Antioxidant and Chemotherapeutic Synergy: Triphala Enhances Doxorubicin Cytotoxicity in Breast Cancer Cells and Reduces Toxicity in Non-Tumorigenic Cells

Background: The combining of antioxidants with chemotherapy is increasingly explored to minimize toxicity in non-cancerous cells during breast cancer treatment. Triphala (TPL), a Thai herbal compound rich in antioxidants, shows potential as a complementary candidate for breast cancer chemotherapy. Objective: This study investigated the combined effects of TPL and low-dose doxorubicin (DOX) on human breast cancer and non-tumorigenic mammary epithelial cells. Methods: TPL’s bioactive compounds were analyzed via high-performance liquid chromatography (HPLC). Cell viability and reactive oxygen species (ROS) levels were assessed in breast cancer (MDA-MB-231, MCF-7) and epithelial (MCF-10A) cells using thiazolyl blue tetrazolium bromide (MTT) and chloromethyl 2′,7′-dichlorodihydrofluorescein diacetate (CM-H2DCFDA) assays in triplicate. Combination index (CI) values were determined with CompuSyn, and quantitative PCR (qPCR) evaluated mRNA expression of apoptosis- and antioxidant-related genes. Results: Gallic acid (11.9%) was identified as the major component in TPL. The combination of TPL and low-dose DOX synergistically enhanced cytotoxicity in MCF-7 and MDA-MB-231 cells. This combination reduced the expression of antioxidant genes SOD1 and GPX1 in MDA-MB-231 (SOD1: P < 0.001, GPX1: P = 0.035), and MCF-7 (SOD1: P = 0.035, GPX1: P = 0.036), leading to increased ROS levels in MDA-MB-231 (P = 0.005) and MCF-7 (P = 0.008). Elevated ROS triggered apoptosis through an increased BAX/BCL2 ratio in MDA-MB-231 (P < 0.001) and MCF-7 (P = 0.020). Conversely, TPL displayed protective effects in non-tumorigenic MCF-10A cells by upregulating SOD1 (P = 0.031) and GPX1 (P < 0.001), reducing ROS (P = 0.002), and lowering the BAX/BCL2 ratio (P< 0.001), thereby promoting cell survival. Conclusions: TPL, in combination with doxorubicin, effectively induces cytotoxicity in breast cancer cells while protecting non-tumorigenic cells, suggesting its potential as a complementary therapy in breast cancer treatment.