Maca
is a protein-enriched edible plant with immunomodulatory activity.
However, the role of proteins in the immunomodulatory activity of
maca is unclear. In this study, peptide products of maca proteins
obtained through in vitro gastrointestinal digestion were isolated
and purified, and the immunomodulatory activities of these peptides
were assessed in macrophages (RAW 264.7 cells). The results show that
the maca protein hydrolysate enhanced the phagocytic capacity and
NO, TNF-α, and IL-6 secretion of RAW 264.7 cells. Forty-five
peptides from known proteins of maca or the cruciferous family were
identified by ultraperformance liquid chromatography–tandem
mass spectrometry in the hydrolysate, and the peptide RNPFLP exhibited
the strongest immunomodulatory activity. Antibody blocking, siRNA,
pathway inhibitors, and western blot assays showed that RNPFLP-activated
RAW 264.7 cells through the NF-κB and MAPK signaling pathways
mediated by TLR2 and TLR4 receptors. An analysis of the structure–activity
relationship showed that the N9-H60 active site
in arginine plays an important role in the immunomodulatory activity
of RNPFLP. This study provides a new understanding of the immunomodulatory
activity of maca.
A polysaccharide, Ali-1, was isolated
from the roots of Eurycoma longifolia, a popular
traditional medicinal herb
in Malaysia. The structure of Ali-1 was characterized by monosaccharide,
methylation, and NMR data analyses. The average molecular weight of
Ali-1 is 14.3 ku, and it is composed of arabinose (14.31%), xylose
(57.69%), galacturonic acid (13.03%), and glucuronic acid (14.86%).
The main chain comprises (1→4)-linked xylose residues. It has
branch points in the main chain; (1→2,4)-linked xylose residues,
1,2-linked glucuronic acid residues, and 1,2-linked arabinose residues
form the branches, and the branches are terminated with T-linked galacturonic
acid residues and T-linked arabinose residues. Ali-1 significantly
improves the pinocytic and phagocytic abilities of RAW264.7 cells
and facilitates cytokine secretion according to an immunostimulation
assay. These results demonstrate that Ali-1 has potential as a functional
supplement for people with compromised immune systems.
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