Bibenzyl–Phenylpropane Hybrids with Immunosuppressive Activities from Dendrobium Nobile Lindl

Fifteen bibenyls and four fluorenones, including five new bibenzyl–phenylpropane hybrids, were isolated from the aerial part of Dendrobium nobile Lindl. Their structures were determined by spectroscopic methods. Bioassay on the LPS–induced proliferations of mouse splenic B lymphocytes, and Con A‐induced T lymphocytes showed that compounds 1, 2, and 14 showed excellent immunosuppressive activities with IC50 values of 1.23, 1.01, and 3.87 μM, respectively, while compounds 3–4, 7, 10, 13, and 15 exhibited moderate immunosuppressive activities with IC50 values ranging from 6.89 to 14.2 μM.