Two new compounds from Dendrobium candidum

Two new compounds were isolated from the stems of Dendrobium candidum: (R)-3,4-dihydroxy-5,4', alpha-trimethoxybibenzyl (1), named dendrocandin A; and 4-[2-](2S,3S)-3-(4-hydroxy-3,5-dimethoxyphenyl)-2-hydroxymethyl-8-methoxy-2,3 -dihydrobenzol[1,4]dioxin-6-yl]ethyl]-1-methoxyl benzene (2), dendrocandin B. Five previdimethoxybihenzyl known bibenyls were also identified: 4,4'-dihydroxy-3,5-dimethoxybibenzyl (3), 3,4-dihydroxy-5,4'-dimethoxybibenzyl (4) 3-O-methylgigantol (5), dendrophenol (6), and gigantol (7).