Displaying publications 1 - 20 of 46 in total

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  1. Plasmodium knowlesi: the emerging zoonotic malaria parasite
    Antinori S, Galimberti L, Milazzo L, Corbellino M
    Acta Trop, 2013 Feb;125(2):191-201.
    PMID: 23088834 DOI: 10.1016/j.actatropica.2012.10.008
    Plasmodium knowlesi was initially identified in the 30s as a natural Plasmodium of Macaca fascicularis monkey also capable of experimentally infecting humans. It gained a relative notoriety in the mid-30s as an alternative to Plasmodium vivax in the treatment of the general paralysis of the insane (neurosyphilis). In 1965 the first natural human infection was described in a US military surveyor coming back from the Pahang jungle of the Malaysian peninsula. P. knowlesi was again brought to the attention of the medical community when in 2004, Balbir Singh and his co-workers reported that about 58% of malaria cases observed in the Kapit district of the Malaysian Borneo were actually caused by P. knowlesi. In the following years several reports showed that P. knowlesi is much more widespread than initially thought with cases reported across Southeast Asia. This infection should also be considered in the differential diagnosis of any febrile travellers coming back from a recent travel to forested areas of Southeast Asia. P. knowlesi can cause severe malaria with a rate of 6-9% and with a case fatality rate of 3%. Respiratory distress, acute renal failure, shock and hyperbilirubinemia are the most frequently observed complications of severe P. knowlesi malaria. Chloroquine is considered the treatment of choice of uncomplicated malaria caused by P. knowlesi.
    Matched MeSH terms: Chloroquine/pharmacology
  2. Molecular markers associated with resistance to commonly used antimalarial drugs among Plasmodium falciparum isolates from a malaria-endemic area in Taiz governorate-Yemen during the transmission season
    Alareqi LMQ, Mahdy MAK, Lau YL, Fong MY, Abdul-Ghani R, Mahmud R
    Acta Trop, 2016 Oct;162:174-179.
    PMID: 27343362 DOI: 10.1016/j.actatropica.2016.06.016
    Since 2005, artesunate (AS) plus sulfadoxine/pyrimethamine (SP) combination has been adopted as the first-line treatment for uncomplicated malaria in Yemen in response to the high level of Plasmodium falciparum resistance to chloroquine (CQ). Therefore, the aim of the present study was to determine the frequency distribution of molecular markers associated with resistance to CQ and AS plus SP combination among P. falciparum isolates from a malaria-endemic area in Taiz governorate, Yemen. Fifty P. falciparum isolates were collected during a cross-sectional study in Mawza district, Taiz, in the period from October 2013 to April 2014. The isolates were investigated for drug resistance-associated molecular markers in five genes, including P. falciparum CQ resistance transporter (pfcrt) 76T and P. falciparum multidrug resistance 1 (pfmdr1) 86Y as markers of resistance to CQ, mutations in the Kelch 13 (K13) propeller domain for resistance to AS, and P. falciparum dihydrofolate reductase (pfdhfr) and P. falciparum dihydropteroate synthase (pfdhps) genes for resistance to SP. Nested polymerase chain reaction was used to amplify target genes in DNA extracts of the isolates followed by restriction fragment length polymorphism for detecting 76T and 86Y mutations in pfcrt and pfmdr1, respectively, and by DNA sequencing for detecting mutations in K13, pfdhfr and pfdhps. All the investigated isolates from Mawza district were harboring the pfcrt 76T mutant and the pfmdr1 N86 wild-type alleles. The pfdhfr 51I/108N double mutant allele was found in 2.2% (1/45) of the isolates; however, no mutations were detected at codons 436, 437, 540, 581 and 613 of pfdhps. All P. falciparum isolates that were successfully sequenced (n=47) showed the K13 Y493, R539, I543 and C580 wild-type alleles. In conclusion, the pfcrt 76T mutant allele is fixed in the study area about six years after the official withdrawal of CQ, possibly indicating its over-the-counter availability and continued use as a self-medication in the study area. However, the almost predominant wild-type alleles of the genes associated with resistance to AS and SP among P. falciparum isolates in the present study indicates the sustained efficacy of the currently adopted first-line treatment of AS plus SP in the study area.
