NADPlle

NADPH (nicotinamide adenine dinucleotide phosphate) is a crucial coenzyme found in all living cells, playing a central role in anabolic reactions, biosynthetic processes, and cellular defense mechanisms. It is a reduced form of NADP+ (nicotinamide adenine dinucleotide phosphate) and functions as a hydride ion carrier in redox reactions, transferring electrons during metabolic pathways.

NADPH is generated primarily through the pentose phosphate pathway (PPP), which occurs in the cytoplasm of cells. This pathway not only produces NADPH but also generates ribose-5-phosphate, an essential precursor for nucleotide synthesis. The PPP is particularly active in cells with high biosynthetic demands, such as rapidly dividing cells or those involved in lipid synthesis, such as adipocytes and hepatocytes.

In addition to its role in biosynthesis, NADPH is vital for maintaining the reduced state of glutathione, a tripeptide that protects cells from oxidative damage. The enzyme glutathione reductase uses NADPH to reduce oxidized glutathione (GSSG) back to its reduced form (GSH), thereby supporting cellular antioxidant defenses. This function is critical in combating reactive oxygen species (ROS) and preventing oxidative stress.

NADPH also contributes to fatty acid and cholesterol synthesis, as it provides reducing power for enzymes like fatty acid synthase and 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase. These processes are essential for membrane formation, steroid hormone production, and energy storage in the form of triglycerides.

Deficiencies in NADPH production or function can impair cellular metabolism, leading to oxidative stress, impaired biosynthesis, and potential cellular dysfunction. Conditions such as diabetes, certain genetic disorders, and exposure to toxins may disrupt NADPH homeostasis, highlighting its importance in maintaining cellular health and function.