Table 1.
Effect of essential oils on a seven-day old stationary phase B. burgdorferi a.
| Essential Oils and Control Drugs | Plant and Extracted Part | Residual Viability (%) after 0.2% EO or 40 μM Antibiotic Treatment | Residual Viability (%) after 0.1% EO Treatment | ||||
|---|---|---|---|---|---|---|---|
| Plate Reader b | Microscope c | p-Value e | Plate Reader b | Microscope c | p-Value e | ||
| Doxycycline | -- | 73 ± 4 | 66 ± 2 | 1.000 | -- | -- | -- |
| Cefuroxime | -- | 58 ± 3 | 55 ± 3 | 0.0016 | -- | -- | -- |
| Daptomycin | -- | 28 ± 5 | 21 ± 1 | 0.0004 | -- | -- | -- |
| Cinnamaldehyde | -- | 26 ± 5 | 0 | 0.0002 | 54 ± 2 | 28 | 0.0016 |
| Garlic | Allium sativum L. (syn. Porrum sativum (L.) Rchb.), bulbs | 25 ± 4 | 0 | 0.0001 | 24 ± 6 | 18 ± 2 | 0.0002 |
| Allspice | Pimenta officinalis Lindl., berries | 21 ± 4 | 0 | 0.0001 | 30 ± 6 | 25 ± 3 | 0.0005 |
| Myrrh | Commiphora myrrha (T. Nees) Engl. (syn. Balsamea myrrha (T. Nees) Oken), resin | 32 ± 3 | 0 | 0.0001 | 35 ± 6 | 25 ± 2 | 0.0009 |
| Hydacheim | Hedychium spicatum Thymus (syn. Gandasulium spicatum (Buch.-Ham. ex Sm.) Kuntze), flowers | 34 ± 4 | 23 ± 2 | 0.0002 | 38 ± 7 | 26 ± 1 | 0.0017 |
| Litsea cubeba | Litsea cubeba (Lour.) Pers. (syn. Benzoin cubeba (Lour.) Hatus., Persea cubeba (Lour.) Spreng.), fruits | 98 ± 4 | ND d | -- | 77 ± 4 | 27 ± 3 | (0.00004) |
| Palmarosa | Cymbopogon martini var. motia Bruno, grass | 26 ± 5 | 0 | 0.0002 | 35 ± 5 | 29 ± 2 | 0.0004 |
| Lemon eucalyptus | Eucalyptus citriodora Hook. (syn. Corymbia citriodora (Hook.) K.D. Hill & L.A.S. Johnson), leaves | 35 ± 6 | 0 | 0.0006 | 39 ± 7 | 29 ± 4 | 0.0015 |
| Amyris | Amyris balsamifera L. (syn. Elemifera balsamifera (L.) Kuntze), wood | 32 ± 3 | 4 ± 2 | 0.0001 | 38 ± 5 | 29 ± 3 | 0.0006 |
| Cumin | Cuminum cyminum L., seeds | 31 ± 3 | 0 | 0.0001 | 31 ± 6 | 30 ± 1 | 0.0005 |
| Thyme white | Thymus vulgaris L. (syn. Origanum thymus (L.) Kuntze), leaves | 37 ± 2 | 26 ± 2 | 0.0001 | 36 ± 1 | 30 ± 2 | 0.0001 |
| Carrot seed | Daucus carota L., seeds | 38 ± 4 | 5 ± 3 | 0.0004 | 40 ± 3 | 60 ± 2 | 0.0003 (0.0705) |
| Head ease | Synergy blend | 41 ± 3 | 25 ± 3 | 0.0003 | 74 ± 4 | 65 ± 1 | 0.8008 |
| Deep muscle | Synergy blend | 42 ± 4 | 3 ± 2 | 0.0004 | 56 ± 4 | 68 ± 4 | 0.0060 (0.3911) |
| Birch | Betula lenta L., bark | 86 ± 5 | 22 ± 2 | (0.00001) | 91 ± 4 | 69 ± 2 | -- |
| Ho wood | Cinnamomum camphora (L.) J. Presl (syn. Cinnamomum camphora (L.) Nees & Eberm., Cinnamomum camphora (L.) Siebold), twigs and bark | 36 ± 4 | 3 ± 2 | 0.0004 | 69 ± 5 | 70 ± 3 | 0.3078 |
| Petitgrain | Citrus aurantium L, trees and leaves | 38 ± 3 | 19 ± 2 | 0.0002 | 71 ± 4 | 70 ± 3 | 0.4743 |
| Fennel sweet | Foeniculum vulgare Mill., seeds | 40 ± 5 | 2 ± 1 | 0.0006 | 72 ± 3 | 75 ± 4 | 0.6235 |
