Flavin adenine dinucleotide (FAD)

Flavin adenine dinucleotide (FAD) is a redox-active coenzyme derived from riboflavin (vitamin B2). It acts as a critical electron carrier in cellular metabolism, particularly within mitochondrial oxidative phosphorylation and the citric acid cycle, where it shuttles electrons between metabolic intermediates and the electron transport chain[1][3][4][6][7][10]. FAD is essential for the function of a broad array of flavoproteins and enzymes, including oxidoreductases, dehydrogenases, and monooxygenases, all of which mediate key oxidative and reductive biochemical reactions[4][6][7]. As a coenzyme, FAD is vital for energy production, amino acid metabolism, fatty acid oxidation, and DNA repair in living systems[1][3][4][6][7][10]. Human cells synthesize FAD from dietary riboflavin via the sequential activities of riboflavin kinase (producing FMN) and FAD synthase[1][5][6]. Disruption of FAD biosynthesis or riboflavin deficiency leads to impaired energy metabolism and can contribute to neurological, metabolic, or mitochondrial disorders[1][4]. Note: Flavin adenine dinucleotide is a metabolite/cofactor, not a conventional therapeutic target such as a receptor, enzyme, or transporter[1][4][10]. Thus, while it is essential for the function of many drug targets, it is not itself directly targeted by therapeutic drugs; instead, it is required for the proper activity of flavoprotein enzymes that are sometimes drug targets[3][4].

Other names

FADFlavin adenine dinucleotide (oxidized form)FADH2 (reduced form)Riboflavin-adenine dinucleotide