- Flavonoid glycosides from the aerial parts of Curcuma comosa
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Four new flavonoid glycosides, curcucomosides A-D (1-4), three known flavonoid glycosides, 5-7, and four known diarylheptanoids, 8-11, were isolated from the ethanol extract of the aerial parts of Curcuma comosa. The structures of the new compounds were established as rhamnazin 3-O-α-l- arabinopyranoside (1), rhamnocitrin 3-O-α-l-arabinopyranoside (2), rhamnazin 3-O-α-l-rhamnopyranosyl-(1→2)-O-α-l-arabinopyranoside (3), and rhamnocitrin 3-O-α-l-rhamnopyranosyl-(1→2)-O-α-l- arabinopyranoside (4) by spectroscopic analysis and chemical reactions whereas those of the known compounds were identified by spectral comparison with those of the reported values.
- Chokchaisiri, Ratchanaporn,Innok, Phongsak,Suksamrarn, Apichart
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- Synthesis of Rhamnazin and Ombuin as methylated metabolites of quercetin
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The methylated metabolites of quercetin, rhamnazin and ombuin are highly likely to develop as anticancer and anti-inflammatory agents. In this study, we synthesized rhamnazin through selective methylation of quercetin hydroxyl group, which has not been reported so far. In addition, a new synthetic method was developed to correct the problems of previous synthetic method of ombuin, one of the methylated metabolites of quercetin.
- Jang, Jongyun,Kang, Dong Wook
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- New Flavonol Glucuronides from the Flower Buds of Syzygium aromaticum (Clove)
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Repeated chromatography of the EtOAc-soluble fraction from the 70% EtOH extract of the flower buds of Syzygium aromaticum (clove) led to the isolation and characterization of four new flavonol glucuronides, rhamnetin-3-O-β-d-glucuronide (1), rhamnazin-3-O-β-d-glucuronide (2), rhamnazin-3-O-β-d-glucuronide-6″-methyl ester (3), and rhamnocitrin-3-O-β-d-glucuronide-6″-methyl ester (4), together with 15 flavonoids (5-19) having previously known chemical structures. The structures of the new compounds 1-4 were determined by interpretation of spectroscopic data, particularly by 1D- and 2D-NMR studies. Six flavonoids (6, 7, 9, 14, 18, and 19) were isolated from the flower buds of S. aromaticum for the first time in this study. The flavonoids were examined for their cytotoxicity against human ovarian cancer cells (A2780) using MTT assays. Among the isolates, pachypodol (19) showed the most potent cytotoxicity on A2780 cells with an IC50 value of 8.02 μM.
- Ryu, Byeol,Kim, Hye Mi,Lee, Jin Su,Lee, Chan Kyu,Sezirahiga, Jurdas,Woo, Jeong-Hwa,Choi, Jung-Hye,Jang, Dae Sik
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p. 3048 - 3053
(2016/05/19)
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- Flavonoid 3′-O-methyltransferase from rice: cDNA cloning, characterization and functional expression
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Plant O-methyltransferases (OMTs) are known to be involved in methylation of plant secondary metabolites, especially phenylpropanoid and flavonoid compounds. An OMT, ROMT-9, was cloned and characterized from rice using a reverse transcriptase polymerase chain reaction (RT-PCR). The blast results for ROMT-9 showed a 73% identity with caffeic acid OMTs from maize and Triticum aestivum. ROMT-9 was expressed in Escherichia coli and its recombinant protein was purified using affinity chromatography. It was then tested for its ability to transfer the methyl group of S-adenosyl-l-methionine to the flavonoid substrates, eriodictyol, luteolin, quercetin, and taxifolin, all of which have a 3′-hydroxyl functional group. The reaction products were analyzed using TLC, HPLC, HPLC/MS, and NMR spectroscopy. The NMR analysis showed that ROMT-9 transferred the methyl group specifically to the 3′-hydroxyl group of quercetin, resulting in the formation of its methoxy derivative. Furthermore, ROMT-9 converted flavonoids containing the 3′-hydroxy functional group such as eriodictyol, luteolin, quercetin and taxifolin into the corresponding methoxy derivatives, suggesting that ROMT-9 is an OMT with strict specificity for the 3′-hydroxy group of flavonoids.
- Kim, Bong-Gyu,Lee, Youngshim,Hur, Hor-Gil,Lim, Yoongho,Ahn, Joong-Hoon
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p. 387 - 394
(2008/02/04)
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- Hibiscatin, a new Flavonol Glucoside from Hibiscus furcatus
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The flower petals of Hibiscus furcatus yield a new flavonol glucoside, designed hibiscatin, along with gossypin (gossyptin-8-O-β-D-glucoside) and gossypitrin (gossypetin-7-O-β-D-glucoside).Based on chemical as well UV, IR, PMR and mass spectral data, hibiscatin has been formulated as 3,5-dihydroxy-7,3'-dimethoxy-4'-O-β-D-glucopyranosylflavone (rhamnazin-4'-O-glucoside).
- Nair, G. Aravindakshan,Joshua, C. P.,Nair, A. G. Ramachandran
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