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.