Displaying publications 1 - 20 of 86 in total

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  1. Fulltext Plasmodium knowlesi exhibits distinct in vitro drug susceptibility profiles from those of Plasmodium falciparum
    van Schalkwyk DA, Blasco B, Davina Nuñez R, Liew JWK, Amir A, Lau YL, et al.
    Int J Parasitol Drugs Drug Resist, 2019 04;9:93-99.
    PMID: 30831468 DOI: 10.1016/j.ijpddr.2019.02.004
    New antimalarial agents are identified and developed after extensive testing on Plasmodium falciparum parasites that can be grown in vitro. These susceptibility studies are important to inform lead optimisation and support further drug development. Until recently, little was known about the susceptibility of non-falciparum species as these had not been adapted to in vitro culture. The recent culture adaptation of P. knowlesi has therefore offered an opportunity to routinely define the drug susceptibility of this species, which is phylogenetically closer to all other human malarias than is P. falciparum. We compared the in vitro susceptibility of P. knowlesi and P. falciparum to a range of established and novel antimalarial agents under identical assay conditions. We demonstrated that P. knowlesi is significantly less susceptible than P. falciparum to six of the compounds tested; and notably these include three ATP4 inhibitors currently under development as novel antimalarial agents, and one investigational antimalarial, AN13762, which is 67 fold less effective against P. knowlesi. For the other compounds there was a less than two-fold difference in susceptibility between species. We then compared the susceptibility of a recent P. knowlesi isolate, UM01, to that of the well-established, older A1-H.1 clone. This recent isolate showed similar in vitro drug susceptibility to the A1-H.1 clone, supporting the ongoing use of the better characterised clone to further study drug susceptibility. Lastly, we used isobologram analysis to explore the interaction of a selection of drug combinations and showed similar drug interactions across species. The species differences in drug susceptibility reported by us here and previously, support adding in vitro drug screens against P. knowlesi to those using P. falciparum strains to inform new drug discovery and lead optimisation.
    Matched MeSH terms: Antimalarials/pharmacology*
  2. Fulltext Gancidin W, a potential low-toxicity antimalarial agent isolated from an endophytic Streptomyces SUK10
    Zin NM, Baba MS, Zainal-Abidin AH, Latip J, Mazlan NW, Edrada-Ebel R
    Drug Des Devel Ther, 2017;11:351-363.
    PMID: 28223778 DOI: 10.2147/DDDT.S121283
    Endophytic Streptomyces strains are potential sources for novel bioactive molecules. In this study, the diketopiperazine gancidin W (GW) was isolated from the endophytic actinobacterial genus Streptomyces, SUK10, obtained from the bark of Shorea ovalis tree, and it was tested in vivo against Plasmodium berghei PZZ1/100. GW exhibited an inhibition rate of nearly 80% at 6.25 and 3.125 μg kg-1 body weight on day four using the 4-day suppression test method on male ICR strain mice. Comparing GW at both concentrations with quinine hydrochloride and normal saline as positive and negative controls, respectively, 50% of the mice treated with 3.125 μg kg-1 body weight managed to survive for more than 11 months after infection, which almost reached the life span of normal mice. Biochemical tests of selected enzymes and proteins in blood samples of mice treated with GW were also within normal levels; in addition, no abnormalities or injuries were found on internal vital organs. These findings indicated that this isolated bioactive compound from Streptomyces SUK10 exhibits very low toxicity and is a good candidate for potential use as an antimalarial agent in an animal model.
    Matched MeSH terms: Antimalarials/pharmacology*
  3. Fulltext A Basis for Rapid Clearance of Circulating Ring-Stage Malaria Parasites by the Spiroindolone KAE609
    Zhang R, Suwanarusk R, Malleret B, Cooke BM, Nosten F, Lau YL, et al.
    J Infect Dis, 2016 Jan 1;213(1):100-4.
    PMID: 26136472 DOI: 10.1093/infdis/jiv358
    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.
    Matched MeSH terms: Antimalarials/pharmacology*
  4. Fulltext Updates on k13 mutant alleles for artemisinin resistance in Plasmodium falciparum
    Zaw MT, Emran NA, Lin Z
    J Microbiol Immunol Infect, 2018 Apr;51(2):159-165.
