Background/Objectives: Breast cancer is the most common cause of death in women worldwide and the most commonly diagnosed cancer. Although several therapeutic approaches are widely used against breast cancer, their adverse effects often lead to symptoms severely affecting the quality of life. Alternative methods have been explored to reduce these adverse effects, and nutraceuticals have yielded promising results. This review will discuss mechanisms of action and potential applications against breast cancer of some nutraceuticals, specifically marjoram, thyme, and persimmon leaves. Methods: A systematic search was conducted across the public databases of PubMed, PubChem, and Google Scholar, with a specific focus on the plant extracts and phytochemicals of interest, as well as the anticarcinogenic mechanisms. Results: Ethnopharmacological and biochemical evidence support the anticarcinogenic role of marjoram, thyme, and persimmon. Numerous phytochemicals contained in these herbs’ extracts, like terpenes and flavonoids, possess remarkable potential to effectively treat breast cancer. Discussion: The phytochemicals contained in the reviewed nutraceuticals target the main cellular pathways involved in cell growth and disrupted in carcinogenesis, such as Nf-κB, MAPK/p38, TNF-α/IL-1β, and PI3K/Akt. The mechanisms of action of these compounds can successfully limit the abnormal growth and proliferation of cancerous breast cells. Conclusions: The potential use of the phytochemicals discussed in this review, either alone or in combination, may offer a valid alternative to chemotherapy against breast cancer with virtually no adverse effects, and further research on these molecules may lead to the identification of additional chemo-preventative and chemotherapeutic candidates.

Background/Objectives: Breast cancer is a prevalent and heterogeneous disease with multiple subtypes, which are defined by characteristics such as molecular biomarkers and metastatic status. This study aimed to profile the metabolic activity of various breast cancer subtypes, both with and without chemotherapy (doxorubicin) application. Methods: Six human breast cell lines were evaluated, two non-tumorigenic controls and four cancerous lines. The cancer lines were clustered as primary-derived, metastasis-derived, triple-negative (TNBC), and strong hormone receptor-positive (ER+/PR+) and analyzed using the Biolog phenotype mammalian microarrays (PM-M1 to PM-M8) to assess metabolic activity via NADH production under a wide array of substrate parameters. Results: Unique metabolic profiles emerged across the subtypes and clusters; the TNBC and metastatic cells demonstrated enhanced utilization of glycolytic and anaerobic substrates consistent with the Warburg effect. The ER+/PR+ cells showed heightened glucose utilization and unique sensitivity to metabolic effectors and doxorubicin. Additionally, significant metabolic differences were observed in nucleoside and amino acid utilization between cancer and control cells, particularly in metastatic and TNBC lines. Conclusions: Our findings reveal the profound metabolic diversity among breast cancer subtypes and highlight distinct substrate dependencies for proliferation. The results additionally provide a framework for developing metabolic biomarkers and targeted therapies for chemotherapy resistance in breast cancer subtypes.