The antimicrobial properties of volatile aromatic
oils and medium-chain
fatty acids derived from edible plants have been recognized since antiquity. To give examples,
Origanum oil, used as a food-
flavoring agent, possesses a broad spectrum of antimicrobial activity due, at least in part, to its high content of phenolic derivatives such as
carvacrol and
thymol. Similarly,
lauric acid, present in heavy concentrations in coconuts, forms
monolaurin in the body that can inhibit the growth of pathogenic microbes. Using Staphylococcus aureus in broth cultures and a microdilution method, comparative efficacy of
Origanum oil, and a constituent
carvacrol, other
essential oils and
monolaurin were examined.
Origanum oil was the most potent of the
essential oils tested and proved bactericidal in culture to two strains of Staphylococcus aureus (ATCC #14154 and #14775) at 0.25 mg/mL. In vitro,
monolaurin's effects mirrored
Origanum oil. The combination of both was bactericidal at the 0.125 mg/mL concentration of each. In two separate In vivo experiments, injected Staphylococcus aureus (ATCC #14775) killed all 14 untreated mice within a 1-week period. In treated mice, over one third survived for 30 days when given oral
Origanum oil daily for 30 days (6/14). Fifty percent of the mice survived for 30 days when receiving daily
vancomycin (7/14) and
monolaurin (4/8). Over 60% of mice survived when receiving a daily combination of
Origanum oil and
monolaurin (5/8).
Origanum oil and/or
monolaurin may prove to be useful
antimicrobial agents for prevention and
therapy of
Staphylococcus aureus infections.