- Gallates of isoorientin and (2S)-1,2-propanediol glucoside from the leaves of Schoepfia jasminodora
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From the 1-BuOH-soluble fraction of a MeOH extract of the leaves of Schoepfia jasminodora collected from Okinawa Island, two new galloyl esters and 15 known compounds were isolated. The structures of the new compounds were elucidated by spectroscopic anal
- Tsuboi, Yoshiko,Doi, Takashi,Matsunami, Katsuyoshi,Otsuka, Hideaki,Shinzato, Takakazu,Takeda, Yoshio
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- Efficient Biotransformation of Luteolin to Isoorientin through Adjusting Induction Strategy, Controlling Acetic Acid, and Increasing UDP-Glucose Supply in Escherichia coli
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Isoorientin is a C-glycosylated derivative of luteolin and exhibits a number of biological properties. In this study, multiple strategies were adopted to improve isoorientin production from luteolin in Escherichia coli. Isoorientin production was improved substantially by adjusting induction strategies and controlling acetic acid accumulation, with maximum isoorientin production reaching 826 mg/L. Additionally, a novel UDP-glucose synthesis pathway was reconstructed in E. coli through cellobiose phosphorylase-catalyzed phosphorolysis of cellobiose for the production of glucose 1-phosphate, which serves as a precursor in UDP-glucose formation. The results from two mechanisms of UDP-glucose formation in E. coli, cellobiose phosphorolysis and sucrose phosphorolysis, were compared. Increasing the UDP-glucose supply resulted in maximal isoorientin production reaching 1371 mg/L. Finally, isoorientin (1059 mg) was obtained from 1 L of fermentation broth by simple purification steps with a yield of 81.5%. Therefore, this study provides an efficient method for isoorientin production and a novel UDP-glucose synthesis pathway.
- Pei, Jianjun,Sun, Qing,Zhao, Linguo,Shi, Hao,Tang, Feng,Cao, Fuliang
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- Acylated flavone 8-C-glucosides from the flowers of Trollius chinensis
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Ten new flavone 8-C-glucosides, trollichinensides A–J, with the substitution of various acyls at C-2″ C-3″ or C-6″ of the glucose moiety, together with thirteen known ones were isolated from the flowers of Trollius chinensis. Spectroscopic analyses including NMR and HRESIMS resulted in the establishment of the structures of these constituents and electronic circular dichroism (ECD) experiment was employed for the determination of the absolute configuration of the glucose residue in these molecules.
- Wei, Jin-Xia,Li, Dan-Yi,Li, Zhan-Lin
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- Flavonoid pattern inheritance in the allopolyploid Spartina anglica – Comparison with the parental species S. maritima and S. alterniflora
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The invasive species Spartina anglica arose in Europe by a cross between the Afro-European species S. maritima (native, paternal ancestor) and the introduced North American S. alterniflora (invasive, maternal ancestor). Aqueous methanolic extracts were prepared from plant tissue for chemotaxonomical comparison between the three species and determination of the phenolic pattern inheritance in S. anglica. A total of 20 phenolic compounds were detected in the aerial tissues of S. anglica and S. alterniflora, but only seven in S. maritima. They were isolated from their respective crude extracts, and their structures were determined according to spectroscopic data analysis and chemical evidence. They all belong to the flavonoid class, with 13 of them identified as C-glycoflavonoid and seven as O-glycoflavonoid. All these products were detected for the first time from S. anglica, fourteen of them for the first time from S. alterniflora, and three of them for the first time from S. maritima. The individual concentrations in the three species were determined by quantitative HPLC. The two parental species were found to differ markedly in their foliar phenolic fingerprint, whereas that of S. anglica showed a clear maternal dominance. Eight of the fourteen major compounds identified were of maternal origin among which, six were over-expressed, only three were from paternal origin but under-regulated, while two originated from the two parents. As far as we know, this work represents the first exhaustive report of the phenolic fingerprints of S. alterniflora and S. anglica and of the phenolic pattern inheritance in S. anglica. The similarity in the phenolic chemistry of the introduced and invasive S. alterniflora to its progeny could play a role in the physiological vigour and invasion success of S. anglica. This work provide a foundation for further studies, considering the reported biological activities of C-glycosidic flavonoids and tricin derivatives, and the lack of knowledge of the ecological chemistry of the genus Spartina.
