Sketch of the edible bird's nest and its important bioactivities

Effects of house-cultivated edible bird's nest on immunoglobulin and cytokine release in vitro

Background and Aim

Edible bird's nest (EBN) is known as the "Caviar of the East" because of its high nutritional and medicinal values. Nevertheless, its effect on human immunity is yet to be explored. This study examined the effects of EBN's aqueous extract (EBNE) on human immunity through the modular immune in vitro construct (MIMIC) model consisting of peripheral tissue equivalent (PTE) and lymphoid tissue equivalent (LTE) modules.

Materials and Methods

One hundred twenty mL of full blood was obtained from four healthy human volunteers. The human immune system was simulated using an in vitro model, called MIMIC. Under EBNE treatment, monocyte transendothelial migration through reversed endothelial layers was observed. Using PTE and LTE modules, monocytes were differentiated into dendritic cells with lipopolysaccharide, then co-cultured with T- and B-cells for cytokine and immunoglobulin (Ig) production. The human cytokine array G2000 and quantitative human Ig isotyping array were used to identify the cytokine profile and Ig isotypes, respectively.

Results

IgE, IgA, and IgG3 levels were significantly raised by EBNE. These cytokines, including brain-derived neurotrophic factor, ciliary neurotrophic factor, glial cell line-derivative neurotrophic factor, insulin-like growth factor 1, and insulin-like growth factor binding protein 4, were generated.

Conclusion

For the first time, this work uses a MIMIC model to illustrate the impact of EBNE on human immune response. This new understanding of EBN's immunoregulatory effect allows for further exploration of how EBN interacts with the human immune system.

The potential cutaneous benefits of edible bird's nest

Edible bird's nest (EBN) is composed of the solidified saliva of swiftlet birds. EBN has been extremely popular in Asian culture for centuries. They are often consumed as a delicacy in the form of bird's nest soup and are believed to have numerous skin benefits. In light of EBN's growing popularity and significant cultural importance, we aim provide a comprehensive review of EBN's potential dermatologic benefits and role in photoaging, anti-inflammation, wound healing, skin barrier enhancement, and skin whitening. While in vitro, in vivo, and preliminary clinical trial results are promising, there is a need for future human clinical research to further validate these findings and establish EBN's efficacy and safety for dermatologic applications.

Revealing Edible Bird Nest as Novel Functional Foods in Combating Metabolic Syndrome: Comprehensive In Silico, In Vitro, and In Vivo Studies

Metabolic dysfunction, which includes intra-abdominal adiposity, glucose intolerance, insulin resistance, dyslipidemia, and hypertension, manifests into metabolic syndrome and related diseases. Therefore, the discovery of new therapies in the fight against metabolic syndrome is very challenging. This study aims to reveal the existence of an edible bird nest (EBN) as a functional food candidate that may be a new alternative in fighting metabolic syndrome. The study included three approaches: in silico molecular docking simulation, in vitro, and in vivo in rats fed on cholesterol- and fat-enriched diets. Four terpenoids of Bakuchiol, Curculigosaponin A, Dehydrolindestrenolide, and 1-methyl-3-(1-methyl-ethyl)-benzene in EBN have been identified through LCMS/MS-QTOF. In molecular docking simulations, Bakuchiol and Dehydrolindestrenolide are considered very potent because they have higher inhibitory power on the four receptors (iNOS, ROS1 kinase, FTO, and lipase) than standard drugs. In vitro tests also provide insight into the antioxidant, antidiabetic, and antiobesity activities of EBN, which is quite feasible due to the smaller EC50 value of EBN compared to standard drugs. Interestingly, in vivo studies also showed significant improvements (p < 0.05) in the lipid profile, blood glucose, enzymatic levels, and inflammatory biomarkers in rats given high-dose dietary supplementation of EBN. More interestingly, high-dose dietary supplementation of EBN upregulates PGC-1α and downregulates HMG-CoA reductase. Comprehensively, it has been revealed that EBN can be novel functional foods for combating metabolic syndrome.

Dietary sialic acids: distribution, structure, and functions

Sialic acids (Sias), a group of over 50 structurally distinct acidic saccharides on the surface of all vertebrate cells, are neuraminic acid derivatives. They serve as glycan chain terminators in extracellular glycolipids and glycoproteins. In particular, Sias have significant implications in cell-to-cell as well as host-to-pathogen interactions and participate in various biological processes, including neurodevelopment, neurodegeneration, fertilization, and tumor migration. However, Sia is also present in some of our daily diets, particularly in conjugated form (sialoglycans), such as those in edible bird's nest, red meats, breast milk, bovine milk, and eggs. Among them, breast milk, especially colostrum, contains a high concentration of sialylated oligosaccharides. Numerous reviews have concentrated on the physiological function of Sia as a cellular component of the body and its relationship with the occurrence of diseases. However, the consumption of Sias through dietary sources exerts significant influence on human health, possibly by modulating the gut microbiota's composition and metabolism. In this review, we summarize the distribution, structure, and biological function of particular Sia-rich diets, including human milk, bovine milk, red meat, and egg.

Enzyme-Digested Edible Bird’s Nest (EBND) Prevents UV and arid Environment-Induced Cellular Oxidative Stress, Cell Death and DNA Damage in Human Skin Keratinocytes and Three-Dimensional Epithelium Equivalents

The aim of this study is to investigate the repressive effects of enzyme-digested edible bird’s nest (EBND) on the combination of arid environment and UV-induced intracellular oxidative stress, cell death, DNA double-strand breaks (DSBs) and inflammatory responses in human HaCaT keratinocytes and three-dimensional (3D) epithelium equivalents. An oxygen radical antioxidant capacity assay showed that EBND exhibited excellent peroxyl radical scavenging activity and significantly increased cellular antioxidant capacity in HaCaT cells. When EBND was administered to HaCaT cells and 3D epitheliums, it exhibited significant preventive effects on air-drying and UVA (Dry-UVA)-induced cell death and apoptosis. Dry-UVA markedly induced intracellular reactive oxygen species (ROS) generation in HaCaT cells and 3D epitheliums as quantified by CellROX® Green/Orange reagents. Once HaCaT cells and 3D epitheliums were pretreated with EBND, Dry-UVA-induced intracellular ROS were significantly reduced. The results from anti-γ-H2A.X antibody-based immunostaining showed that EBND significantly inhibited Dry-UVA-induced DSBs in HaCaT keratinocytes. Compared with sialic acid, EBND showed significantly better protection for both keratinocytes and 3D epitheliums against Dry-UVA-induced injuries. ELISA showed that EBND significantly suppressed UVB-induced IL-6 and TNF-α secretion. In conclusion, EBND could decrease arid environments and UV-induced harmful effects and inflammatory responses in human keratinocytes and 3D epithelium equivalents partially through its antioxidant capacity.

