The phytochemical constituents and antibacterial activity of methanolic and ethanolic leaf and stem extracts of Eucalyptus torelliana, Nigeria

The use of traditional medicines has been observed to increase globally. The search for new antimicrobial agents has increased as a result of increase in microbial infections as well as antimicrobial resistance. The phytochemical and antibacterial activities of ethanolic and methanolic extract of leaves and stem of Eucalyptus torelliana was investigated to detect the presence of secondary metabolites and also evaluate their antibacterial potential. The phytochemical constituents of the powdered leaves and stem of Eucalyptus torelliana were determined using standard methods. The antibacterial susceptibility of bacteria from different sources to the leaves and stem extract was determined using agar diffusion method. Minimum inhibitory concentrations, MIC of the extracts were also determined. Phytochemical screening of Eucalyptus torelliana yielded glycosides, reducing sugars, condensed tannins and terpenoids in both leaf and stem extract while saponins were found only in the leaves extract. The ethanolic and methanolic extracts of Eucalyptus torelliana had antibacterial activities at 20mg/ml and 10mg/ml especially at 20mg/ml where it showed significant difference in their activity in relation to the negative control. The extracts from the stem were observed to have better antibacterial activity compared to the leaves. Gentamicin was used as a positive control. The ethanolic extracts had MIC range between 10mg/ml->10mg/ml while that of the methanolic extracts was >10mg/ml. The results from this study validate the possible use of Eucalyptus torelliana in the production of new antimicrobial agents.