    Matched MeSH terms: Chloroquine/pharmacology
  3. Fulltext Reply to "chloroquine, an antifungal but also a fertility drug"
    Islahudin F, Ting KN, Pleass RJ, Avery SV
    Antimicrob Agents Chemother, 2013 Nov;57(11):5787.
    PMID: 24123347 DOI: 10.1128/AAC.01688-13
    Matched MeSH terms: Chloroquine/pharmacology*
  4. Fulltext No Association between the Plasmodium vivax crt-o MS334 or In9pvcrt Polymorphisms and Chloroquine Failure in a Pre-Elimination Clinical Cohort from Malaysia with a Large Clonal Expansion
    Rumaseb A, Moraes Barros RR, Sá JM, Juliano JJ, William T, Braima KA, et al.
    Antimicrob Agents Chemother, 2023 Jul 18;67(7):e0161022.
    PMID: 37314336 DOI: 10.1128/aac.01610-22
    Increasing reports of resistance to a frontline malaria blood-stage treatment, chloroquine (CQ), raises concerns for the elimination of Plasmodium vivax. The absence of an effective molecular marker of CQ resistance in P. vivax greatly constrains surveillance of this emerging threat. A recent genetic cross between CQ sensitive (CQS) and CQ resistant (CQR) NIH-1993 strains of P. vivax linked a moderate CQR phenotype with two candidate markers in P. vivax CQ resistance transporter gene (pvcrt-o): MS334 and In9pvcrt. Longer TGAAGH motif lengths at MS334 were associated with CQ resistance, as were shorter motifs at the In9pvcrt locus. In this study, high-grade CQR clinical isolates of P. vivax from a low endemic setting in Malaysia were used to investigate the association between the MS334 and In9pvcrt variants and treatment efficacy. Among a total of 49 independent monoclonal P. vivax isolates assessed, high-quality MS334 and In9pvcrt sequences could be derived from 30 (61%) and 23 (47%), respectively. Five MS334 and six In9pvcrt alleles were observed, with allele frequencies ranging from 2 to 76% and 3 to 71%, respectively. None of the clinical isolates had the same variant as the NIH-1993 CQR strain, and none of the variants were associated with CQ treatment failure (all P > 0.05). Multi-locus genotypes (MLGs) at 9 neutral microsatellites revealed a predominant P. vivax strain (MLG6) accounting for 52% of Day 0 infections. The MLG6 strain comprised equal proportions of CQS and CQR infections. Our study reveals complexity in the genetic basis of CQ resistance in the Malaysian P. vivax pre-elimination setting and suggests that the proposed pvcrt-o MS334 and In9pvcrt markers are not reliable markers of CQ treatment efficacy in this setting. Further studies are needed in other endemic settings, applying hypothesis-free genome-wide approaches, and functional approaches to understand the biological impact of the TGAAGH repeats linked to CQ response in a cross are warranted to comprehend and track CQR P. vivax.
    Matched MeSH terms: Chloroquine/pharmacology
  5. Fulltext Pharmacophore modelling of vanillin derivatives, favipiravir, chloroquine, hydroxychloroquine, monolaurin and tetrodotoxin as MPro inhibitors of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2)
    Law WY, Asaruddin MR, Bhawani SA, Mohamad S
    BMC Res Notes, 2020 Nov 11;13(1):527.
    PMID: 33176880 DOI: 10.1186/s13104-020-05379-6
    OBJECTIVES: The aim of this study was to use Ligand-based pharmacophore modelling approach for four established antiviral drugs, namely remdesivir, lopinavir, ritonavir and hydroxychloroquine for COVID-19 inhibitors as training sets. In this study Twenty vanillin derivatives together with monolaurin and tetrodotoxin were used as test sets to evaluate as potential SARS-CoV-2 inhibitors. The Structure-based pharmacophore modelling approach was also performed using 5RE6, 5REX and 5RFZ in order to analyse the binding site and ligand-protein complex interactions.