Effect of ultrasound-assisted pretreatment in combination with heating on characteristics and antioxidant activities of protein hydrolysate from edible bird's nest co-product

Protein hydrolysates (P-HS) from edible bird's nest co-product prepared without and with ultrasound (US) pretreatment in combination with heating before hydrolysis using alcalase at different concentrations were characterized. US treatment of co-product in water at 60% amplitude for 20 min, followed by heating at 95 °C for 3 h was done before enzymatic hydrolysis. The degree of hydrolysis (DH), yield and sialic acid (SL) content of P-HS samples were not different (p > 0.05) when 1 or 2% alcalase was used for hydrolysis. The highest protein content and lightness (L * ) were observed in P-HS prepared from co-product subjected to US treatment (60% amplitude for 20 min) using 1% alcalase for hydrolysis. When antioxidant activities of dried P-HS were determined, P-HS from co-product subjected to US treatment had higher DPPH and ABTS radical scavenging activities, ferrous reducing antioxidant power and oxygen radical absorbance capacity, compared to those prepared from non-US treated co-product. P-HS with higher DH contained greater amount of small peptides having MW lower than 1,883 Da. The P-HS produced under optimum condition had major essential amino acids (EA-A) including leucine, threonine, lysine and valine of 4.28, 3.53, 3.30 and 3.08%, respectively. Therefore, P-HS from co-product could serve as both nutrients and functional ingredients.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-022-05420-5.

Edible Bird's Nest as a Potential Cognitive Enhancer

Cognitive enhancement is defined as the augmentation of the mind's core capabilities through the improvement of internal or external information processing systems. Recently, the focus has shifted to the potential therapeutic effects of natural products in improving cognitive function. Edible bird's nest (EBN) is a natural food substance derived from the saliva of swiftlets. Until today, EBN is regarded as a high-priced nutritious food with therapeutic effects. The effectiveness of dietary EBN supplementation to enhance brain development in mammals has been documented. Although the neuroprotection of EBN has been previously reported, however, the impact of EBN on learning and memory control and its potential as a cognitive enhancer drug remains unknown. Thus, this article aims to address the neuroprotective benefits of EBN and its potential effect as a cognitive enhancer. Notably, the current challenges and the future study direction in EBN have been demonstrated.

Long-Term Wi-Fi Exposure From Pre-Pubertal to Adult Age on the Spermatogonia Proliferation and Protective Effects of Edible Bird’s Nest Supplementation

Children are vulnerable to the radiofrequency radiation (RFR) emitted by Wi-Fi devices. Nevertheless, the severity of the Wi-Fi effect on their reproductive development has been sparsely available. Therefore, this study was conducted to evaluate the Wi-Fi exposure on spermatogonia proliferation in the testis. This study also incorporated an approach to attenuate the effect of Wi-Fi by giving concurrent edible bird’s nest (EBN) supplementation. It was predicted that Wi-Fi exposure reduces spermatogonia proliferation while EBN supplementation protects against it. A total of 30 (N = 30) 3-week-old Sprague Dawley weanlings were divided equally into five groups; Control, Control EBN, Wi-Fi, Sham Wi-Fi, and Wi-Fi + EBN. 2.45 GHz Wi-Fi exposure and 250 mg/kg EBN supplementation were conducted for 14 weeks. Findings showed that the Wi-Fi group had decreased in spermatogonia mitosis status. However, the mRNA and protein expression of c-Kit-SCF showed no significant decrease. Instead, the reproductive hormone showed a reduction in FSH and LH serum levels. Of these, LH serum level was decreased significantly in the Wi-Fi group. Otherwise, supplementing the Wi-Fi + EBN group with 250 mg/kg EBN resulted in a significant increase in spermatogonia mitotic status. Even though EBN supplementation improved c-Kit-SCF mRNA and protein expression, the effects were insignificant. The improvement of spermatogonia mitosis appeared to be associated with a significant increase in blood FSH levels following EBN supplementation. In conclusion, the long-term Wi-Fi exposure from pre-pubertal to adult age reduces spermatogonia proliferation in the testis. On the other hand, EBN supplementation protects spermatogonia proliferation against Wi-Fi exposure.

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.

Why the importance of geo-origin tracing of edible bird nests is arising?

Edible bird's nest (EBN) swiftlet existed naturally 48,000 years ago in caves as their natural dwellings. Nowadays, edible bird's nest has become a very important industry due to its high nutritional, medicinal and economic value. Additionally, edible bird's nest has a long quality guarantee period. Obviously, the nutritional components and medicinal functions vary depending on geographical origins. Recently, the global demand for edible bird's nest has markedly increased, accompanied by the increasing attention of all key players of the global food trade system, i.e., producers, consumers, traders and the authorities to obtain safe and high-quality edible bird's nest. Hence, this target can be accomplished via the enforcement of an efficient and universal geo-tracing technique. Current methods of the geo-tracking of edible bird's nest, i.e., automation, physical and analytical techniques have several limitations and all of them fail to discriminate different quality grades of edible bird's nest. Meanwhile, in many studies and applications, polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) has proven to be a "cutting edge" technique for greatly enhance food traceability from field to fork through its ability in distinguishing the food products in terms of their quality and safety. This article provides an overview of (1) edible bird's nest as a multiuse strategic food product, (2) quality issues associated with edible bird's nest including implications that the site of acquisition of the edible bird's nest has food safety implications, (3) current regulations and geo-tracking approaches to ensure the safety and quality of edible bird's nest with the special focus on polymerase chain reaction-denaturing gradient gel electrophoresis technique as a vigorous and universal geo-tracing tool to be suggested for edible bird's nest geo-traceability.

