Antiviral and antibacterial screening of some Nigerian medicinal plant extracts

Plants from Northern Nigeria with a history of use in both human and veterinary traditional medicine have been investigated in vitro, for antiviral and antibacterial activity and their cytotoxicity against human cells in culture determined. Aqueous extracts were tested against poliovirus, astrovirus, human and Equine herpes simplex virus and canine and bovine parvovirus, using the microtitre plate inhibition test.;Most of the extracts were non toxic to cells in culture and had activity against more than one virus at a dose rate of between 100 and 400 g/100. the most effective of the plant extracts were those of Bauhania thonningi, Anacardium occidentale, Boswelia dalzeilii, Dichrostacyls glomerata and Sterculia setigera, which were found to be active against all the viruses tested. In addition, most of the extracts were active against those Gram positive bacteria tested. Two of the plants, Anogeissus schimperi and Anacardium occidentale, had good antibacterial activity against the Gram negative bacteria Escherichia coli and Pseudomonas aeruginosa.;Attempts were made to isolate and identify the active components in these extracts with activity against both viruses and bacteria using the gel filtration, ion-exchange chromatography and thin layer chromatography. Activities were associated with fractions identified as flavonoids, alkaloids, terpenoids and polyphenols and were found, either individually or in combination, to have antiviral action.;A field trial of the active plant extracts was carried out using cattle with clinical diarrhoea and dysentery and comparing recovery patterns with similar administering extracts to cattle with clinically diagnosed diarrhoea animals treated with a broad spectrum gut-acting antibiotic, neomycin-sulphate. No significant difference (P=0.778) was seen between the extract and the antibiotic in efficacy of treatment.