Displaying publications 1 - 20 of 308 in total

Abstract:
Sort:
  1. Fulltext Antimalarial ceramicines Q-T from Chisocheton ceramicus
    Nugroho AE, Wong CP, Hirasawa Y, Kaneda T, Tougan T, Horii T, et al.
    J Nat Med, 2023 Jun;77(3):596-603.
    PMID: 37162697 DOI: 10.1007/s11418-023-01706-w
    Ceramicines are a series of limonoids that were isolated from the bark of Malaysian Chisocheton ceramicus (Meliaceae) and were known to show various biological activity. Four new limonoids, ceramicines Q-T (1-4) were isolated from the barks of C. ceramicus, and their structures were determined on the basis of the 1D and 2D NMR analyses in combination with calculated 13C chemical shift data. Ceramicines Q-T (1-4) were established to be new limonoids with a cyclopentanone[α]phenanthren ring system with a β-furyl ring at C-17, and without a tetrahydrofuran ring like ceramicine B, which is characteristic of known ceramicines. Ceramicine R (2) exhibited potent antimalarial activity against Plasmodium falciparum 3D7 strain with IC50 value of 2.8 µM.
    Matched MeSH terms: Plasmodium falciparum
  2. Fulltext The occurrence of dihydrofolate reductase (DHFR) point mutation (SER-108-->ASN-108) in Malaysian isolates of Plasmodium falciparum
    Lim PK, Tan SK, Khoo AS, Noor Rain A, Nagappan S, Mak JW
    Southeast Asian J. Trop. Med. Public Health, 1998 Mar;29(1):27-30.
    PMID: 9740263
    Matched MeSH terms: Plasmodium falciparum/enzymology; Plasmodium falciparum/genetics*
  3. Fulltext Coordination of apicoplast transcription in a malaria parasite by internal and host cues
    Kobayashi Y, Komatsuya K, Imamura S, Nozaki T, Watanabe YI, Sato S, et al.
    Proc Natl Acad Sci U S A, 2023 Jul 11;120(28):e2214765120.
    PMID: 37406097 DOI: 10.1073/pnas.2214765120
    The malaria parasite Plasmodium falciparum has a nonphotosynthetic plastid called the apicoplast, which contains its own genome. Regulatory mechanisms for apicoplast gene expression remain poorly understood, despite this organelle being crucial for the parasite life cycle. Here, we identify a nuclear-encoded apicoplast RNA polymerase σ subunit (sigma factor) which, along with the α subunit, appears to mediate apicoplast transcript accumulation. This has a periodicity reminiscent of parasite circadian or developmental control. Expression of the apicoplast subunit gene, apSig, together with apicoplast transcripts, increased in the presence of the blood circadian signaling hormone melatonin. Our data suggest that the host circadian rhythm is integrated with intrinsic parasite cues to coordinate apicoplast genome transcription. This evolutionarily conserved regulatory system might be a future target for malaria treatment.
    Matched MeSH terms: Plasmodium falciparum/genetics; Plasmodium falciparum/metabolism
  4. Susceptibility of Malaysian Plasmodium falciparum isolates to antimalarial drugs after cryopreservation and 12 months of continuous in vitro culture
    Ang HH, Chan KL, Mak JW
    Chemotherapy, 1997 Sep-Oct;43(5):311-5.
    PMID: 9309363 DOI: 10.1159/000239583
    Eleven Malaysian Plasmodium falciparum isolates were cultured in vitro and later subjected to antimalarial evaluations in 96-well microtiter plates. After cryopreservation, the IC50 (nM) for ST 195, ST 196, ST 197, ST 244 and ST 245 isolates were, respectively: 180.9, 198.7, 482.0, 580.0 and 690.1 for chloroquine; 3.4, 3.4, 9.2, 4.0 and 5.8 for mefloquine; 21.9, 10.5, 40.7, 40.1 and 48.7 for quinine; 136.7, 58.8, 116.4, 29.4 and 95.4 for cycloguanil, and 48.3, 57.5, 47.4, 61.5 and 37.8 for pyrimethamine. Before cryopreservation they were 172.5, 141.5, 453.2, 636.0 and 651.6 nM for chloroquine; 4.8, 2.6, 9.0, 6.9 and 5.8 nM for mefloquine; 21.3, 8.3, 41.9, 49.6 and 40.1 nM for quinine, 129.9, 47.3, 109.3, 30.6 and 95.4 nM for cycloguanil, and 45.4, 47.4, 40.2, 66.3 and 36.0 nM for pyrimethamine. IC50 (nM) for Gombak A, Gombak C, ST 9, ST 12, ST 85 and ST 148 isolates after 12 months of continuous in vitro culture were, respectively: 477.0, 492.3, 367.1, 809.4, 566.5 and 341.8 for chloroquine; 2.9, 11.1, 8.5, 16.9, 5.3 and 4.2 for mefloquine; 6.2, 58.3, 52.7, 36.7, 31.8 and 26.2 for quinine; 154.5, 57.2, 130.3, 94.2, 81.4 and 102.9 for cycloguanil, 26.9, 24.9, 43.8, 31.0, 14.1 and 56.7 for pyrimethamine. Before the 12-month culture they were 472.3, 452.9, 352.7, 773.7, 702.7 and 322.7 nM for chloroquine; 2.6, 13.2, 8.5, 17.2, 5.0 and 4.0 nM for mefloquine; 6.2, 85.4, 53.9, 38.5, 35.8 and 38.5 nM for quinine; 106.8, 74.3, 112.4, 89.8, 91.8 and 103.3 nM for cycloguanil, and 26.9, 31.4, 47.0, 28.1, 14.9 and 56.7 nM for pyrimethamine. Thus none of these isolates differed in their original susceptibilities after either of these procedures.
