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Biocatalyzed Generation of Molecular Diversity: Selective Modification of the Saponin Asiaticoside
Author(s) -
Monti Daniela,
Candido Andrea,
Cruz Silva M. Manuel,
Křen Vladimir,
Riva Sergio,
Danieli Bruno
Publication year - 2005
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.200505047
Subject(s) - chemistry , saponin , candida antarctica , triterpene , stereochemistry , glycoside , enzyme , fusarium oxysporum , lipase , organic chemistry , botany , medicine , alternative medicine , pathology , biology
An array of different derivatives of the complex ursane‐type triterpene glycoside asiaticoside ( 1 ), a saponin component isolated from the perennial herb Centella asiatica , was generated by exploiting the stereo‐, regio‐ and site‐selectivity of four groups of enzymes (glycosidases, glycosyltransferases, lipases and laccases). A library of extracellular α‐ L ‐rhamnosidases (31 different items) was obtained by screening 16 different fungal strains under different cultivation conditions, and several of these preparations catalyzed the derhamnosylation of asiaticoside. Specifically, the enzymes produced by Fusarium oxysporum were selected for the synthesis of derhamno‐degluco‐asiaticoside ( 2 ) and also of derhamno‐asiaticoside ( 3 ), by in situ glucose‐inhibition of contaminating β‐ D ‐glucosidases. β‐1,4‐Galactosyltransferase from bovine milk was subsequently used for the galactosylation of the two asiaticoside derivatives 2 and 3 , using 20% v/v DMSO as a cosolvent in order to increase substrate solubility. Finally, new acylated and oxidized derivatives of asiaticoside were also prepared by exploiting the lipase from Candida antarctica (Novozym 435) and the laccase from Trametes pubescens , respectively.