Fuzhuan brick tea (FBT), one of the
unique dark teas, has various
health-promoting functions. In the present study, one polysaccharide
fraction, namely FBTPS-2-1, was extracted and purified from FBT, and
its structure and potential immunostimulatory activity were investigated.
The results showed that FBTPS-2-1,one of typical heteropolysaccharides,
was mainly composed of Gal, Ara, and Glc with little molar content
of Man, Rha, GalA, and GlcA in molar ratio of 46.59:22.13:13.57:8.20:6.02:2.12:1.38
and molecular weight of 748 kDa. The backbone of FBTPS-2-1 contained
→4)-β-d-Galp-(1→4)-β-d-Galp-(1→, →4)-β-d-Galp-(1→4)-α-d-Glcp-(1→, →4)-α-d-Glcp-(1→4)-α-d-Glcp-(1→,
→4)-α-d-Glcp-(1→4)-β-d-Galp-(1→, →3)-β-d-Galp-(1→4)-β-d-Galp-(1→, →3,6)-β-d-Galp-(1→3)-β-d-Galp-(1→
and →3,6)-β-d-Galp-(1→3,6)-β-d-Galp-(1→. The linkages of branches
in FBTPS-2-1 were mainly composed of α-l-Araf-(1→3,6)-β-d-Galp-(1→, →5)-α-l-Araf-(1→3,6)-β-d-Galp-(1→, →6)-β-d-Galp-(1→3,6)-β-d-Galp-(1→, α-l-Araf-(1→3,5)-α-l-Araf-(1→, →3,5)-α-l-Araf-(1→5)-α-l-Araf-(1→, α-d-Galp-(1→3,5)-α-l-Araf-(1→ and →5)-α-l-Araf-(1→6)-β-d-Galp-(1→. Furthermore, FBTPS-2-1 could increase the
phagocytosis of macrophages and promote the secretion of NO and a
variety of inflammatory cytokines, including TNF-α, IL-1β,
and IL-6, indicating noticeable immune enhancement activity. Thus,
FBTPS-2-1 could serve as a potentially functional food to improve
human health by modulating the host immunoreaction.
