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Antimicrobial activity of limonene enantiomers and 1,8‐cineole alone and in combination
Author(s) -
Vuuren S. F. van,
Viljoen A. M.
Publication year - 2007
Publication title -
flavour and fragrance journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.393
H-Index - 70
eISSN - 1099-1026
pISSN - 0882-5734
DOI - 10.1002/ffj.1843
Subject(s) - limonene , chemistry , antimicrobial , enantiomer , essential oil , minimum inhibitory concentration , terpene , monoterpene , antibacterial activity , stereochemistry , chromatography , organic chemistry , bacteria , genetics , biology
Two common essential oil constituents, 1,8‐cineole and limonene, were assessed for antimicrobial activity, using the minimum inhibitory concentration (MIC) microtitre plate method against eight organisms. The limonene enantiomers, i.e. (+), (−) and the racemate, singularly and in combination (1:1) with 1,8‐cineole, were investigated to establish possible interactions. The MIC values were in the ranges 3–27 mg/ml for (+)‐limonene; 2–27 mg/ml for (−)‐limonene and 23 mg/ml for 1,8‐cineole, depending on the pathogen studied. The combinations, when investigated in a 1:1 ratio, mostly indicated reduced activity. Using various ratios of limonene and 1,8‐cineole, the specific interaction was further investigated against Staphylococcus aureus (Gram‐positive), Pseudomonas aeruginosa (Gram‐negative) and a yeast, Cryptococcus neoformans. A figurative representation of the results using isobologram construction indicated that, depending on the ratio and specific enantiomer, an additive, synergistic or antagonistic interaction may be observed. Copyright © 2007 John Wiley & Sons, Ltd.