Immunological Analytical Techniques for Cosmetics Quality Control and Process Monitoring

Cosmetics analysis represents a rapidly expanding field of analytical chemistry as new cosmetic formulations are increasingly in demand on the market and the ingredients required for their production are constantly evolving. Each country applies strict legislation regarding substances in the final product that must be prohibited or regulated. To verify the compliance of cosmetics with current regulations, official analytical methods are available to reveal and quantitatively determine the analytes of interest. However, since ingredients, and the lists of regulated/prohibited substances, rapidly change, dedicated analytical methods must be developed ad hoc to fulfill the new requirements. Research focuses on finding innovative techniques that allow a rapid, inexpensive, and sensitive detection of the target analytes in cosmetics. Among the different methods proposed, immunological techniques are gaining interest, as they make it possible to carry out low-cost analyses on raw materials and finished products in a relatively short time. Indeed, immunoassays are based on the specific and selective antibody/antigen reaction, and they have been extensively applied for clinical diagnostic, alimentary quality control and environmental security purposes, and even for routine analysis. Since the complexity and variability of the matrices, as well as the great variety of compounds present in cosmetics, are analogous with those from food sources, immunological methods could also be applied successfully in this field. Indeed, this would provide a valid approach for the monitoring of industrial production chains even in developing countries, which are currently the greatest producers of cosmetics and the major exporters of raw materials. This review aims to highlight the immunological techniques proposed for cosmetics analysis, focusing on the detection of prohibited/regulated compounds, bacteria and toxins, and allergenic substances, and the identification of counterfeits.

Combined enzymatic hydrolysis and herbal extracts fortification to boost in vitro antioxidant activity of edible bird’s nest solution

Objective

Edible bird’s nest (EBN) is a popular traditional tonic food in Chinese population for centuries. Malaysia is one of the main EBN suppliers in the world. This study aims to explore the best strategy to boost the antioxidant potential of EBN solution.

Methods

In this study, the raw EBN (4%, mass to volume ratio) was initially enzymatic hydrolyzed using papain enzyme to produce EBN hydrolysate (EBNH), then spray-dried into powdered form. Next, 4% (mass to volume ratio) of EBNH powder was dissolved in ginger extract (GE), mulberry leaf extract (MLE) and cinnamon twig extract (CTE) to detect the changes of antioxidant activities, respectively.

Results

Results obtained suggest that enzymatic hydrolysis significantly reduced the viscosity of 4% EBN solution from (68.12 ± 0.69) mPa·s to (7.84 ± 0.31) mPa·s. Besides, the total phenolic content (TPC), total flavonoid content (TFC), total soluble protein, DPPH scavenging activity and ferric reducing antioxidant power (FRAP) were substantially increased following EBN hydrolysis using papain enzyme. In addition, fortification with GE, MLE and CTE had further improved the TPC, TFC, DPPH scavenging activity and FRAP of the EBNH solution. Among the samples, MLE-EBNH solution showed the most superior antioxidant potential at (86.39 ± 1.66)% of DPPH scavenging activity and (19.79 ± 2.96) mmol/L FeSO₄ of FRAP.

Conclusion

This study proved that combined enzymatic hydrolysis and MLE fortification is the best strategy to produce EBN product with prominent in vitro antioxidant potential. This preliminary study provides new insight into the compatibility of EBN with different herbal extracts for future health food production.

Characterization and Extraction Influence Protein Profiling of Edible Bird's Nest

The edible bird nest (EBN) from Aerodramus fuciphagus has been consumed as a Chinese traditional food for health and medicinal purposes due to its elevated nutritional value. The present study focused on the influence of characterization and extraction methods on protein profiling, which could be a guideline for grading the EBN. The proposed extraction method is similar to the common food preparation methods of consumers and thus can accurately establish the bioactive protein available upon human consumption. The characterization includes physicochemical analysis (physical, morphology, elemental composition, and microbial content) and chemical analysis (crude protein and amino acid). The morphology of half-cup EBN was found to be uniformly shaped and rich in calcium as compared to rough surface of stripe-shaped EBN, and there was no significant microbial growth in both types of EBN. The crude protein and amino acid content in half-cup EBN were significantly higher than stripe-shaped EBN. The full stew (FS) and stew (SE) extraction methods produced a maximal yield of soluble protein. Sialic acid content in SE extract (8.47%, w/w) and FS extract (7.91%, w/w) were recorded. About seven parent proteins (39.15 to 181.68 kDa) were identified by LC-MS/MS Q-TOF, namely 78 kDa glucose-regulated protein, lysyl oxidase-3, Mucin-5AC-like, acidic mammalian chitinase-like, 45 kDa calcium-binding protein, nucleobindin-2, and ovoinhibitor-like. In conclusion, the characteristics and extraction methods influence the availability of bioactive protein and peptides, demonstrating the potential usage of EBN in improving its biological activities and nutritional properties.

The Authentication and Grading of Edible Bird's Nest by Metabolite, Nutritional, and Mineral Profiling

Edible bird's nest (EBN) produced by Aerodramus fuciphagus has a high demand for nutritional and medicinal application throughout the world. The present study was to evaluate the authentication of a man-made house EBN, which are half cup and stripe-shaped by FTIR. Next, both samples were compared according to their metabolite, nutritional, and mineral composition. The results indicated that the FTIR spectra of both EBN samples were identical and similar to the reference, suggesting the authenticity of the EBN used. The metabolites that contribute to the possible medicinal properties of EBN were found by using GC-MS. The results of the proximate analysis, followed by the standard AOAC method, inferred that both EBN shapes to be rich in crude protein and carbohydrate contents. However, the proximate composition between the half cup and stripe-shaped EBN showed significant differences. Major mineral elements detected were calcium and sodium, and magnesium contents were significantly different between both EBN. Additionally, the half cup and stripe-shaped EBN had a low level of heavy metal content than the maximum regulatory limit as set by the Malaysian Food Act 1983. This study concludes that the nutritional composition varied between the samples and thus suggests that nutrient content should be considered as criteria for the grading requirement of commercialized EBN.