    PMID: 28711439 DOI: 10.1016/j.jmii.2017.06.009
    BACKGROUND: In the fight against malaria caused by Plasmodium falciparum, the successes achieved by artemisinin were endangered by resistance of the parasites to the drug. Whole genome sequencing approach on artemisinin resistant parasite line discovered k13 gene associated with drug resistance. In vitro and in vivo studies indicated mutations in the k13 gene were linked to the artemisinin resistance.

    METHODOLOGY: The literatures published after April, 2015 up to December, 2016 on k13 mutant alleles for artemisinin resistance in Plasmodium falciparum and relevant literatures were comprehensively reviewed.

    RESULTS: To date, 13 non-synonymous mutations of k13 gene have been observed to have slow parasite clearance. Worldwide mapping of k13 mutant alleles have shown mutants associated with artemisinin resistance were confined to southeast Asia and China and did not invade to African countries. Although in vitro ring stage survival assay of 0-3 h was a recently developed assay, it was useful for rapid detection of artemisinin resistance associated k13 allelic marker in the parasite. Recently, dissemination of k13 mutant alleles was recommended to be investigated by identity of haplotypes. Significant characteristics of well described alleles in the reports were mentioned in this review for the benefit of future studies.

    CONCLUSION: According to the updates in the review, it can be concluded artemisinin resistance does not disseminate to India and African countries within short period whereas regular tracking of these mutants is necessary.

    Matched MeSH terms: Antimalarials/pharmacology*
  5. Antiplasmodial and antioxidant isoquinoline alkaloids from Dehaasia longipedicellata
    Zahari A, Cheah FK, Mohamad J, Sulaiman SN, Litaudon M, Leong KH, et al.
    Planta Med, 2014 May;80(7):599-603.
    PMID: 24723007 DOI: 10.1055/s-0034-1368349
    The crude extract of the bark of Dehaasia longipedicellata exhibited antiplasmodial activity against the growth of Plasmodium falciparum K1 isolate (resistant strain). Phytochemical studies of the extract led to the isolation of six alkaloids: two morphinandienones, (+)-sebiferine (1) and (-)-milonine (2); two aporphines, (-)-boldine (3) and (-)-norboldine (4); one benzlyisoquinoline, (-)-reticuline (5); and one bisbenzylisoquinoline, (-)-O-O-dimethylgrisabine (6). Their structures were determined on the basis of 1D and 2D NMR, IR, UV, and LCMS spectroscopic techniques and upon comparison with literature values. Antiplasmodial activity was determined for all of the isolated compounds. They showed potent to moderate activity with IC50 values ranging from 0.031 to 30.40 µM. (-)-O-O-dimethylgrisabine (6) and (-)-milonine (2) were the two most potent compounds, with IC50 values of 0.031 and 0.097 µM, respectively, that were comparable to the standard, chloroquine (0.090 µM). The compounds were also assessed for their antioxidant activities with di(phenyl)-(2,4,6-trinitrophenyl)iminoazanium (IC50 = 18.40-107.31 µg/mL), reducing power (27.40-87.40 %), and metal chelating (IC50 = 64.30 to 257.22 µg/mL) having good to low activity. (-)-O-O-dimethylgrisabine (6) exhibited a potent antioxidant activity of 44.3 % reducing power, while di(phenyl)-(2,4,6-trinitrophenyl)iminoazanium and metal chelating activities had IC50 values of 18.38 and 64.30 µg/mL, respectively. Thus it may be considered as a good reductant with the ability to chelate metal and prevent pro-oxidant activity. In addition to the antiplasmodial and antioxidant activities, the isolated compounds were also tested for their cytotoxicity against a few cancer and normal cell lines. (-)-Norboldine (4) exhibited potent cytotoxicity towards pancreatic cancer cell line BxPC-3 with an IC50 value of 27.060 ± 1.037 µM, and all alkaloids showed no toxicity towards the normal pancreatic cell line (hTERT-HPNE).
