Antimalarial potential of homeopathic medicines against schizont maturation of Plasmodium berghei in short-term in vitro culture

In vitro assessment of antimalarial drug susceptibility of Plasmodium has been a major research success, which has paved the way for the understanding of parasite and rapid screening of antimalarial drugs for their effectiveness. In the present study a preliminary screening to check the antiplasmodial activity of mother tincture (ϕ) and various potencies (6C, 30C, 200C) of homeopathic medicines Cinchona officinalis/china (Chin.), Chelidonium majus (Chel.) and Arsenicum album (Ars.) were done by assessing the in vitro schizont maturation inhibition assay. A significant reduction in the growth of intraerythrocytic stages of P. berghei was observed with decreasing dilution of ϕ and various potencies of Chin., Chel. and Ars. exhibiting a dose dependent effect. Maximum schizont maturation inhibition was observed by Chin. ϕ (1:1), Chin. 30 (1:1, 1:2) and Chel. 30 (1:1) i.e. 80%. The standard drug CQ at 10 µM concentration exhibited 95.4±1.6% inhibition of schizont maturation. Ars. 30 (1:1) also have been found to possess strong antiplasmodial efficacy with 75.5±2.6% schizont inhibition. The presence of free merozoites in Ars. 200 with weak schizonticidal inhibition activity (40-45%) also pointed towards the ability of parasite to survive in the given drug pressure.

O estudo in vitro da susceptibilidade de Plasmodium a drogras antimaláricas representa um grande avanço nas pesquisas, abrindo novas rotas para o entendimento do parasite e da efetividade de drogas antiomaláricas. Nesse trabalho, realizamos um estudo preliminar da atividade antiplasmódica da tintura mãe (ϕ) e várias potências (6 cH, 30 cH, 200 cH) dos medicamentos homeopáticos China officinalis (Chin), Chelidonium majus (Chel) e Arsenicum album (Ars), através do estudo in vitro da inibição da maturação de esquizontes. Observamos uma redução significativa do crescimento do estágio intra-eritrócito do P. berghei conforme a tintura mãe e demais potências de Chin, Chel e Ars foram diluídas, observando-se um efeito dependente da dose. O máximo de inibição na maturação dos esquizontes (80%) foi observado com Chin ϕ (1:1), Chin 30 cH (1:1, 1:2) and Chel 30 cH (1:1). A droga Cloroquina (CQ), usada como controle, em uma concentração de 10µM, exibiu (95.4 ± 1.6) % de inibição. Ars 30cH (1:1) também apresentou uma forte eficácia antiplasmódica com (75.5 ± 2.6) % de inibição de esquizontes. A presence de merozoites livres com Ars 200 cH e uma fraca atividade inibidora (40-45%) indicam a habilidade do parasita em sobreviver na presença dessa droga.

Effect of dietary iron on the course of Plasmodium berghei malaria in young rats

Clinical and experimental evidence suggests that iron-deficient hosts are less susceptible to severe malaria and that iron supplementation aggravates infection. In the present study, 60 weanling Wistar rats were fed standard diets with different iron concentrations: 21 mg/kg (group 1), 45 mg/kg (group 2) and 113 mg/kg (group 3). Ferrous sulfate (FeSO4 x 7H2O) was added to the normal-iron and iron-supplemented diets (groups 2 and 3, respectively). Data are reported as mean +/- SEM. After 16 days of regimen, eight rats from each group were killed to measure serum iron concentration (SI) and transferrin saturation capacity (TSC). At this moment, rats from group 1 were underweight and their dietary intake was significantly lower than that of animals from the other groups. Severe iron deficiency (SI = 49.2 +/- 4.5 micrograms/100 ml and TSC = 8.3 +/- 0.7 per cent ) was observed in rats from group 1, while the animals from the other groups were iron-sufficient (group 2: SI = 186.5 +/- 28.5 micrograms/100 ml and TSC = 27.3 +/- 3.4 per cent ; group 3: SI = 137.3 +/- 18.2 micrograms/100 ml and TSC = 21.3 +/- 2.3 per cent ). Nine animals from each group were then infected with the malaria parasite Plasmodium berghei, whereas three animals from each group were used as noninfected controls. Parasitemias ( per cent of infected red blood cells) peaked 7 days post-infection in animals from groups 2 and 3 (mean values of 2.4 per cent and 1.7 per cent , respectively), but in animals from group 1 parasitemias increased until the 9th day post-infection (mean at peak, 2.3 per cent ) and parasite clearance was significantly slower than in the other groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Studies on the infectivity of gametocytes of Plasmodium berghei (NK 65) in Anopheles stephensi.

The infectivity of gametocytes of Plasmodium berghei (NK 65) has been studied in laboratory bred Anopheles stephensi. Mosquitoes were fed daily on infected male and female Mastomys natalensis and subsequent development of the oocysts was monitored in the midguts. Maximum number of oocysts were found in mosquitoes which were fed on infected female mastomys on D8 and in male mastomys on D7 post-inoculation. During the next peak of gametocytaemia, very few oocysts developed. These findings suggest that gametocytes are maximally infective only during the first peak, later on their infectivity declines although having sufficient number of gametocytes in the circulation.

Antimalarial chemotherapy with natural products and chemically defined molecules

In the present work we have described the in vivo antimalarial actrivity of six different plants. Two of them (Verninia brasiliana and Eupatorium squalidum) were tested in a randomic approach among 273 crude extracts from plants; four (Acanhospermum australe, Esenbeckia febrifuga, Lisianthus specious and Tachia guianensis) were selected after screening 22 crude extracts from different medicinal and some of them showed antimalarial activity in vitro. Some aspects of recent research with natural products aiming to produce drugs are discussed.