Displaying publications 1 - 20 of 307 in total

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  1. ent-Dioncophylleine A and related dehydrogenated naphthylisoquinoline alkaloids, the first Asian dioncophyllaceae-type alkaloids, from the "new"plant species Ancistrocladus benomensis
    Bringmann G, Dreyer M, Kopff H, Rischer H, Wohlfarth M, Hadi HA, et al.
    J Nat Prod, 2005 May;68(5):686-90.
    PMID: 15921410
    Three new fully dehydrogenated naphthylisoquinoline alkaloids, the 7,1'-coupled ent-dioncophylleine A (3a), the likewise 7,1'-coupled 5'-O-demethyl-ent-dioncophylleine A (4), and the 7,8'-linked dioncophylleine D (5), have been isolated from the leaves of the recently described Malaysian highland liana Ancistrocladusbenomensis. All of them lack an oxygen function at C-6; this so-called Dioncophyllaceae-type structural subclass had previously been found only in naphthylisoquinoline alkaloids from West and Central African plants. Moreover, compounds 3a and 4 are the first fully dehydrogenated, i.e., only axially chiral, naphthylisoquinoline alkaloids of this type that are optically active; compound 5, by contrast, is fully racemic, due to its configurationally unstable biaryl axis. The structural elucidation was achieved by spectroscopic and chiroptical methods. Biological activities of these alkaloids against different protozoan parasites are described.
    Matched MeSH terms: Plasmodium falciparum/drug effects
  2. [Various general aspects of of the problem of chloroquine-resistant Plasmodium falciparum malaria in the South-East Asia]
    Orlov VS
    Med Parazitol (Mosk), 1980 Jul-Aug;49(4):11-5.
    PMID: 6999319
    Matched MeSH terms: Plasmodium falciparum/drug effects*
  3. 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
  4. Variation in intronic microsatellites and exon 2 of the Plasmodium falciparum chloroquine resistance transporter gene during modification of artemisinin combination therapy in Thailand
    Seethamchai S, Buppan P, Kuamsab N, Teeranaipong P, Putaporntip C, Jongwutiwes S
    Infect Genet Evol, 2018 11;65:35-42.
    PMID: 30016713 DOI: 10.1016/j.meegid.2018.07.015
    The amino acid substitution at residue 76 of the food vacuolar transmembrane protein encoded by the chloroquine resistance transporter gene of Plasmodium falciparum (Pfcrt) is an important, albeit imperfect, determinant of chloroquine susceptibility status of the parasite. Other mutations in Pfcrt can modulate susceptibility of P. falciparum to other antimalarials capable of interfering with heme detoxification process, and may exert compensatory effect on parasite growth rate. To address whether nationwide implementation of artemisinin combination therapy (ACT) in Thailand could affect sequence variation in exon 2 and introns of Pfcrt, we analyzed 136 P. falciparum isolates collected during 1997 and 2016 from endemic areas bordering Myanmar, Cambodia and Malaysia. Results revealed 6 haplotypes in exon 2 of Pfcrt with 2 novel substitutions at c.243A > G (p.R81) and c.251A > T (p.N84I). Positive selection was observed at amino acid residues 75, 76 and 97. Four, 3, and 2 alleles of microsatellite (AT/TA) repeats occurred in introns 1, 2 and 4, respectively, resulting in 7 different 3-locus haplotypes. The number of haplotypes and haplotype diversity of exon 2, and introns 1, 2 and 4 were significantly greater among isolates collected during 2009 and 2016 than those collected during 1997 and 2008 when 3-day ACT and 2-day ACT regimens were implemented nationwide, respectively (p 
    Matched MeSH terms: Plasmodium falciparum/drug effects*; Plasmodium falciparum/genetics*; Plasmodium falciparum/isolation & purification
  5. 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: Plasmodium falciparum/drug effects*
  6. Use of avidin-biotin-glucose oxidase complex to detect antimalarial antibody in serum by light microscopy
    Lee M, Lambros C
    Am J Trop Med Hyg, 1988 Aug;39(2):145-9.