    RESULTS: The pharmacophore modelling mode of 5RE6 displayed two Hydrogen Bond Acceptors (HBA) and one Hydrophobic (HY) interaction. Besides, the pharmacophore model of 5REX showed two HBA and two HY interactions. Finally, the pharmacophore model of 5RFZ showed three HBA and one HY interaction. Based on ligand-based approach, 20 Schiff-based vanillin derivatives, showed strong MPro inhibition activity. This was due to their good alignment and common features to PDB-5RE6. Similarly, monolaurin and tetrodotoxin displayed some significant activity against SARS-CoV-2. From structure-based approach, vanillin derivatives (1) to (12) displayed some potent MPro inhibition against SARS-CoV-2. Favipiravir, chloroquine and hydroxychloroquine also showed some significant MPro inhibition.

    Matched MeSH terms: Chloroquine/pharmacology*; Hydroxychloroquine/pharmacology
  6. Fulltext In vitro and in vivo antimalarial evaluations of myrtle extract, a plant traditionally used for treatment of parasitic disorders
    Naghibi F, Esmaeili S, Abdullah NR, Nateghpour M, Taghvai M, Kamkar S, et al.
    Biomed Res Int, 2013;2013:316185.
    PMID: 24455686 DOI: 10.1155/2013/316185
    Based on the collected ethnobotanical data from the Traditional Medicine and Materia Medica Research Center (TMRC), Iran, Myrtus communis L. (myrtle) was selected for the assessment of in vitro and in vivo antimalarial and cytotoxic activities. Methanolic extract of myrtle was prepared from the aerial parts and assessed for antiplasmodial activity, using the parasite lactate dehydrogenase (pLDH) assay against chloroquine-resistant (K1) and chloroquine-sensitive (3D7) strains of Plasmodium falciparum. The 4-day suppressive test was employed to determine the parasitemia suppression of the myrtle extract against P. berghei in vivo. The IC50 values of myrtle extract were 35.44 µg/ml against K1 and 0.87 µg/ml against 3D7. Myrtle extract showed a significant suppression of parasitaemia (84.8 ± 1.1% at 10 mg/kg/day) in mice infected with P. berghei after 4 days of treatment. Cytotoxic activity was carried out against mammalian cell lines using methyl thiazol tetrazolium (MTT) assay. No cytotoxic effect on mammalian cell lines up to 100 µg/mL was shown. The results support the traditional use of myrtle in malaria. Phytochemical investigation and understanding the mechanism of action would be in our upcoming project.
    Matched MeSH terms: Chloroquine/pharmacology*
  7. Effect of chloroquine on cultured fibroblasts: release of lysosomal hydrolases and inhibition of their uptake
    Wiesmann UN, DiDonato S, Herschkowitz NN
    Biochem Biophys Res Commun, 1975 Oct 27;66(4):1338-43.
    PMID: 4
    Matched MeSH terms: Chloroquine/pharmacology*
  8. Synthesis and biological evaluation of hydantoin derivatives as potent antiplasmodial agents
    Chin EZ, Chang WJ, Tan HY, Liew SY, Lau YL, Ng YL, et al.
    Bioorg Med Chem Lett, 2024 May 01;103:129701.
