Chemical constituents from Dendrobium chrysanthum and their chemotaxonomic significance

Nineteen known compounds were isolated from the 75% alcohol extract of the stems of Dendrobium chrysanthum, including four phenols (1-4), three alkaloids (5-7), six phenanthrenes (8-13), three monoterpenes (14-16), and three lignans (17-19). This is the first report on compounds 3 (trans-3,4,5-trimethoxylcinnamyl alcohol), 5 (1-(6-hydroxy-[3]pyridyl)-propan-1-one), 16 ((+)-(1S,5R)-verbenon-10-oic acid) and 18 (cinnacassin F) isolated from the family Orchidaceae, compounds 2 (3-hydroxy-4,5-dimethoxypropiophenone) and 7 (1H-Indole-3-carbaldehyde) from the genus Dendrobium, and compounds 1 (syringaldehyde), 4 (apocynin), 8 (confusarin), 9 (nudol), 10 (orchinol), 11 (ephemeranthol-A), 12 (5,7-dimethoxyphenanthrene-2,6-diol), 13 (moscatilin), 15 (loliolide), 17 (3,3' -bis(3,4-dihydro-4-hydroxy-6-methoxy-2H-1-benzopyran) and 19 ((+)-syringaresinol) from D. chrysanthum. It is worth mentioning that compounds 6 (carbofuran) and 14 ((6R,7aR)-7a-hydroxy-3,6-dimethyl-5,6,7,7a-tetrahydrobenzofuran-2(4H)-one) have not been previously reported from any plant. Their structures were elucidated on the basis of NMR spectroscopic data. Moreover, the chemotaxonomic significance of the isolated compounds is discussed.