    PMID: 3044152
    An immunohistochemical assay was developed combining an avidin-biotin-glucose oxidase complex procedure (ABC-GO) with light microscopy to detect specific antibody against Plasmodium falciparum. Thin blood films were prepared from culture material of P. falciparum and fixed with acetone. Antibody was detected by successive incubations with test serum, biotinylated goat antihuman antibody, avidin-biotin-glucose oxidase complex, and glucose oxidase substrate. In the presence of reactive serum, a blue precipitate formed on the parasites and could be visually observed with a 40x objective. Sera from patients with single infections for P. vivax or P. ovale were unreactive. No cross-reactivity was observed with sera from patients with rheumatoid arthritis, filariasis, amebiasis, schistosomiasis, dengue, scrub typhus, leptospirosis, or toxoplasmosis. The sensitivity of ABC-GO is comparable to that of the indirect fluorescent antibody test.
    Matched MeSH terms: Plasmodium falciparum/immunology*
  7. Fulltext Updates on malaria incidence and profile in Malaysia from 2013 to 2017
    Hussin N, Lim YA, Goh PP, William T, Jelip J, Mudin RN
    Malar J, 2020 Jan 31;19(1):55.
    PMID: 32005228 DOI: 10.1186/s12936-020-3135-x
    BACKGROUND: To date, most of the recent publications on malaria in Malaysia were conducted in Sabah, East Malaysia focusing on the emergence of Plasmodium knowlesi. This analysis aims to describe the incidence, mortality and case fatality rate of malaria caused by all Plasmodium species between Peninsular Malaysia and East Malaysia (Sabah and Sarawak) over a 5-year period (2013-2017).

    METHODS: This is a secondary data review of all diagnosed and reported malaria confirmed cases notified to the Ministry of Health, Malaysia between January 2013 and December 2017.

    RESULTS: From 2013 to 2017, a total of 16,500 malaria cases were notified in Malaysia. The cases were mainly contributed from Sabah (7150; 43.3%) and Sarawak (5684; 34.4%). Majority of the patients were male (13,552; 82.1%). The most common age group in Peninsular Malaysia was 20 to 29 years (1286; 35.1%), while Sabah and Sarawak reported highest number of malaria cases in age group of 30 to 39 years (2776; 21.6%). The top two races with malaria in Sabah and Sarawak were Bumiputera Sabah (5613; 43.7%) and Bumiputera Sarawak (4512; 35.1%), whereas other ethnic group (1232; 33.6%) and Malays (1025; 28.0%) were the two most common races in Peninsular Malaysia. Plasmodium knowlesi was the commonest species in Sabah and Sarawak (9902; 77.1%), while there were more Plasmodium vivax cases (1548; 42.2%) in Peninsular Malaysia. The overall average incidence rate, mortality rate and case fatality rates for malaria from 2013 to 2017 in Malaysia were 0.106/1000, 0.030/100,000 and 0.27%, respectively. Sarawak reported the highest average incidence rate of 0.420/1000 population followed by Sabah (0.383/1000). Other states in Peninsular Malaysia reported below the national average incidence rate with less than 0.100/1000.

    CONCLUSIONS: There were different trends and characteristics of notified malaria cases in Peninsular Malaysia and Sabah and Sarawak. They provide useful information to modify current prevention and control measures so that they are customised to the peculiarities of disease patterns in the two regions in order to successfully achieve the pre-elimination of human-only species in the near future.

    Matched MeSH terms: Plasmodium falciparum/isolation & purification
  8. 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: Plasmodium falciparum/drug effects*; Plasmodium falciparum/genetics; Plasmodium falciparum/isolation & purification*
  9. Fulltext Ultraviolet-visible study on acid-base equilibria of aporphine alkaloids with antiplasmodial and antioxidant activities from Alseodaphne corneri and Dehaasia longipedicellata
    Zahari A, Ablat A, Omer N, Nafiah MA, Sivasothy Y, Mohamad J, et al.
    Sci Rep, 2016;6:21517.