    Matched MeSH terms: Plasmodium falciparum/drug effects*
  5. Fulltext Lateral Flow Recombinase Polymerase Amplification Assays for the Detection of Human Plasmodium Species
    Lai MY, Abdul Hamid M, Jelip J, Mudin RN, Lau YL
    Am J Trop Med Hyg, 2023 May 03;108(5):882-886.
    PMID: 36913921 DOI: 10.4269/ajtmh.22-0657
    This study highlights the development of two lateral flow recombinase polymerase amplification assays for the diagnosis of human malaria. The lateral flow cassettes contained test lines that captured biotin-, 6-carboxyfluorescein, digoxigenin-, cyanine 5-, and dinitrophenyl-labeled amplicons. The overall process can be completed in 30 minutes. Recombinase polymerase amplification coupled with lateral flow had a detection limit of 1 copy/µL for Plasmodium knowlesi, Plasmodium vivax, and Plasmodium falciparum. No cross-reactivity was observed among nonhuman malaria parasites such as Plasmodium coatneyi, Plasmodium cynomolgi, Plasmodium brasilanium, Plasmodium inui, Plasmodium fragile, Toxoplasma gondii, Sarcocystis spp., Brugia spp., and 20 healthy donors. It is rapid, highly sensitive, robust, and easy to use. The result can be read without the need for special equipment and thus has the potential to serve as an effective alternative to polymerase chain reaction methods for the diagnosis of malaria.
    Matched MeSH terms: Plasmodium falciparum/genetics
  6. The Potential of β Carbolin Alkaloids to Hinder Growth and Reverse Chloroquine Resistance in Plasmodium falciparum
    Ibraheem ZO, Abdul Majid R, Mohd Noor S, Mohd Sidek H, Basir R
    Iran J Parasitol, 2015 Oct-Dec;10(4):577-83.
    PMID: 26811724
    Nowadays, scourge of malaria as a fatalistic disease has increased due to emergence of drug resistance and tolerance among different strains of Plasmodium falciparum. Emergence of chloroquine (CQ) resistance has worsened the calamity as CQ is still considered the most efficient, safe and cost effective drug among other antimalarials. This urged the scientists to search for other alternatives or sensitizers that may be able to augment CQ action and reverse its resistance.
    Matched MeSH terms: Plasmodium falciparum
  7. Clonal diversity in single isolates of Malaysian Plasmodium falciparum
    Ang HH, Chan KL, Mak JW
    Med Trop (Mars), 1996;56(4):349-51.
    PMID: 9112620
    Six clones were derived from each of five isolates of Malaysian Plasmodium falciparum and characterized with regard to susceptibility to schizontocidal drugs, chloroquine, mefloquine, and quinine. The 5 isolates were found to be resistant to chloroquine and sensitive to mefloquine and quinine. Most of the clones displayed susceptibility patterns similar to those of their parent isolate, except ST9/D8 clone which became sensitive to chloroquine, C/C10 and ST148/A5 clones which became resistant to mefloquine and to quinine respectively. This diversity in susceptibility to schizontocidal drugs would likely have been overlooked by assessment of natural uncloned isolates against antimalarial drugs.
    Matched MeSH terms: Plasmodium falciparum/drug effects*; Plasmodium falciparum/genetics*; Plasmodium falciparum/isolation & purification
  8. Assembly of ligands interaction models for glutathione-S-transferases from Plasmodium falciparum, human and mouse using enzyme kinetics and molecular docking
    Al-Qattan MN, Mordi MN, Mansor SM
    Comput Biol Chem, 2016 10;64:237-249.
