N-acetyl-D-mannosamine

Metabolomics was first applied to explore the formation pathway and regulatory factors for advanced glycation end products (AGEs) in preserved egg yolk (PEY) during pickling. Most reactions that contributed to formation of AGEs, including oxidation and/or degradation of matrix/precursors and Maillard reaction, occurred primarily in PEY in early stage, and lipid oxidation occurred prior to protein oxidation. Additionally, the formation of N^ε-carboxymethyl-lysine (CML) in PEY was mainly attributed to glyoxal derived from D-glucuronic acid in early stage based on the correlation between metabolites and AGEs. Reactive oxygen radicals from oxidized lipids also promoted the enrichment of CML and N^ε-carboxymethyl-lysine (CEL). Moreover, during later stage, the accumulation of CEL was enhanced through methylglyoxal from Schiff bases, and acidic compounds could inhibit AGEs via hindering Maillard reaction. This manuscript pioneered the application of metabolomics to reveal the formation pathway of AGEs, and will provide new perspective on AGEs formation in foods.

N‐linked glycosylation stands as a pivotal quality attribute for monoclonal antibodies (mAbs), particularly the high mannose (Man5) variant, which significantly influences the pharmacokinetics of mAbs. Traditional approaches to modulate Man5 have frequently resulted in suboptimal outcomes. In this investigation, we introduced a novel additive, N‐acetyl‐d‐mannosamine (ManNAc), which selectively targeted and reduced Man5 without compromising other product quality attributes (PQAs). The study further examined optimal concentrations and timing for the incorporation of ManNAc in the mAbs expression process utilizing CHO‐K1 cells within a fed‐batch shaker flask culture mode. In the ManNAc titration experiments, we established groups at concentrations of 5, 10, 15, 20, 40, 60, 80, and 100 mM. The findings revealed a concentration‐dependent decrease in Man5, with reductions reaching as low as 2.9% from an initial 8.9%. Importantly, cellular growth, metabolism, and other PQAs remained unaffected. Regarding the timing of ManNAc addition, groups were set for days N‐1, 0, 5, and 11. The results indicated that ManNAc addition on Day 11 did not affect Man5 levels, whereas earlier additions proved effective. A full factorial design was employed to assess the interplay between ManNAc concentration and addition timing, revealing no significant interaction. Consequently, it is recommended to administer 20–40 mM ManNAc prior to Day 4. The strategy of introducing 20 mM ManNAc on Day 0 has been successfully implemented across 12 clones, achieving an average Man5 reduction of 46%. Collectively, these findings delineate a novel and efficacious strategy for the Man5 modulation, promising enhanced control over this critical quality attribute in mAbs production.