    PMID: 26898753 DOI: 10.1038/srep21517
    The UV-vis spectra of isocorydine 1, norisocorydine 2 and boldine 3 were studied in 2% v/v acetonitrile, at constant ionic strength (0.1 M NaCl, 35 degree Celsius). The pK(a) values of isocorydine 1 and norisocorydine 2 were 11.75 and 12.07, respectively. Boldine 3 gave a pK(a) value of 9.16 and 10.44. All of the alkaloids 1-3 were stable at physiological pH; thereby all of them will not ionize, thus permitting the basic nitrogen to be protonated and accumulated within the acidic food vacuole of Plasmodium via pH trapping. Subsequently, acidic food vacuoles that have been neutralized by alkaloids would result in enhancement of the antiplasmodial activity. The alkaloids showed antiplasmodial activity against Plasmodium falciparum and antioxidant activities; DPPH radical scavenging, metal chelating and ferric reducing power. The antioxidant properties of the alkaloids under investigation revealed that in addition to the antiplasmodial activity, the alkaloids can also prevent oxidative damage. It can be prevented by binding free heme and neutralizing the electrons produced during the Plasmodium falciparum mediated haemoglobin destruction in the host. Slightly basic properties of the aforementioned alkaloids, along with their antioxidant activities, are advantageous in improving the suppression of malaria infection that cause less damage to the host.
    Matched MeSH terms: Plasmodium falciparum
  10. Triazole hybrid compounds: A new frontier in malaria treatment
    Ravindar L, Hasbullah SA, Rakesh KP, Hassan NI
    Eur J Med Chem, 2023 Nov 05;259:115694.
    PMID: 37556947 DOI: 10.1016/j.ejmech.2023.115694
    Reviewing the advancements in malaria treatment, the emergence of triazole hybrid compounds stands out as a groundbreaking development. Combining the advantages of triazole and other moieties, these hybrid compounds offer a new frontier in the battle against malaria. Their potential as effective antimalarial agents has captured the attention of researchers and holds promise for overcoming the challenges posed by drug-resistant malaria strains. We focused on their broad spectrum of antimalarial activity of diverse hybridized 1,2,3-triazoles and 1,2,4-triazoles, structure-activity relationship (SAR), drug-likeness, bioavailability and pharmacokinetic properties reported since 2018 targeting multiple stages of the Plasmodium life cycle. This versatility makes them highly effective against both drug-sensitive and drug-resistant strains of P. falciparum, making them invaluable tools in regions where resistance is prevalent. The synergistic effects of combining the triazole moiety with other pharmacophores have resulted in even greater antimalarial potency. This approach has the potential to circumvent existing resistance mechanisms and provide a more sustainable solution to malaria treatment. While triazole hybrid compounds show great promise, further research and clinical trials are warranted to fully evaluate their safety, efficacy and long-term effects. As research progresses, these compounds can potentially revolutionize the field and contribute to global efforts to eradicate malaria, ultimately saving countless lives worldwide.
    Matched MeSH terms: Plasmodium falciparum
  11. Fulltext Treatment failure of falciparum malaria with Fansidar in Tawau Sabah. January-June, 1982
    Tan HS, Tan PE
    Med J Malaysia, 1983 Sep;38(3):217-23.
    PMID: 6369092
    One hundred and ten consecutive patients with falciparum malaria were treated with Fansidar and primaquine. Of the 61 patients who were followed up at one week, 4 (6.5%) failed to clear their parasitemia (1 R III and 3 R Il treatment failures). Of the subsequent 40 patients who were seen again at one month, another 3 (7.5%) had recrudesced (R 1 treatment failure). A total of 7 patients thus experienced some form of treatment failure in the cohort of 40 who completed the one month follow up. Only 1 of these 7patients (with R III treatment) failure) failed to respond to repeat Fansidar treatment, and may be the only one with true Fansidar resistance. The overall treatment failure rate of 17.5% (95% confidence interval: 6-29%) in the cohort who completed the study is consistent with the known clinical efficacy of Fansidar. These results suggest no significant Fansidar resistance in falciparum malaria found in Sabah.
    Matched MeSH terms: Plasmodium falciparum
  12. Transmission dynamics and estimates of malaria vectorial capacity for Anopheles balabacensis and An. flavirostris (Diptera: Culicidae) on Banggi island, Sabah, Malaysia
    Hii JL, Kan S, Vun YS, Chin KF, Tambakau S, Chan MK, et al.
    Ann Trop Med Parasitol, 1988 Feb;82(1):91-101.
