Simplified preparation of the ginsenoside-Rh2 minor saponin from ginseng
摘要:
Condensation of the 12-O-acetylderivative of 20(S)-protopanaxadiol [dammar-24-ene-3 beta,12 beta,20(S)-triol] with tetra-O-acetyl-alpha-D-glucopyranosyl bromide in the presence of silver oxide in dichloroethane, followed by deprotection with sodium methoxide in methanol, results in formation of the 3-O-beta-D-glucopyranosyldammar-24-ene-3 beta,12 beta,20(S)-triol identical with natural ginsenoside-Rh-2. The 12-O-acetyl-20(S)-protopanaxadiol is easily prepared from betulafolienetriol via the 3-keto-12-O-acetylderivative followed by NaBH4 reduction. This comparatively simple five-step synthesis makes this hitherto rare ginsenoside relatively accessible. (C) 1997 Elsevier Science Ltd.
Synthesis of ginsenoside Rg3, a minor constituent of Ginseng Radix
摘要:
Glycosylation of 12 beta-acetoxy-dammar-24-en-3 beta,20(S)-diol (4), with hepta-O-acetyl-alpha-sophorosyl bromide (5) under catalysis by Ag2CO3 or Ag2O afforded a chromatographically unseparated mixture of the alpha-and beta-linked octaacetates 6 and 7 in an approximately 2.5:1 ratio. After deprotection and chromatographic purification, the free alpha- (8) and beta-glycosides (9) were obtained. Sophoroside 9 was identical in all respects with ginsenoside Rg(3), the minor component of Ginseng Radix rubra. All compounds were fully characterized by H-1 and C-13 NMR spectroscopy, (C) 1997 Elsevier Science Ltd. All rights reserved.
Compounds and their preparation for the treatment of Alzheimer's disease by inhibiting beta-amyloid peptide production
申请人:Landry W. Donald
公开号:US20060014729A1
公开(公告)日:2006-01-19
The present invention provides novel dammarane compounds, compositions (e.g., pharmaceutical compositions) comprising the dammarane compounds, and methods for the synthesis of these dammarane compounds. Additionally, the present invention provides methods for inhibiting beta-amyloid peptide production and methods for treating or preventing a pathological condition, particularly, neurodegeneration diseases (e.g., Alzheimer's disease), using these dammarane compounds.
Simplified preparation of the ginsenoside-Rh2 minor saponin from ginseng
作者:Lyubov N. Atopkina、Nina I. Uvarova、Georgi B. Elyakov
DOI:10.1016/s0008-6215(97)00184-5
日期:1997.10
Condensation of the 12-O-acetylderivative of 20(S)-protopanaxadiol [dammar-24-ene-3 beta,12 beta,20(S)-triol] with tetra-O-acetyl-alpha-D-glucopyranosyl bromide in the presence of silver oxide in dichloroethane, followed by deprotection with sodium methoxide in methanol, results in formation of the 3-O-beta-D-glucopyranosyldammar-24-ene-3 beta,12 beta,20(S)-triol identical with natural ginsenoside-Rh-2. The 12-O-acetyl-20(S)-protopanaxadiol is easily prepared from betulafolienetriol via the 3-keto-12-O-acetylderivative followed by NaBH4 reduction. This comparatively simple five-step synthesis makes this hitherto rare ginsenoside relatively accessible. (C) 1997 Elsevier Science Ltd.
Synthesis of ginsenoside Rg3, a minor constituent of Ginseng Radix
作者:Victor Ph. Anufriev、Galina V. Malinovskaya、Vladimir A. Denisenko、Nina I. Uvarova、Georgi B. Elyakov、Shin-Il Kim、Nam-In Baek
DOI:10.1016/s0008-6215(97)00217-6
日期:1997.11
Glycosylation of 12 beta-acetoxy-dammar-24-en-3 beta,20(S)-diol (4), with hepta-O-acetyl-alpha-sophorosyl bromide (5) under catalysis by Ag2CO3 or Ag2O afforded a chromatographically unseparated mixture of the alpha-and beta-linked octaacetates 6 and 7 in an approximately 2.5:1 ratio. After deprotection and chromatographic purification, the free alpha- (8) and beta-glycosides (9) were obtained. Sophoroside 9 was identical in all respects with ginsenoside Rg(3), the minor component of Ginseng Radix rubra. All compounds were fully characterized by H-1 and C-13 NMR spectroscopy, (C) 1997 Elsevier Science Ltd. All rights reserved.