N-substituted phthalimide-carboxylic acid hybrids as dual-targeted aldose reductase inhibitors: Synthesis, mechanistic insights, and cancer-relevant profiling

Aldose Reductase (ALR2; AKR1B1), a NADPH-dependent cytosolic oxidoreductase, plays a central role in the polyol pathway and is implicated in hyperglycemia-induced tissue injury. Beyond its metabolic function, elevated ALR2 expression has been reported in several malignancies, including hepatocellular and pulmonary carcinomas, highlighting its potential as a therapeutic target in metabolic-oncologic interface. In this study, a novel set of eleven N-substituted phthalimide-carboxylic acid derivatives (5a-5k) was synthesized and evaluated for ALR2 inhibition, pharmacokinetic characteristics, and cancer-selective safety. Among the series, compound 5f demonstrated the highest inhibitory potency (K_I = 7.34 nM), outperforming epalrestat (K_I = 232.1 nM). Glide docking positioned 5f within the ALR2 active site (GlideScore: -6.71 kcal/mol), stabilized via key contacts with Tyr48, His110, and Cys298, along with π-π stacking at Trp219. MM-GBSA analysis corroborated strong binding affinity (ΔG = -64.86 kcal/mol). DFT-derived quantum descriptors, logP, TPSA, and solvation energies supported its favorable interaction profile. ADME/Tox predictions indicated high GI absorption, no P-gp or CYP liabilities, and acceptable bioavailability. In vitro cytotoxicity assays showed negligible activity of 5f against A549 and Hep3B Cancer cell lines (IC₅₀ > 160 μM) and no toxicity toward L929 fibroblasts, reflecting safety for long-term use. Transcriptomic data from CCLE and DepMap confirmed AKR1B1 overexpression in these Cancer models. Network analysis linked ALR2 to redox imbalance and inflammation, suggesting its broader role in tumorigenesis.

Aldose reductase inhibitors; Lead optimization; Molecular docking and MM-GBSA; N-substituted phthalimides; Polyol pathway modulation; Protein-protein interaction; Structure-activity-energy relationship.