Anti-microbial, Anti-Diabetic and Anti-Quorum Sensing Activity of the Essential Oil of Dialium Guineense Willd. Grown in South-West Nigeria

Dialium guineense essential oil possesses various biological and biochemical activities. The present study is based on determination of antimicrobial, anti-diabetic, anti-cholinesterase, anti-biofim, anti-antibiotic resistance modifying activities and anti-quorum sensing potential of essential oil. Chemical compounds in essential oil were recognised by retention indices using gas chromatograph-mass spectroscopy (GC-MS). A total of 45 compounds were present in the essential oil of which 12 are most active. Essential oil of D. guineense showed highest anti-bacterial activity in the form of zone of inhibition, produced 23 mm zone against Staphylococcus aureus and 15 mm against Escherichia coli. D. guineense oil at various concentrations showed excellent anti-diabetic and anti-cholinesterase activities. Since many active compounds were present in D. guineense oil so authors of this study planned to observe effect of D. guineense oil on quorum sensing regulated virulence factors and thus bio-film formation in pathogens Essential oil reduced bio-film formation considerably at all concentrations against E. coli, Staphylococcus aureus and Pseudomonas aeruginosa. Determination of quorum sensing (QS) inhibitory activity was demonstrated by reduction in pyocyanin (73.93%), total protease (68.59%) and chitinase activity (66.18%) in Pseudomonas aeruginosa at 1 mg/mL of D. guineense oil compared to control. Essential oil at all concentrations tested showed synergistic effect. Since essential oil showed anti-microbial, anti-biofilm and quorum sensing regulated anti-pathogenic activities. Based on results mentioned above, it is concluded that bioactive chemicals from D. guineense oil can act as an anti-infective agent by controlling growth, bio-film formation and signalling pathways of pathogenic microbes as well as other diseases.