Xanthosine 5'-monophosphate disodium salt (XMP-Na2, CAS 25899-70-1) is a nucleotide derivative, specifically the disodium salt of the 5'-monophosphate ester of xanthosine. It is a white to off-white crystalline powder that is soluble in water. Structurally, it consists of a xanthine base linked to a ribose sugar, which is phosphorylated at the 5' position. This compound is primarily known as a key intermediate in the biosynthesis of guanosine monophosphate (GMP) within the purine nucleotide metabolic pathway. Its most significant commercial application is in the food industry as a flavor enhancer. XMP is one of the ribonucleotides that, when combined with monosodium glutamate (MSG) or other nucleotides like inosine monophosphate (IMP), produces a strong synergistic umami taste, significantly enhancing the savory flavor of processed foods, soups, sauces, and snacks. It is often used in the form of disodium 5'-ribonucleotides (I+G), which is a mixture of IMP and GMP salts, where XMP serves as a precursor. While its primary use is as a food additive, it also finds application in biochemical research as a substrate or standard in studies related to nucleotide metabolism, enzymology, and molecular biology.