additive and synergistic antimicrobial effects of select frankincense and myrrh oils – a combination from the pharaonic pharmacopoeia

• Published in: Letters in applied microbiology Vol. 54; no. 4; pp. 352 - 358
• Main Authors: de Rapper, S, Van Vuuren, S.F, Kamatou, G.P.P, Viljoen, A.M, Dagne, E
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-04-2012; Blackwell
• Subjects: additive effect; Anti-Infective Agents - chemistry; Anti-Infective Agents - pharmacology; antimicrobial activity; antimicrobial properties; Bacillus cereus; Bacteria - drug effects; Biological and medical sciences; Boswellia; Boswellia - chemistry; combination; Commiphora; Commiphora - chemistry; Commiphora myrrha; Cryptococcus neoformans; Drug Synergism; essential oils; Ethiopia; frankincense; Fundamental and applied biological sciences. Psychology; gas chromatography; Gas Chromatography-Mass Spectrometry; mass spectrometry; Microbial Sensitivity Tests; Microbiology; minimum inhibitory concentration; myrrh; oils; Oils, Volatile - chemistry; Oils, Volatile - pharmacology; Pseudomonas aeruginosa; synergy; Terpenes - pharmacology; Yeasts - drug effects; Ethiopia; synergy; myrrh; Applied microbiology; frankincense; Boswellia; antimicrobial activity; Synergism; Commiphora; Antimicrobial agent; combination
• ISSN: 0266-8254; 1472-765X
• DOI: 10.1111/j.1472-765X.2012.03216.x

Aims: The in vitro antimicrobial activity of three essential oil samples of frankincense (Boswellia rivae, Boswellia neglecta and Boswellia papyrifera) and two essential oil samples of myrrh and sweet myrrh (Commiphora guidotti and Commiphora myrrha), collected from different regions of Ethiopia, was investigated independently and in combination to determine their anti‐infective properties. Methods and Results: The microdilution minimum inhibitory concentration (MIC) assay was performed, whereby it was noted that generally Cryptococcus neoformans (MIC values in the range of 0·8–1·4 mg ml−1) and Pseudomonas aeruginosa (MIC values in the range of 0·5–1·3 mg ml−1) often appeared to be the most susceptible micro‐organisms against oils of both Boswellia and Commiphora spp. When assayed in various combinations, the frankincense and myrrh oils displayed synergistic, additive and noninteractive properties, with no antagonism noted. When investigating different ratio combinations against Bacillus cereus, the most favourable combination was between B. papyrifera and C. myrrha. The composition of the oils was determined by gas chromatography coupled to mass spectrometry (GC–MS) to document the specific chemotypes used in the study, and the chemical profiles were found to be congruent with previously reported data. Conclusions: The majority of interactions identified synergistic and additive effects, with strong synergism noted between B. papyrifera and C. myrrha. Significance and Impact of the Study: Frankincense and myrrh essential oils have been used in combination since 1500 bc; however, no antimicrobial investigations have been undertaken to confirm their effect in combination. This study validates the enhanced efficacy when used in combination against a selection of pathogens.