    PMID: 27475235 DOI: 10.1016/j.compbiolchem.2016.07.007
    BACKGROUND: Glutathione-s-transferases (GSTs) are enzymes that principally catalyze the conjugation of electrophilic compounds to the endogenous nucleophilic glutathione substrate, besides, they have other non-catalytic functions. The Plasmodium falciparum genome encodes a single isoform of GST (PfGST) which is involved in buffering the toxic heme, thus considered a potential anti-malarial target. In mammals several classes of GSTs are available, each of various isoforms. The human (human GST Pi-1 or hGSTP1) and mouse (murine GST Mu-1 or mGSTM1) GST isoforms control cellular apoptosis by interaction with signaling proteins, thus considered as potential anti-cancer targets. In the course of GSTs inhibitors development, the models of ligands interactions with GSTs are used to guide rational molecular modification. In the absence of X-ray crystallographic data, enzyme kinetics and molecular docking experiments can aid in addressing ligands binding modes to the enzymes.

    METHODS: Kinetic studies were used to investigate the interactions between the three GSTs and each of glutathione, 1-chloro-2,4-dinitrobenzene, cibacron blue, ethacrynic acid, S-hexyl glutathione, hemin and protoporphyrin IX. Since hemin displacement is intended for PfGST inhibitors, the interactions between hemin and other ligands at PfGST binding sites were studied kinetically. Computationally determined binding modes and energies were interlinked with the kinetic results to resolve enzymes-ligands interaction models at atomic level.

    RESULTS: The results showed that hemin and cibacron blue have different binding modes in the three GSTs. Hemin has two binding sites (A and B) with two binding modes at site-A depending on presence of GSH. None of the ligands were able to compete hemin binding to PfGST except ethacrynic acid. Besides bind differently in GSTs, the isolated anthraquinone moiety of cibacron blue is not maintaining sufficient interactions with GSTs to be used as a lead. Similarly, the ethacrynic acid uses water bridges to mediate interactions with GSTs and at least the conjugated form of EA is the true hemin inhibitor, thus EA may not be a suitable lead.

    CONCLUSIONS: Glutathione analogues with bulky substitution at thiol of cysteine moiety or at γ-amino group of γ-glutamine moiety may be the most suitable to provide GST inhibitors with hemin competition.

    Matched MeSH terms: Plasmodium falciparum/enzymology*; Plasmodium falciparum/metabolism; Plasmodium falciparum/chemistry
  9. Fulltext Walsogynes H-O from Walsura chrysogyne
    Nugroho AE, Nakajima S, Wong CP, Hirasawa Y, Kaneda T, Shirota O, et al.
    J Nat Med, 2022 Jan;76(1):94-101.
    PMID: 34351584 DOI: 10.1007/s11418-021-01556-4
    Eight new limonoids, walsogynes H-O (1-8) were isolated from the barks of Walsura chrysogyne, and their structures were determined on the basis of the 1D and 2D NMR data. Walsogynes H-M (1-6) and O (8) were concluded to be 11,12-seco limonoids with a dodecahydro-1H-naphtho[1,8-bc:3,4-c']difuran skeleton, and walsogyne N (7) to be 11,12-seco limonoid sharing a unique dodecahydronaphtho[1,8-bc:5,4-b'c']difuran skeleton. Walsogynes H-O (1-8) exhibited potent antimalarial activity against Plasmodium falciparum 3D7 strain with IC50 value of 2.5, 2.6, 1.6, 2.5, 1.5, 2.6, 2.1, and 1.1 µM, respectively.
    Matched MeSH terms: Plasmodium falciparum
  10. Plasmodium knowlesi circumsporozoite protein: genetic characterisation and predicted antigenicity of the central repeat region
    Tan JH, Cheong FW, Lau YL, Fong MY
    Trop Biomed, 2023 Mar 01;40(1):37-44.
    PMID: 37356002 DOI: 10.47665/tb.40.1.004
    Circumsporozoite protein (CSP) central repeat region is one of the main target regions of the RTS,S/AS01 vaccine for falciparum infection as it consists of immunodominant B cell epitopes. However, there is a lack of study for P. knowlesi CSP central repeat region. This study aims to characterise the CSP repeat motifs of P. knowlesi isolates in Peninsular Malaysia. CSP repeat motifs of 64 P. knowlesi isolates were identified using Rapid Automatic Detection and Alignment of Repeats (RADAR). Antigenicity of the repeat motifs and linear B cell epitopes were predicted using VaxiJen 2.0, BepiPred-2.0 and BCPred, respectively. A total of 35 dominant repeat motifs were identified. The repeat motif "AGQPQAQGDGANAGQPQAQGDGAN" has the highest repeat frequency (n=15) and antigenicity index of 1.7986. All the repeat regions were predicted as B cell epitopes. In silico approaches revealed that all repeat motifs were antigenic and consisted of B cell epitopes which could be designed as knowlesi malaria vaccine.
