Chemical properties and antioxidant activity of a water-soluble polysaccharide from Dendrobium officinale.
Two new phenanthrene and 9, 10-dihydrophenanthrene derivatives (1–2) with six known congeners (3–8) were isolated from the extraction of stems of Dendrobium officinale. Compounds 1 and 2 were based on carbon skeleton in which phenanthrene and 9, 10-dihydrophenanthrene moiety were linked with a phenylpropane unit through a dioxane bridge, respectively. Their structures were determined by comprehensive NMR spectroscopic data, the absolute configuration of new compounds were determined by comparing their experimental and calculated ECD for the first time. All the compounds were investigated contains two cancer cell lines (HI-60, THP-1). All the isolates showed cytotoxicity, especially compound 4 showed markedly cytotoxic activities against HI-60 and THP-1 cell lines with IC50 values of 11.96 and 8.92 μM.