    PMID: 3041932
    Holoendemic malaria transmission in two small isolated forest communities and a coastal village was studied by (1) all night human bait collections of Anopheles species from inside and outside houses and (2) buffalo-biting and CDC light-trapping catches during March and November 1984. During the same period thick and thin blood films were collected from the human population, and spleen rates were determined in children from two to nine years of age. Using both the immunoradiometric assay (IRMA) and the dissection technique, more sporozoite-positive infections were detected in An. balabacensis and An. flavirostris in November than in March. IRMA confirmed the presence of Plasmodium falciparum sporozoites. An average of 76.2% of the An. balabacensis population lived long enough to have reached a point where infectivity with P. falciparum was possible in November. Although fewer than five adult females bit humans per night at any time, a resident could theoretically have received more than 160 infective bites in one year. A high frequency of feeding on humans, coupled with increased anopheline life expectancy, contributed to high estimates of falciparum malaria vectorial capacity (number of infections distributed per case per day); for An. balabacensis (1.44-7.44 in March and 9.97-19.7 in November) and for An. flavirostris (0.19-5.14 in March and 6.27-15.8 in November). These high values may explain the increased malaria parasite rates obtained from at least two forest communities. Correlation between actual and calculated rates of gametocytaemia was poorest in Kapitangan due to inadequate sampling of the human population. In Banggi island, malaria is stable and holoendemic, and the population enjoys a high degree of immunity.
    Matched MeSH terms: Plasmodium falciparum
  13. Fulltext Tracking origins and spread of sulfadoxine-resistant Plasmodium falciparum dhps alleles in Thailand
    Alam MT, Vinayak S, Congpuong K, Wongsrichanalai C, Satimai W, Slutsker L, et al.
    Antimicrob Agents Chemother, 2011 Jan;55(1):155-64.
    PMID: 20956597 DOI: 10.1128/AAC.00691-10
    The emergence and spread of drug-resistant Plasmodium falciparum have been a major impediment for the control of malaria worldwide. Earlier studies have shown that similar to chloroquine (CQ) resistance, high levels of pyrimethamine resistance in P. falciparum originated independently 4 to 5 times globally, including one origin at the Thailand-Cambodia border. In this study we describe the origins and spread of sulfadoxine-resistance-conferring dihydropteroate synthase (dhps) alleles in Thailand. The dhps mutations and flanking microsatellite loci were genotyped for P. falciparum isolates collected from 11 Thai provinces along the Burma, Cambodia, and Malaysia borders. Results indicated that resistant dhps alleles were fixed in Thailand, predominantly being the SGEGA, AGEAA, and SGNGA triple mutants and the AGKAA double mutant (mutated codons are underlined). These alleles had different geographical distributions. The SGEGA alleles were found mostly at the Burma border, while the SGNGA alleles occurred mainly at the Cambodia border and nearby provinces. Microsatellite data suggested that there were two major genetic lineages of the triple mutants in Thailand, one common for SGEGA/SGNGA alleles and another one independent for AGEAA. Importantly, the newly reported SGNGA alleles possibly originated at the Thailand-Cambodia border. All parasites in the Yala province (Malaysia border) had AGKAA alleles with almost identical flanking microsatellites haplotypes. They were also identical at putatively neutral loci on chromosomes 2 and 3, suggesting a clonal nature of the parasite population in Yala. In summary, this study suggests multiple and independent origins of resistant dhps alleles in Thailand.
    Matched MeSH terms: Plasmodium falciparum/drug effects*; Plasmodium falciparum/genetics; Plasmodium falciparum/metabolism*
  14. Therapeutic equivalence of a low dose artemisinin formulation in falciparum malaria patients
    Wong JW, Yuen KH, Nagappan S, Shahul WS, Ho SS, Gan EK, et al.
    J Pharm Pharmacol, 2003 Feb;55(2):193-8.