    Matched MeSH terms: Plasmodium falciparum
  11. Fulltext Serological evaluation of risk factors for exposure to malaria in a pre-elimination setting in Malaysian Borneo
    Byrne I, William T, Chua TH, Patterson C, Hall T, Tan M, et al.
    Sci Rep, 2023 Aug 10;13(1):12998.
    PMID: 37563178 DOI: 10.1038/s41598-023-39670-w
    Malaysia has reported no indigenous cases of P. falciparum and P. vivax for over 3 years. When transmission reaches such low levels, it is important to understand the individuals and locations where exposure risks are high, as they may be at greater risk in the case of a resurgence of transmission. Serology is a useful tool in low transmission settings, providing insight into exposure over longer durations than PCR or RDT. We ran blood samples from a 2015 population-based survey in northern Sabah, Malaysian Borneo on a multiplex bead assay. Using supervised machine learning methods, we characterised recent and historic exposure to Plasmodium falciparum and P. vivax and found recent exposure to P. falciparum to be very low, with exposure to both species increasing with age. We performed a risk-factor assessment on environmental, behavioural, demographic and household factors, and identified forest activity and longer travel times to healthcare as common risk-factors for exposure to P. falciparum and P. vivax. In addition, we used remote-sensing derived data and geostatistical models to assess environmental and spatial associations with exposure. We created predictive maps of exposure to recent P. falciparum in the study area and showed 3 clear foci of exposure. This study provides useful insight into the environmental, spatial and demographic risk factors for P. falciparum and P. vivax at a period of low transmission in Malaysian Borneo. The findings would be valuable in the case of resurgence of human malarias in the region.
    Matched MeSH terms: Plasmodium falciparum
  12. Cross-resistance between "Daraprim" and proguanil
    Wilson T, Edeson JFB
    Br Med J, 1953;1:731.
    A letter from Drs. G. I. Robertson, D. G. Davey, and Sir Hamilton Fairley (December 6, 1952, p. 1255) reported that a proguanil-resistant strain of Plasmodium falciparum from Malaya had proved to be resistant also to pyrimethamine (" daraprim "). Proguanil-resistance in Malayan strains of P. falciparum has been recognized since 19491; and if a true cross-resistance exists, this might-as implied by Dr. J. S. K. Boyd (February 7, p. 337)-go far to explain the pyrimethamine failures described in our paper (January 31, p. 253). Proguanil has been so widely used throughout Malaya for the past six years that there can be few strains of parasite which have not yet come into contact with it; thus there is little chance of deciding now how the "parent" strains (without previous contact with proguanil) might have responded to pyrimethamine. We have not, however, been able to confirm that there is any consistent cross-resistance between these two drugs in naturally acquired falciparum malaria since pyrimethamine was first used in Malaya in 1951. Pyrimethamine failures have been successfully treated with normal doses of proguanil, and proguanilresistant infections have responded readily to pyrimethamine. In some of these cases an interval of several days was allowed to elapse between treatments, so the possibility of a combined action of the two drugs should have 'been small. We consider that these apparently conflicting results can best be explained by assuming that some present-day strains of P. falciparum in Malaya possess a " natural" resistance to pyrimethamine, whether or not any particular strain is also demonstrably resistant to proguanil. With this species of parasite, a true cross-resistance has still to be proved. REFERENCE 1 British Medical Journal, 1950. 1, 147.
    Matched MeSH terms: Plasmodium falciparum
  13. Fulltext Anthraquinones with antiplasmodial activity from the roots of Rennellia elliptica Korth. (Rubiaceae)
    Osman CP, Ismail NH, Ahmad R, Ahmat N, Awang K, Jaafar FM
    Molecules, 2010;15(10):7218-26.
