- The substrate specificity of a glucoamylase with steroidal saponin-rhamnosidase activity from Curvularia lunata
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In previous work, we studied and reported that an enzyme from Curvularia lunata 3.4381 had the novel specificity to hydrolyze the terminal rhamnosyl at C-3 position of steroidal saponin and obtained four transformed products; the enzyme was purified and ascertained as glucoamylase (EC 3.2.1.3 GA). In this work, the enzyme exhibiting steroidal saponin-rhamnosidase activity was systematically studied on 21?steroidal saponins and 6 ginsenosides. The results showed that the α-1,2-linked end-rhamnosyl residues at C-3 position of steroidal saponins could be hydrolyzed to corresponding secondary steroidal saponins, among which 18 compounds were isolated and identified, including 3 new secondary compounds. For the furostanosides having glucosyl residues at the C-26 position, hydrolysis occurred first at end-rhamnosyl at C-3 position to produce secondary furostanosides. The reaction of hydrolyzing glucosyl at C-26 position depended considerably on longer reaction times yielding the corresponding secondary spirostanosides (without rhamnosyl and glucosyl residues). The enzyme had the strict specificity for the terminal α-1,2-linked rhamnosyl residues of linear chain, or the terminal α-1,2-linked rhamnosyl residues with branched chain of 1,4-linked glycosyl residues of sugar chain at C-3 position of steroidal saponins, it was not specific for different aglycones, different glycons, and the number of glycon of sugar chain of steroidal saponin. The end-rhamnosyl of ginsenosides and p-nitrophenyl-α-l-rhamnopyranoside (pNPR) could not be hydrolyzed by the enzyme from C. lunata.
- Feng, Bing,Kang, Li-ping,Ma, Bai-ping,Quan, Bo,Zhou, Wen-bin,Wang, Yong-ze,Zhao, Yu,Liu, Yi-xun,Wang, Sheng-qi
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p. 6796 - 6812
(2008/09/17)
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- The synthesis of gracillin and dioscin: Two typical representatives of spirostanol glycosides
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Two representative spirostanol saponins that have the typical structure for the sugar moiety, diosgenyl α-L-rhamnopyranosyl-(1→2)-[β-D-glucopyranosyl-(1→3)]- β-D-glucopyranoside (gracillin) and diosgenyl α-L-rhamnopyranosyl-(1→2)-[α-L-rhamnopyranosyl-(1→4)]- β-D-glucopyranoside (dioscin), were easily synthesized by a general approach. A procedure using guanidine for the selective deblocking of acetyl while retaining benzoyl protecting groups is described.
- Zou, Chuan-Chun,Hou, Shu-Jie,Shi, Yang,Lei, Ping-Sheng,Liang, Xiao-Tian
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p. 721 - 727
(2007/10/03)
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- Synthesis of diosgenyl α-L-rhamnopyranosyl-(1 → 2)-[β-D- glucopyranosyl-(1 → 3)]-β-D-glucopyranoside (gracillin) and related saponins
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Diosgenyl α-L-rhamnopyranosyl-(1 → 2)-[β-D-glucopyranosyl-(1 → 3)]- β-D-glucopyranoside (gracillin), a monodesmosidic saponin isolated from paris, dioscorea, and costacea species with promising cardiovascular and antitumor activities, was synthesized by s
- Li, Chuan,Yu, Biao,Liu, Meizheng,Hui, Yongzheng
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p. 189 - 195
(2007/10/03)
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- A FUROSTANOL GLUCURONIDE FROM SOLANUM LYRATUM
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A new furostanol glucuronide and three known glycosides, SL-0, aspidistrin and methyl proto-aspidistrin, were isolated from the fresh immature berries of Solanum lyratum.The structure of the new compound was characterized as 26-O-β-D-glucopyranosyl-(22ξ,25R)-3β,22,26-trihydroxyfurost-5-ene 3-O-α-L-rhamnopyranosyl-(1 -> 2)- 3)>-β-D-glucopyranoside. Key Word Index - Solanum lyratum; Solanaceae; furostanol glucuronide.-24β-ethyl-5α-cholesta-7,trans-22,25(27)-trien-3β-ol; spinasteryl-β-D-glucopyranoside.
- Yahara, Shoji,Murakami, Naomi,Yamasaki, Masaki,Hamada, Toshiyuki,Kinjo, Jun-ei,Nohara, Toshihiro
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p. 2748 - 2750
(2007/10/02)
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