[1-13Cfru]lactulose

[1-13Cfru]lactulose is a labeled version of lactulose, a synthetic disaccharide used as a laxative and prebiotic. The labeling with carbon-13 at position 1 allows tracking of the molecule in metabolic studies, as well as in the food industry for quality control and authenticity testing. The usage of [1-13Cfru]lactulose is mainly focused on measuring the colonic fermentation and absorption of the molecule. After oral administration, lactulose is not digested in the small intestine and reaches the colon intact, where it is fermented by the gut microbiota. The produced metabolites, such as short-chain fatty acids and gases, are absorbed and can be measured in blood, breath, or urine samples. This process is used to evaluate the gut microbiome and gut-brain axis, as well as to diagnose and monitor gastrointestinal disorders, such as irritable bowel syndrome and inflammatory bowel disease. Chemically, [1-13Cfru]lactulose is a non-reducing sugar composed of galactose and fructose, linked by a β-(1→4) glycosidic bond. The labeled carbon-13 is located at position 1 of the fructose moiety, which is important for the detection and quantification of the molecule by nuclear magnetic resonance spectroscopy and mass spectrometry. Moreover, the stable isotope labeling provides additional information on the metabolism of lactulose, such as the fate of the carbon atoms and the kinetics of the reactions.