    PMID: 38484804 DOI: 10.1016/j.bmcl.2024.129701
    Malaria, a devastating disease, has claimed numerous lives and caused considerable suffering, with young children and pregnant women being the most severely affected group. However, the emergence of multidrug-resistant strains of Plasmodium and the adverse side effects associated with existing antimalarial drugs underscore the urgent need for the development of novel, well-tolerated, and more efficient drugs to combat this global health threat. To address these challenges, six new hydantoins derivatives were synthesized and evaluated for their in vitro antiplasmodial activity. Notably, compound 2c exhibited excellent inhibitory activity against the tested Pf3D7 strain, with an IC50 value of 3.97 ± 0.01 nM, three-fold better than chloroquine. Following closely, compound 3b demonstrated an IC50 value of 27.52 ± 3.37 µM against the Pf3D7 strain in vitro. Additionally, all the hydantoins derivatives tested showed inactive against human MCR-5 cells, with an IC50 value exceeding 100 μM. In summary, the hydantoin derivative 2c emerges as a promising candidate for further exploration as an antiplasmodial compound.
    Matched MeSH terms: Chloroquine/pharmacology
  9. Quantitative assessment of Malaysian plasmodium falciparum clones to schizontocidal drugs before and after cryopreservation
    Ang HH, Cheang HS
    Chemotherapy, 1999 Nov-Dec;45(6):446-51.
    PMID: 10567775
    Thirty clones were obtained from five Malaysian Plasmodium falciparum isolates using the limiting dilution method. These clones were then subjected to antimalarial testing using the modified in vitro microtechnique. The results showed that ST 85/B3, GC/C10 and ST 85/A2 clones decreased their susceptibilities to 19, 41 and 28% whilst ST 12/F8, ST 85/B3 and ST 85/B3 clones showed increases of 6, 43 and 21%, respectively, against chloroquine, mefloquine and quinine after cryopreservation. Further results also indicated that GC/B4, GC/B7, GC/C10, ST 85/A5, ST 85/D3, ST 148/F8 clones did not show any change (up to 2 decimal places) against chloroquine, ST 12/D5, ST 12/E8, ST 12/F8, ST 148/A5 clones against quinine after cryopreservation. They, however, maintained their original susceptibilities after cryopreservation.
    Matched MeSH terms: Chloroquine/pharmacology
  10. Variability in schizonticidal drug susceptibility amongst clones and isolates of Plasmodium falciparum
    Ang HH, Chan KL, Mak JW
    Chemotherapy, 1997 Mar-Apr;43(2):142-7.
    PMID: 9084924
    Plasmodium falciparum isolates from Malaysia, Africa and Thailand were cultured in vitro following the method of Trager and Jensen and subsequently cloned using the limiting dilution method of Rosario. These clones were presently characterized against three schizonticidal drugs, chloroquine, mefloquine and quinine, using the modified in vitro microtechnique. Results showed that all the clones derived from Gombak A isolate were chloroquine-resistant with average IC50 values ranging at 0.1377-1.0420 microM (0.007-0.058 mefloquine activity), sensitive to mefloquine at 0.0032-0.0103 microM and quinine at 0.0025-0.0428 microM (0.075-3.080 mefloquine activity). Similarly, the TGR clone displayed resistance to chloroquine at 0.1715-0.5875 microM (0.002-0.029 mefloquine activity) but were also sensitive to mefloquine at 0.0008-0.0058 microM and quinine at 0.0055-0.0700 microM (0.055-0.202 mefloquine activity). In contrast, four out of six Gambian clones were sensitive to chloroquine at 0.0047-0.0172 microM (0.122-0.617 mefloquine activity) but all were sensitive to mefloquine at 0.0008-0.0029 and 0.0016-0.0102 microM (0.096-1.813 mefloquine activity). In general, most of the clones displayed susceptibility patterns similar to that of their parent isolates against the three schizonticidal drugs except Gm/B2 and Gm/H5 Gambian clones were chloroquine-resistant at 0.3427 microM (0.006 mefloquine activity) and 0.2260 microM (0.004 mefloquine activity), respectively. Further results indicated that they were pure clones compared to their parent isolates as their schizonticidal drug susceptibilities were statistically different (p < 0.05) except Gm/C6 and TGR/B7 clones against mefloquine (p < 0.05).
