Evaluation of antibacterial, free radical scavenging activities and phytochemical composition of Boswellia dalzielii Hutch extracts

Abstract

Ethanol extract and essential oil of Boswellia dalzielii leaves were screened for their antibacterial and antiradical activities by using microdilution and 1, 1-diphenyl-2-picrylhydrazyl (DPPH) free radical methods respectively. Ethanol extract was submitted to a phytochemical screening and the essential oil to Gas Chromatography-Mass Spectrometry (GC/MS) analysis. Antibacterial studies reveal a MIC of 1.25 mg/ml for ethanol extract and 1.25 μl/ml of essential oil on Methicillin-resistant Staphylococcus aureus, but no MIC on Staphylococcus aureus. The essential oil was more powerful radical scavenging activity with EC50 value of 1.25 μg/mL which greater than the standard antioxidants, ascorbic acid (EC50 = 5 μg/mL). The phytochemical screening reveals the presence of metabolites mainly 3.56 ±0.06 mg GAE/ g of extract of total polyphenol and 1.24±0.01 mg QE/ g of extract. GC-MS results show the presence of: Zerumbone (33.69%), α-phellandrene (11.80%), alpha α-pinene (9.71%), Germacrene D (9.08%) ß - phellandrene (8.19%) and Trans ß – caryophyllene (7.45%) like major compounds. These compounds could be responsible for the antibacterial and scavenging activities.