• Proceedings of the Botanical Society of Korea Conference
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• 1998.07a
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• pp.79-82
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• 1998

White and blue/white varieties of Torenia hybrida cv. Summerwave (SWB) were successfully obtained from the blue variety of by cosuppressing gene expression of two of the enzymes involved in anthocyanin biosynthesis; chalcone synthase (CHS) and dihydroflavonol 4-reductase (DFR). Such molecular brceding is the only precise and efficient way to widen the flower color variation of SWB due to its male and female sterility. Flower color and the degree of suppression varies depending on the transgenic lines. The dorsal and ventral petal lobes and corolla tube consistently lose anthocyanins prior to lateral petal lobes. A pink variety was also obtained by cosuppressing the flavonoid 3`5`-hydroxylase (F3`5`H) gene. Yellow torenia was obtained from T-33, an in-house cultivar that contained both carotenoids and anthocyanins, by blockage of anthocyanin biosynthesis with cosuppressing CHS or DFR genes.

• Korean Journal of Breeding Science
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• v.40 no.4
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• pp.422-429
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• 2008

In this work, we analyzed the activity of control enzymes of flower color biosynthesis, chalcone synthase (CHS) and flavanone 3-hydroxylase (FHT) using biochemical and enzymological methods in Lilium longiflorum and 11 Lilium cultivars. The results obtained are as follows ; Naringenin (NAR) was synthesized in all Lilium cultivars tested by the catalytic activity of CHS which used malonyl-CoA and 4-coumaryol-CoA as substrates. Substrate-specific activity of CHS was observed because eridictiol (ERI), which uses caffeoyl-CoA as a substrate, was not detected in tested cultivars. In next step, dihydroflavone product was synthesized by FHT using flavanones as a substrate. FHT synthesized dihydrokaempferol (DHK) by using NAR as substrates. A remarkable activity of FHT was observed in other 11 cultivars.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.15
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• pp.6317-6325
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• 2015

Ginkgo biloba extract (GBE) is a popular phytomedicine and has been used for disorders of the central nervous system, cardiovascular, renal, respiratory, and circulatory diseases. Although GBE is a complex mixture of over 300 compounds, its major components are 24% flavonoids and 6% terpene lactones. In this study, we tested the inhibitory effects of the three major flavonoids (kaempferol, quercetin, and isorhamnetin) from GBE, independently and as mixtures, on aromatase activity using JEG-3 cells (human placental cells) and recombinant proteins (human placental microsome). In both systems, kaempferol showed the strongest inhibitory effects among the three flavonoids; the flavanoid mixtures exerted increased inhibitory effects. The results of exon I.1-driven luciferase reporter gene assays supported the increased inhibitory effects of flavonoid mixtures, accompanied by suppression of estrogen biosynthesis. In the RT-PCR analysis, decreased patterns of aromatase promoter I.1 mRNA expressions were observed, which were similar to the aromatase inhibition patterns of flavonoids and their mixtures. The present study demonstrated that three flavonoids synergistically inhibit estrogen biosynthesis through aromatase inhibition, decrease CYP19 mRNA, and induce transcriptional suppression. Our results support the usefulness of flavonoids in adjuvant therapy for breast cancer by reducing estrogen levels with reduced adverse effects due to estrogen depletion.

• Journal of Applied Biological Chemistry
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• v.62 no.1
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• pp.1-6
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• 2019

The flavonoid, isokaempferide, has various biological activities such as hepatoprotective, antimicrobial and antiproliferative effect and is extracted from Amburana cearensis and Cirsium rivulare (Jacq.). Biotransformation is an alternative tool for the synthesis of value-added flavonoids with inexpensive substrates. Here, to synthesize isokaempferide from naringenin, two genes, PFLS and Rice O-mthyltransferae-9 were introduced in Escherichia coli. Although isokaempferide was successfully synthesized, the amount of biosynthesis was no high. In order to increase the yields of isokaempferide, S-adenosylmethionine (SAM) used as a methyl donor was increased by deleting MetJ, which is a transcriptional regulator related to SAM biosynthetic pathway. Next we optimized the cell concentration and substrate feed concentration with the engineered E. coli strain. Through these strategies, the biosynthesis of isokaempferide was increased up to 87 mg/L.