Geographical Factor Influences the Metabolite Distribution of House Edible Bird's Nests in Malaysia

Background: Edible Bird's Nest (EBN) is famously consumed as a food tonic for its high nutritional values with numerous recuperative and therapeutic properties. EBN is majority exploited from swiftlet houses but the differences in terms of metabolite distribution between the production site of house EBN is not yet fully understood. Therefore, this study was designed to identify the metabolite distribution and to determine the relationship pattern for the metabolite distribution of house EBNs from different locations in Malaysia. Methods: The differences of metabolite distribution in house EBN were studied by collecting the samples from 13 states in Malaysia. An extraction method of eHMG was acquired to extract the metabolites of EBN and was subjected to non-targeted metabolite profiling via liquid chromatography-mass spectrometry (LC-MS). Unsupervised multivariate analysis and Venn diagram were used to explore the relationship pattern among the house EBNs in Malaysia. The geographical distribution surrounded the swiftlet house was investigated to understand its influences on the metabolite distribution. Results: The hierarchical clustering analysis (HCA) combined with correlation coefficient revealed the differences between the house EBNs in Malaysia with four main clusters formation. The metabolites distribution among these clusters was unique with their varied combination of geographical distribution. Cluster 1 grouped EBNs from Selangor, Melaka, Negeri Sembilan, Terengganu which geographically distributed with major oil palm field in township; Cluster 2 included Perak and Sarawak with high distribution of oil palm in higher altitude; Cluster 3 included Perlis, Kelantan, Kedah, Penang from lowland of paddy field in village mostly and Cluster 4 grouped Sabah, Pahang, Johor which are majorly distributed with undeveloped hills. The metabolites which drove each cluster formation have happened in a group instead of individual key metabolite. The major metabolites that characterised Cluster 1 were fatty acids, while the rest of the clusters were peptides and secondary metabolites. Conclusion: The metabolite profiling conducted in this study was able to discriminate the Malaysian house EBNs based on metabolites distribution. The factor that most inferences the differences of house EBNs were the geographical distribution, in which geographical distribution affects the distribution of insect and the diet of swiftlet.

A preliminary study on the effects of E-Z Mixin® and EquiPlus® extenders supplemented with Edible Bird's Nest on the quality of chilled Arabian stallion semen

The aim of this study was to evaluate the effects of adding different concentrations of edible bird’s nest (EBN) which is secreted by swiftlet birds (Aerodramus fuciphagus), into EquiPlus® and E-Z Mixin® extenders on the quality of chilled Arabian stallion semen at various storage times (0, 24 and 48 h). Ten ejaculates were collected from five stallions, and diluted using the two extenders containing 0% (control), 0.12%, 0.24% and 0.24% of EBN + seminal plasma (SP). All the diluted semen samples were then cooled and stored at 5 °C, and examined at 0, 24 and 48 h. Sperm kinetic parameters were assessed using computer assisted sperm analysis (CASA) and viability were assessed using Hoechst33342/PI stain. In both extenders, total motility (TM) and progressive motility (PM) were significantly higher at 0.12% and 0.24% compared to 0.24% + SP at 24 and 48 h. At 0.12%, E-Z mixin® treated semen had significantly higher TM and PM than EquiPlus^® at 24 and 48 h. At 0.12% and 0.24%, average path velocity (VAP), straight-line velocity (VSL) and curvilinear velocity (VCL) were significantly higher in E-Z mixin® treated semen compared to EquiPlus^® at 24 and 48 h. Comparisons between the two extender types at different concentrations of EBN showed no significant difference in lateral head amplitude (ALH), linearity (LIN), straightness (STR), beat cross frequency (BCF) and viability, irrespective of the storage time. The percentage of viable was significantly higher in E-Z mixin® than EquiPlus® at 0 and 48 h in control and 0.12%. Supplementation of the E-Z mixin^® extender with 0.12% and 0.24% EBN concentrations in the absence of SP provided better CASA parameters such as TM, PM, VAP, VSL, and VCL at 24 and 48 h storage time. In conclusion, the results of this study indicated that chilled semen from Arabian stallion that was extended using E-Z mixin® and supplemented with 0.12% and 0.24% EBN concentrations performed better and yielded superior results in sperm kinetic parameters and % viable compared to EquiPlus® at 24 and 48 h storage time.

Edible Bird's Nest: The Functional Values of the Prized Animal-Based Bioproduct From Southeast Asia-A Review

Edible Bird's Nest (EBN) is the most prized health delicacy among the Chinese population in the world. Although some scientific characterization and its bioactivities have been studied and researched, no lights have been shed on its actual composition or mechanism. The aim of this review paper is to address the advances of EBN as a therapeutic animal bioproduct, challenges and future perspectives of research involving EBN. The methodology of this review primarily involved a thorough search from the literature undertaken on Web of Science (WoS) using the keyword "edible bird nest". Other information were obtained from the field/market in Malaysia, one of the largest EBN-producing countries. This article collects and describes the publications related to EBN and its therapeutic with diverse functional values. EBN extracts display anti-aging effects, inhibition of influenza virus infection, alternative traditional medicine in athletes and cancer patients, corneal wound healing effects, stimulation of proliferation of human adipose-derived stem cells, potentiate of mitogenic response, epidermal growth factor-like activities, enhancement of bone strength and dermal thickness, eye care, neuroprotective and antioxidant effects. In-depth literature study based on scientific findings were carried out on EBN and its properties. More importantly, the future direction of EBN in research and development as health-promoting ingredients in food and the potential treatment of certain diseases have been outlined.

