GC-MS Analysis of Commiphora molmol Oleo-Resin Extracts which Inhibit the growth of Bacterial Triggers of Selected Autoimmune Diseases

Abstract

Introduction: Myrrh has been used traditionally for the inhibition of microbial growth and for the treatment of rheumatic diseases. Despite this, myrrh extracts are yet to be tested for the ability to inhibit the growth of the bacterial triggers of autoimmune inflammatory diseases. Methods: Solvent extracts prepared from commercially obtained myrrh resin were analysed for the ability to inhibit the growth of bacterial species associated with initiating rheumatoid arthritis (P. mirabilis), ankylosing spondylitis (K. pneumoniae) and multiple sclerosis (A. baylyi, P. aeruginosa) by disc diffusion assay, and quantified by MIC determination. Toxicity was determined by Artemia franciscana bioassay. The most potent inhibitory extract was investigated using non-targeted GC-MS head space analysis (with screening against a compound database) for the identification and characterization of individual components in the crude plant extracts. Results: Methanolic myrrh extract inhibited the growth of all bacterial species tested. The growth inhibition of this extract was particularly notable against P. mirabilis and K. pneumoniae, with MIC values substantially < 1000 μg/mL for both reference and clinical bacterial strains. Indeed, the MIC values of the methanolic extract against P. mirabilis reference and clinical strains were 572 and 463 μg/mL respectively. The methanolic extract also inhibited the growth of A. baylyi (MIC approximately 3000 μg/mL) and P. aeruginosa (MIC approximately 1800 μg/mL). However, the MICs against these bacteria was indicative of only moderate inhibitory activity. The aqueous, ethyl acetate, chloroform and hexane extracts also inhibited the growth of all bacterial species, albeit with moderate (MIC values 1000-5000 μg/mL) to low efficacy (MIC values >5000 μg/mL) against all bacterial species. All myrrh extracts were non-toxicin the Artemia franciscana bioassay, with LC50 values substantially above 1000 μg/mL. Non-biased GC-MS headspace analysis of the methanolic extracti dentified a high diversity of monoterpenoids and sesquiterpenoid. Conclusion: The lack of toxicity and the inhibitory activity of the methanolic myrrh extract against microbial triggers of rheumatoid arthritis, ankylosing spondylitis and multiple sclerosis indicates its potential in the treatment and prevention of these diseases.