Oral squamous cell carcinoma (OSCC) represents ~90% of all oral cancers, being the eighth most common cancer in men. The overall 5-year survival rate is only 39% for metastatic cancers, and currently used chemotherapeutics can cause important side effects. Thus, there is an urgency in developing new and effective anti-cancer agents. As both chalcones and 1,2,3-triazoles are valuable pharmacophores/privileged structures in the search for anticancer compounds, in this work, new 1,2,3-triazole-chalcone hybrids were synthesized and evaluated against oral squamous cell carcinoma. By using different in silico, in vitro, and in vivo approaches, we demonstrated that compound 1f has great cytotoxicity and selectivity against OSCC (higher than carboplatin and doxorubicin) and other cancer cells in addition to showing minimal toxicity in mice. Furthermore, we demonstrate that induced cell death occurs by apoptosis and cell cycle arrest at the G2/M phase. Moreover, we found that 1f has a potential affinity for MDM2 protein, similar to the known ligand nutlin-3, and presents a better selectivity, pharmacological profile, and potential to be orally absorbed and is not a substrate of Pg-P when compared to nutlin-3. Therefore, we conclude that 1f is a good lead for a new chemotherapeutic drug against OSCC and possibly other types of cancers.

Background/Objectives: Pyruvate kinase M2, a central regulator of cancer cell metabolism, has garnered significant attention as a promising target for disrupting the metabolic adaptability of tumor cells. This study explores the potential of the Mannich base derived from lawsone (MB-6a) to interfere with PKM2 enzymatic activity both in vitro and in silico. Methods: The antiproliferative potential of MB-6a was tested using MTT assay in various cell lines, including SCC-9, Hep-G2, HT-29, B16-F10, and normal human gingival fibroblast (HGF). The inhibition of PKM2 mediated by MB-6a was assessed using an LDH-coupled assay and by measuring ATP production. Docking studies and molecular dynamics calculations were performed using Autodock 4 and GROMACS, respectively, on the tetrameric PKM2 crystallographic structure. Results: The Mannich base 6a demonstrated selective cytotoxicity against all cancer cell lines tested without affecting cell migration, with the highest selectivity index (SI) of 4.63 in SCC-9, followed by B16-F10 (SI = 3.9), Hep-G2 (SI = 3.4), and HT-29 (SI = 2.03). The compound effectively inhibited PKM2 glycolytic activity, leading to a reduction of ATP production both in the enzymatic reaction and in cells treated with this naphthoquinone derivative. MB-6a showed favorable binding to PKM2 in the ATP-bound monomers through docking studies (PDB ID: 4FXF; binding affinity scores ranging from −6.94 to −9.79 kcal/mol) and MD simulations, revealing binding affinities stabilized by key interactions including hydrogen bonds, halogen bonds, and hydrophobic contacts. Conclusions: The findings suggest that MB-6a exerts its antiproliferative activity by disrupting cell glucose metabolism, consequently reducing ATP production and triggering energetic collapse in cancer cells. This study highlights the potential of MB-6a as a lead compound targeting PKM2 and warrants further investigation into its mechanism of action and potential clinical applications.

Oral squamous cell carcinoma (OSCC) remains a major global health burden, and current platinum-based chemotherapeutics are constrained by systemic toxicity and acquired resistance, motivating the search for novel antitumor agents. Naphthoquinones are a privileged scaffold in anticancer drug discovery. Here, we report the synthesis of 18 1,4-naphthoquinone esters (1–18), 14 of which are novel, and their first evaluation as anticancer agents against three OSCC cell lines (SCC-4, SCC-9, and SCC-25) and primary human gingival fibroblasts. Derivative 14 emerged as the lead compound, displaying a geometric mean IC50 of 5.0 μM and a geometric mean selectivity index of 9.15, outperforming, in terms of selectivity, the chemotherapeutic standards carboplatin, lapachol, and shikonin. Mechanistically, 14 induced cell death through a combined apoptotic–autophagic pathway, evidenced by membrane blebbing, G2/M arrest, sub-G1 DNA fragmentation, caspase 3/7 activation, and LC3-puncta formation, with wortmannin-mediated rescue indicating that autophagy contributes to cell death, and without detectable induction of reactive oxygen species. This phenotype was accompanied by pronounced disorganization of the actin and tubulin cytoskeletal networks, evidenced by confocal fluorescence microscopy and reduced anisotropy of both networks. Derivative 14 induced less than 5% hemolysis at concentrations up to 1000 μM and was well tolerated in C57BL/6 mice at intraperitoneal doses up to 600 mg/kg, with no mortality or morphological alterations. In silico analyses showed no violations of Lipinski’s rule of five and a topological polar surface area within the range associated with good membrane permeability, while reverse molecular docking pointed to the DNA-binding domains of topoisomerase IIα and IIβ as plausible molecular targets, with binding modes and energies comparable to doxorubicin. Together, these findings establish 14 as a selective and well-tolerated 1,4-naphthoquinone derivative, with a proposed mechanism of action, warranting further preclinical development against OSCC.