Trematocidal activity of aqueous crude extract of Ocimum gratissimum leaves

The effect of Ocimum gratissimum, (scent) leaf extract on Paramphistomum cervi and Fasciola hepatica were investigated. Five different concentrations of leaf extract (2mg, 4mg, 6mg, 8mg and 10mg/ml) were prepared and administered in vitro in sample petridishes containing P. cervi and F. hepatica collected from cattle slaughtered at Apiapum abattoir. A total of 10 of each of the parasites were kept inside each sample petridish. Mortality of the parasites was monitored for 1,2,3,4 and 5 hour duration. The mean cumulative mortality and probit (quantal concentration-response) analysis were performed to determine the lethal concentration (LC₅₀) of the plant leaf extract on the trematode. The trematocidal activities of the plant extract were time and concentration dependent. The cumulative mortality (%) of the trematodes occasioned by administration of leaf extracts range from 6.67–76.67% at the end of 5 hour at (2mg/ml) for F. hepatica and 10.67–70.00% for P. cervi. At the highest concentration (10mg/ml) of O. gratissimum, 100% mortality was attained in just 4 hours of exposure of P. Cervi with a range of 76.67–100% whereas 4 hours was required for the same result for F. hepatica having a range of 66.67–100% mortality. The LC₅₀ values decreased with increase in time of exposure for both species of parasites. The 5h LC₅₀ of, O. gratissimum (2.63mg/ml), recorded against P. cervi was higher than the corresponding value 2.02mg/ml, for F. hepatica. The smaller the LC₅₀ value the more lethal the extract and susceptibility the organism is to the extract. The results revealed that O. gratissimum (scent leaf) may be employed as anthelmintic against trematode parasites P. cervi and F. hepatica although efficacy of the extract may be influenced by route of administration of extract, health status of the host animal and nutritional state as well as general physiologic conditions of the animal in vivo administration.