Materials and Methods: The drug interaction between rosmarinic acid, thymoquinone, and docetaxel, as the chemotherapeutic drug, was analyzed using the Chou-Talalay method along with CompuSyn. To understand the number of cell proliferation of MDA-MB231 breast cancer, a tetrazolium-based colorimetric assay (MTT assay) was investigated. DAPI and the flowcytometric assay were harnessed to evaluate the morphology and the percentage of apoptosis, respectively. Real-time polymerase chain reaction (PCR) was used to recognize the association between the NF-κB pathway and program cell death signal.

Results: The IC50 values for docetaxel, rosmarinic, and Thymoquinone were 2.6 ± 0.62 nM, 15.6 ± 2.4 μM, and 35.5 ± 3.4 μM, respectively. MDA-MB231 breast cancer showed combination index value following three combination recipes; rosmarinic acid + docetaxel, thymoquinone + docetaxel, rosmarinic acid + thymoquinone + docetaxel was 0.26, 0.55, and 0.08, which designated a remarkable synergistic effect. The cultivation of the tumor cells under the exposition of docetaxel and rosmarinic, as well as thymoquinone, discovered a substantial upsurge in the anti-proliferative manner of docetaxel from 60% to 82%, along with a double-fold surge in the number of dead cells. mRNA levels exhibited a noticeable decline in IκB-α as an indicator of NF-κB activation and the decline of survivin and Bcl-2 escorted by a surge in pro-apoptotic Bad mRNA levels (P < 0.05).

Conclusions: By considering our results, the co-administration of docetaxel, rosmarinic, and thymoquinone can be figured out as a promising adjuvant therapy besides other treatment protocols.