Sesquiterpene amino ether and cytotoxic phenols from Dendrobium wardianum Warner

Abstract A new bibenzyl derivative, dendrocandin V ( 1 ) and a new sesquiterpene amino ether, wardianumine A ( 2 ), together with eleven known compounds, including phenanthrenes (denbinobin ( 3 ), 9,10-dihydro-denbinobin ( 4 ), mostatin ( 5 ), loddigesiinols A ( 6 )), bibenzyls (moscatilin ( 7 ), 5-hydroxy-3,4′-dimethoxybibenzyl ( 8 ), 3,4-dihydroxy-5,4′-dimethoxy bibenzyl ( 9 ), dendrocandin A ( 10 ), gigantol ( 11 ), dendrocandin U ( 12 )) and an alkaloids (dihydroshihunine, 13 ) were isolated from the EtOH extraction of stems of Dendrobium wardianum Warner. Isolation of the new compound 2 indicated that N , N -dimethylethanolamine as the key adduction in the synthesis of dendroxine and its analogs in Dendrobium species. The hypothetical biosynthetic pathway of 2 was then postulated. Inspired by literature and traditional usage of the herbal medicine, some compounds were sent for cytotoxic activity and the results indicated that compounds 1 , 3 , 4 , 5 showed cytotoxic activities against five human cancer cell lines (HL-60, A-549, SMMC-7721, MCF-7, and SW-480) with IC50 from 2.33–38.48 μM. Among those compounds, 3 and 4 showed cell line selectivity with strong activity comparable to DDP.