Three new phenanthrene derivatives (1, 2, 4), one new fluorenone (3), and
four
known compounds (5–8) were isolated
from the ethyl acetate extract of Dendrobium crumenatum Sw. stems using column chromatography. The chemical structures were
elucidated by analysis of spectroscopic data. The absolute configuration
of 4 was determined by electronic circular dichroism
calculation. We also evaluated the immunomodulatory effects of compounds
isolated from D. crumenatum in human peripheral blood
mononuclear cells from healthy individuals and those from patients
with multiple sclerosis in vitro. Dendrocrumenol B (2) and dendrocrumenol D (4) showed strong immunomodulatory
effects on both CD3+ T cells and CD14+ monocytes.
Compounds 2 and 4 could reduce IL-2 and
TNF production in T cells and monocytes that were treated with phorbol-12-myristate-13-acetate
and ionomycin (PMA/Iono). Deep immune profiling using high-dimensional
single-cell mass cytometry could confirm immunomodulatory effects
of 4, quantified by the reduction of activated T cell
population under PMA/Iono stimulation, in comparison to the stimulated
T cells without treatment.