Arbutus pavarii Pamp is a medicinal plant commonly used by local tribes in East Libya

for the treatment of many diseases, such as gastritis, renal infections, cancer and kidney diseases.

In this study, the antibacterial activity of the leaf and stem bark extracts of the plant against

methicillin-resistant Staphylococcus aureus (MRSA), as well as the metabolite profiles of the bioactive

fractions, was investigated. The antibacterial activity was determined by disc diffusion method,

minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), while the

microbial reduction by the bioactive fraction was evaluated using time–kill test. The bioactive

fraction was further subjected to ultrahigh-performance liquid chromatography–mass spectrometry

(UHPLC-ESI-MS/MS) analysis to putatively identify the chemical constituents contained therein.

All the extracts and fractions showed different levels of antibacterial activity on the tested MRSA

strains. The highest total antibacterial activity, i.e., 4007.6 mL/g, was exhibited by the crude leaf

methanolic extract. However, the ethyl acetate fraction of the leaf showed moderate to significant

antibacterial activity against MRSA at low MIC (0.08–1.25 mg/mL). Metabolite profiling of this fraction

using UHPLC-ESI-MS/MS resulted in the putative identification of 28 compounds, which included

phenolic acids, flavan-3-ols and flavonols. The results of this study showed that the ethyl acetate

fraction of Arbutus pavarii leaf possessed potential antibacterial activity against MRSA and hence can

be further explored for pharmaceutical applications as a natural antibacterial agent.

0

0