title: Three new bibenzyl derivatives from Dendrobium candidum.
abstract: Three new compounds were isolated from the stems of Dendrobium candidum: (S)-3,4,4'-trihydroxy-5,alpha-dimethoxybibenzyl (1), named dendrocandin C; (S)-3,4,4'-trihydroxy-5-methoxy-alpha-ethoxybibenzyl (2), named dendrocandin D; and 3,3',4,4'-tetrahydroxy-5-methoxybibenzyl (3), named dendrocandin E. Their structures were elucidated by 1D- and 2D-NMR spectroscopy and mass spectroscopy. The isolated compounds exhibited potent antioxidant activity in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging test, with IC(50) values of 34.2, 34.5, and 15.6 microM for compounds 1, 2, and 3, respectively. Vitamin C was used as positive control with IC(50) 23.2 microM.
authors.affiliation: Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, P.R. China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Chun-Lan
authors.initials: CL
authors.lastname: Wang
authors.forename: Ya-Jun
authors.initials: YJ
authors.lastname: Wang
authors.forename: Shun-Xing
authors.initials: SX
authors.lastname: Guo
authors.forename: Jun-Shan
authors.initials: JS
authors.lastname: Yang
authors.forename: Xiao-Mei
authors.initials: XM
authors.lastname: Chen
authors.forename: Pei-Gen
authors.initials: PG
authors.lastname: Xiao
mesh_terms: D000975:Antioxidants / Q000737:chemistry* / Q000302:isolation & purification; D001205:Ascorbic Acid / Q000737:chemistry; D001632:Bibenzyls / Q000737:chemistry* / Q000302:isolation & purification; D001713:Biphenyl Compounds; D031667:Dendrobium / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D000432:Methanol; D010851:Picrates; D012997:Solvents; D021241:Spectrometry, Mass, Electrospray Ionization; D013056:Spectrophotometry, Ultraviolet
chemical_list: D000975:Antioxidants; D001632:Bibenzyls; D001713:Biphenyl Compounds; D010851:Picrates; D012997:Solvents; C539110:dendrocandin C; C004931:1,1-diphenyl-2-picrylhydrazyl; D001205:Ascorbic Acid; D000432:Methanol