title: Smith degradation, an efficient method for the preparation of cycloastragenol from astragaloside IV.
abstract: Cycloastragenol (CA) is the genuine sapogenin of astragaloside IV (ASI). This study focuses on the preparation of CA from ASI. Five hydrolysis methods were compared including H2SO4 hydrolysis, HCl hydrolysis, two-phase acid hydrolysis, mild acid hydrolysis, and Smith degradation. Seven hydrolysis products were purified, and five of them were identified as new compounds. The results indicated that Smith degradation was the most effective approach to prepare CA. In contrast, mild acid hydrolysis produced CA at a low yield, accompanied with the artificial sapogenin astragenol. The other three acid hydrolysis methods mainly produced astragenol. Furthermore, the reaction conditions for Smith degradation were optimized as follows: ASI was dissolved in 60% MeOH-H2O solution, oxidized with 5 equiv. NaIO4 for 12h, followed by reduction with 3 equiv. NaBH4 for 4h, and finally acidified with 1M H2SO4 at pH2 for 24h. Under the optimal conditions, CA could be prepared from ASI at a yield of 84.4%.
authors.affiliation: State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing, China.
authors.forename: Lin-min
authors.initials: LM
authors.lastname: Feng
authors.affiliation: State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing, China.
authors.forename: Xiong-hao
authors.initials: XH
authors.lastname: Lin
authors.affiliation: State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing, China.
authors.forename: Fei-xia
authors.initials: FX
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Cao
authors.affiliation: State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing, China.
authors.forename: Xue
authors.initials: X
authors.lastname: Qiao
authors.affiliation: State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing, China.
authors.forename: De-an
authors.initials: DA
authors.lastname: Guo
authors.affiliation: State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing, China. Electronic address: yemin@bjmu.edu.cn.
authors.forename: Min
authors.initials: M
authors.lastname: Ye
mesh_terms: D000143:Acids / Q000737:chemistry; D027885:Astragalus propinquus / Q000737:chemistry*; D002853:Chromatography, Liquid; D004365:Drugs, Chinese Herbal / Q000737:chemistry*; D006868:Hydrolysis; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D015394:Molecular Structure; D010084:Oxidation-Reduction; D012502:Sapogenins / Q000737:chemistry* / Q000302:isolation & purification; D012503:Saponins / Q000737:chemistry*; D014315:Triterpenes / Q000737:chemistry*
chemical_list: D000143:Acids; D004365:Drugs, Chinese Herbal; D012502:Sapogenins; D012503:Saponins; D014315:Triterpenes; C052064:astragaloside A; C061014:cycloastragenol
keywords: Acid hydrolysis; Astragaloside IV; Cycloastragenol; Smith degradation