Effect of Hydrolyzed Bird's Nest on β-Cell Function and Insulin Signaling in Type 2 Diabetic Mice

Type 2 diabetes mellitus is characterized by both resistance to the action of insulin and defects in insulin secretion. Bird’s nest, which is derived from the saliva of swiftlets are well known to possess multiple health benefits dating back to Imperial China. However, it’s effect on diabetes mellitus and influence on the actions of insulin action remains to be investigated. In the present study, the effect of standardized aqueous extract of hydrolyzed edible bird nest (HBN) on metabolic characteristics and insulin signaling pathway in pancreas, liver and skeletal muscle of db/db, a type 2 diabetic mice model was investigated. Male db/db diabetic and its euglycemic control, C57BL/6J mice were administered HBN (75 and 150 mg/kg) or glibenclamide (1 mg/kg) orally for 28 days. Metabolic parameters were evaluated by measuring fasting blood glucose, serum insulin and oral glucose tolerance test (OGTT). Insulin signaling and activation of inflammatory pathways in liver, adipose, pancreas and muscle tissue were evaluated by Western blotting and immunohistochemistry. Pro-inflammatory cytokines were measured in the serum at the end of the treatment. The results showed that db/db mice treated with HBN significantly reversed the elevated fasting blood glucose, serum insulin, serum pro-inflammatory cytokines levels and the impaired OGTT without affecting the body weight of the mice in all groups. Furthermore, HBN treatment significantly ameliorated pathological changes and increased the protein expression of insulin, and glucose transporters in the pancreatic islets (GLUT-2), liver and skeletal muscle (GLUT-4). Likewise, the Western blots analysis denotes improved insulin signaling and antioxidant enzyme, decreased reactive oxygen species producing enzymes and inflammatory molecules in the liver and adipose tissues of HBN treated diabetic mice. These results suggest that HBN improves β-cell function and insulin signaling by attenuation of oxidative stress mediated chronic inflammation in the type 2 diabetic mice.

Edible Bird's Nest Supplementation Improves Male Reproductive Parameters of Sprague Dawley Rat

Edible bird’s nest (EBN) is reported to have a positive in vitro proliferative effect and contain male reproductive hormones. Spermatogonia cells proliferate during spermatogenesis under male reproductive hormones stimulation that include testosterone, follicle-stimulating hormone (FSH), and luteinizing hormone (LH). Characterization of EBN through liquid chromatography-mass spectrometry (LCMS) has found testosterone as a base peak. Six types of amino acids, estradiol and sialic acid were among the major peaks that have been characterized. Based on the presence of these reproductive components, this study evaluated different doses of EBN on sperm parameters and male reproductive hormones of Sprague Dawley rats. Sixteen Sprague Dawley rats at the age of eight weeks were randomly and equally divided into four groups, which are Control, 10 mg/kg BW/d 50 mg/kg BW/d, and 250 mg/kg BW/d EBN group. The rats were fed with EBN enriched pellet daily and water ad-libitum. Rats were sacrificed and the organ was weighed for organ coefficients after eight weeks of treatment. Sperm concentration, percentage of sperm motility, and sperm viability were evaluated. Meanwhile, ELISA method was used to measure testosterone, FSH, and LH. Findings showed that there were no significant differences in organ coefficient between groups. Supplementation of 250 mg/kg BW/d EBN demonstrated a significant increase in sperm concentration, percentage of sperm motility as well as FSH and LH level compared to 10 mg/kg BW/d group. There was a dose-dependent increase in testosterone level but was not significant between groups. Based on these findings, EBN is concluded to have crucial effects on male reproductive parameters.

Potential Residual Contaminants in Edible Bird's Nest

Edible bird’s nest (EBN) is recognized as a nourishing food among Chinese people. The efficacy of EBN was stated in the records of traditional Chinese medicine and its activities have been reported in many researches. Malaysia is the second largest exporter of EBNs in the world, after Indonesia. For many years, EBN trade to China was not regulated until August 2011, when a safety alert was triggered for the consumption of EBNs. China banned the import of EBNs from Malaysia and Indonesia due to high level of nitrite. Since then, the Malaysia government has formulated Malaysia Standards for swiftlet farming (MS 2273:2012), edible bird’s nest processing plant design and management (MS 2333:2010), and edible bird’s nest product quality (MS 2334:2011) to enable the industry to meet the specified standards for the export to China. On the other hand, Indonesia's EBN industry formulated a standard operating procedure (SOP) for exportation to China. Both countries can export EBNs to China by complying with the standards and SOPs. EBN contaminants may include but not limited to nitrite, heavy metals, excessive minerals, fungi, bacteria, and mites. The possible source of contaminants may come from the swiftlet farms and the swiftlets or introduced during processing, storage, and transportation of EBNs, or adulterants. Swiftlet house design and management, and EBN processing affect the bird’s nest color. Degradation of its optical quality has an impact on the selling price, and color changes are tied together with nitrite level. In this review, the current and future prospects of EBNs in Malaysia and Indonesia in terms of their quality, and the research on the contaminants and their effects on EBN color changes are discussed.

Efficacy of Edible Bird's Nest on Cognitive Functions in Experimental Animal Models: A Systematic Review

Edible bird’s nest (EBN) is constructed from saliva of swiftlets birds and consumed largely by Southeast and East Asians for its nutritional value and anti-aging properties. Although the neuroprotection of EBN in animals has been reported, there has not been yet systemically summarized. Thus, this review systemically outlined the evidence of the neuroprotective activity of EBN in modulating the cognitive functions of either healthy or with induced-cognitive dysfunction animals as compared to placebos. The related records from 2010 to 2020 were retrieved from PubMed, Scopus, Web of Science and ScienceDirect using pre-specified keywords. The relevant records to the effect of EBN on cognition were selected according to the eligibility criteria and these studies underwent appraisal for the risk of bias. EBN improved the cognitive functions of induced-cognitive dysfunction and enhanced the cognitive performance of healthy animals as well as attenuated the neuroinflammations and neuro-oxidative stress in the hippocampus of these animals. Malaysian EBN could improve the cognitive functions of experimental animals as a treatment in induced cognitive dysfunction, a nutritional cognitive-enhancing agent in offspring and a prophylactic conservative effect on cognition against exposure to subsequent noxious cerebral accidents in a dose-depended manner through attenuating neuroinflammation and neuro-oxidative stress. This systemic review did not proceed meta-analysis.