    Matched MeSH terms: Chloroquine/pharmacology
  11. Fulltext Efficacy of Artesunate-mefloquine for Chloroquine-resistant Plasmodium vivax Malaria in Malaysia: An Open-label, Randomized, Controlled Trial
    Grigg MJ, William T, Menon J, Barber BE, Wilkes CS, Rajahram GS, et al.
    Clin Infect Dis, 2016 Jun 01;62(11):1403-1411.
    PMID: 27107287 DOI: 10.1093/cid/ciw121
    BACKGROUND: Chloroquine (CQ)-resistant Plasmodium vivax is increasingly reported throughout southeast Asia. The efficacy of CQ and alternative artemisinin combination therapies (ACTs) for vivax malaria in Malaysia is unknown.

    METHODS: A randomized, controlled trial of CQ vs artesunate-mefloquine (AS-MQ) for uncomplicated vivax malaria was conducted in 3 district hospitals in Sabah, Malaysia. Primaquine was administered on day 28. The primary outcome was the cumulative risk of treatment failure by day 28 by Kaplan-Meier analysis.

    RESULTS: From 2012 to 2014, 103 adults and children were enrolled. Treatment failure by day 28 was 61.1% (95% confidence interval [CI], 46.8-75.6) after CQ and 0% (95% CI, 0-.08) following AS-MQ (P < .001), of which 8.2% (95% CI, 2.5-9.6) were early treatment failures. All patients with treatment failure had therapeutic plasma CQ concentrations at day 7. Compared with CQ, AS-MQ was associated with faster parasite clearance (normalized clearance slope, 0.311 vs 0.127; P < .001) and fever clearance (mean, 19.0 vs 37.7 hours; P =001) and with lower risk of anemia at day 28 (odds ratio = 3.7; 95% CI, 1.5-9.3; P =005). Gametocytes were present at day 28 in 23.8% (10/42) of patients following CQ vs none with AS-MQ (P < .001). AS-MQ resulted in lower bed occupancy: 4037 vs 6510 days/1000 patients (incidence rate ratio 0.62; 95% CI, .60-.65; P < .001). One patient developed severe anemia not regarded as related to their AS-MQ treatment.

    CONCLUSIONS: High-grade CQ-resistant P. vivax is prevalent in eastern Malaysia. AS-MQ is an efficacious ACT for all malaria species. Wider CQ-efficacy surveillance is needed in vivax-endemic regions with earlier replacement with ACT when treatment failure is detected.Clinical Trials Registration NCT01708876.

    Matched MeSH terms: Chloroquine/pharmacology*
  12. A novel nano-anti-malarial induces redox damage and elicits cytokine response to the parasite
    Das S, Tripathy S, Pramanik P, Saha B, Roy S
    Cytokine, 2021 08;144:155555.
    PMID: 33992538 DOI: 10.1016/j.cyto.2021.155555
    Emergence and spread of resistant parasites to the newest chemotherapeutic anti-malarial agents are the biggest challenges against malaria control programs. Therefore, developing a novel effective treatment to reduce the overgrowing burden of multidrug resistant malaria is a pressing need. Herein, we have developed a biocompatible and biodegradable, non-toxic chitosan-tripolyphosphate-chloroquine (CS-TPP CQ) nanoparticle. CS-TPP CQ nanoparticles effectively kill the parasite through redox generation and induction of the pro- and anti-inflammatory cytokines in both sensitive and resistant parasite in vitro. The in vitro observations showed a strong inhibitory effect (p 
    Matched MeSH terms: Chloroquine/pharmacology
  13. Roxithromycin potentiates the effects of chloroquine and mefloquine on multidrug-resistant Plasmodium falciparum in vitro
    Min TH, Khairul MF, Low JH, Che Nasriyyah CH, A'shikin AN, Norazmi MN, et al.
    Exp Parasitol, 2007 Apr;115(4):387-92.
