Proliferating cell nuclear antigen (PCNA) is a critical regulator of DNA replication and repair, and its cancer-associated isoforms represent promising therapeutic targets. The small molecule AOH1996 has been previously reported as a PCNA inhibitor with potent antiproliferative activity. Here, a series of novel AOH1996-based structural analogs were synthesized using structure–activity relationship (SAR) and scaffold-hopping strategies, including 1,2,3-triazole, glycine, and amide derivatives with diverse aromatic and polar substituents. The antiproliferative activity of these compounds was evaluated in MCF-7 (breast cancer) and U87 (glioblastoma) cell lines using the MTT assay. The parent compound AOH1996 exhibited the strongest cytotoxicity, reducing cell viability below 30% at 10 μM. Among the analogs, compounds 1f, 2b, 3b, 3c, and 3d demonstrated significant activity, reducing MCF-7 viability by 60–70% and U87 viability to 30–40% at 10 μM. SAR analysis revealed that electron-withdrawing or moderately lipophilic substituents on the amide side chain and aromatic extensions on the triazole ring enhanced potency, while bulky or strongly electron-donating groups diminished activity. ADMET predictions indicated that most derivatives possessed favorable drug likeness and absorption potential, but high plasma protein binding, short predicted half-lives, and potential cardiotoxicity represent limitations that will require further optimization. Several active compounds were predicted to inhibit P-glycoprotein, suggesting their potential to overcome multidrug resistance. Overall, compounds 2b and 3b showed relatively favorable predicted profiles and can serve as useful lead scaffolds for further optimization and experimental validation.
Jonušienė et al. (2026) studied this question.