Royal jelly (RJ), a natural honeybee product, has a wide range of antibacterial activities. N-glycosylated major royal jelly protein 2 (N-MRJP2), purified from RJ, can inhibit the growth of Paenibacillus larvae (P. larvae, Gram-positive), a contagious etiological agent of the American foulbrood disease of honeybees. However, the inhibitory mechanism is largely unknown. Antibacterial assay and membrane proteome were conducted to investigate the inhibition capacity of RJ from different instar larvae and P. larvae treated by N-MRJP2, respectively. The similar antibacterial efficiency of RJ from different larval instar indicates that RJ is vital for the adaptive immune defense of small larvae. The killing of P. larvae by N-MRJP2 is achieved by disturbing the cell wall biosynthesis, increasing the permeability of cell membrane, hindering aerobic respiration, restraining cell division and inducing cell death. This demonstrates that RJ is critical for the passive immunity of immature larvae and N-MRJP2 can be used as natural antibiotic substance to resist P. larvae, even for other gram-positive bacteria. This constitutes solid evidence that RJ and N-MRJP2 have potentials as novel antibacterial agents.

Queen bee larva (QBL), as a by-product of royal jelly, is a kind of protein-rich edible insect. However, the development and utilization of QBL have been very limited for an extended period, resulting in considerable economic waste. Notably, QBL has substantial potential for anti-aging treatments; however, systematic studies have been scarce. The present study aimed to analyze the effects of freeze-dried QBL powder (QBLP) treatment in a D-galactose (D-gal)-induced-aging mouse and to explore the mechanisms. A behavioral test indicated that QBLP-treated mice had improved cognitive function and memory decline caused by aging compared to untreated aged mice. Furthermore, QBLP treatment improved organ index in aged mice and prevented pathological damage to the brain tissue. Concomitantly, treatment of D-gal-induced-aging mice with QBLP significantly reduced the oxidative damage of serum and increased the skin moisture content of aging mice. Finally, integrated analyses of the gut microbiota and the serum metabolome showed that QBLP supplementation altered the composition of the gut microbiota, enriched biochemical pathways associated with amino acid metabolism, and adjusted serum concentrations of beneficial free amino acids. Overall, QBLP can improve symptoms related to D-gal-induced aging in mice by regulating gut microbiota structure and amino acid metabolism.

Glycosylation alterations have emerged as significant indicators in the landscape of cancer diagnosis, with aberrant N-glycans standing out as potential biomarkers. The existing methods for purifying N-glycans mainly rely on their hydrophilicity, affinity, and size. These methods exhibit relatively weak binding forces and low specificity based on non-covalent interactions. Moreover, the current liquid chromatography-based N-glycan purification and detection techniques must be bettered for clinical settings' rapid diagnostic requirements. Here, we have developed a method involving the covalent binding of graphene modified with photocleavable amino groups to N-glycans in hepatocellular carcinoma (HCC) patients' serum glycoproteins. The N-glycans are identified using MALDI-TOF/TOF MS, catering to the requirements of biological research and the diagnosis of liver cancer disease. Specifically, amino-functionalized graphene is linked with photocleavable groups bearing hydrazide functional group, then undergoes acyl hydrazone covalent reaction with aldehyde groups on the side chains of oxidized monosaccharides to capture the N-glycans. Finally, under UV irradiation at a wavelength of 356 nm for 15 s, the ortho-nitrobenzyl photocleavable groups undergo cleavage, completing the release of captured N-glycans, which are then subjected to MALDI-TOF/TOF MS mass spectrometry for detection. Our findings demonstrate significant differences in the N-glycan profiles between serum samples of liver cancer patients and healthy individuals. These differences are characterized by increased abundance and molecular weight of N-glycans. Through biomarker screening, one N-glycan with an m/z ratio of 1847.01 shows the potential to serve as a diagnostic biomarker for liver cancer (P < 0.05). Our research underscores the potential of photocleavable amino-modified graphene for detecting aberrant N-glycans in HCC patients' serum to elucidate the intricate between aberrant N-glycan alterations and HCC. This research paves the way for developing novel biomarkers, diagnostic strategies, and therapeutic interventions to combat this complex disease. Graphical Abstract

Drying is an important processing method for extending the shelf life of aquatic products; however, different drying methods may exert distinct effects on protein quality. At present, the effects of sun drying and vacuum freeze-drying on the protein quality of Hippocampus abdominalis remain unclear. This study compared the protein content, amino acid composition, and physicochemical properties of Hippocampus abdominalis subjected to the two drying methods and further characterized changes in the proteomic profile using proteomic analysis. The results showed that the sun-dried group had a higher crude protein content (68.57% vs. 61.86%), whereas the freeze-dried group exhibited greater total amino acid retention (58.79% vs. 48.87%), water-holding capacity (WHC), and oil-holding capacity (OHC). However, no significant differences were observed in protein solubility or surface hydrophobicity between the two groups. Proteomic analysis further revealed that most differentially abundant proteins showed higher relative abundance in the freeze-dried group and were mainly associated with muscle structural stability, amino acid metabolism, and energy metabolism. Overall, the two drying methods affected the protein quality of Hippocampus abdominalis at multiple levels, including nutritional composition and physicochemical properties, while proteomic analysis provided further molecular-level insights into these quality differences.