ETD

• Cyclic amides
• Inhibitors
• LDH
• N-Alkylation
• NAD-mimetic
• O-Alkylation

Among the most characteristic metabolic phenotypes observed in tumours is the Warburg effect, whereby cancer cells rely predominantly on glycolysis for energy production even under normoxic conditions. This metabolic reprogramming confers under advantages to the tumour, including enhanced metastatic potential, acidosis, and uncontrolled proliferation. In recent years, increasing attention has been directed toward L-lactate, a key metabolite recognized as a crucial energy source for cancer cells and as a contributor to chemoresistance. Elevated intracellular lactate levels lead to protein “lactylation”, affecting both histone and non-histone proteins, ultimately resulting in p53 silencing and modulation of DNA repair mechanisms.
The enzyme responsible for converting pyruvate into lactate is lactate dehydrogenase (LDH), an NAD-dependent oxidoreductase composed of four subunits (H and M) arranged in various combinations. The reductive conversion is primarily mediated by the LDH-5 isoform, which consists of four LDHA subunits. Current research focuses on this isoform and on the identification of selective inhibitors aimed at counteracting tumour invasiveness, metastasis, and proliferation. However, significant challenges arise in the discovery of such compounds, largely due to the structural characteristics of the active site, narrow and deep, and to the highly polar cofactor-binding pocket. Previously synthesized inhibitors were deigned to compete with NADH and/or pyruvate at their respective binding sites, but they have shown poor cellular permeability, due to excessive polarity, and limited selectivity.

Our research focused on the synthesis of innovative molecules designed to act as cell-permeable bioprecursors of the NAD cofactor, enabling them to exploit the same enzymes involved in the NAD salvage pathway for the metabolic activation. Following this strategy, the intracellular generation of dinucleotide-based LDHA inhibitors would be achieved, potentially reducing enzymatic activity and lactate production by competing with endogenous NADH at the cofactor-binding site.