| Rhodiola wallichiana [?HK? S H Fu var Cholaensis?Praeg? S H Fu]. belongs to Crassulaceae Rhodiola, which is widely distributed in Tibet, Sichuan, Yunnan and other places of China. As a Chinese folk medicine, its utilization can be traced back to “Sheng Nong's herbal classic” from 2000 years ago and “A Supplement to Recipes Worth A Thousand Gold?Qianjin Yi Fang?” in the Tang dynasty as well as in “Compendium of Materia Medica” in the Ming dynasty. Rhodiola preparations have adaptogenic effect on body function with the ability of physiological function adjusting and life-span increasing, and therefore is also titled to Plateu ginseng or Arctic rose. Modern investigations revealed the cardioprotective, neuroprotective, anti-fatigue, anti-aging, anti-radiation activity and immune-modulating effect of Rhodiola rosea. Rhodiola contains glycosides, coumarins,flavones, essential oils, sterols, phenolics and organic acids?gallic, oxalic, citric, malic, succinic? and inorganic trace elements. To further explore the bioactive chemical constituents from this traditional medicine, this paper carried out the chemical constituent studies.The ethanol extraction of Rhodiola wallichiana was obtained by 75% Et OH reflux heated extraction method. Then it was extracted successively with petroleum ether, ethyl acetate, n-butyl alcohol using decompress concentrating. The extractions were then passed through Silica gel, Toyopearl HW-40 and preparative HPLC, from which 22 compounds were isolated and purified. Next, the structures of these isolated compounds were determined using comprehensive analysis of UV, IR, MS, as well as 1D and 2D NMR analysis. These compounds were identified as follows: p-hydroxyphenethyl anisate?1?,?+?-8-hydroxypinoresinol?2?, tyrosol?3?, Tyrosyl hydroxyphenyl acetate?4?, caffeic acid?5?, 4-hydroxylcinnamic acid?6?, ferulic acid?7?, methyl cinnamate?8?, 2'-hydroxy-4'-methoxyacetophenone?9?, vanillic acid?10?, ethyl gallate?11?, gallic acid?12?, 3,4-dihydroxy-5-methoxybenzoic acid?13?, 4-hydroxybenzoic acid?14?, syringic acid?15?, vanillin?16?, 3,4-dihydroxybenzoic acid?17?,?R?-Mellein?18?, 5,7-dihydroxychromone?19?, ?-Sitostenone?20?, stigmastane-3,6-dione?21?, 2-furoic acid?22?. Compounds 1?2?4?9?10?11?18-22 were isolated from the genus Rhodiola for the first time, and compounds 5?6?14?16?17 were isolated from this plant for the first time.The antioxidant activities of these isolated compounds were further examined by DPPH free radical scavenging assay. Results showed that compounds 6?7?11?12?14?17 were of strong DPPH free radical scavenging capability at the concentration of 50 ?mol?L-1, with the scavenging rate of 66.4%, 74.7%, 90.8%, 89.1%, 84.5% and 86.4%, respectively. |
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