Evaluation of Antioxidant-Rich Mexican Oregano (Lippia graveolens) Infusion and Carvacrol: Impact on Metabolic Activity and Cytotoxicity in Breast Cancer Cell Lines

<b>Background/Objectives:</b> The search for natural alternatives in breast cancer (BC) management has spurred interest in plant-derived extracts, particularly oregano variants and their bioactive compound carvacrol (Cv). However, Mexican oregano (<i>Lippia graveolens</i>) infusion (MoI) remains unexplored. This study aimed to chemically characterize MoI and compare its anticancer effects with Cv across BC cell lines, including aggressive triple-negative (TN) subtypes. <b>Methods:</b> MoI was analyzed for composition, antioxidant capacity (ABTS, DPPH, FRAP, total phenols/flavonoids), and phytochemical profile (FTIR, HPLC). Anticancer activity was assessed via MTT and LDH assays. <b>Results:</b> MoI exhibits strong antioxidant capacity and concentration-dependent antiproliferative effects, with IC50 values ranging from 0.08 to 0.18 mg/mL across BC lines, significantly higher (i.e., less cytotoxic) than Cv IC50 of 121-211 µM. Importantly, MoI displayed markedly lower cytotoxicity toward non-cancerous cells (IC50 0.18 mg/mL) compared to Cv (IC50 110 µM). <b>Conclusions:</b> While both agents reduced metabolic activity, Cv induced a more acute suppression. These findings position MoI as a promising, selective candidate for BC therapy, particularly for poor-prognosis subtypes like TN BC, warranting further mechanistic investigation.