Antibacterial Activities of Essential Oil and Fractions of Ethanolic extract of Echinops kebericho Tuber

Abstract

Background: Echinops kebericho is an endemic medicinal plant in Ethiopia traditionally used for treatment of various infectious diseases through different routes of administration such as inhalation, orally chewed, and topically sprayed to affected area. This study investigated antibacterial activity of the essential oil (EO) and the different fractions of ethanolic extract of Echinops kebericho tuber. Results: MIC of EO ranged from 78.125 μg/ml – 625 μg/ml and it was most active against methicillin resistant S. aureus (MRSA, NCTC 12493). Ethyl acetate fraction showed better activity against MRSA (NCTC 12493), MIC = 39.075 μg/ml followed by E. faecalis (ATCC 49532), MIC = 78.125 μg/ml and was least active against K. pneumonia (ATCC 700603), MIC = 1250 μg/ml. MIC of hexane fraction ranged from 156.2- μg/ml to E. faecalis (ATCC 49532) to 1250 μg/ml to E. coli (NCTC 11954). Chloroform fraction MIC ranged from 312.5 - 2500μg/ml; while butanol fraction could be considered pharmacologically inactive as its MIC value is 2500 μg/ml for all and no activity shown for E. coli (NCTC 11954). The MIC of DMSO against all strains ranged 12.5- 25 % w/v. The MIC estimated by OD measurement correlated well with that of resazurin assay method. Conclusion: Essential oil and ethyl acetate fraction showed noteworthy antibacterial activity, and MRSA was the most susceptible strain. Further study, however, should be done to investigate the effect on the isolated active component(s).