Dimeric Anthraquinone Rugulosin A Induces Apoptosis in Lung Adenocarcinoma and Targets PI3K/AKT/MAPK Pathways In Silico

Cytotoxic anthraquinones are natural products that modulate apoptosis and oncogenic signaling pathways. In this study, three fungal anthraquinones citreorosein (1), skyrin (2), and rugulosin A (3) were investigated for cytotoxic, antiproliferative, and pro-apoptotic effects using in vitro assays. Rugulosin A (3) exhibited cytotoxic activity against six tumorigenic cell lines (IC50 = 0.138–1.475 μM). Although less potent than the nanomolar-range reference drug Epothilone B (IC50 < 0.1 μM), rugulosin A showed submicromolar-to-low micromolar efficacy with notable selectivity toward cancer cells, which is considered significant for an unoptimized natural product scaffold. Its antiproliferative activity against K562 cells (GI50 = 3.69 μM), benchmarked against Imatinib (GI50 = 0.373 μM), also falls within the active range of natural product leads. Caspase-Glo 3/7 and CellEvent assays demonstrated concentration-dependent apoptosis induction by 3 (p < 0.05), supported by Western blot detection of cleaved PARP-1 and caspase-3. Network pharmacology analysis identified ten potential gene targets enriched in oncogenic pathways, with AKT1, PIK3CA, and MAPK14 p38α emerging as putative key regulators. Molecular docking revealed strong binding energies (−10.1, −9.8, and −11.0 kcal/mol), along with a stable molecular dynamics simulations data. These findings highlight rugulosin A (3) as a promising anticancer lead that modulates major apoptosis signaling pathways.