Antiplasmodial Activity of the Root Extracts of Cochlospermum tinctorium in Mice Experimentally Infected with Clinical Isolates of Plasmodium berghei berghei (NK 65)

Abstract

Aims: To determine in vivo the antiplasmodial activity of two chromatographic fractions obtained from Cochlospermum tinctorium A. Rich root bark extract against Plasmodium berghei berghei in mice. Methodology: Two chromatographic fractions were obtained from the crude methanolic extract of C. tinctorium root bark using petroleum ether (Fraction 1) and ethanol (Fraction 2) which were tested to determine their antiplasmodial activity in Swiss Albino mice infected with P. berghei berghei. Fraction 1 was administered at dose levels of 50, 100 and 200mg/kg/day, while fraction 2 was administered at dose levels of 25, 50 and 100 mg/kg/day. Chloroquine at 5 mg/kg per day was used as positive control and 0.2 ml normal saline was applied per day as sham. Results: Fraction 1had a percentage antiplasmodial activity of 80.67%, 64.14% and 69.71% for the dose level of 50, 100 and 200 mg/kg respectively. Data shows that fraction 1 treatment was not dose dependent as the lowest dosage of 50 mg/kg/day produced the highest percentage antiplasmodial activity of 80.67%, while 5 mg/kg chloroquine gave 100% cure. The effects of all treatments were significantly different (p<0.05). Fraction 2 produced a dose dependent antiplasmodial activity of 62.42%, 65.70% and 98.17% in infected mice treated with 25, 50 and 100 mg/kg/day of the fraction respectively in direct proportion. Only the 100 mg/kg fraction antiplasmodial activity was not significantly different (p>0.05) from that of 5 mg/kg chloroquine. The Median survival time post infection for infected mice treated with sham was 11 days, for infected mice treated with 50, 100 and 200mg/kg of fraction 1, the median survival time was 15.5, 15.5 and 19 days respectively, the log-rank (Mantle-Cox) test value of p<0.05 showed that survival curves are significantly different. The median survival time post infection for mice treated with 0.2ml normal saline per day was 11days, for mice treated with 25, 50 and 100mg/kg of fraction 2 the median survival time post infection was 19, 18.5 and 18 days respectively, Log-rank (Mantle-Cox) test value of p<0.05 indicates that survival curves are significantly different. The high antiplasmodial activity of 100 mg/kg fraction 1 was countered by its low survival time indicating a probable increase in toxicity to the mice with increase in dosage. The mean Packed Cell Volume (PCV) for infected mice treated with 50, 100 and 200 mg/kg fraction 1, the mean PCV was 36.83%, 32.42% and 37.96% respectively, while infected mice treated with25, 50 and 100mg/kg the mean PCV was 40.22%, 27.50% and 43.04% respectively. Since the mean PCV for infected mice treated with sham was 29.50%and 43.40% for 5mg/kg chloroquine treated mice, both fractions of C. tinctorium possess anaemia ameliorating property. However, only that of 25 and 100 mg/kg fraction 2 were the same as that of 5 mg/kg chloroquine (p>0.05).There was however no significant difference (p>0.05) in the mean percentage antiplasmodial activity of fraction 2 (65.26%) which was higher than that of fraction 1 (62.90%). Conclusion: C. tinctorium root bark extractpossess antimalarial and anaemia ameliorating properties which validates its use in traditional medicine for the treatment of malaria.