Fatigue, accompanied by modern life style and high-intensity exercise, has become a common human condition. Meanwhile, human health is closely related to the function of immune system, and the impaired function of immune system will also lead to fatigue. Consequently, it is urgent to find natural anti-fatigue and immune-enhancing compounds without side-effects.

Recently, a research team led by Prof. LI Pengcheng from the Institute of Oceanology of the Chinese Academy of Sciences (IOCAS) obtained the special sequence of peptides from monkfish (Lophius litulon) protein, and proved that monkfish peptides had anti-fatigue and immunity-enhancing effect. They also found that monkfish peptides could regulate immune function by regulating receptors involved in inflammatory responses.

The study was published in Journal of Functional Foods on April 28.

The researchers used a series of separation and purification techniques, including ultrafiltration, gel filtration chromatography and reverse high-performance liquid chromatography, to obtain specific sequences of peptides. They found the peptides could significantly increase antioxidant enzyme activities, hepatic glycogen and lactate dehydrogenase contents, and decrease blood urea nitrogen and blood lactic acid contents in exercise-induced fatigue mice.

What's more, they found the monkfish peptides could enhance spleen lymphocytes proliferation and natural killer cells activity in mice. Transcriptomics analysis showed that there were 205 genes up-regulated and 1,040 genes down-regulated after the mice were fed with monkfish peptides. The peptides could inhibit inflammatory cytokines activation by down-regulating the chemokine and Nucleotide Oligomerization Domain (NOD)-like receptor signaling pathways, thereby modulating the mice immune response.

"The monkfish peptides could be applied in healthcare products associated with anti-fatigue and immunity enhancing," said WANG Xueqin, first author of the study.