'Results: In all three generations, study indices among the treated and control groups were not significantly different (the values P > 0.05). These indices included the rate of fecundation, numbers of fetuses of each mother mouse, numbers of offspring of each mother mouse, mean body weights of offspring. Early lethal fetuses, lately lethal fetuses, monsters and innate abnormally offspring were not found in P, FI and F2 generations. The necessary feeding - day numbers that offspring of P and F 1 generations reached their body weights about 20g were different insignificantly (the values P> 0.05) among the treated and control groups. \r\n', u'Conclusion: The combination DHA-PQP was found to cause no genome mutations in mice at the oral dose of 120 mg per kg per day for 5 consecutive days. \r\n', u'
Subject(s)
FetusABSTRACT
The coupling procedure of antimalarial agent (SR2) onto polymeric carrier (SR1) by covalent bond (amide linkage) was studied. Some factors of drug coupling reaction was investigated.
Subject(s)
Antimalarials , Pharmaceutical Preparations , Drug TherapyABSTRACT
After a single oral dosed mg/kg) of nitroquine to the mice infected with Plasmodium yoelii,the morphological changes of the parasites were studied with optical and electron microscopy.Enlarged nucleus and some red granules scattered over the cytoplasm in the late trophozoites were observed under optical microscope,which may correspond to the autophagocytic vacuo-les or membranous residual bodies seen under electron microscope.Thirty minutes after the drug administration,the number of mitochondria with matrix cavitation was increased,the endoplasmic reticulum dilated,and ribosomes separated,detached,or disaggregated.Then the pelliculous complex and nuclear membrane of the parasites proliferated to form multi-layered structure with spiral curv?s or myelin sheath-like structure in the cytoplasm.The nuclear membrane was swollen and proliferated and the perinuclear cisterna was widened.In the late stage of drug action,the structure of the parasites was broken down to form a large number of autophagocytes.The findings indicate that nitroquine interferes with the structure and function of the cell membrane,cytoplasm and nucleus of malaria parasites and exerts its anti-malarial effects from many aspects.
ABSTRACT
The effects of nitroquine on the sporogonic development of Plasmo-dium yoelii were observed under electron microscopy. The female mosquitoes were fed directly with 10% sucrose solution containing 0.1%Nitroquine.It was found that the oocysts were smaller and markedly degenerated as compared with that of the control. The surface of the oocysts was rough and uneven. Under a transmission electron microscope, the cytoplasm of the affected oocysts contained vacuoles; the membane of mitochondria and uncleus was damaged; and the number of residual bodies increased.No sporoblast formation was seen in most of the affectes oocysts. The nuclear membrane of the degenerated sporozoites was thickened and the density of nuclear matrix decreased markedly as compared with that of the control. These results indicate that the nucleus and the membrane are mainly affected during the sporogonic development of P. yoelii by nitroquine.
ABSTRACT
The toxic effects of nitroquine-dapson compound(NQD) per os in mice and dogs were studied. The therapeutic index of NQD in mice(1911) is the highest among the six antimalarial preparations studied. The toxic effects(50mg/kg/ day for 3 successive days per os) in dogs were similar to those of nitroquine. They manifested themselves as the injury on the adrenal cortex and on the intestinal epithelium. When folic acid (4 mg/kg/day for 4 successive days) or folinic acid(0.3 mg/kg/day for 4 successive days) was administered intramuscularly to the toxicated animals, both the death rate and the incidence of diarrhea were greatly reduced. Pathological study confirmed that the injury on the intestinal epithelium was much milder and the goblet cell was much more numerous in the treated than in the untreated. The results suggest that folic acid or folinic acid can protect the less differentiated cells in the intestinal crypts, so that the clinical manifestations of NQD toxicity are reduced after treatment.