Determination and isolation of chemical constituents from the dried stems of Rubus amabilis Focke*
2017, 40 (10):
Objective To study the chemical constituents from the dried stems of Rubus amabilis (Focke). Method The chemical constituents of R. amabilis were extracted with boiled water, then isolated and purified with various chromatographic columns including silica gel, reversed phase and gelatin chromatography and crystallization methods. The structure was identified by using different spectroscopic and chromatographic techniques including nuclear magnetic resonance and mass spectrum. The liquid chromatography-mass spectrometry-ion trap-time of flight (LC/MS-IT-TOF) method was also applied to analyze the ingredients. The chromatographic separation was performed on SunFireTM C18 column (4.6 mm×150 mm, 5 μm) with gradient elution of methanol (A)-0.5% formic acid aqueous solution (B). Multistage mass spectrometry data of different compounds was obtained by using electrospray ionization source and monitoring in positive and negative ion modes. Results There were 5 chemical constituents isolated from the plant including 1, 2, 8-trimethoxy-6-hydroxyxanthone, 2α, 3α, 19α, 23-tetraydroxy-urs-12-en-28-oic acid, oleanolic acid, (+)-catechin and (-)-epicatechin. Twenty-seven compounds including 5 diterpenoids, 1 monoterpenoid, 1 xanthone, 11 flavones and 9 triterpenoids were identified based on the characteristic MS/MS fragment ions data with chemical standards and published literatures. These constituents were determined to be 1-hydroxyl-3,7,8-trimethoxylxanthone, 7-epiphlomiol, ent-kaur-16-ene-9-ol, ent-16β,17-dihydroxy-kauran-19-oic acid, ent-kauran-3α(β),16β,17-triol, rubusoside, rubusoside B, pinfaenoic acid, isopinfaenoic acid, 19α-hydroxylursolic acid, 2α,19α-dihydroxyl-ursan-12-en-28-oic acid, 2α-hydroxylursolic acid, 2α,3α-dihydroxyl-oleanan-12-en-28-oic acid, camelliagenin A, camelliagenin C, tormentic acid, procyanidin B1-B8, isoquercitrin, quercetin and kumata kenin. Conclusion Compound 1 was isolated from Rosaceae for the first time. Compounds 20 and 21 were obtained from Rubus firstly. The rest constituents were firstly found from the plant.
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