    PMID: 12631411
    We have evaluated the therapeutic equivalence of a beta-cyclodextrin-artemisinin complex at an artemisinin dose of 150 mg, with a commercial reference preparation, Artemisinin 250 at a recommended dose of 250 mg. One hundred uncomplicated falciparum malarial patients were randomly assigned to orally receive either beta-cyclodextrin-artemisinin complex (containing 150 mg artemisinin) twice daily for five days or the active comparator (containing 250 mg artemisinin) twice daily for five days. The patients were hospitalized for seven days and were required to attend follow up assessments on days 14, 21, 28 and 35. All patients in both treatment groups were cured of the infection and achieved therapeutic success. At day seven of treatment, all patient blood was clear of the parasites and the sublingual temperature of all patients was less than 37.5 degrees C. Moreover, the parasite clearance time in both treatment groups was similar, being approximately three days after initiation of treatment. Comparable plasma artemisinin concentrations were observed between patients in both treatment groups at 1.5 and 3.0 h, although slightly higher levels were obtained with patients in the beta-cyclodextrin-artemisinin complex-treated group. The beta-cyclodextrin-artemisinin complex at a dose of 150 mg artemisinin was therapeutically equivalent to 250 mg Artemisinin 250. Additionally, patients receiving beta-cyclodextrin-artemisinin complex showed less variability in their plasma artemisinin concentrations at 1.5 h post-dosing, which suggested a more consistent rate of drug absorption.
    Matched MeSH terms: Plasmodium falciparum/drug effects
  15. The use of transgenic parasites in malaria vaccine research
    Othman AS, Marin-Mogollon C, Salman AM, Franke-Fayard BM, Janse CJ, Khan SM
    Expert Rev Vaccines, 2017 Jul;16(7):1-13.
    PMID: 28525963 DOI: 10.1080/14760584.2017.1333426
    INTRODUCTION: Transgenic malaria parasites expressing foreign genes, for example fluorescent and luminescent proteins, are used extensively to interrogate parasite biology and host-parasite interactions associated with malaria pathology. Increasingly transgenic parasites are also exploited to advance malaria vaccine development. Areas covered: We review how transgenic malaria parasites are used, in vitro and in vivo, to determine protective efficacy of different antigens and vaccination strategies and to determine immunological correlates of protection. We describe how chimeric rodent parasites expressing P. falciparum or P. vivax antigens are being used to directly evaluate and rank order human malaria vaccines before their advancement to clinical testing. In addition, we describe how transgenic human and rodent parasites are used to develop and evaluate live (genetically) attenuated vaccines. Expert commentary: Transgenic rodent and human malaria parasites are being used to both identify vaccine candidate antigens and to evaluate both sub-unit and whole organism vaccines before they are advanced into clinical testing. Transgenic parasites combined with in vivo pre-clinical testing models (e.g. mice) are used to evaluate vaccine safety, potency and the durability of protection as well as to uncover critical protective immune responses and to refine vaccination strategies.
    Matched MeSH terms: Plasmodium falciparum/genetics; Plasmodium falciparum/immunology*
  16. Fulltext The suitability of P. falciparum merozoite surface proteins 1 and 2 as genetic markers for in vivo drug trials in Yemen
    Al-abd NM, Mahdy MA, Al-Mekhlafi AM, Snounou G, Abdul-Majid NB, Al-Mekhlafi HM, et al.
    PLoS One, 2013;8(7):e67853.
    PMID: 23861823 DOI: 10.1371/journal.pone.0067853
    The accuracy of the conclusions from in vivo efficacy anti-malarial drug trials depends on distinguishing between recrudescences and re-infections which is accomplished by genotyping genes coding P. falciparum merozoite surface 1 (MSP1) and MSP2. However, the reliability of the PCR analysis depends on the genetic markers' allelic diversity and variant frequency. In this study the genetic diversity of the genes coding for MSP1 and MSP2 was obtained for P. falciparum parasites circulating in Yemen.
    Matched MeSH terms: Plasmodium falciparum/classification; Plasmodium falciparum/genetics*
  17. 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: Plasmodium falciparum/drug effects
  18. The return of chloroquine-sensitive Plasmodium falciparum parasites in Jazan region, southwestern Saudi Arabia over a decade after the adoption of artemisinin-based combination therapy: analysis of genetic mutations in the pfcrt gene
    Madkhali AM, Abdulhaq AA, Atroosh WM, Ghzwani AH, Zain KA, Ghailan KY, et al.
    Parasitol Res, 2021 Nov;120(11):3771-3781.
