• Journal of Applied Biological Chemistry
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• v.51 no.2
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• pp.57-60
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• 2008

Eight compounds, including 2 flavones, luteolin (1) and apigenin (2), 2 flavonols, kaempferol (3) and quercetin (4), and 4 flavonoid glucosides, luteolin-7-O-${\beta}$-D-glucoside (5), apigetrin (6), astragalin (7), and isoquercitrin (8), isolated from the whole herb of Sonchus oleraceus L. were analyzed on the basis of chemical and spectroscopic evidence. This was the first time to report compounds 3, 4, 6, 7 and 8 from the Sonchus oleraceus L. The antioxidant activities of the isolated flavonoids and their glucoside derivatives were evaluated by DPPH free radical-scavenging assay, showing that compounds 1, 3, 4 and 8 exhibited stronger antioxidant activities compared with ${\alpha}$, tocopherol and curcumin. Flavonoids containing more hydroxyl groups exhibited better antioxidant activities. The antioxidant activity of flavonols was superior to their corresponding flavones, and that of aglycone are more potent than their glucoside derivatives.

• Journal of Microbiology and Biotechnology
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• v.28 no.2
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• pp.298-304
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• 2018

The single-vessel multienzyme UDP-${\alpha}$-$\text\tiny{D}$-glucose recycling system was coupled with a forward glucosylation reaction to produce novel glucose moiety-conjugated derivatives of different tetracycline antibiotic analogs. Among five tetracycline analogs used for the reaction, four molecules (chlorotetracycline, doxytetracycline, meclotetracycline, and minotetracycline) were accepted by a glycosyltransferase enzyme, YjiC, from Bacillus licheniformis to produce glucoside derivatives. However, the enzyme was unable to conjugate sugar units to rolitetracycline. All glucosides of tetracycline derivatives were characterized by ultraviolet absorbance maxima, ultra-pressure liquid chromatography coupled with photodiode array, and high-resolution quadruple time-of-flight electrospray mass spectrometry analyses. These synthesized glucosides are novel tetracycline derivatives.

• Natural Product Sciences
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• v.9 no.4
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• pp.213-219
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• 2003

Five aromatic compounds, of which two are new glucosides, and six flavonols were isolated and identified for the first time from the flower heads and aerial shoots of Helichrysum conglobatum (Asteraceae). Their structures were established on the basis of chemical and spectroscopic methods including UV, MS, 1D- and 2D-NMR. Some fractions and isolates were screened for anti-microbial activities. This is the first report of the isolation of the chemical constituents of this species.

• Korean Journal of Pharmacognosy
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• v.13 no.1
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• pp.1-6
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• 1982

Gentiana uchiyamana Nakai is a perennial herb in Gentianaceous plants. From the root of Gentiana uchiyamana Nakai, the bitter secoiridoid glucosides were isolated and identified as gentiopicroside and swertiamarin. A high-performance liquid chromatographic method for quantitative determination of bitter component, i.e. gentiopicroside in the roots of Gentiana scabra and G. uchiyamana Nakai was developed, using a ${\mu}$-Bondapak $C_{18}$ column and methanol-water mobile phases. The content of gentiopicroside was calculated from calibration curve previously prepared using the standard, 3.55% in the roots of Gentiana scabra and 1.58% in Gentiana uchiyamana Nakai.

• Natural Product Sciences
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• v.8 no.4
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• pp.141-143
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• 2002

Two flavone glucosides have been isolated from the leaves of Helianthus tuberosus (jerusalem artichoke). Their structures were identified as kaempferol 3-O-glucoside (1) and quercetin 7-O-glucoside (2) by spectroscopic analysis and confirmed by comparison with reported data. These flavonoids were isolated for the first time from this plant part.

• Archives of Pharmacal Research
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• v.29 no.7
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• pp.587-590
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• 2006

Three naphthopyrone glucosides, cassiaside (1), $rubrofusarin-6-O-{\beta}-D-gentiobioside$ (2), and $toralactone-9-O-{\beta}-D-gentiobioside$ (3), were isolated from the BuOH-soluble extract of the seeds of Cassia tora as active constituents, using an in vitro bioassay based on the inhibition of advanced glycation end products (AGEs) to monitor chromatographic fractionation. The structures of 1-3 were determined by spectroscopic data interpretation, particularly by extensive 1D and 2D NMR studies. All the isolates (1-3) were evaluated for the inhibitory activity on AGEs formation in vitro.

