Yolkin- A Polypeptide Complex Isolated From Chicken Egg Yolk with Potential Neuroprotective and Antioxidative Activity

Abstract

Background Yolkin, the polypeptide complex isolated from chicken egg yolk as a fraction accompanying immunoglobulin IgY, possess immunoregulatory activity and improves cognitive function of aged rats. However, the mechanism of its action was not clear. In the development of neurodegenerative diseases, the oxidative stress, permanent inflammation and decreased level of neurotrophic factors are included. Therefore the upregulation of the level of neuroprotective factors and activation of antioxidant system are the key manners to control the nervous system function. In this study, we aimed to investigate the effect of polypeptide complex yolkin on brain-derived neurotrophic factor (BDNF) production and on reduction of oxidative stress. Methods In the present study PC12 Tet On cell line and human whole blood were used to investigate the neuroprotective activity of yolkin. Viability of PC12 Tet On cells exposed to various concentrations of yolkin was determined by MTT assay. The level of BDNF released in response to yolkin by both PC12 cells and human whole blood was determined by ELISA. The influence of yolkin on intracellular ROS level was determined using DCFH-DA assay. Antioxidant capacity of yolkin was determined by DPPH assay, FRAP method and FE (II) ion chelation method. Results The results obtained showed that yolkin is not antioxidant but significantly reduces intracellular oxidative stress induced by hydrogen peroxide application. Yolkin also stimulates both PC12 Tet On neuronal cells and cells of human whole blood to release of BDNF in dose-dependent manner. Conclusions Our study showed that the natural origin regulatory substances such as yolkin may be useful as an efficient bioactive compound for the treatment of impairments of central nervous system accompanying neurodegenerative diseases e.g. Alzheimer's and Parkinson's.

Yolkin Isolated from Hen Egg Yolk as a Natural Immunoregulator, Activating Innate Immune Response in BMDM Macrophages

“…Whereas fractions of MW higher than 16 kDa are glycoproteins corresponding also to the amino acid sequence of vitellogenin II starting at position 1572aa [6]. Our studies obtained up to now have demonstrated that yolkin possesses immunoregulatory, antioxidant, and neuroprotective activities, stimulating human whole blood (ex-vivo) to produce a wide spectrum of cytokines [6][7][8], downregulating the level of intracellular free oxygen radicals, and stimulating neuron-like cells to produce brain-derived neurotrophic factor (BDNF) [9].…”

Comparative Studies of Yolkin Preparations Isolated from Egg Yolks of Selected Bird Species

“…Yolkin stimulated rat pheochromocytoma PC12 Tet on cell lines to secrete the mature form of BDNF. It also has been found that yolkin induced production of this neurotrophin in a human whole blood cells [10,14] . This protein complex has also pro‐cognitive properties, as it influenced the proper functioning of spatial and episodic memory of young and old rats presenting neurodegenerative changes [15] …”

“…It also has been found that yolkin induced production of this neurotrophin in a human whole blood cells. [10,14] This protein complex has also pro-cognitive properties, as it influenced the proper functioning of spatial and episodic memory of young and old rats presenting neurodegenerative changes. [15] Hen's eggs are widely available and cheap raw material for isolation of bioactive compounds.…”

A Novel Mechanism of Macrophage Activation by the Natural Yolkin Polypeptide Complex from Egg Yolk

“…Yolkin has moderated ageing symptoms and supported learning functions in both young and old rats [ 8 ]. Furthermore, it was found that the peptide complex also has antioxidant activity, which is fundamental for protection against oxidative damage and stimulates neuron-like PC12 cells and human whole blood to secrete the mature form of brain-derived neurotrophic factor (BDNF) [ 6 , 9 ]. These results suggest that the yolkin polypeptide complex may have a positive therapeutic effect both in immunodeficiency and in human neurodegenerative diseases, such as Alzheimer’s disease.…”