Antimalarial Activity

Antimalarial activities were performed by in vivo experiment in mice. In order to determine ED₅₀, animals were divided into seven groups of five mice, one was negative control group and six were treated groups. The negative control group was given CMC Na 0,5% once a day orally, and treated groups were fed with suspension of 90% ethanol extract of C. spectabilis leaves with the dose of 50, 75, 100, 150, 200 and 250 mg/kg body weight of mice once a day orally.

Further investigation to determine the effective dose of extract was also performed. Two kind of experiments were conducted in parallel. First, the ethanol extract of C.spectabilis leaves was administered in multiple doses (twice and thrice daily). Second, it was administered in single dose (once daily) orally at a dose of 150 mg/kg of body weight.

Antimalarial activity of ethanol extract of C. spectabilis leaves were conducted by 4-day suppressive test of Peters (Phillipson and Wright, 1991). Each mouse was inoculated intraperitonially on the first day (day 0/ D0) with 0.2 ml of P. berghei-infected blood (1%), and followed by treatment of the malarial- infected mouse with ethanol extract of C. spectabilis in concentration of 50, 75, 100, 150, 200 or 250 mg/kg bodyweight. The extract was administered orally for four consecutive days.

On the fourth day after treatment (D4), the percentage of parasitaemia in P. berghei–infected mouse was evaluated by collecting blood from the tail of mice, and the parasitaemia was examined by gram staining. Parasitaemia level was determined by counting the number of parasite–infected erythrocytes per 3000 erythrocytes, and the ED₅₀ was calculated by probit analysis. The ED₅₀ representing 50% suppresion of parasite when it is compared to untreated control.

Average percentage of parasite’s inhibition was calculated as following :

X_e = % parasitaemia growth of the treated

X_k = % parasitaemia growth of negatif control