Cytostatic Effects of Hydroalcoholic Extract of Justicia spicigera on LNCaP Prostate Cancer Cells: Cell Cycle Arrest and Apoptosis Induction

Justicia spicigera, a medicinal plant traditionally used in Mexican ethnomedicine, remains underexplored for its potential anticancer activity against prostate cancer. This study evaluates the cytostatic and apoptotic effects of a hydroalcoholic extract of J. spicigera on androgen-sensitive LNCaP prostate cancer cells. Phytochemical characterization via TLC, HPLC, LC-MS, and NMR confirmed the presence of kaempferitrin, β-sitosterol, and cryptoxanthin derivatives. Dose-dependent antiproliferative effects were observed in MTT and trypan blue assays, with significant cytotoxicity emerging at ≥500 µg/mL. Flow cytometry revealed G0/G1 cell cycle arrest at 250 µg/mL and marked apoptosis at 500 µg/mL and above, as evidenced by Annexin V/PI staining. At lower doses, the extract exhibited a cytostatic effect, inhibiting proliferation without inducing apoptosis. The dual behavior suggests that the extract modulates cell cycle checkpoints and apoptotic pathways in a dose-dependent manner. Unlike conventional chemotherapeutics, J. spicigera may offer a less toxic alternative by selectively impairing tumor cell proliferation at sub-lethal concentrations. The observed dose-dependent effects open new avenues for investigating plant-derived compounds as modulators of prostate cancer cell proliferation and survival.