(Spiro) phenanthrenes and bibenzyls in Dendrobium chrysotoxum Lindl and their cytotoxic as well as anti-pulmonary fibrosis activities

The stems of Dendrobium chrysotoxum Lindl are used as medicinal herbs and for nutraceutical beverages and functional food products. In order to obtain an in-depth understanding of the bioactive compounds in the stems of D. chrysotoxum Lindl, an exhaustive chemical examination was carried out. A total of 20 undescribed compounds (1-20) along with 40 known ones (21-60) were isolated. The structures of 1-20 were elucidated based on spectroscopic analysis and theoretical quantum calculations. The unreported compounds consist of 7 spirophenanthrenes (1-7), 4 diphenanthrenes (8-11), 1 9,10-dihydrophenanthrene derivative (12), 1 phenanthropyran (13), 2 monophenanthrenes (14 and 15), 1 dimeric bibenzyl (16), and 3 bibenzyls (17-20). Six compounds 1b, 3b, 4a, 4b, 8, and 16 exhibited remarkable cytotoxic activity against HCCLM3 cancer cells with IC₅₀ values of 1.68 μM-6.60 μM. Compounds 10, 15, and fimbriadimerbibenzyl D displayed significant anti-pulmonary fibrosis with IC₅₀ values of 1.82 ± 0.02 μM to 3.68 ± 0.03 μM.