Determination and quantification of the in vitro activity of Aloe marlothii (A. Berger) subsp. marlothii and Elephantorrhiza elephantina (Burch.) skeels acetone extracts against Ehrlichia ruminantium

Abstract

An Ehrlichia ruminantium culture system was utilized for the anti-rickettsial evaluation of two ethnoveterinary plants, Elephantorrhiza elephantina and Aloe marlothii. Well-established E. ruminantium cultures were incubated with the plant leaf acetone extracts and compared to oxytetracycline and untreated controls. Effectivity was established by comparing the percentage parasitised cells and the calculation of both EC₅₀ and extrapolated EC₉₀ in µg/ml. The plant extracts were also screened for antibacterial activity using bioautography. Elephantorrhiza elephantina and A. marlothii demonstrated anti-ehrlichial activity with an EC₅₀ of 111.4 and 64.5 µg/ml and EC ₉₀ of 228.9 and 129.9 µg/ml, respectively. The corresponding EC₅₀ and EC₉₀ for oxytetracycline was 0.29 and 0.08 µg/ml. Both plants appeared to produce their inhibitory activity by a similar mechanism, unrelated to that of the tetracyclines. Both the plant acetone extracts demonstrated antibacterial activity against Escherichia coli and Staphylococcus aureus (ATCC strains).