    Matched MeSH terms: Antimalarials/pharmacology*
  6. Lansium domesticum: skin and leaf extracts of this fruit tree interrupt the lifecycle of Plasmodium falciparum, and are active towards a chloroquine-resistant strain of the parasite (T9) in vitro
    Yapp DT, Yap SY
    J Ethnopharmacol, 2003 Mar;85(1):145-50.
    PMID: 12576213
    Malaria remains a global problem in the light of chloroquine-resistant strains of Plasmodium falciparum. New compounds are needed for the development of novel antimalarial drugs. Seed, leaf, and fruit skin extracts of Lansium domesticum, a common fruit tree in South-East Asia, are used by indigenous tribes in Sabah, Malaysia for treating malaria. The skin and aqueous leaf extracts of the tree were found to reduce parasite populations of the drug sensitive strain (3D7) and the chloroquine-resistant strain (T9) of P. falciparum equally well. The skin extracts were also found to interrupt the lifecycle of the parasite. The data reported here indicate that extracts of L. domesticum are a potential source for compounds with activity towards chloroquine-resistant strains of P. falciparum.
    Matched MeSH terms: Antimalarials/pharmacology*
  7. Fulltext Assessment of antiproliferative and antiplasmodial activities of five selected Apocynaceae species
    Wong SK, Lim YY, Abdullah NR, Nordin FJ
    BMC Complement Altern Med, 2011;11:3.
    PMID: 21232161 DOI: 10.1186/1472-6882-11-3
    Studies have shown that the barks and roots of some Apocynaceae species have anticancer and antimalarial properties. In this study, leaf extracts of five selected species of Apocynaceae used in traditional medicine (Alstonia angustiloba, Calotropis gigantea, Dyera costulata, Kopsia fruticosa and Vallaris glabra) were assessed for antiproliferative (APF) and antiplasmodial (APM) activities, and analysed for total alkaloid content (TAC), total phenolic content (TPC) and radical-scavenging activity (RSA). As V. glabra leaf extracts showed wide spectrum APF and APM activities, they were further screened for saponins, tannins, cardenolides and terpenoids.
    Matched MeSH terms: Antimalarials/pharmacology*
  8. Fulltext Ferroquine and its derivatives: new generation of antimalarial agents
    Wani WA, Jameel E, Baig U, Mumtazuddin S, Hun LT
    Eur J Med Chem, 2015 Aug 28;101:534-51.
    PMID: 26188909 DOI: 10.1016/j.ejmech.2015.07.009
    Malaria has been teasing human populations from a long time. Presently, several classes of antimalarial drugs are available in market, but the issues of toxicity, lower efficacy and the resistance by malarial parasites have decreased their overall therapeutic indices. Thus, the search for new promising antimalarials continues, however, the battle against malaria is far from over. Ferroquine is a derivative of chloroquine with antimalarial properties. It is the most successful of the chloroquine derivatives. Not only ferroquine, but also its derivatives have shown promising potential as antimalarials of clinical interest. Presently, much research is dedicated to the development of ferroquine derivatives as safe alternatives to antimalarial chemotherapy. The present article describes the structural, chemical and biological features of ferroquine. Several classes of ferroquine derivatives including hydroxyferroquines, trioxaferroquines, chloroquine-bridged ferrocenophanes, thiosemicarbazone derivatives, ferrocene dual conjugates, 4-N-substituted derivatives, and others have been discussed. Besides, the mechanism of action of ferroquine has been discussed. A careful observation has been made into pharmacologically significant ferroquine derivatives with better or equal therapeutic effects to that of chloroquine and ferroquine. A brief discussion of the toxicities of ferroquine derivatives has been made. Finally, efforts have been made to discuss the current challenges and future perspectives of ferroquine-based antimalarial drug development.
    Matched MeSH terms: Antimalarials/pharmacology*
  9. Fulltext Heterologous Expression of a Novel Drug Transporter from the Malaria Parasite Alters Resistance to Quinoline Antimalarials
    Tindall SM, Vallières C, Lakhani DH, Islahudin F, Ting KN, Avery SV
    Sci Rep, 2018 02 06;8(1):2464.
