Table 2: In vitro studies of essential oils in combination with conventional chemotherapy agents.

Cell linesChemotherapy drug used alone and concentrationEO constituent used alone and concentrationCombined EO and chemotherapy drugReference

Prostate cancer cell (DU-145)Docetaxel IC50 2.8 nMd-limonene IC50 2.8 mMIC50 docetaxel 1.9 mM and d-limonene 0.2 mM[22]

Human breast cancer (MCF-7)Paclitaxel 0.025 µg/mL−1 resulted in 28% cell growth inhibitionβ-caryophyllene resulted in no inhibition of cell growthβ-caryophyllene 2.5 µg/mL−1 and Paclitaxel 0.025 µg/mL−1 resulted in 50% cell growth inhibitionβ-caryophyllene 10 µg/mL−1 and Paclitaxel 0.025 µg/mL−1 resulted in 68% cell growth inhibition[23]

Human colorectal adenocarcinoma (DLD-1)Paclitaxel 0.025 µg/mL−1 resulted in 17.3% cell growth inhibitionβ-caryophyllene resulted in no inhibition of cell growthβ-caryophyllene 2.5 µg/mL−1 and Paclitaxel 0.025 µg/mL−1 resulted in 91% cell growth inhibitionβ-caryophyllene 10 µg/mL−1 and Paclitaxel 0.025 µg/mL−1 resulted in 189% cell growth inhibition[23]

Mouse fibroblast (L-929)Paclitaxel 0.025 µg/mL−1 resulted in 18.4% cell growth inhibitionβ-caryophyllene resulted in no inhibition of cell growthβ-caryophyllene 2.5 µg/mL−1 and Paclitaxel 0.025 µg/mL−1 resulted in 36% cell growth inhibitionβ-caryophyllene 10 µg/mL−1 and Paclitaxel 0.025 µg/mL−1 resulted in 123% cell growth inhibition[23]