| Cornmint | Mentha arvensis, leaf | 35 ± 5 | 0 | 0.0004 | 68 ± 4 | 85 ± 1 | 0.1359 |
| Citrus blast | Synergy blend | 51 ± 5 | >70 | 0.0039 | 71 ± 5 | >70 | 0.5865 |
| Nutmeg | Myristica fragrans Houtt., seeds | 43 ± 4 | >70 | 0.0008 | 71 ± 4 | >70 | 0.6533 |
| Alive | Synergy blend | 40 ± 4 | >70 | 0.0004 | 71 ± 3 | >70 | 0.5228 |
| New beginning | Synergy blend | 48 ± 4 | >70 | 0.0013 | 75 ± 4 | >70 | 0.5107 |
| Happy | Synergy blend | 47 ± 4 | >70 | 0.0009 | 78 ± 2 | >70 | -- |
| Meditation | Synergy blend | 55 ± 4 | >70 | 0.0041 | 79 ± 4 | >70 | -- |
| Deep forest | Synergy blend | 61 ± 1 | >70 | 0.0039 | 79 ± 3 | >70 | -- |
| Copaiba | Copaifera officinalis (Jacq.) L., balsm | 51 ± 2 | >70 | 0.0007 | 79 ± 2 | >70 | -- |
| Balsam fir | Abies balsamea (L.) Mill. (syn. Peuce balsamea (L.) Rich.), needles | 57 ± 5 | >70 | 0.0124 | 80 ± 1 | >70 | -- |
| Juniper Berry | Juniperus communis L., berries | 56 ± 5 | >70 | 0.0086 | 82 ± 3 | >70 | -- |
| Camphor | Cinnamomum camphora (L.) J. Presl (syn. Cinnamomum camphora (L.) Nees & Eberm., Cinnamomum camphora (L.) Siebold), wood | 58 ± 3 | >70 | 0.0047 | 82 ± 3 | >70 | -- |
| Vetiver | Vetiveria zizanioides (L.) Nash (syn. Phalaris zizanioides L.), root | 41 ± 3 | >70 | 0.0003 | 82 ± 5 | >70 | -- |
| Fir needle | Abies sibirica Ledeb. (syn. Pinus sibirica (Ledeb.) Turcz.), needles | 60 ± 3 | >70 | 0.0109 | 83 ± 5 | >70 | -- |
| Sleep tight | Synergy blend | 57 ± 5 | >70 | 0.0130 | 85 ± 6 | >70 | -- |
| Turmeric | Curcuma longa L. (syn. Kua domestica (L.) Medik.), root | 50 ± 2 | >70 | 0.0007 | 93 ± 3 | >70 | -- |
| Elemi | Canarium luzonicum (Blume) A. Gray (syn. Pimela luzonica Blume), resin | 58 ± 3 | >70 | 0.0059 | 95 ± 2 | >70 | -- |
| Parsley seed | Petroselinum sativum Hoffm., seeds | 64 ± 5 | >70 | 0.0645 | 97 ± 3 | >70 | -- |
a A seven-day old B. burgdorferi stationary phase culture was treated with essential oils or control drugs for 7 days. Bold type indicates the essential oils that had better or similar activity compared with 40 μM daptomycin used as the positive persister-drug control. b Residual viable (mean ± SD) B. burgdorferi was calculated according to the regression equation and ratios of Green/Red fluorescence obtained by SYBR Green I/PI assay [22]. c Residual viability (mean ± SD) calculated by fluorescence microscope measurements. d Autofluorescence of essential oil is too strong to be observed under fluorescence microscope. e p-value of the standard t-test for the 0.1% essential oil treated group versus doxycycline treated control group was calculated by data of the plate reader or microscope test (shown in the brackets). The essential oil groups with higher residual viability than control group were not included in the standard t-test.