    PMID: 17118354
    Chloroquine (CQ) and mefloquine (MQ) are no longer potent antimalarial drugs due to the emergence of resistant Plasmodium falciparum. Combination therapy has become the standard for many regimes in overcoming drug resistance. Roxithromycin (ROM), a known p-glycoprotein inhibitor, is reported to have antimalarial activity and it is hoped it will potentiate the effects of both CQ/MQ and reverse CQ/MQ-resistance. We assayed the effects of CQ and MQ individually and in combination with ROM on synchronized P. falciparum (Dd2 strain) cultures. The IC(50) values of CQ and MQ were 60.0+/-5.0 and 16.0+/-3.0 ng/ml; these were decreased substantially when combined with ROM. Isobolograms indicate that CQ-ROM combinations were relatively more synergistic (mean FICI 0.70) than MQ-ROM (mean FICI 0.85) with their synergistic effect at par with CQ-verapamil (VRP) (mean FICI 0.64) and MQ-VRP (mean FICI 0.60) combinations. We conclude that ROM potentiates the CQ/MQ response on multidrug-resistant P. falciparum.
    Matched MeSH terms: Chloroquine/pharmacology*
  14. In vitro susceptibility studies of Malaysian Plasmodium falciparum isolates and clones against schizontocidal drugs
    Ang HH, Chan KL, Mak JW
    Folia Parasitol., 1998;45(3):196-8.
    PMID: 9805783
    Five Malaysian isolates of the protozoan Plasmodium falciparum Welch were cultured in vitro following the method of Trager and Jensen (1976, 1977) and subsequently cloned using the limiting dilution method of Rosario (1981). Thirty clones were obtained and were later characterized against schizontocidal drugs, chloroquine, mefloquine and quinine, using the modified in vitro microtechnique. Results showed that these local isolates were heterogeneous and most of the clones exhibited similar pattern of susceptibility as their parent isolate except for ST 168 clone and two ST 195 clones that were sensitive but two ST 165 clones, two ST 168 clones and five ST 195 clones were resistant against quinine, respectively. Results also indicated that they were pure clones compared to their parent isolate because their drug susceptibility studies were significantly different (p < 0.05).
    Matched MeSH terms: Chloroquine/pharmacology
  15. Chloroquine resistant malaria in West Malaysia
    Sandosham AA, Fredericks HJ, Ponnampalam JT, Seow CL, Ismail O, Othman AM, et al.
    J Trop Med Hyg, 1975 Mar;78(3):54-8.
    PMID: 1095776
    Chloroquine resistance is a well established entity in South East Asia, and presents a problem of increasing importance. Strains of P. falciparum resistant to chloroquine have also been found to be resistant to amodiaquine and a combination of pyrimethamine and sulphadoxine. Knowledge of the drug sensitivity of the strains of malaria parasite in a given locality is important so that the right choice of drugs can be made in treatment of the disease. The treatment of chloroquine resistant malaria in West Malaysia is a subject of another paper but suffice it to say that increased doses of chloroquine have still been found to be effective in treating many cases of falciparum malaria from areas of chloroquine resistance.
    Matched MeSH terms: Chloroquine/pharmacology
  16. Fluoxetine potentiates chloroquine and mefloquine effect on multidrug-resistant Plasmodium falciparum in vitro
    Khairul MF, Min TH, Low JH, Nasriyyah CH, A'shikin AN, Norazmi MN, et al.
    Jpn J Infect Dis, 2006 Oct;59(5):329-31.
    PMID: 17060702
    Fluoxetine (FLX), a P-glycoprotein inhibitor with antimalarial activity, is promising candidate for reversing chloroquine/mefloquine (CQ/MQ) resistance. The Dd2 strain of CQ- and MQ-resistant Plasmodium falciparum was synchronized and assayed with various concentrations of CQ/MQ individually and in combination with FLX or verapamil (VPL). Our results indicated the 50% inhibitory concentration values of CQ and MQ were greatly lowered when FLX was used simultaneously. Isobolograms indicated that CQ-FLX combinations are more synergistic (mean fractional inhibitory concentration [FIC] index 0.55) than MQ-FLX (mean FIC index 0.64), and their synergistic effect was better than or at par with CQ-VPL (mean FIC index 0.88) and MQ-VPL (mean FIC index 0.60) combinations. We conclude that the FLX potentiates the CQ and MQ response on multidrug-resistant P. falciparum at clinically achievable concentrations.
