UDP-glucose:(6-methoxy)podophyllotoxin 7-O-glucosyltransferase from suspension cultures of Linum nodiflorum
摘要:
Cell cultures of Linum species store 6-methoxypodophyllotoxin (MPTOX), podophyllotoxin (PTOX) and related lignans as O-glucosides. UDP-glucose:(M)PTOX 7-O-glucosyltransferase has been detected and characterised in protein preparations of suspension-cultured cells of Linum nodiflorum L. (Linaceac). The maximal lignan glucoside contents in the cells are preceded by a rapid increase of the specific glucosyltransferase, activity on day six of the culture period. MPTOX glucoside is the major lignan with up to 1.18 mg g(-1) of the cell dry wt which is more than 30-fold of the PTOX glucoside content. Of the three aryltetralin lignans tested as substrates, PTOX and MPTOX display comparable apparent K-m values of 4.7 and 5.4 mu M, respectively. 5'-Demethoxy-6-methoxypodophyllotoxin is converted with the highest velocity of 25.2 pkat mg(-1) while also possessing a higher K-m of 14.7 mu M. Two-substrate test series indicate that all three compounds compete for the active site of a single protein. The structurally similar lignan O-peltatin acts as competitive inhibitor as well. However, the 6-O-glucosidation is most likely catalysed by a separate enzyme. The (M)PTOX 7-O-glucosyltransferase works best at a pH around 9 and a temperature around 35 degrees C. A 15-30% increase of the reaction rate is effected by the addition of 0.9 mM Mn2+. (C) 2007 Elsevier Ltd. All rights reserved.
The Large-Scale Isolation of Deoxypodophyllotoxin from Rhizomes of Anthriscus sylvestris Followed by Its Bioconversion into 5-Methoxypodophyllotoxin β-d-Glucoside by Cell Cultures of Linum flavum
摘要:
Dried rhizomes of Anthriscus sylvestris contained 0.39% deoxypodophyllotoxin (1). An isolation procedure with an extraction efficiency of 51.2% was developed for this commercially unavailable lignan. The isolated 1 was subsequently complexed with dimethyl-P-cyclodextrin and fed to cell suspension cultures of Linum flavum by which it was bioconverted into 5-methoxypodophyllotoxin-beta-D-glucoside (2). After 7 days the cells contained 4.41% of this product on a dry-weight basis. An isolation procedure for compound 2 was developed, with an extraction efficiency of 83.4%.
作者:Arturo San Feliciano、Jose M. Miguel del Corral、Marina Gordaliza、Angeles Castro
DOI:10.1016/0031-9422(90)85460-w
日期:1990.1
Four new natural products, β-peltatin-B methyl ether, podorhizol acetate, 2′-methoxyepipicropodophyllotoxin and 2′-methoxypicropodophyllotoxin, were isolated from the lignan fraction of a n -hexane extract from the leaves of Juniperussabina , along with picropodophyllotoxone, epipodophyllotoxin, (+)-dihydrosesamin, podorhizol, anhydropodorhizol, epipicropodophyllotoxin and 2′-methoxypodophyllotoxin
Cell cultures of Linum species store 6-methoxypodophyllotoxin (MPTOX), podophyllotoxin (PTOX) and related lignans as O-glucosides. UDP-glucose:(M)PTOX 7-O-glucosyltransferase has been detected and characterised in protein preparations of suspension-cultured cells of Linum nodiflorum L. (Linaceac). The maximal lignan glucoside contents in the cells are preceded by a rapid increase of the specific glucosyltransferase, activity on day six of the culture period. MPTOX glucoside is the major lignan with up to 1.18 mg g(-1) of the cell dry wt which is more than 30-fold of the PTOX glucoside content. Of the three aryltetralin lignans tested as substrates, PTOX and MPTOX display comparable apparent K-m values of 4.7 and 5.4 mu M, respectively. 5'-Demethoxy-6-methoxypodophyllotoxin is converted with the highest velocity of 25.2 pkat mg(-1) while also possessing a higher K-m of 14.7 mu M. Two-substrate test series indicate that all three compounds compete for the active site of a single protein. The structurally similar lignan O-peltatin acts as competitive inhibitor as well. However, the 6-O-glucosidation is most likely catalysed by a separate enzyme. The (M)PTOX 7-O-glucosyltransferase works best at a pH around 9 and a temperature around 35 degrees C. A 15-30% increase of the reaction rate is effected by the addition of 0.9 mM Mn2+. (C) 2007 Elsevier Ltd. All rights reserved.
The Large-Scale Isolation of Deoxypodophyllotoxin from Rhizomes of <i>Anthriscus sylvestris</i> Followed by Its Bioconversion into 5-Methoxypodophyllotoxin β-<scp>d</scp>-Glucoside by Cell Cultures of <i>Linum flavum</i>
作者:Wim Van Uden、Jeroen A. Bos、Gesiena M. Boeke、Herman J. Woerdenbag、Niesko Pras
DOI:10.1021/np960748o
日期:1997.4.1
Dried rhizomes of Anthriscus sylvestris contained 0.39% deoxypodophyllotoxin (1). An isolation procedure with an extraction efficiency of 51.2% was developed for this commercially unavailable lignan. The isolated 1 was subsequently complexed with dimethyl-P-cyclodextrin and fed to cell suspension cultures of Linum flavum by which it was bioconverted into 5-methoxypodophyllotoxin-beta-D-glucoside (2). After 7 days the cells contained 4.41% of this product on a dry-weight basis. An isolation procedure for compound 2 was developed, with an extraction efficiency of 83.4%.