Biotransformation Of Steroidal Saponins From Rhizoma Dioscorea Nipponica By Aspergillus Oryzae

In this work, water-soluble total saponins extracted from Rhizoma Dioscorea Nipponica were biotransformed by Aspergillus oryzae and eleven steroidal saponins were purified from transformed products. Their structures were identified as follows: 26-O-β-D-glucopyranosyl-25(R)-22-hydroxyl-5-ene-furostane-3β,26-diol-3-O-{[α-L-rham nopyranosyl-(1→2)]-α-L-rhamnopyranosyl-(1→4)}-β-D-glucopyranoside (compound 1), progracillin(compound 2), 26-O-β-D-glucopyranosyl-25(R)-22- hydroxy-5-ene-furostane -3β,26-diol-3-O-[α-L-rhamnopyranosyl-(1→4)]-β-D-glucopyranoside(compound 3), 26-O-β-D-glucopyranosyl-25(R)-5,20(22)-diene-furostane-3β,26-diol-3-O-[α-L-rhamnopy-ranosyl-(1→4)]-β-D-glucopyranoside (compound 4), 26-O-β-D-glucopyranosyl-25(R)-5, 20(22)-diene-furostane-3β, 26-diol-3-O-{[α-L-rhamnopy- ranosyl-(1→2)]- α -L-rhamnopyranosyl-(1→4)}-β-D-glucopyranoside(compound 5) 25(R)-22-hydroxyl-5-ene-furostane-3β,26-diol-3-OH-26-O-β-D-glucopyranoside(compound 6),Diosgenin-3 -O-[α-L-rhamnopyranosyl-(1→4)]-β-D-glucopyranoside(compound 7), diosgenin -3-O-{[α-L- rhamnopyranosyl-(1→2)]-α-L-rhamnopyranosyl-(1→4)}-β-D-glucopyranoside(compound 8), 25(R)-5-ene-spirostane-21-methyl-3β-hydroxyl-3-O-[α-L-rhamnopyranosyl-(1→4)]-β-D-glucopyranoside(compound 9), 25(R)-5-ene-7-ketone-spirostane-3β-hydroxyl-3-O-[α-L-rhamnopyranosyl-(1→4)]-β -D-glucopyranoside(compound 10), gracillin(compound 11). Compound 9 and 10 are novel compounds and copound 3, 4, 5, 6 and 7 are new compounds that have never been reported to purified from Rhizoma Dioscorea Nipponica. It is the first time that Aspergillus oryzae have been used to convert steroidal saponins to modify the structure.