Bibenzyl and naphthalene derivatives from Dendrobium chrysanthum and their anti-hepatic-steatosis activities

In this study, 16 new compounds, six bibenzyls (1–6) and 10 naphthalenes (7–13), including three pairs of naphthalene enantiomers and three known compounds (14–16), were isolated from Dendrobium chrysanthum. Structurally, compounds 1–5 are previously undescribed dimeric bibenzyls, uniquely linked by unusual carbon bonds. The structures of the compounds were determined using spectroscopy and X-ray crystallography. The screening results indicated that 1, 2, and 5 showed remarkable lipid-lowering activities in FFA-induced HepG2 cells, with EC50 values ranging from 3.13 to 6.57 μM. Moreover, 1, 2, and 5 significantly decreased both the mRNA and protein levels of the target SREBP-1c, and 5 also reduced PPARα mRNA and protein levels. Therefore, 1, 2, and 5 are potential drugs against hepatic steatosis by targeting PPARα or SREBP-1c.