Recovery of value-added glycopeptides from edible bird's nest (EBN) co-products: enzymatic hydrolysis, physicochemical characteristics and bioactivity

BACKGROUND

Processing of edible bird's nest (EBN) requires extensive washing to remove impurities and produces huge amounts of EBN co-products, which contain mainly feathers with glycoproteins attached, which are usually discarded. This study was conducted to recover the valuable EBN glycoproteins from the waste material. Enzymatic hydrolysis was applied to recover EBN glycopeptides from EBN co-products (EBN_coP ) and processed cleaned EBN (EBN_clean ) was used as control, which were then freeze-dried into EBN hydrolysates (EBNh_coP and EBNh_clean , respectively).

RESULTS

The recovery yield for EBNh_clean and EBNh_coP were 89.09 ± 0.01% and 47.64 ± 0.26%, respectively, indicating nearly 50% of glycopeptide can be recovered from the waste material. Meanwhile, N-acetylneuraminic acid, a major acid sugar in EBN glycoproteins, of EBNh_coP increased by 229% from 58.6 ± 3.9 to 192.9 ± 3.1 g kg^-1 , indicating the enzymatic hydrolysis removed impurities and thus enhanced the N-acetylneuraminic acid content. Total soluble protein was more than 330 g kg^-1 for all the samples. Colour parameter showed that hydrolysate samples have greater L* (lightness) values. Chroma result indicates the intensity of all the samples were low (< 11). Fourier-transform infrared (FTIR) spectrum displayed that the EBNh_coP exhibited similar functional groups with EBNh_clean , indicating that the EBN_coP has similar functionality as EBN_clean . Significantly higher (P ≤ 0.05) 1,1-diphenyl-2-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) activities were reported in EBNh_coP after the enzymatic reaction.

CONCLUSION

EBNh_coP were successfully recovered from low value EBN_coP with enhanced antioxidant activities. The findings of this work are beneficial for the EBN industry to reduce wastage and enhance economic values of EBN co-products, both economically and nutritionally. © 2020 Society of Chemical Industry.

Calcite Deposits Differentiate Cave from House-Farmed Edible Bird's Nest as shown by SEM-EDX, ATR-FTIR and Raman Microspectroscopy

The difference between the swiftlet white edible bird's nest from limestone caves versus house-farmed ones, especially in response to high temperature and stewing time in water where the latter type would disintegrate readily, has been a puzzle for a long time. We show that edible bird's nests from the limestone caves have calcite deposits on the surface of the nest cement as compared to the house-farmed nests which are built by swiftlets on timber planks. The micron and sub-micron calcite particles are seen in SEM-EDX and further characterized by ATR-FTIR and Raman microspectroscopy. The calcite deposits make it possible for the cave nest to retain a gelatinous texture under the harsh retort conditions at 121 °C for 20 mins in commercial bottling. We show that house-farmed nests can be soaked in CaCl₂ (aq) followed by rinsing with Na₂ CO₃ (aq) to grow the same calcite deposits on the nest cement with the same characteristic as cave nests. Therefore, there should no longer be a need to harvest cave nests, and we can better conserve the dwindling population and natural habitats of cave swiftlets.

Molecular analysis of edible bird's nest and rapid authentication of Aerodramus fuciphagus from its subspecies by PCR-RFLP based on the cytb gene

Edible bird's nest (EBN), for its great nutritional value, is widely used around the world, especially in China and Singapore. EBNs of different origins and types may vary in price and quality. Nowadays, birds' nests are difficult to identify morphologically, except for some whole bird's nests of which origins can be roughly identified. In this study, forty-two samples were collected from different regions for sequencing analysis and phylogenetic classification to initially determine their origins. Two stable enzyme digestion sites were found in the analysis of restriction maps of the species. Then, a quick and specific PCR-RFLP method was established to identify the EBN samples' origins. The genetic identification results indicated that the forty-two samples were from five origins. With the Af/g-486bp-F/R primer and restriction enzyme Taq I, Aerodramus fuciphagus (A. fuciphagus) was efficiently differentiated from the other species. Furthermore, the cytb-592bp-F/R primer and the BamH I enzyme were found to be useful in distinguishing Aerodramus fuciphagus (A. fuciphagus) from its subspecies (Aerodramus germani, A. germani). The PCR-RFLP method provides a potential tool for the rapid discrimination of A. fuciphagus at the species and even the subspecies levels to ensure the quality of the EBN products.

Untargeted metabolite profiling on the water-soluble metabolites of edible bird's nest through liquid chromatography-mass spectrometry

Background and Aim

Edible bird's nest (EBN) is the nutrient-rich salivary bioproduct produced by swiftlets in Southeast Asia. Currently, researchers are exploring the therapeutic effects of EBN, such as cell growth promotion, antioxidant content, antiviral effects, bone strengthening, eyes care, and neuroprotection bioactivities. The therapeutic effects of EBN have been studied through different extraction methods but the metabolites profile of the EBN in each extract has not yet been elucidated. This study aimed to profile the water-soluble metabolites of EBN prepared in different extraction methods. Subsequently, an extraction method will be selected as an ideal extraction method for untargeted metabolite profiling on the water-soluble metabolites in EBN.

Materials and Methods

In this study, water-soluble metabolites of EBN extracted by the four extraction methods were subjected to metabolite profiling through liquid chromatography-mass spectrometry (LC-MS). The extraction methods were acid extraction(ABN), pancreatic extraction (EzBN), eHMG extraction, and spray drying of HMG extraction (pHMG). The metabolite profiles, such as the number of metabolites and their identities in each extraction method, were evaluated through LC-MS analysis.