    Matched MeSH terms: Chloroquine/pharmacology*
  17. 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: Chloroquine/pharmacology
  18. Antiplasmodial studies of Eurycoma longifolia Jack using the lactate dehydrogenase assay of Plasmodium falciparum
    Chan KL, Choo CY, Abdullah NR, Ismail Z
    J Ethnopharmacol, 2004 Jun;92(2-3):223-7.
    PMID: 15138004 DOI: 10.1016/j.jep.2004.02.025
    The roots of Eurycoma longifolia Jack have been used as traditional medicine to treat malaria. A systematic bioactivity-guided fractionation of this plant was conducted involving the determination of the effect of its various extracts and their chemical constituents on the lactate dehydrogenase activity of in vitro chloroquine-resistant Gombak A isolate and chloroquine-sensitive D10 strain of Plasmodium falciparum parasites. Their antiplasmodial activity was also compared with their known in vitro cytotoxicity against KB cells. Four quassinoids, eurycomanone (1), 13,21-dihydroeurycomanone (3), 13 alpha(21)-epoxyeurycomanone (4), eurycomalactone (6) and an alkaloid, 9-methoxycanthin-6-one (7), displayed higher antiplasmodial activity against Gombak A isolate but were less active against the D10 strain when compared with chloroquine. Amongst the compounds tested, 1 and 3 showed higher selectivity indices obtained for the cytotoxicity to antiplasmodial activity ratio than 14,15 beta-dihydroxyklaineanone (2), eurycomanol (5), 6 and 7.
    Matched MeSH terms: Chloroquine/pharmacology
  19. Effect of 7-day daily replacement of culture medium containing Eurycoma longifolia Jack constituents on the Malaysian Plasmodium falciparum isolates
    Ang HH, Chan KL, Mak JW
    J Ethnopharmacol, 1995 Dec 15;49(3):171-5.
    PMID: 8824743 DOI: 0.1016/0378-8741(95)01321-0
    Six Malaysian chloroquine-resistant Plasmodium falciparum isolates were cultured in vitro following the candle-jar method. Antimalarial evaluations of daily replacement of culture medium containing chloroquine and a semi-purified extract of Eurycoma longifolia Jack (containing 13 beta, 18-dihydroeurycomanol (1), eurycomanol-2-O-beta-D-glucopyranoside (2), eurycomanol (3) and eurycomanone (4)) were performed on 6-well plates at 37 degrees C for a week. Presence or absence of the parasites was determined microscopically on thin-film Giemsa-stained preparations. Results showed that the antimalarial activity of Eurycoma longifolia Jack was dose-dependent and reached a maximum of < 50% at 0.07-5.00 micrograms ml-1 after 1 day post-treatment. However, complete inhibitions were observed at 1.25-5.00 micrograms ml-1 extract after 3 days post-treatment and 0.62 and 0.31 micrograms ml-1 after 4 and 6 days post-treatment, respectively. Further results indicated that chloroquine exhibited total inhibition at concentrations > 2.50 and 0.62 micrograms ml-1 after 1 and 2 days post-treatment, respectively and at all concentrations after 3 days post-treatment.
    Matched MeSH terms: Chloroquine/pharmacology
  20. Choroquine-resistant Plasmodium falciparum malaria in the United Kingdom
    Cowan GO, Parry ES
    Lancet, 1968 Nov 02;2(7575):946-8.
    PMID: 4176265
    Matched MeSH terms: Chloroquine/pharmacology
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