- Synthesis of quercetin glycosides and their melanogenesis stimulatory activity in B16 melanoma cells
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4′-O-β-d-Glucopyranosyl-quercetin-3-O-β-d-glucopyranosyl- (1→4)-β-d-glucopyra-noside (3) was isolated from Helminthostachys zeylanica root extract as a melanogenesis acceleration compound and was synthesized using rutin as the starting material Related compounds were also synthesized to understand the structure-activity relationships in melanin biosynthesis Melanogenesis activities of the glycosides were determined by measuring intracellular melanin content in B16 melanoma cells Among the synthesized quercetin glycosides, quercetin-3-O-β-d-glucopyranoside (1), quercetin-3-O-β-d-glucopyranosyl-(1→4)-β-d-glucopyranoside (2), and 3 showed more potent intracellular melanogenesis acceleration activities than theophyline used as positive control in a dose-dependent manner with no cytotoxic effect
- Yamauchi, Kosei,Mitsunaga, Tohru,Batubara, Irmanida
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p. 937 - 944
(2014/02/14)
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- Cloning and functional characterisation of two regioselective flavonoid glucosyltransferases from Beta vulgaris
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Two full-length cDNAs encoding flavonoid-specific glucosyltransferases, UGT73A4 and UGT71F1, were isolated from a cDNA library of Beta vulgaris (Amaranthaceae) cell suspension cultures. They displayed high identity to position-specific betanidin and flavonoid glucosyltransferases from Dorotheanthus bellidiformis (Aizoaceae) and to enzymes with similar substrate specificities from various plant families. The open reading frame of the sequences encode proteins of 476 (UGT73A4) and 492 (UGT71F1) amino acids with calculated molecular masses of 54.07 kDa and 54.39 kDa, and isoelectric points of 5.8 and 5.6, respectively. Both enzymes were functionally expressed in Escherichia coli as His- and GST-tagged proteins, respectively. They exhibited a broad substrate specificity, but a distinct regioselectivity, glucosylating a variety of flavonols, flavones, flavanones, and coumarins. UGT73A4 showed a preference for the 4′- and 7-OH position in the flavonoids, whereas UGT71F1 preferentially glucosylated the 3- or the 7-OH position. Glucosylation of betanidin, the aglycone of the major betacyanin, betanin, in B. vulgaris was also observed to a low extent by both enzymes. Several O-glycosylated vitexin derivatives isolated from leaves of young B. vulgaris plants and rutin obtained from B. vulgaris tissue culture are discussed as potential endogenous products of UGT73A4 and UGT71F1. The results are analyzed with regard to evolution and specificity of plant natural product glucosyltransferases.
- Isayenkova, Judith,Wray, Victor,Nimtz, Manfred,Strack, Dieter,Vogt, Thomas
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p. 1598 - 1612
(2008/02/12)
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- Glucosylation of Quercetin by a Cell Suspension Culture of Vitis sp.
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A cell suspension culture of a Vitis hybrid converted quercetin to six glucosides.Their structures were identified as quercetin 3-O-β-D-glucopyranoside, quercetin 3,4'-di-O-β-D-glucopyranoside, quercetin 3,7-di-O-β-D-glucopyranoside, isorhamnetin 3-O-β-D-glucopyranoside, isorhamnetin 3,4'-di-O-β-D-glucopyranoside, and isorhamnetin 3,7-di-O-β-D-glucopyranoside by UV, FD-MS, 1H-NMR, 13C-NMR spectroscopy and TLC analysis.The course of conversion was also investigated and it was shown that quercetin 3-O-glucoside reached the maximum yield of 31 percent in 24 hr and then gradually disappeared accompanied by the production of quercetin 3,4'- and 3,7-di-O-glucosides.Although the same rise and fall relationship was observed between isorhamnetin 3-O-glucoside and isorhamnetin 3,4'- or 3,7-di-O-glucoside, their conversion ratios were much lower than those of quercetin glucosides.
- Kodama, Tohru,Ishida, Hidekatsu,Kokubo, Tetsuro,Yamakawa, Takashi,Noguchi, Hiroshi
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p. 3283 - 3288
(2007/10/02)
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