Edible bird's nest regulates glucose and lipid metabolic disorders via the gut-liver axis in obese mice.

Edible bird's nest (EBN) is a traditional food known for its nourishing and functional properties and is found to be involved in anti-oxidation, anti-aging, and anti-influenza mechanisms, immune regulation, and improving cardiovascular diseases, among others. However, the potential of EBN to improve glycolipid metabolism disorders in high-fat-diet induced obesity and the underlying mechanisms remain unexplored. We examined the effects of EBN on glycolipid metabolism in obese mice fed a high-fat diet. Male C57BL/6J mice were fed a high-fat diet for 8 weeks to establish an obesity model. The obese mice were selected and divided into six groups: two model control groups (normal and high-fat diets) and four intervention groups [Neu5Ac and low-, medium-, and high-dose EBN], with 12 mice in each group. After 10 weeks of continuous gavage intervention, only mice in the high-dose EBN intervention group had lower body weight and total fat content, especially visceral fat. Meanwhile, intervention with three doses of EBN reduced serum FBG, TC, LDL, Ox-LDL, IL-1ß, IL-6, and TNF-α levels and increased serum HDL levels and energy expenditure. Using the high dosage as a paradigm, EBN intervention increased the sialic acid content in LDL, decreased TMAO in the liver, and increased GLP-1 levels in sera. EBN increased the colonic abundances of Akkermansia, Lactobacillus, and Desulfovibrio and reduced those of Lysinibacillus and Bacillus. The changes in the microbial community contribute to increasing colonic bile acids, reducing lipopolysaccharide synthesis to protect the intestinal barrier, and lowering inflammation levels. Changes were also observed in colonic transcripts and metabolites and liver gene transcripts and metabolites, which were mainly enriched in pathways of glycolipid metabolism, immune function amelioration, inflammatory signal mitigation, circadian rhythm, bile acid metabolism and insulin resistance. Therefore, EBN may enhance the gut microbiota and intestinal immunity, relieve chronic inflammation levels in serum, improve antioxidant capacity and circadian rhythm in the liver, promote bile acid metabolism, and decrease lipid absorption and lipid synthesis via the gut-liver axis. Consequently, this may reduce blood lipid and fat accumulation as well as improve islet function and reduce blood glucose levels.

Identification of the Wound Healing Activity Peptidome of Edible Bird's Nest Protein Hydrolysate and the In Silico Evaluation of Its Transport and Absorption Potential in Skin.

In this study, edible bird's nest (EBN) was proven to be a suitable source of bioactive peptides via enzymatic hydrolysis. The ultrafiltration component of the EBN peptides (EBNPs, Mw < 3 000 Da) could be responsible for moderate moisture retention and filaggrin synthesis. It was found that EBNP had a great capacity to protect HaCaT keratinocytes from DNA damage caused by UVB-irradiation and enhance wound healing by increasing the migratory and proliferative potential of cells. Furthermore, the external application of EBNP could effectively repair high glycolic acid concentration-induced skin burns in mice. A total of 1 188 peptides, predominantly the hydrophobic amino acids (e.g., Leu, Val, Tyr, Phe), were identified in the EBNP by liquid chromatography with tandem mass spectrometry (LC-MS/MS). Molecular docking showed that hydrophobic tripeptides from EBNP had a good binding affinity to proton-dependent oligopeptide transporter PepT1. Our data indicated that the hydrophobic amino acid-rich EBNP plays an important role in skin wound healing.

Determination of 3'-Sialyllactose in Edible Bird's Nests and the Effect of Stewing Conditions on the 3'-Sialyllactose Content of Edible Bird's Nest Products.

Sialyllactose is an acidic oligosaccharide that has an immune-protective effect against pathogens and contributes to developing the immune system and intestinal microbes. In this study, a method for the determination of 3'-sialyllactose by high-performance liquid chromatography tandem mass spectrometry was established. The sample was treated with 0.1% formic acid methanol solution, and the gradient elution was performed with 0.05% formic acid water and 0.1% formic acid acetonitrile. The hydrophilic liquid chromatographic column was used for separation. The results showed that the linearity was good in the concentration range of 1~160 µg/L. The limit of detection (LOD) and the limit of quantification (LOQ) of the method were 0.3 µg/kg and 1.0 µg/kg, the recovery range was 91.6%~98.4%, and the relative standard deviation (RSD) was 1.5%~2.2%. This method is fast and sensitive. In addition, the 3'-sialyllactose content in edible bird's nest products produced by different processes was studied. It was found that within the tested range, 3'-sialyllactose in edible bird's nest products increased with the intensity of stewing and increased with the addition of sugar. In short, the results provided a new method for detecting the nutritional value of edible bird's nests, as well as a new direction for improving the nutritional value of edible bird's nest products.

[Determination and level investigation of 45 hormones in edible bird's nest by solid phase extraction-high performance liquid chromatography-tandem mass spectrometry].