    PMID: 34561749 DOI: 10.1007/s00436-021-07323-4
    This study investigated the polymorphism in the P. falciparum chloroquine resistance transporter (pfcrt) gene 11 years after chloroquine (CQ) cessation in Jazan region, southwestern Saudi Arabia. Two hundred and thirty-five P. falciparum isolates were amplified to detect mutations in the pfcrt gene. The pfcrt 76 T molecular marker for CQ resistance was detected in 66.4% (156/235) of the isolates, while the K76 CQ-sensitive wild type was detected in 33.6%. The pfcrt 74I and pfcrt 75E point mutations were each found to be present in 56.2% of isolates, while only four isolates (1.7%) were found to carry the pfcrt 72S mutation. Moreover, four pfcrt haplotypes were identified as follows: the CVIET triple-allele (56.2%), SVMET double-allele (1.7%) and CVMNT single-allele (8.5%) mutant haplotypes and the CVMNK wild haplotype (33.6%). The analysis also revealed significant associations between the prevalence of mutant pfcrt alleles and haplotypes and the age group, governorate and nationality of the patients as well as the parasitaemia level (p falciparum strains in Jazan region over a decade after CQ discontinuation, with about one third of the isolates analysed carrying the pfcrt K76 CQ-sensitive wild allele and the CVMNK ancestral wild haplotype. Although the reintroduction of CQ cannot be recommended at present in Saudi Arabia, these findings support the rationale for a potential future role for CQ in malaria treatment. Therefore, continuous molecular and in vitro monitoring mutations of pfcrt polymorphism in Jazan region is highly recommended.
    Matched MeSH terms: Plasmodium falciparum/genetics
  19. The prospect of malaria elimination in the Arabian Peninsula: a population genetic approach
    Al-Hamidhi S, Mahdy MA, Idris MA, Bin Dajem SM, Al-Sheikh AA, Al-Qahtani A, et al.
    Infect Genet Evol, 2014 Oct;27:25-31.
    PMID: 24981966 DOI: 10.1016/j.meegid.2014.06.015
    In the Arabian Peninsula malaria control is progressing steadily, backed by adequate logistic and political support. As a result, transmission has been interrupted throughout the region, with exception of limited sites in Yemen and Saudi Arabia. Here we examined Plasmodium falciparum parasites in these sites to assess if the above success has limited diversity and gene flow.
    Matched MeSH terms: Plasmodium falciparum/classification; Plasmodium falciparum/genetics*
  20. Fulltext The presence of Plasmodium malariae and Plasmodium knowlesi in near malaria elimination setting in western Indonesia
    Nainggolan IRA, Syafutri RD, Sinambela MN, Devina C, Handayani, Hasibuan BS, et al.
    Malar J, 2022 Nov 05;21(1):316.
    PMID: 36333701 DOI: 10.1186/s12936-022-04335-y
    BACKGROUND: Indonesia is progressing towards malaria elimination. To achieve this goal, intervention measures must be addressed to cover all Plasmodium species. Comprehensive control measures and surveillance programmes must be intensified. This study aims to determine the prevalence of microscopic and submicroscopic malaria in Langkat district, North Sumatera Province, Indonesia.

    METHODS: A cross-sectional survey was conducted in six villages in Langkat district, North Sumatera Province in June 2019. Data were recorded using a standardized questionnaire. Finger pricked blood samples were obtained for malaria examination using rapid diagnostic test, thick and thin blood smears, and polymerase chain reaction.

    RESULTS: A total of 342 individuals were included in the study. Of them, one (0.3%) had a microscopic Plasmodium malariae infection, no positive RDT examination, and three (0.9%) were positive for P. malariae (n = 1) and Plasmodium knowlesi (n = 2). The distribution of bed net ownership was owned by 40% of the study participants. The participants had a house within a radius of 100-500 m from the forest (86.3%) and had the housing material of cement floor (56.1%), a tin roof (82.2%), wooden wall (35.7%), bamboo wall (28.1%), and brick wall (21.6%).

    CONCLUSION: Malaria incidence has substantially decreased in Langkat, North Sumatera, Indonesia. However, submicroscopic infection remains in the population and may contribute to further transmission. Surveillance should include the detection of microscopic undetected parasites, to enable the achievement of malaria elimination.

    Matched MeSH terms: Plasmodium falciparum
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