In-ovo evaluation of the antiviral activity of methanolic root-bark extract of the African Baobab (<i>Adansonia digitata</i> Lin)

Abstract

Application of ethnoveterinary medicine in the control of poultry diseases is being embraced in many parts of the world for more profitable production. This study investigated the antiviral property of the root-bark extract of the African Baobab tree (Adansonia digitata Lin) against Newcastle disease virus. One hundred and seventy five specific antibody negative embryonated chicken eggs and a field strain of Newcastle disease virus were used to test for the antiviral activity of the methanolic root bark extract of the tree. Following a 2-h exposure of the virus to eight graded concentrations of the extract, it was incubated at 37°C and observed 12-hourly for mortality. Dead embryos were spot tested for haemagglutinating activity. The 100EID₅₀ concentration of the virus and the highest concentration of the extract were inoculated as positive and negative controls, respectively. All eggs inoculated with the virus alone as well as 5 and 2 mg/ml extract/virus suspensions, died by 72 h post inoculation, while no mortality was observed amongst those inoculated with 250 and 200 mg/ml virus/extract suspensions as well as those inoculated with the pure extract. Mortalities of 40, 40 and 20%, due to viral activity were recorded for 25, 50 and 100 mg/ml suspensions, respectively. This study showed that methanolic rootbark extract of A. digitata has antiviral activity against Newcastle disease virus in ovo, particularly when used at dose rates of 200 and 250 mg/ml.

Key words: Ethnoveterinary, African Baobab, antiviral activity, Newcastle disease virus.