Edible bird's nests (EBNs), a food of animal origin, are temporary nests built by swiftlets to foster their offspring. As EBNs and their products are widely accepted by consumers, the safety of hormones in EBNs has also received increasing attention. The establishment of a method for hormone analysis in EBNs and the investigation of hormone levels based on the analytical method are the most effective measures to eliminate any safety concerns. In this study, a multi-residue method was developed for the simultaneous determination of 45 hormones in EBNs, including estrogens, progesterones, androgens, and cortical hormones. EBN samples (1.0 g) were weighed into 50 mL polypropylene centrifuge tubes and mixed with 8 mL of pure water. Then, the samples were extracted twice with 15 mL of acetonitrile and ethyl acetate (1∶1, v/v) under ultrasonic-assisted conditions for 30 min, and the protein in the EBN samples was precipitated at 4000 r/min for 5 min. The clear supernatants were loaded onto a hydrophilic-lipophilic balanced (HLB) SPE column, which was previously activated with methanol (3 mL) followed by pure water (3 mL). The cartridge was washed with 3 mL of pure water and 3 mL of 50% methanol aqueous solution. The hormones were eluted with 3 mL of methanol. A rapid analysis was performed using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The hormones in the extracting solution were separated on a Phenomenex Kinetex C18 column (100 mm×2.1 mm, 2.6 µm) and eluted by gradient elution with acetonitrile-0.1% formic acid aqueous solution (ESI+) or acetonitrile-water (ESI-). Qualitative and quantitative analyses were performed using the multiple reaction monitoring (MRM) mode. The HPLC-MS/MS results showed good linearity in the range of 0.20-20.0 µg/L with correlation coefficients (R2) ≥0.9990. For the 45 hormones, the limits of detection (LODs, S/N≥3) were 0.04-0.70 µg/kg and the limits of quantification (LOQs, S/N≥10) were 0.16-2.00 µg/kg. The recoveries of five hormones, namely, fluorometholone, budesonide, aldosterone, fluocinonide, and ethinylestradiol, were 40.2%-63.6%. Owing to the low recoveries, this method might be suitable only for qualitative testing of the five hormones. The recoveries of the other 40 target analytes were between 72.2% and 112.3% at spiked levels of 2.0, 4.0, and 20.0 µg/kg with relative standard deviations (RSDs) of 2.5%-11.6%. The method is characterized by easy operation, rapidness, high precision, and high sensitivity for the 40 compounds. Thus, this method is suitable for determination of the 40 hormones from EBNs for qualitative testing and quantitation. The proposed method was used to analyze 1021 EBN samples from Malaysia, Indonesia, Thailand, and Vietnam from 2017 to 2021. Only three hormones, progesterone, boldenone, and androstenedione, were identified in the EBN samples, while the levels of the other hormones were lower than their individual LODs. The detected rates of progesterone, boldenone, and androstenedione were 100%, 79%, and 89%, respectively. The contents of progesterone, boldenone, and androstenedione in the EBN samples were 0.097-3.58 µg/kg, 0-0.096 µg/kg and 0-1.77 µg/kg, respectively. The levels of hormones in EBNs were compared with those in eggs, pure milk, and dairy products, which were also animal-derived foods. Androstenedione was detected in all egg samples monitored, and its content was higher than that in EBN samples, pure milk, and dairy products. The content of boldenone was similar among the four products investigated in this study. Based on risk assessment using progesterone, the dietary intake was found to be 3.54 µg/d from milk >1.09 µg/d from eggs >0.0030 µg/d from EBNs. The results showed that the levels of hormones in EBNs were much lower than those in eggs, milk, and dairy products for daily consumption. Based on this investigation, the health effect of the hormones in EBNs may be insignificant.

A Study on the Skin Whitening Activity of Digesta from Edible Bird's Nest: A Mucin Glycoprotein.

Edible bird's nest (EBN) is an unusual mucin glycoprotein. In China, it is popular among consumers due to its skin whitening activity. However, the relationship between protein, sialic acid, and the whitening activity of EBN after digestion is still unclear. In the present work, the whitening activity (antioxidant activity and tyrosinase inhibitory activity) of digested EBN were studied by HepG2 and B16 cell models. The dissolution rate of protein and sialic acid was 49.59% and 46.45% after the simulated digestion, respectively. The contents of free sialic acid and glycan sialic acid in EBN digesta were 17.82% and 12.24%, respectively. HepG2 cell experiment showed that the digested EBN had significant antioxidant activity, with EC50 of 1.84 mg/mL, and had a protective effect on H2O2-induced oxidative damage cells. The results of H2O2-induced oxidative damage showed that the cell survival rate increased from 40% to 57.37% when the concentration of digested EBN was 1 mg/mL. The results of the B16 cell experiment showed that the digested EBN had a significant inhibitory effect on tyrosinase activity, and the EC50 value of tyrosinase activity was 7.22 mg/mL. Cell experiments showed that free sialic acid had stronger antioxidant activity and tyrosinase inhibitory activity than glycan sialic acid. The contribution rate analysis showed that protein component was the main antioxidant component in digestive products, and the contribution rate was 85.87%; free sialic acid was the main component that inhibited tyrosinase activity, accounting for 63.43%. The products of the complete digestion of EBN are suitable for the development of a new generation of whitening health products.