Parasitic Sensitivity Tests

Publication Title: 
Parasitology Research

The absence of a vaccine and the rampant resistance to almost all antimalarial drugs have accentuated the urgent need for new antimalarial drugs and drug targets for both prophylaxis and chemotherapy. The aim of the study was to discover effective plant extracts against Plasmodium falciparum. In the present study, the hexane, chloroform, ethyl acetate, acetone, and methanol extracts of Citrus sinensis (peel), Leucas aspera, Ocimum sanctum, Phyllanthus acidus (leaf), Terminalia chebula (seed) were tested for their antimalarial activity against chloroquine (CQ)-sensitive (3D7) strain of P.

Author(s): 
Bagavan, Asokan
Rahuman, Abdul Abdul
Kamaraj, Chinnaperumal
Kaushik, Naveen Kumar
Mohanakrishnan, Dinesh
Sahal, Dinkar
Publication Title: 
Antimicrobial Agents and Chemotherapy

Our previous studies have shown that riboflavin has activity against Plasmodium falciparum asexual-stage parasites in vitro. In the present study we examine the gametocytocidal activity of riboflavin and the interaction of riboflavin with some commonly used antimalarial drugs against the asexual forms of P. falciparum in vitro. The addition of riboflavin to P. falciparum cultures killed gametocytes at all stages, even those at late stages (III to V), which are not affected by many of the commonly used antimalarials.

Author(s): 
Akompong, T.
Eksi, S.
Williamson, K.
Haldar, K.
Publication Title: 
Antimicrobial Agents and Chemotherapy

Desbutyl-benflumetol (DBB) is a novel antimalarial compound closely related to benflumetol (lumefantrine), of which it is a putative metabolite. The in vitro response of Plasmodium falciparum to DBB was studied in Mae Hong Son and Mae Sot, in northwest Thailand, in 1997 and 1998. In total, 155 fresh isolates were successfully tested using the World Health Organization standard in vitro microtest system (Mark II). The mean 50% effective concentration (EC(50)) and 90% effective concentration of DBB were 6.36 and 31.09 nmol/liter, respectively.

Author(s): 
Noedl, H.
Allmendinger, T.
Prajakwong, S.
Wernsdorfer, G.
Wernsdorfer, W. H.
Publication Title: 
The American Journal of Tropical Medicine and Hygiene

Combining artesunate with existing antimalarial drugs may improve cure rates, delay emergence of resistance, and reduce transmission. We performed a randomized comparative trial to quantify the effect of adding artesunate to sulfadoxine-pyrimethamine in the treatment of uncomplicated falciparum malaria in Indonesia.

Author(s): 
Tjitra, E.
Suprianto, S.
Currie, B. J.
Morris, P. S.
Saunders, J. R.
Anstey, N. M.
Publication Title: 
The American Journal of Tropical Medicine and Hygiene

In vitro drug susceptibility profiles were assessed in 75 Plasmodium falciparum isolates from 4 sites in Myanmar. Except at Mawlamyine, the site closest to the Thai border, prevalence and degree of resistance to mefloquine were lower among the Myanmar isolates as compared with those from Thailand. Geometric mean concentration that inhibits 50% (IC50) and 90% (IC90) of Mawlamyine isolates were 51 nM (95% confidence interval [CI], 40-65) and 124 nM (95% CI, 104-149), respectively.

Author(s): 
Wongsrichanalai, C.
Lin, K.
Pang, L. W.
Faiz, M. A.
Noedl, H.
Wimonwattrawatee, T.
Laoboonchai, A.
Kawamoto, F.
Publication Title: 
Antimicrobial Agents and Chemotherapy

Parallel in vitro tests, assessing the inhibition of schizont maturation, were conducted with 31 fresh isolates of Plasmodium falciparum from Thailand, using artemisinin, doxycycline, and combinations of both. The activities of artemisinin and doxycycline are obviously not correlated. Both compounds showed consistent synergism at 50% effective concentration (EC(50)), EC(90), and EC(99) levels.

Author(s): 
Sponer, Ulrike
Prajakwong, Somsak
Wiedermann, Gerhard
Kollaritsch, Herwig
Wernsdorfer, Gunther
Wernsdorfer, Walther H.
Publication Title: 
The American Journal of Tropical Medicine and Hygiene

Cross-resistance may be considered one of the most important factors leading to decreased drug susceptibility of Plasmodium falciparum. The study aimed to determine whether clinically relevant cross-sensitivity of P. falciparum existed between artemisinin and mefloquine. Seventy-six patients with falciparum malaria were admitted and treated with artemisinin derivatives. Treatment response parameters were assessed and in vitro drug sensitivity tests were performed with artemisinin, mefloquine, quinine, and chloroquine.

Author(s): 
Noedl, H.
Wernsdorfer, W. H.
Krudsood, S.
Wilairatana, P.
Viriyavejakul, P.
Kollaritsch, H.
Wiedermann, G.
Looareesuwan, S.
Publication Title: 
Antimicrobial Agents and Chemotherapy

The interactions of artemisinin with atovaquone, quinine, and mefloquine were investigated in three Plasmodium falciparum strains (strains F-32, FCR-3, and K-1) by an in vitro culture assay. The parasites were cultured for 48 h in the presence of different concentrations and proportions of two drugs at a time in a checkerboard design. The response parameters were determined, and the sums of the fractional inhibitory concentrations (sigmaFICs) of the drug combinations were calculated for different degrees of inhibition (50% effective concentration [EC50], EC90, and EC99).

Author(s): 
Gupta, S.
Thapar, M. M.
Wernsdorfer, W. H.
Bjorkman, A.
Publication Title: 
Bulletin of the World Health Organization

OBJECTIVE: To evaluate the therapeutic efficacy of sulfadoxine-pyrimethamine, amodiaquine, and the sulfadoxine-pyrimethamine-amodiaquine combination for the treatment of uncomplicated Plasmodium falciparum malaria in young children in Cameroon.

Author(s): 
Basco, Leonardo K.
Same-Ekobo, Albert
Ngane, Vincent Foumane
Ndounga, Mathieu
Metoh, Theresia
Ringwald, Pascal
Soula, Georges
Publication Title: 
The American Journal of Tropical Medicine and Hygiene

Mutations at five positions in the Plasmodium falciparum multidrug-resistance gene 1 (pfmdr1), initially thought to confer resistance to chloroquine, have been associated with in vitro resistance to amino alcohols and artemisinin derivatives in more recent studies. To assess the possible association between drug resistance phenotype and pfmdrl polymorphisms and establish the baseline pfmdr1 sequence data in Yaoundé, Cameroon, the in vitro drug sensitivity pattern was determined for 64 clinical isolates by isotopic microtest.

Author(s): 
Basco, Leonardo K.
Ringwald, Pascal

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