Antiplasmodial activity of flavonol quercetin and its analogues in Plasmodium falciparum: evidence from clinical isolates in Bangladesh and standardized parasite clones.

Malaria is still a major threat in many parts of the world with resistance spreading to almost all classes of antimalarials. The limited arsenal of available antimalarial drugs emphasizes the urgent need for novel antimalarial compounds. Owing to the fact that novel leads from nature have traditionally played a pivotal role in the development of various classes of antimalarials, we investigated a set of eight naturally occurring dietary flavonoids and their analogues for their antiplasmodial activity on clinical field isolates in southeastern Bangladesh and culture-adapted chloroquine-sensitive and chloroquine-resistant parasite clones. Except for taxifolin, all the other flavonoids had 50% inhibitory concentrations below 14 µM, both in the field and laboratory-adapted parasites. Neither of the flavonoids showed any activity correlation with chloroquine. The quercetin analogue rutin (7.10 ± 10.32 µM) was the most active substance in field isolates as well as laboratory-adapted cultures (3.53 ± 13.34 µM in 3D7 and 10.38 ± 15.08 µM in K1), providing the first evidence of its activity against Plasmodium falciparum parasites. Thus, our results provide important evidence of the antimalarial activity of flavonoids in traditional use and thus warrant further investigation of these compounds as potential antiplasmodial agents.

Evidence of a major reservoir of non-malarial febrile diseases in malaria-endemic regions of Bangladesh.

In malaria-endemic regions any febrile case is likely to be classified as malaria based on presumptive diagnosis largely caused by a lack of diagnostic resources. A district-wide prevalence study assessing etiologies of fever in 659 patients recruited in rural and semi-urban areas of Bandarban district in southeastern Bangladesh revealed high proportions of seropositivity for selected infectious diseases (leptospirosis, typhoid fever) potentially being misdiagnosed as malaria because of similarities in the clinical presentation. In an area with point prevalences of more than 40% for malaria among fever cases, even higher seroprevalence rates of leptospirosis and typhoid fever provide evidence of a major persistent reservoir of these pathogens.