Determination of Inhibitory Effect of PKM2 Enzyme and Antitumoral Activity of Novel Coumarin-naphthoquinone Hybrids

Mannich Base Derived from Lawsone Inhibits PKM2 and Induces Neoplastic Cell Death

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.

Antitumoral effect thought ROS production of the sesquiterpene lactone centratherin isolated from Eremanthus crotonoides, an endemic plant from Brazil

Cancer is a global public health problem, requiring the development of new and more effective drugs for treatment. Eremanthus crotonoides, is a common plant found in the Brazilian Cerrado and Atlantic Forest and is used as a traditional medicinal plant in some regions. This study evaluated the potential antitumor effect of centratherin, a compound isolated from E. crotonoides leaves, against cancer cells. In colorectal cancer cells, centratherin showed greater toxicity than carboplatin while maintaining comparable selectivity to the control. Although centratherin did not induce classical apoptotic phenotypes and was not inhibited by Zvad, it did induce elevated levels of reactive oxygen species (ROS) that was responsible for cell death explaining its toxicity. in silico analysis, showed that this substance has high oral bioavailability and intestinal absorption. Centratherin was found to be selective against colon cancer cells and, therefore may be considered for future studies on colorectal cancer (CRC) studies.