Abstract:
The objective of this study was to investigate the chemical constituents and biological activities of Dendrobium ellipsophyllum, a plant with no previous reports. The results led to the isolation of ten known compounds, consisting of three bibenzyls (moscatilin, 4,4’-dihydroxy-3,5-dimethoxybibenzyl, 4,5,4’-trihydroxy-3,3’-dimethoxybibenzyl), four flavonoids ((2S-homoeriodictyol, (2S)-eriodictyol, chrysoeriol and luteolin), a dihydrophenanthrene, a chromone and a phenylpropanoids (4,5-dihydroxy-2,3-dimethoxy-9,10-dihydrophennthrene, 5,7-dihydroxy-chromen-4-one and phloretic acid, respectively). Their structures were determined by spectroscopic analysis (NMR, MS) and comparision with the previously reported data. The results from bioassays revealed that 4,5,4’-trihydroxy-3,3’-dimethoxybibenzyl and luteolin had moderate cytotoxic activity against KB oral cavity cancer cells (IC50 61.93 and 56.22 μM, respectively), as compared with the positive controls ellipticine (IC50 4.99 μM) and doxorubicin (IC50 1.53 μM). The two compounds had cytotoxicity on MCF-7 breast cancer cells (IC50 135.48 and 68.01 μM, respectively), in comparison with tamoxifen (IC50 20.46 μM and doxorubicin (IC50 26.29 μM). 4,4’-Dihydroxy-3,5-dimethoxybibenzyl, 4,5,4’-trihydroxy-3,3’-dimethoxybibenzyl, chrysoeriol and luteolin showed anti-metastatic activity on H292 lung cancer cells, displaying apoptosis induction and anoikis sensitizing activities. 4,5,4’-Trihydroxy-3,3’-dimethoxybibenzyl (IC50 96.56 μM) possessed highest cytotoxic activity and the fastest action in sensitizing the cells to anoikis at the concentrations of 1 and 5 μM. Significant effects could be detected as early as 6 hours after exposure to the cells. Moreover, 4,4’-dihydroxy-3,5-dimethoxybibenzyl showed weak anti-herpes simplex virus activity against HSV-1 and HSV-2 with IC50 313.61 ± 40.40 and 334.56 ± 52.66 μM, respectively.