    PMID: 29410428 DOI: 10.1038/s41598-018-20816-0
    Antimalarial drug resistance hampers effective malaria treatment. Critical SNPs in a particular, putative amino acid transporter were recently linked to chloroquine (CQ) resistance in malaria parasites. Here, we show that this conserved protein (PF3D7_0629500 in Plasmodium falciparum; AAT1 in P. chabaudi) is a structural homologue of the yeast amino acid transporter Tat2p, which is known to mediate quinine uptake and toxicity. Heterologous expression of PF3D7_0629500 in yeast produced CQ hypersensitivity, coincident with increased CQ uptake. PF3D7_0629500-expressing cultures were also sensitized to related antimalarials; amodiaquine, mefloquine and particularly quinine. Drug sensitivity was reversed by introducing a SNP linked to CQ resistance in the parasite. Like Tat2p, PF3D7_0629500-dependent quinine hypersensitivity was suppressible with tryptophan, consistent with a common transport mechanism. A four-fold increase in quinine uptake by PF3D7_0629500 expressing cells was abolished by the resistance SNP. The parasite protein localised primarily to the yeast plasma membrane. Its expression varied between cells and this heterogeneity was used to show that high-expressing cell subpopulations were the most drug sensitive. The results reveal that the PF3D7_0629500 protein can determine the level of sensitivity to several major quinine-related antimalarials through an amino acid-inhibitable drug transport function. The potential clinical relevance is discussed.
    Matched MeSH terms: Antimalarials/pharmacology*
  10. Current progress in antimalarial pharmacotherapy and multi-target drug discovery
    Tibon NS, Ng CH, Cheong SL
    Eur J Med Chem, 2020 Feb 15;188:111983.
    PMID: 31911292 DOI: 10.1016/j.ejmech.2019.111983
    Discovery and development of antimalarial drugs have long been dominated by single-target therapy. Continuous effort has been made to explore and identify different targets in malaria parasite crucial for the malaria treatment. The single-target drug therapy was initially successful, but it was later supplanted by combination therapy with multiple drugs to overcome drug resistance. Emergence of resistant strains even against the combination therapy has warranted a review of current antimalarial pharmacotherapy. This has led to the development of the new concept of covalent biotherapy, in which two or more pharmacophores are chemically bound to produce hybrid antimalarial drugs with multi-target functionalities. Herein, the review initially details the current pharmacotherapy for malaria as well as the conventional and novel targets of importance identified in the malaria parasite. Then, the rationale of multi-targeted therapy for malaria, approaches taken to develop the multi-target antimalarial hybrids, and the examples of hybrid molecules are comprehensively enumerated and discussed.
    Matched MeSH terms: Antimalarials/pharmacology*
  11. Leucophyllinines A and B, bisindole alkaloids from Leuconotis eugeniifolia
    Tang Y, Nugroho AE, Hirasawa Y, Tougan T, Horii T, Hadi AHA, et al.
    J Nat Med, 2019 Jun;73(3):533-540.
    PMID: 30911994 DOI: 10.1007/s11418-019-01297-5
    Two new bisindole alkaloids, leucophyllinines A (1) and B (2) consisting of eburnane and quebrachamine-type skeletons were isolated from the bark of Leuconotis eugeniifolia, and their structures were elucidated on the basis of spectroscopic data. Leucophyllinines A and B showed antiplasmodial activities against Plasmodium falciparum 3D7.
    Matched MeSH terms: Antimalarials/pharmacology*
  12. Fulltext Anti-malarial and anti-inflammatory effects of Gleichenia truncata mediated through inhibition of GSK3β
    Suhaini S, Liew SZ, Norhaniza J, Lee PC, Jualang G, Embi N, et al.
    Trop Biomed, 2015 Sep;32(3):419-33.
