4-Chloro-5-fluoro-1H-pyrrolo(2,3-b)pyridine

Adenosine 5'-monophosphate activated protein kinase (AMPK) is a key enzymatic protein involved in linking the energy sensing to the metabolic manipulation. It is a serine/threonine kinase activated by several upstream kinases. AMPK is a heterotrimeric protein complex regulated by AMP, ADP, and ATP allosterically. AMPK is ubiquitously expressed in various tissues of the living system such as heart, kidney, liver, brain and skeletal muscles. Thus malfunctioning of AMPK is expected to harbor several human pathologies especially diseases associated with metabolic and mitochondrial dysfunction. AMPK activators including synthetic derivatives and several natural products that have been found to show therapeutic relief in several animal models of disease. AMP, 5-Aminoimidazole-4-carboxamide riboside (AICA riboside) and A769662 are important activators of AMPK which have potential therapeutic importance in diabetes and diabetic complications. AMPK modulation has shown beneficial effects against diabetes, cardiovascular complications and diabetic neuropathy. The major impact of AMPK modulation ensures healthy functioning of mitochondria and energy homeostasis in addition to maintaining a strict check on inflammatory processes, autophagy and apoptosis. Structural studies on AMP and AICAR suggest that the free amino group is imperative for AMPK stimulation. A769662, a non-nucleoside thienopyridone compound which resulted from the lead optimization studies on A-592107 and several other related compound is reported to exhibit a promising effect on diabetes and its complications through activation of AMPK. Subsequent to the discovery of A769662, several thienopyridones, hydroxybiphenyls pyrrolopyridones have been reported as AMPK modulators. The review will explore the structure-function relationships of these analogues and the prospect of targeting AMPK in diabetes and diabetic complications.

Dimethyl sulfoxide is a widely used solvent in organic synthesis and in the pharmaceutical industry because of its low cost, stability, and low toxicity. Multicomponent reactions are an advanced approach that has become an efficient, economical, and eco-friendly substitute for the conventional sequential multi-step synthesis of various biologically active compounds. This approach was adopted for the synthesis of previously unknown 2-(2,4-diamino-3-cyano-5H-chromeno[2,3-b]pyridin-5-yl)malonic acids via transformation of salicylaldehydes, malononitrile dimer, and malonic acid. It was shown that the use of DMSO at room temperature makes it possible to synthesize previously unavailable compounds. The investigation of the reaction mechanism using 1H-NMR monitoring made it possible to confirm the proposed mechanism of the transformation. The structure of synthesized 5H-chromeno[2,3-b]pyridines was confirmed by 2D-NMR spectroscopy.

Aberrant energy status contributes to multiple metabolic diseases, including obesity, diabetes, and cancer, but the underlying mechanism remains elusive. Here, we report that ketogenic-diet-induced changes in energy status enhance the efficacy of anti-CTLA-4 immunotherapy by decreasing PD-L1 protein levels and increasing expression of type-I interferon (IFN) and antigen presentation genes. Mechanistically, energy deprivation activates AMP-activated protein kinase (AMPK), which in turn, phosphorylates PD-L1 on Ser283, thereby disrupting its interaction with CMTM4 and subsequently triggering PD-L1 degradation. In addition, AMPK phosphorylates EZH2, which disrupts PRC2 function, leading to enhanced IFNs and antigen presentation gene expression. Through these mechanisms, AMPK agonists or ketogenic diets enhance the efficacy of anti-CTLA-4 immunotherapy and improve the overall survival rate in syngeneic mouse tumor models. Our findings reveal a pivotal role for AMPK in regulating the immune response to immune-checkpoint blockade and advocate for combining ketogenic diets or AMPK agonists with anti-CTLA4 immunotherapy to combat cancer.