mode of antistaphylococcal action of Eleutherine americana

• Published in: FEMS immunology and medical microbiology Vol. 57; no. 2; pp. 193 - 201
• Main Authors: Ifesan, Beatrice Olawumi Temilade, Joycharat, Nantiya, Voravuthikunchai, Supayang Piyawan
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.11.2009; Blackwell Publishing Ltd; Blackwell; Oxford University Press
• Subjects: Anti-Bacterial Agents - pharmacology; Antibacterial agents; antimethicillin-resistant Staphylococcus aureus; Bacteriology; Biological and medical sciences; Bulbs; Cell Count; Cell Membrane - drug effects; Cell walls; cytoplasmic leakage; Dose-Response Relationship, Drug; Drug resistance; Eleutherine; Eleutherine americana; Fundamental and applied biological sciences. Psychology; Inoculum; Iridaceae - chemistry; Leakage; membrane morphology; Methicillin; Microbial Sensitivity Tests; Microbiology; Microscopes; Microscopy, Electron; Minimum inhibitory concentration; Miscellaneous; Morphology; Plant Extracts - pharmacology; Sodium chloride; Sodium Chloride - pharmacology; Staphylococcus aureus; Staphylococcus aureus - drug effects; Staphylococcus infections; antimethicillin-resistant; cytoplasmic leakage; membrane morphology; Resistance; antimethicillin-resistant Staphylococcus aureus; Immunology; Microbiology; Morphology; Bacteria; Micrococcales; Micrococcaceae; Eleutherine americana; Staphylococcus aureus
• ISSN: 0928-8244; 1574-695X; 2049-632X
• DOI: 10.1111/j.1574-695X.2009.00599.x

The anti-methicillin-resistant Staphylococcus aureus (anti-MRSA) activity and the possible mechanism of action of a crude extract from red bulbs of Eleutherine americana Merr. were investigated. The crude ethanolic extract from E. americana produced minimum inhibitory concentrations (MICs) of 62.5-1000 and 250 μg mL⁻¹ against MRSA isolates and the reference strains, respectively. Treatment of S. aureus ATCC 27664 with a crude extract at 2MIC reduced the inoculum size by 5 log at 24 h compared with the control. The combined effect of the extract and 7.5% NaCl on the enterotoxin-producing ATCC strain resulted in no detection of organisms within 24 h compared with the control. The release of cell materials after extract treatment was determined by measuring OD₂₆₀ nm, the treatment resulted in cytoplasmic leakage. Determination of OD₆₂₀ nm showed that the extract did not cause gross cell wall damage. However, observation of S. aureus cells under an electron microscope after treatment with 2MIC and 4MIC of the crude extract revealed that the extract caused damage to membrane morphology. A knowledge of the mechanism of action of the E. americana extract may offer useful hints in the search for novel antibacterial substance.