Chemical characterization and in vitro antioxidant and antimicrobial activities of essential oil from Commiphora wildii Merxm. (omumbiri) resin

Abstract The resin of the plant Commiphora wildii Merxm. (omumbiri) is traditionally used by Ovahimba women (Kunene, Namibia) as the main ingredient for their perfume. Although essential oil produced from the resin by steam distillation is sold commercially, its detailed chemical composition and biological properties are not known. Knowledge on the potential antimicrobial and antioxidant activities of C. wildii essential oil is desired by perfume, cosmetics, and detergent manufacturers, in order to add value to their products when using the oil as an ingredient. Furthermore, once the oil has been chemically characterized, the concentrations of the bioactive constituents can be monitored for quality‐control purposes. In this study the chemical characterization of the volatile constituents of the essential oil of C. wildii resin was performed using gas chromatography–mass spectrometry (GC–MS) and GC coupled to a flame ionization detector (GC–FID). Fifty compounds were identified in the oil, most of which were terpenoids. The major compounds were α‐pinene (50.0% w/w), heptane (24.0% w/w), and β‐pinene (11.7% w/w). The antimicrobial activity of the oil was determined against Candida albicans , Escherichia coli , Klebsiella pneumaniaea , and Staphylococcus aureus . The best antimicrobial activity was noted against S. aureus , with a minimum inhibitory concentration (MIC) of 8 mg ml –1 . Biofilm reduction was below 40%, but inhibition was between 93% ( K. pneumaniaea ) and 99% ( C. albicans ). An 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging assay revealed the antioxidant potential of the oil (with a half‐maximal inhibitory concentration, IC 50 , of 0.2257 mg ml –1 ).These results may be used by different industries to guide the formulation of their products and also to assess the safety of this oil when used as an ingredient.