Carboxyl Amidation of Chlorogenic Acid Improves Anti-Inflammatory Activity and Biosafety via Potent AKR1B1 Inhibition in LPS-Induced Macrophages

Abstract

Persistent inflammation driven by excessive AKR1B1 activation contributes to the progression of multiple chronic inflammatory diseases. Natural chlorogenic acid (CGA) exhibits anti-inflammatory activity but suffers from poor membrane permeability, while its laurate ester derivative (CGL) shows clear dose-dependent cytotoxicity in macrophages. Here, we synthesized a novel chlorogenic acid amide derivative (CGAA) by selective amidation of the aliphatic carboxyl group on the quinic acid moiety of CGA, fully preserving the chiral polyphenol scaffold. Structural identity was confirmed by HSQC, HMBC, FTIR and HR-ESI-MS. CCK-8 assays demonstrated that CGAA maintained > 95% viability of RAW264.7 cells at 100 μM, displaying markedly superior cellular safety relative to CGL. In LPS-stimulated RAW264.7 macrophages, CGAA dose-dependently suppressed NO, TNF-α and IL-6 production and exhibited stronger antioxidant activity than both CGA and CGL. Temperature-gradient CETSA, DARTS and enzymatic assays established direct binding and potent inhibition of AKR1B1 by CGAA (IC50 = 7.85 μM). Molecular docking revealed that the newly introduced amide forms an additional hydrogen bond with ILE-260, enhancing ligand–target affinity. This carboxyl-amidation strategy simultaneously improves the cellular safety and AKR1B1 inhibitory potency of CGA, providing a rational approach for developing low-toxicity polyphenol-based anti-inflammatory leads.