Bioactive bibenzyl derivatives and fluorenones from Dendrobium nobile.
Bioassay-guided fractionation of the 60% ethanol extract of the stems of Dendrobium nobile using the DPPH assay led to the isolation of two new bibenzyl derivatives, nobilin D (1) and nobilin E (2), and a new fluorenone, nobilone (3), together with seven known compounds (4-10). Their structures were determined on the basis of spectroscopic analyses. Compounds 1, 2, 4, 7, 8, and 10 exhibited significant antioxidant activity higher than or equivalent to vitamin C in the DPPH assay, and compounds 1, 3, 4, and 7-10 displayed higher antioxidant activity than vitamin C in the ORAC assay. Compounds 1, 2, and 10 also exhibited stronger inhibitory effects on NO production than resveratrol.
Zhang
Xue
X
Research Institute of Tsinghua University in Shenzhen, Key Laboratory for New Drugs Research of Traditional Chinese Medicine in Shenzhen, Shenzhen 518057, People's Republic of China.
Xu
Jie-Kun
JK
Wang
Jue
J
Wang
Nai-Li
NL
Kurihara
Hiroshi
H
Kitanaka
Sumumu
S
Yao
Xin-Sheng
XS
D000975:Antioxidants / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D001632:Bibenzyls / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D001713:Biphenyl Compounds; D031667:Dendrobium / Q000737:chemistry*; D004365:Drugs, Chinese Herbal / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D005449:Fluorenes / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D009569:Nitric Oxide / Q000096:biosynthesis / Q000378:metabolism; D010851:Picrates / Q000494:pharmacology; D018547:Plant Stems / Q000737:chemistry; D010946:Plants, Medicinal / Q000737:chemistry*; D000077185:Resveratrol; D045788:Sesquiterpenes, Germacrane; D013267:Stilbenes / Q000494:pharmacology
D000975:Antioxidants; D001632:Bibenzyls; D001713:Biphenyl Compounds; D004365:Drugs, Chinese Herbal; D005449:Fluorenes; D010851:Picrates; D045788:Sesquiterpenes, Germacrane; D013267:Stilbenes; C517578:nobilin D; C517579:nobilin E; C517580:nobilone; D009569:Nitric Oxide; C004931:1,1-diphenyl-2-picrylhydrazyl; D000077185:Resveratrol