Results

The identity of metabolites present in the four extraction methods is inconsistent. Based on LC-MS analysis, only one and six metabolites were extracted differently through EzBN and ABN, respectively, in the first pre-screening. Through the second LC-MS screening on pHMG and eHMG extraction methods, eHMG was selected as an ideal extraction method due to the highest numbers of water-soluble metabolites with an amount of 193 was detected. Besides, eHMG extraction method was able to extract sialic acid and a high percentage of secondary metabolites.

Conclusion

This study suggests that eHMG is the ideal extraction method for extracting higher number of water-soluble metabolites from EBN and could be further developed as an extraction method for industry application. In addition, this study also has identified the types of primary and secondary metabolites present in EBN.

Edible Bird's Nest Protects Against Hyperglycemia-Induced Oxidative Stress and Endothelial Dysfunction

Increased oxidative stress by hyperglycemia is a major cause of vascular complications in diabetes. Bird's nest, which is made from the saliva of swiftlets has both medicinal and nutritional values dated back to ancient China. However, its role in improving endothelial dysfunction due to diabetes is yet to be elucidated. The present study examined the protective effect and mechanism of action of the aqueous extract of hydrolyzed edible bird nest (HBN) on endothelium in models of diabetes, in vitro and in vivo. Male db/m+ and db/db mice were orally administered with or without HBN and glibenclamide for 28 days, followed by vascular reactivity studies in mouse aortas. Human umbilical vein endothelial cells (HUVECs) and isolated mouse aorta from C57BL/6J were treated with high glucose (HG), HBN, sialic acid (SA), glibenclamide, and apocynin, respectively. The effects of HBN on reactive oxygen species (ROS) production and nitric oxide (NO) bioavailability were assessed by Western blot, 2',7'-dichlorofluorescin-diacetate (DCF-DA), and 4-amino-5-methylamino-2',7' difluorofluorescein (DAF-FM DA) in HUVECs, isolated mouse aorta, and db/db diabetic mice. HBN significantly reversed the endothelial dysfunction in diabetic mice and isolated mouse aorta. HBN normalized ROS over-production of NOX2 and nitrotyrosine, reversed the reduction of anti-oxidant marker, SOD-1 as well as restored NO bioavailability in both HUVECs challenged with HG and in db/db diabetic mice. Similarly, HG-induced elevation of oxidative stress in HUVECs were reversed by SA, glibenclamide, and apocynin. This attests that HBN restores endothelial function and protects endothelial cells against oxidative damage induced by HG in HUVECs, isolated mouse aorta, and db/db diabetic mice via modulating ROS mechanism, which subsequently increases NO bioavailability. This result demonstrates the potential role of HBN in preserving endothelial function and management of micro- or macrovascular complications in diabetes.

The role of edible bird's nest and mechanism of averting lead acetate toxicity effect on rat uterus

Aim

This study aimed to evaluate the protective effect of edible bird's nest (EBN) supplement on the uteri of rats exposed to lead acetate (LA) toxicity.

Materials and Methods

Five treatment groups were established as follows: Group 1 (C), which was given distilled water; Group 2 (T0), which was administered with LA (10 mg/kg body weight [BW]); and Groups 3 (T1), 4 (T2), and 5 (T3), which were given LA (10 mg/kg BW) plus graded concentrations of 30, 60, and 120 mg/kg BW of EBN, respectively. Rats were euthanized at week 5 to collect blood for superoxide dismutase (SOD) assay, and uterus for histomorphological study and expression analyses of epidermal growth factor (EGF), vascular endothelial growth factor (VEGF), and proliferating cell nuclear antigen (PCNA).

Results

Results revealed that LA causes destruction of uterine lining cells and necrosis of uterine glands of exposed rats without EBN supplement while the degree of damage decreased among EBN treated groups; T3 showed the highest ameliorating effect against LA toxicity, as well as an increased number of uterine glands. Increased levels of SOD were also achieved in EBN supplemented groups than the controls. Results of immunohistochemistry showed significantly higher expressions of EGF, VEGF, and PCNA levels (p<0.05) in T3 compared to other treatments. EBN maintained upregulation of antioxidant - reactive oxygen species balance.

Conclusion

The findings showed that EBN could ameliorate the detrimental effects of LA toxicity on the uterus possibly by enhancing enzymatic antioxidant (SOD) activity as well as expressions of EGF, VEGF, and PCNA with cell proliferation roles.

Effects of EBN on embryo implantation, plasma concentrations of reproductive hormones, and uterine expressions of genes of PCNA, steroids, growth factors and their receptors in rats

This study was conducted to determine the effect of edible bird's nest (EBN) supplement on uterine function and embryo-implantation rate. A total of 24 adult female rats, divided equally into four groups, were treated with different doses of EBN for 8 weeks. In the last week of treatment, intact fertile male rats were introduced into each group (three per group) for overnight for mating. On day 7 post-mating (post-implantation), blood samples were collected from the hearts of anaesthetised rats that were later sacrificed. The uteri were removed for assessment of embryo implantation rate, histological and electron microscopic examination, and immunohistochemical analyses. Results showed that as the concentration of EBN supplemented increased, the pregnancy and embryo implantation rates were also increased in the treated groups; significantly at G3 and G4. Although histological evaluation did not show much difference among the groups, scanning electron microscopic examination showed enhanced development of elongated microvilli and pinopods in G4. Results also revealed up-regulated expressions of epidermal growth factor (EGF), EGF receptor (EGFR), vascular endothelial growth factor (VEGF), proliferating cell nulear antigen (PCNA), and progesterone and estrogen receptors (P₄R, E₂R) in the uteri of treated groups. Moreover, plasma E₂, P₄, growth hormone (GH) and prolactin (P) levels were higher (p < 0.05) in G3 and G4. The EBN increased the antioxidant (AO) and total AO capacities (TAC) and reduced oxidative stress (OS) levels in pregnant rats. In conclusion, findings of this study revealed that EBN enhances fertility and embryo implantation rate via promoting proliferation and differentiation of uterine structures as evidenced by the upregulation of the expressions of steroid receptors, EGF, EGFR, VEGF, and PCNA in the uterus. Furthermore, observations of improved growth of ultrastructural pinopods that assist in embryo attachment with uterine epithelium, increased concentrations of E₂, P₄, GH and P levels, as well as increased AO capacities with reduced OS levels in the treated groups might reflect additional possible mechanisms by which EBN enhances embryo implantation rate and pregnancy success.