• Journal of Microbiology and Biotechnology
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• v.34 no.5
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• pp.1154-1163
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• 2024

Glucosylation is a well-known approach to improve the solubility, pharmacological, and biological properties of flavonoids, making flavonoid glucosides a target for large-scale biosynthesis. However, the low yield of products coupled with the requirement of expensive UDP-sugars limits the application of enzymatic systems for large-scale. C. glutamicum is a Gram-positive and generally regarded as safe (GRAS) bacteria frequently employed for the large-scale production of amino acids and biofuels. Due to the versatility of its cell factory system and its non-endotoxin producing properties, it has become an attractive system for the industrial-scale biosynthesis of alternate products. Here, we explored the cell factory of C. glutamicum for efficient glucosylation of flavonoids using apigenin as a model flavonoid, with the heterologous expression of a promiscuous glycosyltransferase, YdhE from Bacillus licheniformis and the endogenous overexpression of C. glutamicum genes galU1 encoding UDP-glucose pyrophosphorylase and pgm encoding phosphoglucomutase involved in the synthesis of UDP-glucose to create a C. glutamicum cell factory system capable of efficiently glucosylation apigenin with a high yield of glucosides production. Consequently, the production of various apigenin glucosides was controlled under different temperatures yielding almost 4.2 mM of APG1(apigenin-4'-O-β-glucoside) at 25℃, and 0.6 mM of APG2 (apigenin-7-O-β-glucoside), 1.7 mM of APG3 (apigenin-4',7-O-β-diglucoside) and 2.1 mM of APG4 (apigenin- 4',5-O-β-diglucoside) after 40 h of incubation with the supplementation of 5 mM of apigenin and 37℃. The cost-effective developed system could be used to modify a wide range of plant secondary metabolites with increased pharmacokinetic activities on a large scale without the use of expensive UDP-sugars.

• Molecules and Cells
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• v.25 no.2
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• pp.312-316
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• 2008

Flavanone $3{\beta}$-hydroxylases (F3H) are key enzymes in the synthesis of flavonol and anthocyanin. In this study, three F3H cDNAs from Oryza sativa (OsF3H-1 ~3) were cloned by RT-PCR and expressed in E. coli as gluthatione S-transferase (GST) fusion proteins. The purified recombinant OsF3Hs used flavanone, naringenin and eriodictyol as substrates. The reaction products with naringen and eriodictyol were determined by nuclear magnetic resonance spectroscopy to be dihydrokaempferol and taxifolin, respectively. OsF3H-1 had the highest enzymatic activity whereas the overall expression of OsF3H-2 was highest in all tissues except seeds. Flavanone $3{\beta}$-hydroxylase could be a useful target for flavonoid metabolic engineering in rice.

• KSBB Journal
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• v.26 no.2
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• pp.93-99
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• 2011

Glycosylation is a key mechanism in determining diversity of natural products, and influencing their bioactivities. This approach requires a core set of glycosyltransferase that synthesizes the diverse sugar structures observed in nature. Recently, the researchers have begun to alter the sugar moiety and glycosylation patterns of natural products both in vivo E. coli system and in vitro for their glycodiversification. This review highlights new glycosylation tools using microbialproduced deoxysugar and a flexible glycosyltransferase on natural plant-flavonoids to generate novel glycoforms with useful biological activity.

• Korean Journal of Pharmacognosy
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• v.29 no.2
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• pp.75-78
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• 1998

In the course of phytochemical studies for the aerial parts of Ajuga multiflora, one flavonoid and two iridoid glycosides were isolated and identified as apigenin (1), 8-O-acetylharpagide (2) and harpagide (3) on the basis of spectroscopic evidence.

• 한국약용작물학회:학술대회논문집
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• 2010.10a
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• pp.386-387
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• 2010

• FLOWER RESEARCH JOURNAL
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• v.17 no.4
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• pp.308-315
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• 2009

The activities of flower color biosynthesis-controlling enzymes, flavonoid 3'hydroxy lase (F3'H) and dihydroflavonol 4-reductase (DFR), were analyzed in Llium longijlorum and 11 lily cultivars using biochemical and enzymological methods. Dihydroquercetin (DHQ) product was synthesized by F3'H using dihydrokaempferol (DHK) as a substrate in Lilium longiflorum. F3'H activity was also detected in the eight cultivars tested. The substrate-specific activity of F3'H was observed because eridictiol (ERI), which uses naringenin (NAR) as a substrate, was not detected in the tested cultivars. Leucocyanidin (LCy) product was synthesized by DFR using DHQ as a substrate in Lilium longiflorum. DFR activity was also detected in 'Le Reve', 'Montreux', 'Monte Negro', 'Etude', 'Acapulco', and 'Star Gazer', but not in 'Siberia', 'Royal Race', 'Nove Cento', 'Elite', and 'Cannes'. Substrate-specific activity of DFR was observed because leucopelargonidin (LPg), which uses DHK as a substrate, was not detected in the tested cultivars.