    PMID: 20966871 DOI: 10.3390/molecules15107218
    Dichloromethane root extract of Rennellia elliptica Korth. showed strong inhibition of Plasmodium falciparum growth in vitro with an IC₅₀ value of 4.04 µg/mL. A phytochemical study of the dichloromethane root extract has led to the isolation and characterization of a new anthraquinone, 1,2-dimethoxy-6-methyl-9,10-anthraquinone (1), and ten known anthraquinones: 1-hydroxy-2-methoxy-6-methyl-9,10-anthraquinone (2), nordamnacanthal (3), 2-formyl-3-hydroxy-9,10-anthraquinone (4), damnacanthal (5), lucidin-ω-methyl ether (6), 3-hydroxy-2-methyl-9,10-anthraquinone (7), rubiadin (8), 3-hydroxy-2-methoxy-6-methyl-9,10-anthraquinone (9), rubiadin-1-methyl ether (10) and 3-hydroxy-2-hydroxymethyl-9,10-anthraquinone (11). Structural elucidation of all compounds was accomplished by modern spectroscopic methods, notably 1D and 2D NMR, IR, UV and HREIMS. The new anthraquinone 1, 2-formyl-3-hydroxy-9,10-anthraquinone (4) and 3-hydroxy-2-methyl-9,10-anthraquinone (7) possess strong antiplasmodial activity, with IC₅₀ values of 1.10, 0.63 and 0.34 µM, respectively.
    Matched MeSH terms: Plasmodium falciparum/drug effects*
  14. 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: Plasmodium falciparum/drug effects*
  15. 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: Plasmodium falciparum/drug effects*
  16. Electrophoretic variations of peptidase E (PEPE) in characterizing clones and isolates of Plasmodium falciparum from different geographical areas
    Ang HH, Chan KL, Mak JW
    Folia Parasitol., 1997;44(2):128-30.
    PMID: 9269721
    Six clones were obtained from each Plasmodium falciparum (Welch, 1897) isolate from different geographical areas, Gombak A (Malaysian), Gombak C (Malaysian), ST 9 (Malaysian, ST 12 (Malaysian), ST 85 (Malaysian, ST 148 (Malaysian), Gambian (African) and TGR (Thailand) isolates using the limiting dilution method (Rosario 1981). Forty-eight clones were obtained and were characterized by an electrophoresis isoenzyme analysis of PEPE (Peptidase E) (EC. 3.4.11 or 13). Results showed that they were pure clones as they were monovariant with regards to this enzyme unlike their parent isolates which were divariant.
    Matched MeSH terms: Plasmodium falciparum/enzymology*
  17. Fulltext Diagnosis of malaria by enzymatic detection of polymerase chain reaction products
    Normaznah Y, Furuta T, Saniah K, Noor Rain A, Kojima S, Mak JW
    Southeast Asian J. Trop. Med. Public Health, 1997 Jun;28(2):432-3.
    PMID: 9444035
    Matched MeSH terms: Plasmodium falciparum/enzymology
  18. Short report: development of a new diagnostic method for Plasmodium falciparum infection using a reverse transcriptase-polymerase chain reaction
    Abdullah NR, Furuta T, Taib R, Kita K, Kojima S, Wah MJ
    Am J Trop Med Hyg, 1996 Feb;54(2):162-3.
    PMID: 8619441
    We describe here a reverse transcriptase-polymerase chain reaction method for the detection of malaria parasites. Ten in vitro-cultured isolates of Plasmodium falciparum and 16 specimens from patients infected with P. falciparum were used to examine the specificity and sensitivity of the test. The sensitivity of the test was 0.3 parasites per microliter of blood. Specificity was determined by matching the sequences of the specimens' DNA to published sequences of 18S ribosomal RNA genes in the species-specific region. The test proved to be very sensitive and specific for the detection of P. falciparum infection.
    Matched MeSH terms: Plasmodium falciparum/isolation & purification
  19. Malaria--an overview
    Gilles HM
    J Infect, 1989 Jan;18(1):11-23.
    PMID: 2644358
    The epidemiology, clinical features, diagnosis, prognosis, management, chemotherapy and chemoprophylaxis of malaria are reviewed.
    Matched MeSH terms: Plasmodium falciparum/drug effects
  20. A sensitive malaria immunoperoxidase assay for the detection of Plasmodium falciparum antibody
    Lim TS
    Am J Trop Med Hyg, 1988 Mar;38(2):255-7.
    PMID: 3281491
    A new and rapid malaria immunoperoxidase assay using the enzyme horseradish peroxidase in place of fluorescein isothiocyanate was developed to allow the serological measurement of antimalarial antibody by light microscopy. Acetone-fixed thin blood films prepared from cultured Plasmodium falciparum were used as the source of antigen. This malaria immunoperoxidase assay is as sensitive as, and occasionally more sensitive than, the indirect fluorescent antibody assay. It is easy to perform and the antigen used does not show cross-reactivity with sera from nonmalarial diseases.
    Matched MeSH terms: Plasmodium falciparum/immunology*
Related Terms
Filters
Contact Us

Please provide feedback to Administrator ([email protected])

External Links