Cytotoxic and Computational Profiling of 20 Indole Alkaloids Across Five Breast Cancer Cell Lines

Abstract

Indole alkaloids are a structurally diverse class of natural compounds known for their potent anticancer properties, including the ability to induce apoptosis and inhibit cell proliferation and metastasis. This study aimed to evaluate the cytotoxic potential of 20 indole alkaloids against breast cancer cell lines, investigate their molecular interactions with five key cancer-related proteins (Bcl-2, Caspase-3, CDK4, NF-κB, and MMP-9), and assess their pharmacokinetic and toxicity profiles. Cytotoxicity was tested using the MTT assay across five breast cancer cell lines: MCF-7, T47D, MDA-MB-231, BT-474, and 4T1. Vincristine exhibited the most potent cytotoxicity (IC₅₀: 0.05–0.10 µM), followed by vinblastine and camptothecin. Triple-negative breast cancer (TNBC) cells demonstrated higher resistance compared to luminal subtypes, indicating subtype-specific drug responses. Structure–activity relationship analysis revealed that the presence of lactone rings and hydrophobic side chains enhanced cytotoxic activity. Molecular docking using AutoDock 4.2 identified irinotecan, sanguinarine, and piperine as top binders, with binding affinities ranging from –8.5 to –10.9 kcal/mol. Molecular dynamics simulations confirmed the stability of ligand–target interactions (RMSF < 3 Å). ADMET predictions using SwissADME and pkCSM indicated that all three compounds possessed favorable drug-like properties and high gastrointestinal absorption, though sanguinarine and piperine showed potential mutagenicity or carcinogenicity. The integrated in vitro and in silico approach supports the further exploration of irinotecan, sanguinarine, and piperine as promising multi-target anticancer agents. Notably, tylophorine and vincristine also emerged as potent candidates with favorable pharmacological profiles, warranting further preclinical validation for breast cancer therapy.