Nitration of Tyrosine in the Mucin Glycoprotein of Edible Bird's Nest Changes Its Color from White to Red

The edible bird's nest (EBN) of the swiftlet Aerodramus fuciphagus, a mucin glycoprotein, is usually white in color, but there also exist the more desirable red or "blood" EBN. The basis of the red color has been a puzzle for a long time. Here, we show that the nitration of the tyrosyl residue to the 3-nitrotyrosyl (3-NTyr) residue in the glycoprotein is the cause of the red color. Evidence for the 3-NTyr residue comes from (a) the quantitative analysis of 3-NTyr in EBN by enzyme-linked immunosorbent assay, (b) the ultraviolet-visible absorption spectra of red EBN as a function of pH being similar to 3-nitrotyrosine (3-NT), (c) the change in the color of red EBN from yellow at low pH to red at high pH just like 3-NT, and (d) strong Raman nitro bands at 1330 cm^-1 (symmetric -NO₂ stretch) and 825 cm^-1 (-NO₂ scissoring bend) for red EBN. The high concentrations of nitrite and nitrate in red EBN are also explained.

Rapid authentication of edible bird's nest by FTIR spectroscopy combined with chemometrics

BACKGROUND

Edible bird's nests (EBNs) have been traditionally regarded as a kind of medicinal and healthy food in China. For economic reasons, they are frequently subjected to adulteration with some cheaper substitutes, such as Tremella fungus, agar, fried pigskin, and egg white. As a kind of precious and functional product, it is necessary to establish a robust method for the rapid authentication of EBNs with small amounts of samples by simple processes. In this study, the Fourier transform infrared spectroscopy (FTIR) system was utilized and its feasibility for identification of EBNs was verified.

RESULTS

FTIR spectra data of authentic and adulterated EBNs were analyzed by chemometrics analyses including principal component analysis, linear discriminant analysis (LDA), support vector machine (SVM) and one-class partial least squares (OCPLS). The results showed that the established LDA and SVM models performed well and had satisfactory classification ability, with the former 94.12% and the latter 100%. The OCPLS model was developed with prediction sensitivity of 0.937 and specificity of 0.886. Further detection of commercial EBN samples confirmed these results.

CONCLUSION

FTIR is applicable in the scene of rapid authentication of EBNs, especially for quality supervision departments, entry-exit inspection and quarantine, and customs administration. © 2017 Society of Chemical Industry.

Effect of Maternal Administration of Edible Bird's Nest on the Learning and Memory Abilities of Suckling Offspring in Mice

Although human brains continue developing throughout the underage developmental stages, the infancy period is considered the most important one for the whole life. It has been reported that sialic acid from edible bird's nest (EBN) can facilitate the development of brain and intelligence. In this study, by oral administration of EBN to female mice during the pregnancy or lactation period, the effects of EBN on the levels of sialic acid in mouse milk were determined using high-performance liquid chromatography (HPLC). Furthermore, the spatial learning performances of their offspring were assessed using the Morris water maze test. Additionally, cerebral malondialdehyde (MDA), superoxide dismutase (SOD), choline acetyltransferase (ChAT), and acetylcholinesterase (AChE) in cubs nursed by the female mice given the EBN homogenate were examined, while BDNF immunohistochemical staining and neuron count in hippocampi were investigated as well. These results showed that administration with EBN in maternal mice during pregnancy or lactation period can improve the learning and memory functions in their offspring, possibly by increasing the activities of SOD and ChAT and, at the meantime, decreasing the levels of MDA and activities of AChE. Moreover, BDNF levels for CA1, CA2, and CA3 regions in hippocampi and the numbers of dyed neurons in CA1, CA2, CA3, and DG regions among the offspring were significantly enhanced due to the intake of EBN by the maternal mice. We concluded that maternal administration of EBN during the pregnancy and lactation periods can improve the spatial learning performances in the offspring.

De novo transcriptome analysis shows differential expression of genes in salivary glands of edible bird's nest producing swiftlets

BACKGROUND

Edible bird's nest (EBN), produced from solidified saliva secretions of specific swiftlet species during the breeding season, is one of the most valuable animal by-products in the world. The composition and medicinal benefits of EBN have been extensively studied, however, genomic and transcriptomic studies of the salivary glands of these birds have not been conducted.

RESULTS

The study described the transcriptomes of salivary glands from three swiftlet species (28 samples) generated by RNASeq. A total of 14,835 annotated genes and 428 unmapped genes were cataloged. The current study investigated the genes and pathways that are associated with the development of salivary gland and EBN composition. Differential expression and pathway enrichment analysis indicated that the expression of CREB3L2 and several signaling pathways involved in salivary gland development, namely, the EGFR, BMP, and MAPK signaling pathways, were up-regulated in swiftlets producing white EBN (Aerodramus fuciphagus) and black EBN (Aerodramus maximus) compared with non-EBN-producing swiftlets (Apus affinis). Furthermore, MGAT, an essential gene for the biosynthesis of N-acetylneuraminic acid (sialic acid), was highly expressed in both white- and black-nest swiftlets compared to non-EBN-producing swiftlets. Interspecies comparison between Aerodramus fuciphagus and Aerodramus maximus indicated that the genes involved in N-acetylneuraminic and fatty acid synthesis were up-regulated in Aerodramus fuciphagus, while alanine and aspartate synthesis pathways were up-regulated in Aerodramus maximus. Furthermore, gender-based analysis revealed that N-glycan trimming pathway was significantly up-regulated in male Aerodramus fuciphagus from its natural habitat (cave) compared to their female counterpart.

CONCLUSIONS

Transcriptomic analysis of salivary glands of different swiftlet species reveal differential expressions of candidate genes that are involved in salivary gland development and in the biosynthesis of various bioactive compounds found in EBN.