    PMID: 26695202 MyJurnal
    Gleichenia truncata is a highland fern from the Gleicheniaceae family known for its traditional use among indigenous communities in Asia to treat fever. The scientific basis of its effect has yet to be documented. A yeast-based kinase assay conducted in our laboratory revealed that crude methanolic extract (CME) of G. truncata exhibited glycogen synthase kinase-3 (GSK3)-inhibitory activity. GSK3β is now recognized to have a pivotal role in the regulation of inflammatory response during bacterial infections. We have also previously shown that lithium chloride (LiCl), a GSK3 inhibitor suppressed development of Plasmodium berghei in a murine model of malarial infection. The present study is aimed at evaluating G. truncata for its anti-malarial and anti-inflammatory effects using in vivo malarial and melioidosis infection models respectively. In a four-day suppressive test, intraperitoneal injections of up to 250 mg/kg body weight (bw) G. truncata CME into P.berghei-infected mice suppressed parasitaemia development by >60%. Intraperitoneal administration of 150 mg/kg bw G. truncata CME into Burkholderia pseudomallei-infected mice improved survivability by 44%. G. truncata CME lowered levels of pro-inflammatory cytokines (TNF-α, IFN-γ) in serum and organs of B. pseudomallei-infected mice. In both infections, increased phosphorylations (Ser9) of GSK3β were detected in organ samples of animals administered with G. truncata CME compared to controls. Taken together, results from this study strongly suggest that the anti-malarial and anti-inflammatory effects elicited by G. truncata in part were mediated through inhibition of GSK3β. The findings provide scientific basis for the ethnomedicinal use of this fern to treat inflammation-associated symptoms.
    Matched MeSH terms: Antimalarials/pharmacology*
  13. Fulltext Molecular characterization of Plasmodium falciparum antifolate resistance markers in Thailand between 2008 and 2016
    Sugaram R, Suwannasin K, Kunasol C, Mathema VB, Day NPJ, Sudathip P, et al.
    Malar J, 2020 Mar 04;19(1):107.
    PMID: 32127009 DOI: 10.1186/s12936-020-03176-x
    BACKGROUND: Resistance to anti-malarials is a major threat to the control and elimination of malaria. Sulfadoxine-pyrimethamine (SP) anti-malarial treatment was used as a national policy for treatment of uncomplicated falciparum malaria in Thailand from 1973 to 1990. In order to determine whether withdrawal of this antifolate drug has led to restoration of SP sensitivity, the prevalence of genetic markers of SP resistance was assessed in historical Thai samples.

    METHODS: Plasmodium falciparum DNA was collected from the Thailand-Myanmar, Thailand-Malaysia and Thailand-Cambodia borders during 2008-2016 (N = 233). Semi-nested PCR and nucleotide sequencing were used to assess mutations in Plasmodium falciparum dihydrofolate reductase (pfdhfr), P. falciparum dihydropteroate synthase (pfdhps). Gene amplification of Plasmodium falcipaurm GTP cyclohydrolase-1 (pfgch1) was assessed by quantitative real-time PCR. The association between pfdhfr/pfdhps mutations and pfgch1 copy numbers were evaluated.

    RESULTS: Mutations in pfdhfr/pfdhsp and pfgch1 copy number fluctuated overtime through the study period. Altogether, 14 unique pfdhfr-pdfhps haplotypes collectively containing quadruple to octuple mutations were identified. High variation in pfdhfr-pfdhps haplotypes and a high proportion of pfgch1 multiple copy number (51% (73/146)) were observed on the Thailand-Myanmar border compared to other parts of Thailand. Overall, the prevalence of septuple mutations was observed for pfdhfr-pfdhps haplotypes. In particular, the prevalence of pfdhfr-pfdhps, septuple mutation was observed in the Thailand-Myanmar (50%, 73/146) and Thailand-Cambodia (65%, 26/40) border. In Thailand-Malaysia border, majority of the pfdhfr-pfdhps haplotypes transaction from quadruple (90%, 9/10) to quintuple (65%, 24/37) during 2008-2016. Within the pfdhfr-pfdhps haplotypes, during 2008-2013 the pfdhps A/S436F mutation was observed only in Thailand-Myanmar border (9%, 10/107), while it was not identified later. In general, significant correlation was observed between the prevalence of pfdhfr I164L (ϕ = 0.213, p-value = 0.001) or pfdhps K540E/N (ϕ = 0.399, p-value ≤ 0.001) mutations and pfgch1 gene amplification.

