Background: Infectious diseases are responsible for millions of deaths a year worldwide.
Antibiotics, which have saved so many lives and improved life expectancy, may become ineffective
due to a worrying increase in bacterial resistance. Some of the appropriate actions that could be initiated
to address this problem are to develop and search for new antimicrobial substances from medicinal
plants, and combine antibiotics with antimicrobials agents isolated from a reservoir of bioactive
Objectives: The purpose of this work was to study the chemical composition of the essential oil and
hydrosol extract of Plumbago europaea, to evaluate their in-vitro antimicrobial activities and evaluate
in-vitro combinatory antimicrobial effect of hydrosol extract with Gentamicin and Amphotericin
B against a large panel of microorganisms in an effort to reduce their minimum effective dose and
minimizing their side effects.
Methods: The essential oil and hydrosol extract obtained from the roots of Plumbago europaea were
analyzed by GC/MS and tested for their antibacterial and antifungal activities against twelve different
strains of microorganisms. The effectiveness, in-vitro, of the association between the hydrosol
extract and both Gentamicin and Amphotericin B was also investigated using the checkerboard
Results: The obtained results revealed that nine and four components, representing for 92.4% and
97.4% of the total essential oil and hydrosol extract composition were identified, respectively and
hydrosol extract was more active than the essential oil against all screened microorganisms, with interesting
MIC values (19 μg/mL). An important effect of hydrosol extract was obtained in decreasing
the MIC of Gentamicin and Amphotericin B in all tested combinations.
Conclusion: The in-vitro combination of the hydrosol extract with Gentamicin and Amphotericin B
led to substantial MIC reduction against all tested microorganisms. This combination can help to reduce
the minimum effective dose of antimicrobial drugs used, which may help to decrease their side
effects; and deliver these medicines with similar potency.