• Bulletin of the Korean Chemical Society
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• v.24 no.11
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• pp.1680-1682
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• 2003

• Microbiology and Biotechnology Letters
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• v.32 no.1
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• pp.29-36
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• 2004

$\alpha$-Cyclodextrin glucanotransferase excreted from a newly isolated Geobacillus thermosacchalytycus was purified through the ultrafiltraion, hydrophobic Sepharose CD-4B affinity chromatography, and gel filtration on Sephadex G-75, respectively. The molecular weight of the purified CGTase was 69 kDa and its N-terminal amino acid sequence was determined to be Asn-Leu-Asn-Lys-Val-Asn-Phe-Val-Ser-Asp-Val-Val-Val-Gln-Ile. The optimum pH and temperature were pH 6.0 and$ 60^{\circ}C$, respectively, and stably at the pH range of 6.0-8.0 and $60^{\circ}C$ in the presence of $Ca^{++}$. The excreted CGTase from the thermophilic G. thermosacchalytycus was $\alpha$-type showing a high coupling activity for the transglycosylation on various glucosides. The coupling reaction was carried out according to the random ternary complex mechanism.m.

• Journal of Life Science
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• v.21 no.3
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• pp.464-467
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• 2011

Quercetin is a major flavonoid present in onions, which acts as an antioxidant. Quercetin exists both as a free compound and conjugated with carbohydrates, primarily as glucosides in onion. Aged black onion was made through a 30 day aging process in which the onions were kept in an environment of $60^{\circ}C$ and high humidity (90% RH). Quercetin and quercetin glucosides were assayed in onion bulbs before and after the aging process, using high performance liquid chromatography-electrospray ion trap mass spectrometry (HPLC-ESI/MS/MS). Quercetin mono- and diglucosides were identified in fresh onion bulbs, whereas quercetin aglycone was the only form present in aged black onion bulbs. These findings indicate that the quercetin mono- and di-glucosides present in fresh onions undergo complete deglycosylation during the aging process. Such profiling will provide a rapid method that can be used to assess changes in the two major quercetin glycosides during the aging process of onion bulbs.

• Microbiology and Biotechnology Letters
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• v.49 no.2
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• pp.174-180
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• 2021

Chalcones exhibit multiple biological activities. Various studies have attempted to modify the structure of chalcones with a special focus on the addition of substituents to the benzene rings. However, these chemical modifications did not improve the water solubility and bioavailability of chalcones. Glycosylation can markedly affect the physical and chemical properties of hydrophobic compounds. Here, we evaluated the ability of a highly promiscuous glycosyltransferase (GT) BsGT1 from Bacillus subtilis ATCC 6633 to biosynthesize chalcone glucosides. Purified BsGT1 catalyzed the conversion of 4'-hydroxychalcone (compound 1), 4'-hydroxy-4-methylchalcone (compound 2), and 4-hydroxy-4'-methoxychalcone (compound 3), into chalcone 4'-O-β-D-glucoside (compound 1a), 4-methylchalcone 4'-O-β-D-glucoside (compound 2a), and 4'-methoxychalcone 4-O-β-D-glucoside (compound 3a), respectively. To avoid the addition of expensive uridine diphosphate glucose (UDP-Glc), a whole-cell biotransformation system was employed to provide a natural intracellular environment for in situ co-factor regeneration. The yields of compounds 1a, 2a, and 3a were as high as 90.38%, 100% and 74.79%, respectively. The successful co-expression of BsGT1 with phosphoglucomutase (PGM) and UDP-Glc pyrophosphorylase (GalU), which are involved in the biosynthetic pathway of UDP-Glc, further improved the conversion rates of chalcones (the yields of compounds 1a and 3a increased by approximately 10%). In conclusion, we demonstrated an effective whole-cell biocatalytic system for the enzymatic biosynthesis of chalcone β-D-glucoside derivatives.