- Grignon-Dubois, Micheline,De Montaudouin, Xavier,Rezzonico, Bernadette
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- C-Glycosyl Flavones from Two Eastern Siberian Species of Silene
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Flavonoids from Silene aprica Turcz. and S. samojedorum (Sambuk) Oxelman (Caryophyllaceae) growing in Baikal region were studied for the first time. A total of 14 compounds including three new compounds 1–3 were isolated. Their structures were established using UV, IR, and NMR spectroscopy and mass spectrometry. Apigenin-6-C-(2″-O-α-L-arabinopyranosyl-6″-O-acetyl)-β-D-glucopyranoside (sileneside A, 1) and apigenin-6-C-(2″-O-β-D-glucopyranosyl-6″-O-acetyl)-β-D-glucopyranoside (sileneside B, 2) were observed in S. aprica; 1 and luteolin-6-C-(2″-O-α-L-arabinopyranosyl-6″-O-acetyl)-β-D-glucopyranoside (sileneside C, 3), in S. samojedorum.
- Olennikov,Chirikova
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p. 642 - 647
(2019/08/08)
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- Biosynthesis of natural and novel C-glycosylflavones utilising recombinant Oryza sativa C-glycosyltransferase (OsCGT) and Desmodium incanum root proteins
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The rice C-glycosyltransferase (OsCGT) is one of only a small number of characterised plant C-glycosyltransferases (CGT) known. The enzyme C-glucosylates a 2-hydroxyflavanone substrate with UDP-glucose as the sugar donor to produce C-glucosyl-2-hydroxyflavanones. We tested substrate specificity of the enzyme, using synthetic 2-hydroxyflavanones, and showed it has the potential to generate known natural CGFs that have been isolated from rice and also other plants. In addition, we synthesised novel, unnatural 2-hydroxyflavanone substrates to test the B-ring chemical space of substrate accepted by the OsCGT and demonstrated the OsCGT capacity as a synthetic reagent to generate significant quantities of known and novel CGFs. Many B-ring analogues are tolerated within a confined steric limit. Finally the OsCGT was used to generate novel mono-C-glucosyl-2-hydroxyflavanones as putative biosynthetic intermediates to examine the potential of Desmodium incanum biosynthetic CGTs to produce novel di-C-glycosylflavones, compounds implicated in the allelopathic biological activity of Desmodium against parasitic weeds from the Striga genus.
- Hao,Caulfield,Hamilton,Pickett,Midega,Khan,Wang,Hooper
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- Controlled acid hydrolysis and kinetics of flavone C-glycosides from trollflowers
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Acid hydrolysis mechanisms of orientin-2″-O-galactopyranoside (OGA), orientin and other flavone C-glycosides in the trollflowers (Trollius chinensis Bunge) were studied in this report for the first time. Hydrolysis parameters including temperature, acidity, solvent and reaction time were comprehensively investigated. OGA could be hydrolyzed to orientin, followed by an isomerization to isoorientin via a reversible Wessely-Moser rearrangement reaction under stronger acidic conditions. A first-order kinetic model fitted the hydrolysis process of OGA well. Under the optimal hydrolysis conditions of 80 °C, 1.0 mol/L H+ and 7 h reaction time, about 77% OGA was transformed to orientin with no detectable isoorientin. These results could be helpful for better understanding of the acid hydrolysis kinetics of flavone C-glycosides, as well as the preparation of these valuable components under controlled acid hydrolysis conditions.
- Dou, Mian,He, Xi-Hui,Sun, Yan,Peng, Fang,Liu, Jiang-Yun,Hao, Li-Li,Yang, Shi-Lin
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p. 255 - 258
(2015/03/30)
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- An effective synthesis of isoorientin: The regioselective synthesis of a 6-C-glucosylflavone
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Isoorientin, a 6-C-β-D-glucopyranosyl-3',4',5,7-tetrahydroxyflavone, was synthesized in a 15% overall yield, in ten steps, starting from the commercially available phloroacetophenone. The C-glucosyl phloroacetophenone derivative, a synthetic intermediate that contains a free hydroxyl group that is para to the glucosyl moiety, was obtained by hydrogenolysis by taking advantage of differences in the hydrogenolysis rates between a benzyl protecting group and a 2-methylbenzyl protecting group. Aldol condensation of the C-glucosyl phloroacetophenone derivative with 3,4-bis-benzyloxybenzaldehyde afforded the corresponding chalcone as a precursor of the 6-C-glucosyl flavone. Construction of the flavone system by application of I2-DMSO, followed by deprotection, yielded isoorientin. (C) 2000 Elsevier Science Ltd.
- Kumazawa, Toshihiro,Minatogawa, Tomomi,Matsuba, Shigeru,Sato, Shingo,Onodera, Jun-Ichi
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p. 507 - 513
(2007/10/03)
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