Selective anticancer activity of imidazolium salts in prostate cancer cells via ROS-mediated mechanisms

Prostate cancer remains a major therapeutic challenge, particularly in advanced and treatment-resistant disease. Imidazolium salts (IS) are tunable compounds with reported biological activity and potential anticancer applications. In this study, a series of structurally tailored IS, including C₁₀MImCl, C₁₆MImCl, C₁₆BnImCl, and related analogues, was synthesized and evaluated in androgen-independent prostate cancer cells (PC-3 and DU145), androgen-responsive LNCaP cells, and non-tumorigenic prostate epithelial cells (PNT2). The biological activity of the synthesized IS was evaluated through complementary viability, imaging, and cell-death assays in PC-3, DU145, LNCaP, and PNT2 cells. In both prostate cancer cell lines, IS induced a concentration-dependent reduction in cell viability, whereas non-tumorigenic PNT2 cells maintained comparatively high viability within the tested concentration range. Consistently, IC₅₀ values were obtained for PC-3 and DU145 cells, but not for PNT2 cells, whose viability did not decrease below 50%, supporting a differential sensitivity between malignant and non-tumorigenic prostate cells. Complementary experiments in androgen-responsive LNCaP cells confirmed the cytotoxic activity of the selected compounds and demonstrated that their antitumor effects were not restricted to androgen-independent prostate cancer models. Beyond cytotoxicity, IS reduced wound closure capacity in PC-3 and DU145 cells, while this process was largely preserved in PNT2 cells. Mechanistic experiments in DU145 cells demonstrated that oxidative stress contributes to the cytotoxic response, as NAC pre-treatment significantly reduced compound-induced ROS accumulation. MitoBright staining further revealed mitochondrial morphological alterations, particularly after exposure to C₁₆MImCl and C₁₆BnImCl. Finally, selected IS retained biological activity in both DU145 and LNCaP 3D spheroids, reducing spheroid growth and inducing morphological alterations in these tumor-like models. Overall, these findings indicate that structurally tailored IS exert marked cytotoxic activity against prostate cancer cells while showing lower toxicity toward non-tumorigenic prostate epithelial cells under the tested conditions. Their activity appears to involve oxidative stress-associated mechanisms and may be influenced by structural features such as alkyl chain length and benzyl substitution, supporting further investigation of IS as anticancer scaffolds for prostate cancer.