    CONCLUSIONS: Despite withdrawal of SP as anti-malarial treatment for 17 years, the border regions of Thailand continue to display high prevalence of antifolate and anti-sulfonamide resistance markers in falciparum malaria. Significant association between pfgch1 amplification and pfdhfr (I164L) or pfdhps (K540E) resistance markers were observed, suggesting a compensatory mutation.

    Matched MeSH terms: Antimalarials/pharmacology*
  14. Malaria, anti malarial drugs and the role of melatonin
    Srinivasan V, Mohamed M, Zakaria R, Ahmad AH
    Infect Disord Drug Targets, 2012 Oct;12(5):371-9.
    PMID: 23082960
    Malaria, one of the most deadly diseases of our time affects more than 200 million people across the globe and is responsible for about one million deaths annually. Until recently Plasmodium falciparum has been the main cause for malarial infection in human beings but now Plasmodium knowlesi from Malaysia remains as one of the most virulent parasite spreading fast not only in Malaysia but in different parts of the world. Hence there is urgent need for the global fight to control malaria. Global malaria eradication program by use of insecticide spraying has resulted in good response in the past. Treatment of malaria infected patients with anti-malarial drugs has helped to eliminate malarial infections successfully but with increased resistance displayed by malarial parasites to these drugs there is resurgence of malaria caused both by drug resistance as well as by infection caused by new malarial species like Plasmodium knowlesi. With recent advances on molecular studies on malarial parasites it is now clear that the pineal hormone melatonin acts as a cue for growth and development of Plasmodium falciparum. Same may be true for Plasmodium knowlesi also. Hence treatment modalities that can effectively block the action of melatonin on Plasmodium species during night time by way of using either bright light therapy or use of melatonin receptor blocking can be considered as useful approaches for eliminating malarial infection in man.
    Matched MeSH terms: Antimalarials/pharmacology*
  15. Differential effects of ketoconazole and primaquine on the pharmacokinetics and tissue distribution of imatinib in mice
    Soo GW, Law JH, Kan E, Tan SY, Lim WY, Chay G, et al.
    Anticancer Drugs, 2010 Aug;21(7):695-703.
    PMID: 20629201
    Imatinib, a selective inhibitor of c-KIT and Bcr-Abl tyrosine kinases, approved for the treatment of chronic myelogenous leukemia and gastrointestinal stromal tumors, shows further therapeutic potential for gliomas, glioblastoma, renal cell carcinoma, autoimmune nephritis and other neoplasms. It is metabolized by CYP3A4, is highly bound to alpha-1-acid glycoprotein and is a P-glycoprotein substrate limiting its brain distribution. We assess imatinib's protein binding interaction with primaquine, which also binds to alpha-1-acid glycoprotein, and its metabolic interaction with ketoconazole, which is a CYP3A4 inhibitor, on its pharmacokinetics and biodistribution. Male ICR mice, 9-12 weeks old were given imatinib PO (50 mg/kg) alone or co-administered with primaquine (12.5 mg/kg), ketoconazole (50 mg/kg) or both, and imatinib concentration in the plasma, kidney, liver and brain was measured at prescheduled time points by HPLC. Noncompartmental pharmacokinetic parameters were estimated. Primaquine increased 1.6-fold plasma AUC(0)--> infinity, C(Max) decreased 24%, T(Max) halved and t(1/2) and mean residence time were longer. Ketoconazole increased plasma AUC(0)-->infinity 64% and doubled the C(Max), but this dose did not affect t(1/2) or mean residence time. When ketoconazole and primaquine were co-administered, imatinib AUC(0)-->infinity and C(Max) increased 32 and 35%, respectively. Ketoconazole did not change imatinib's distribution efficiency in the liver and kidney, primaquine increased it two-fold and it was larger when both the drugs were co-administered with imatinib. Ketoconazole did not change brain penetration but primaquine increased it approximately three-fold. Ketoconazole and primaquine affect imatinib clearance, bioavailability and distribution pattern, which could improve the treatment of renal and brain tumors, but also increase toxicity. This would warrant hepatic and renal functions monitoring.
