Abstract Riboflavin. or vitamin B2. is an essential nutrient that serves as a precursor to flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN). The binding of the FAD and/or FMN cofactors to flavoproteins is critical for regulating their assembly and activity. https://theplayfulcollectivees.shop/product-category/gift-cards/