Advances in biosynthetic preparation and application of human milk oligosaccharides

Human milk oligosaccharides (HMOs) are bioactive molecules present in human milk and play an important role in shaping up infant gut microbiota and enhancing infant immunity and ability against infection by various pathogens. The development of HMOs in the field of infant nutrition and health has led to their use as functional ingredients in infant formula and foods. The biosynthetic preparation, industrial scale production and commercial application of HMOs have gained increasing momentum and public attention. The present review focuses on the synthesis and applications of 2'-FL, 3-FL, DFL, LNT, LNnT, LNT II, 3'-SL, and 6'-SL, placing an emphasis on various synthetic strategies and recent advancements in the field. It identifies the challenges in HMO synthesis and proposes future directions for HMO synthesis. The review is also intended to provide some insights for optimization of large-scale production to support future application of HMOs in food and pharmaceutical fields.