Abstract:
Background: The increasing antimicrobial resistance exhibited by wound infecting bacteria
has led to extensive research on the antimicrobial activity of selected medicinal plants.
Objective: To investigate and compare the antibacterial activity of five medicinal plants,
Asparagus falcatus L./Hathavariya (Rhizome & roots), Cinnamomum verum J. Presl/Kurundu
(Stem bark), Coriandrum sativum L./Koththamalli (Leaves), Nigella sativa L./Kaluduru
(Seeds), Trachyspermum involucratum (Roxb.) Maire/Asamodagam (Seeds), against common
wound infecting bacteria Pseudomonas aeruginosa (ATCC 27853) and Staphylococcus aureus
(ATCC 25923)
Methods: Total of 15 plant extracts were prepared in aqueous, ethanol and acetone and
screened for antibacterial activity against each test strains triplicated by agar disk diffusion
method with positive control. Average Zone of Inhibition (ZOI) was calculated. The Minimum
Inhibitory Concentration (MIC) and Minimum Bacterial Concentration (MBC) were
determined by broth dilution and drop plate methods respectively only for plant extracts which
showed a zone of inhibition.
Results: Acetone extract of Cinnamomum verum J. Presl (average (±SD) ZOI of 6 (±0.00)
mm with MIC of 50 mg/ mL and MBC of 100 mg/ mL), ethanol extract of Cinnamomum
verum J. Presl (average ZOI of 10.33 (±0.58) mm with MIC of 3.125 mg/mL and MBC of 6.25
mg/ mL), and acetone extract of Nigella sativa L. (average ZOI of 10.33 (±0.58) mm with MIC
of 3.125 mg/ mL and MBC of 6.25 mg/ mL) have shown antibacterial activity on
Pseudomonas aeruginosa. Ethanol extract of Cinnamomum verum J. Presl showed
antibacterial activity (average ZOI of 19.66 (±0.58) mm with MIC of 100 mg/ mL and MBC of
>100 mg/ mL) on Staphylococcus aureus.
Conclusions: Ethanol and acetone extracts of Cinnamomum verum J. Presl and acetone extract
of Nigella sativa L. were found to be effective against tested strains while remaining plant
extracts did not possess antibacterial effect against tested strains.
