Further study on the 1,4-alpha-transglucosylation of rubusoside, a sweet steviol-bisglucoside from Rubus suavissimus.
Rubusoside (the beta-D-glucosyl ester of 13-O-beta-D-glucosyl-steviol), which is the major sweet principle of leaves of Rubus suavissimus S. Lee, was subjected to 1,4-alpha-transglucosylation by the cyclodextringlucanotransferase-starch system (the CGTase system). The tri- and tetra-glucosylated products were isolated together with the mono- and di-glucosylated products, which had already been isolated. A prominent increase in intensity of the sweetness was observed for the compounds which were di- and tri-glucosylated at the 13-O-glucosyl moiety. This result further substantiated the structure-sweetness relationship for 1,4-alpha-glucosylated compounds of steviol-glycosides reported previously. For protection of the 19-COO-glucosyl moiety against glucosylation by the CGTase system, the 4-hydroxyl group of the 19-COO-glucosyl moiety was beta-galactosylated by the beta-galactosidase-lactose system. This galactosylated compound was subjected to a regio-selective glucosylation of the 13-O-glucosyl moiety by the CGTase system, which was followed by enzymic elimination of the galactosyl group to furnish an exclusive preparation of the improved sweeteners just mentioned.
Institute of Pharmaceutical Sciences, Hiroshima University School of Medicine, Japan.
K
K
Ohtani
Y
Y
Aikawa
H
H
Ishikawa
R
R
Kasai
S
S
Kitahata
K
K
Mizutani
S
S
Doi
M
M
Nakaura
O
O
Tanaka
D002240:Carbohydrate Sequence; D004224:Diterpenes / Q000737:chemistry* / Q000302:isolation & purification; D045786:Diterpenes, Kaurane; D005960:Glucosides / Q000737:chemistry* / Q000302:isolation & purification; D006031:Glycosylation; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010945:Plants, Edible / Q000032:analysis; D013549:Sweetening Agents / Q000737:chemistry / Q000302:isolation & purification
D004224:Diterpenes; D045786:Diterpenes, Kaurane; D005960:Glucosides; D013549:Sweetening Agents; C056177:rubusoside