    Matched MeSH terms: Antimalarials/pharmacology*
  16. The screening of extracts from Goniothalamus scortechinii, Aralidium pinnatifidum and Andrographis paniculata for anti-malarial activity using the lactate dehydrogenase assay
    Siti Najila MJ, Noor Rain A, Mohamad Kamel AG, Syed Zahir SI, Khozirah S, Lokman Hakim S, et al.
    J Ethnopharmacol, 2002 Oct;82(2-3):239-42.
    PMID: 12242001
    Goniothalamus scortechinii, Andrographis paniculata and Aralidium pinnatifidum were selected for the study based on their ethnomedicinal values. They were screened for anti-malarial activity towards Plasmodium falciparum in vitro using the lactate dehydrogenase (LDH) assay. The crude extract of G. scortechinii exhibited the most potent schizonticidal activity compared to the other extracts. It is effective against both the chloroquine resistant isolate, Gombak A and the sensitive strain, D10 of Plasmodium falciparum. Furthermore a better IC(50) value was obtained against the resistant strain, (9 microg/ml) compared to the sensitive strain, 40 microg/ml. When the crude extract was fractionated into 3 fractions, the chloroform fraction yielded the best activity, exhibiting equipotency against both strains of parasite used; IC(50) of 23.53 microg/ml against Gombak A and 21.06 microg/ml against D10.
    Matched MeSH terms: Antimalarials/pharmacology*
  17. Smart nanocrystals of artemether: fabrication, characterization, and comparative in vitro and in vivo antimalarial evaluation
    Shah SM, Ullah F, Khan S, Shah SM, de Matas M, Hussain Z, et al.
    Drug Des Devel Ther, 2016;10:3837-3850.
    PMID: 27920499
    Artemether (ARTM) is a very effective antimalarial drug with poor solubility and consequently low bioavailability. Smart nanocrystals of ARTM with particle size of 161±1.5 nm and polydispersity index of 0.172±0.01 were produced in <1 hour using a wet milling technology, Dena(®) DM-100. The crystallinity of the processed ARTM was confirmed using differential scanning calorimetry and powder X-ray diffraction. The saturation solubility of the ARTM nanocrystals was substantially increased to 900 µg/mL compared to the raw ARTM in water (145.0±2.3 µg/mL) and stabilizer solution (300.0±2.0 µg/mL). The physical stability studies conducted for 90 days demonstrated that nanocrystals stored at 2°C-8°C and 25°C were very stable compared to the samples stored at 40°C. The nanocrystals were also shown to be stable when processed at acidic pH (2.0). The solubility and dissolution rate of ARTM nanocrystals were significantly increased (P<0.05) compared to those of its bulk powder form. The results of in vitro studies showed significant antimalarial effect (P<0.05) against Plasmodium falciparum and Plasmodium vivax. The IC50 (median lethal oral dose) value of ARTM nanocrystals was 28- and 54-fold lower than the IC50 value of unprocessed drug and 13- and 21-fold lower than the IC50 value of the marketed tablets, respectively. In addition, ARTM nanocrystals at the same dose (2 mg/kg) showed significantly (P<0.05) higher reduction in percent parasitemia (89%) against P. vivax compared to the unprocessed (27%), marketed tablets (45%), and microsuspension (60%). The acute toxicity study demonstrated that the LD50 value of ARTM nanocrystals is between 1,500 mg/kg and 2,000 mg/kg when given orally. This study demonstrated that the wet milling technology (Dena(®) DM-100) can produce smart nanocrystals of ARTM with enhanced antimalarial activities.
    Matched MeSH terms: Antimalarials/pharmacology*
  18. Exploring Promising Immunomodulatory Potential of Natural and Synthetic 1,3-Diphenyl-2-propen-1-one Analogs: A Review of Mechanistic Insight
    Safdar MH, Hasan H, Afzal S, Hussain Z
    Mini Rev Med Chem, 2018;18(12):1047-1063.
