Essential oils for antibacterial benefits:
Antibacterial and antifungal activity of ten essential oils in vitro
1Regional Medical Research Centre, (Indian Council of Medical Research), Bhubaneswar, India.
The essential oils of aegle, ageratum, citronella, eucalyptus, geranium, lemongrass, orange, palmarosa, patchouli and
peppermint, were tested for antibacterial activity against 22 bacteria, including Gram-positive cocci and rods and
Gram-negative rods, and twelve fungi (3 yeast-like and 9 filamentous) by the disc diffusion method. Lemongrass,
eucalyptus, peppermint and orange oils were effective against all the 22 bacterial strains. Aegle and palmarosa oils
inhibited 21 bacteria; patchouli and ageratum oils inhibited 20 bacteria and citronella and geranium oils were inhibitory to 15
and 12 bacterial strains, respectively. All twelve fungi were inhibited by seven oils (aegle, citronella, geranium, lemongrass,
orange, palmarosa and patchouli). Eucalyptus and peppermint oils were effective against eleven fungi. Ageratum oil was
inhibitory to only four fungi tested. The MIC of eucalyptus, lemongrass, palmarosa and peppermint oils ranged from 0.16 to >
20 microliters ml-1 for eighteen bacteria and from 0.25 to 10 microliters ml-1 for twelve fungi.
Immune-modifying and antimicrobial effects of Eucalyptus oil and simple inhalation devices.
Eucalyptus oil (EO) and its major component, 1,8-cineole, have antimicrobial effects against many
bacteria, including Mycobacterium tuberculosis and methicillin-resistant Staphylococcus aureus (MRSA),
viruses, and fungi (including Candida). Surprisingly for an antimicrobial substance, there are also
immune-stimulatory, anti-inflammatory, antioxidant, analgesic, and spasmolytic effects. Of the white blood
cells, monocytes and macrophages are most affected, especially with increased phagocytic activity.
Application by either vapor inhalation or oral route provides benefit for both purulent and non-purulent
respiratory problems, such as bronchitis, asthma, and chronic obstructive pulmonary disease (COPD).
There is a long history of folk usage with a good safety record. More recently, the biochemical details
behind these effects have been clarified. Although other plant oils may be more microbiologically active,
the safety of moderate doses of EO and its broad-spectrum antimicrobial action make it an attractive
alternative to pharmaceuticals. EO has also been shown to offset the myelotoxicity of one chemotherapy
agent. Whether this is a general attribute that does not decrease the benefit of chemotherapy remains to
be determined. This article also provides instruction on how to assemble inexpensive devices for vapor
Potential of rosemary oil to be used in drug-resistant infections.
To evaluate the antimicrobial activity potential of the essential oil of rosemary specifically for its efficacy
against the drug-resistant mutants of Mycobacterium smegmatis, Escherichia coli, and Candida albicans.
Antibacterial, antifungal, and drug resistance-modifying activity was evaluated both qualitatively and
quantitatively following disc diffusion and broth dilution assay procedures.
The rosemary essential oil was found to be more active against the gram-positive pathogenic bacteria
except E. faecalis and drug-resistant mutants of E. coli, compared to gram-negative bacteria. Similarly, it
was found to be more active toward nonfilamentous, filamentous, dermatophytic pathogenic fungi and
drug-resistant mutants of Candida albicans.
Our findings suggest that characterization and isolation of the active compound(s) from the rosemary oil
may be useful in counteracting gram-positive bacterial, fungal, and drug-resistant infections.
Antimicrobial activity of clove and rosemary essential oils alone and in combination.
In the present study, the antimicrobial activity of the essential oils from clove (Syzygium aromaticum (L.)
Merr. et Perry) and rosemary (Rosmarinus officinalis L.) was tested alone and in combination. The
compositions of the oils were analysed by GC/MS. Minimum inhibitory concentrations (MIC) against three
Gram-positive bacteria, three Gram-negative bacteria and two fungi were determined for the essential oils
and their mixtures. Furthermore, time-kill dynamic processes of clove and rosemary essential oils against
Staphylococcus epidermidis, Escherichia coli and Candida albicans were tested. Both essential oils
possessed significant antimicrobial effects against all microorganisms tested. The MICs of clove oil ranged
from 0.062% to 0.500% (v/v), while the MICs of rosemary oil ranged from 0.125% to 1.000% (v/v). The
antimicrobial activity of combinations of the two essential oils indicated their additive, synergistic or
antagonistic effects against individual microorganism tests. The time-kill curves of clove and rosemary
essential oils towards three strains showed clearly bactericidal and fungicidal processes of (1)/(2) x MIC,
MIC, MBC and 2 x MIC.
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