The potential of harmaline on triple negative breast cancer: harmaline-DNA interaction related apoptosis, anti-metastasis, and in silico analysis.

Breast cancer, particularly triple-negative breast cancer (TNBC), remains a therapeutic challenge owing to limited targeted treatment options and high metastatic potential. This study aimed to investigate the in vitro and in silico anticancer effects of harmaline, a naturally occurring β-carboline alkaloid, against the MDA-MB-231 breast cancer cell line, focusing on its cytotoxic, apoptotic, DNA-binding, and protein interaction potential. Cytotoxicity assessment by MTT assay revealed a significant reduction in cell viability with an IC50 value of 99.53 µM, further confirmed by LDH release indicating membrane damage. Apoptosis induction was evidenced through Annexin V/PI staining, DNA fragmentation, nuclear condensation, and mitochondrial depolarization. Morphological alterations and wound healing assays demonstrated harmaline's ability to inhibit migration, indicating its anti-migratory activity. Flow cytometry revealed G2/M phase cell cycle arrest, implicating interference with DNA replication and repair processes. Biophysical studies, including ultraviolet-visible (UV-Vis), fluorescence, circular dichroism, FTIR, and KI quenching analyses demonstrated that harmaline interacts with DNA through a mixed binding mode involving both intercalative and groove-associated interactions, leading to conformational alterations in the DNA helix. Complementary molecular docking studies showed harmaline interacting with key cancer-associated proteins with moderate affinity, supporting a multi-target therapeutic mechanism. These results position harmaline as a promising candidate for further preclinical development and structure-based optimization in breast cancer therapy.