    PMID: 29173165 DOI: 10.2174/1389557517666171123212039
    The immune system is an intricate and coordinated nexus serving as a natural defense to preclude internal and external pathogenic insults. The deregulation in the natural balance of immunological functions as a consequence of either over expression or under expression of immune cells tends to cause disruption of homeostasis in the body and may lead to development of numerous immune system disorders. Chalcone moieties (1,3-diphenyl-2-propen-1-one) have been well-documented as ideal lead compounds or precursors to design a wide range of pharmacologically active agents to down-regulate various immune disorders. Owing to their unique structural and molecular framework, these α, β-unsaturated carbonyl-based moieties have also gained remarkable recognition due to their other multifarious pharmacological properties including antifungal, anti-inflammatory, anti-malarial, antibacterial, anti-tuberculosis, and anticancer potential. Though a great number of methodologies are currently being employed for their synthesis, this review mainly focuses on the natural and synthetic chalcone derivatives that are exclusively synthesized via Claisen-Schmidt condensation reaction and their immunomodulatory prospects. We have critically reviewed the literature and provided convincing evidence for the promising efficacy of chalcone derivatives to modulate functioning of various innate and adaptive immune players including granulocytes, mast cells, monocytes, macrophages, platelets, dendritic cells, natural killer cells, and T-lymphocytes.
    Matched MeSH terms: Antimalarials/pharmacology
  19. The effects of hydroxychloroquine on endothelial dysfunction
    Rahman R, Murthi P, Singh H, Gurusinghe S, Mockler JC, Lim R, et al.
    Pregnancy Hypertens, 2016 Oct;6(4):259-262.
    PMID: 27939463 DOI: 10.1016/j.preghy.2016.09.001
    Hydroxychloroquine is an anti-malarial drug which, due to its anti-inflammatory and immunomodulatory effects, is widely used for the treatment of autoimmune diseases. In a model of systemic lupus erythematosus hydroxychloroquine has been shown to exert protective endothelial effects. In this study, we aimed to investigate whether hydroxychloroquine was endothelial protective in an in vitro model of TNF-α and preeclamptic serum induced dysfunction. We showed that hydroxychloroquine significantly reduced the production of TNF-α and preeclamptic serum induced endothelin-1 (ET-1). Hydroxychloroquine also significantly mitigated TNF-α induced impairment of angiogenesis. These findings support the further assessment of hydroxychloroquine as an adjuvant therapy in preeclampsia.
    Matched MeSH terms: Antimalarials/pharmacology*
  20. Fulltext Evaluation of the sensitivity in vitro of Plasmodium falciparum and in vivo of Plasmodium chabaudi Malaria to various drugs and their combinations
    Rahman NNNA
    Med J Malaysia, 1997 Dec;52(4):390-8.
    PMID: 10968116
    K1 strain of Plasmdoium falciparum is resistant in vitro to chloroquine, pyrimethamine and sulfadoxine. Response of this strain to combinations of antimalarial drugs in the in vitro hypoxanthine incorporation test was coupled with that of a line of strain NF54 relatively sensitive to chloroquine and fully sensitive to other antimalarials. Pyrimethamine and sulfadoxine showed potentiative synergism against NF54 and less marked against K1. Erythromycin and chloroquine showed potentiation, but less marked against NF54. Quinine and clindamycin had an additive effect against NF54 but potentiated against K1. Combinations of chloroquine with quinine or amodiaquine or of amodiaquine with clindamycin or erythromycin showed mild antagonistic or additive effects. In vivo studies in mice, using the 4-day suppressive test, the AS(3CQ) clone of Plasmodium chabaudi was resistant to pyrimethamine and chloroquine but sensitive to sulfadoxine. Similar combinations as above were carried out and their responses were compared between the resistant and sensitive strains. For both strains, the combinations of chloroquine-erythromycin, pyrimethamine-sulfadoxine, quinine-clindamycin showed potentiation; antagonistic effects were observed in chloroquine-amodiaquine combinations whereas when amodiaquine combined with erythromycin the effect was additive. Amodiaquine-clindamycin and chloroquine-quinine combinations have an antagonistic effect against the sensitive strain but additive against the resistant strain.
    Matched MeSH terms: Antimalarials/pharmacology*
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