17654-26-1Relevant articles and documents
Enzymatic activity of cell-free extracts from Burkholderia oxyphila OX-01 bio-converts (+)-catechin and (-)-epicatechin to (+)-taxifolin
Otsuka, Yuichiro,Matsuda, Motoki,Sonoki, Tomonori,Sato-Izawa, Kanna,Goodell, Barry,Jelison, Jody,Navarro, Ronald R.,Murata, Hitoshi,Nakamura, Masaya
, p. 2473 - 2479 (2016)
This study characterized the enzymatic ability of a cell-free extract from an acidophilic (+)-catechin degrader Burkholderia oxyphila (OX-01). The crude OX-01 extracts were able to transform (+)-catechin and (-)-epicatechin into (+)-taxifolin via a leucocyanidin intermediate in a two-step oxidation. Enzymatic oxidation at the C-4 position was carried out anaerobically using H2O as an oxygen donor. The C-4 oxidation occurred only in the presence of the 2R-catechin stereoisomer, with the C-3 stereoisomer not affecting the reaction. These results suggest that the OX-01 may have evolved to target both (+)-catechin and (-)-epicatechin, which are major structural units in plants.
Acidic hydrolysis of astilbin and its application for the preparation of taxifolin from Rhizoma Smilacis Glabrae
Qiu, Xiao-Lin,Zhang, Qing-Feng
, p. 290 - 294 (2021)
The acidic hydrolysis of astilbin to produce its aglycone, taxifolin, was investigated in this study. The effects of aq. HCl concentration and temperature on the reaction were studied, and the kinetic parameters were calculated. The results showed that with higher aq. HCl concentration and temperature, the hydrolysis of astilbin became faster. The activation energy of the hydrolysis reaction under 1 mol L?1 aq. HCl was calculated with a value of 148.6 kJ mol?1. The reaction was successfully applied to produce taxifolin from a sample of Rhizoma Smilacis Glabrae. A simple method for the purification of taxifolin from Rhizoma Smilacis Glabrae was developed with purity of 97.5%.
Structural and mechanistic studies on anthocyanidin synthase catalysed oxidation of flavanone substrates: The effect of C-2 stereochemistry on product selectivity and mechanism
Welford, Richard W.D.,Clifton, Ian J.,Turnbull, Jonathan J.,Wilson, Stuart C.,Schofield, Christopher J.
, p. 3117 - 3126 (2005)
During the biosynthesis of the tricyclic flavonoid natural products in plants, oxidative modifications to the central C-ring are catalysed by Fe(II) and 2-oxoglutarate dependent oxygenases. The reactions catalysed by three of these enzymes; flavone synthase I, flavonol synthase and anthocyanidin synthase (ANS), are formally desaturations. In comparison, flavanone 3β-hydroxylase catalyses hydroxylation at the C-3 pro-R position of 2S-naringenin. Incubation of ANS with the unnatural substrate (±)-naringenin results in predominantly C-3 hydroxylation to give cis-dihydrokaempferol as the major product; trans-dihydrokaempferol and the desaturation product, apigenin are also observed. Labelling studies have demonstrated that some of the formal desaturation reactions catalysed by ANS proceed via initial C-3 hydroxylation followed by dehydration at the active site. We describe analyses of the reaction of ANS with 2S- and 2R-naringenin substrates, including the anaerobic crystal structure of an ANS - Fe-2-oxoglutarate-naringenin complex. Together the results reveal that for the 'natural' C-2 stereochemistry of 2S-naringenin, C-3 hydroxylation predominates (>9:1) over desaturation, probably due to the inaccessibility of the C-2 hydrogen to the iron centre. For the 2R-naringenin substrate, desaturation is significantly increased relative to C-3 hydroxylation (ca. 1:1); this is probably a result of both the C-3 pro-S and C-2 hydrogen atoms being accessible to the reactive oxidising intermediate in this substrate. In contrast to the hydroxylation-elimination desaturation mechanism for some ANS substrates, the results imply that the ANS catalysed desaturation of 2R-naringenin to form apigenin proceeds with a syn-arrangement of eliminated hydrogen atoms and not via an oxygenated (gem-diol) flavonoid intermediate. Thus, by utilising flavonoid substrates with different C-2 stereochemistries, the balance between C-3 hydroxylation or C-2, C-3 desaturation mechanisms can be altered. The Royal Society of Chemistry 2005.
TAXIFOLIN APIOSIDE AND DAVURICIIN M1, A HYDROLYSABLE TANNIN FROM ROSA DAVURICA
Yoshida, Takashi,Jin, Zhe Xiong,Okuda, Takuo
, p. 2177 - 2182 (1989)
Key Word Index - Rosa davurica; Rosaceae; (+)-taxifolin-3-O-β-D-apio-D-furanoside; dihydroflavonol apioside; tannin; davuriciin M1; ellagitannin.Abstract - The structure of a dihydroflavonol glycoside from the roots of Rosa davurica has been characterized as (+)-taxifolin-3-O-β-D-apio-D-furanoside. A new hydrolysable tannin, davuriciin M1, together with three known hydrolysable tannins, have also been isolated.The structure of new tannin was elucidated by spectroscopic and chemical methods.
Optimization of the biosynthesis of b-ring ortho-hydroxy lated flavonoids using the 4-hydroxyphenylacetate 3-hydroxylase complex (Hpabc) of escherichia coli
Chen, Yang,Gao, Liping,Gui, Lin,Guo, Lina,Lei, Ting,Li, Yan,Ma, Xiubing,Ruan, Haixiang,Wang, Longji,Wang, Yunsheng,Xia, Tao
, (2021/05/31)
Flavonoids are important plant metabolites that exhibit a wide range of physiological and pharmaceutical functions. Because of their wide biological activities, such as anti-inflammatory, antioxidant, antiaging and anticancer, they have been widely used in foods, nutraceutical and pharmaceuticals industries. Here, the hydroxylase complex HpaBC was selected for the efficient in vivo production of ortho-hydroxylated flavonoids. Several HpaBC expression vectors were constructed, and the corresponding products were successfully detected by feeding naringenin to vector-carrying strains. However, when HpaC was linked with an S-Tag on the C terminus, the enzyme activity was significantly affected. The optimal culture conditions were determined, including a substrate concentration of 80 mg·L?1, an induction temperature of 28?C, an M9 medium, and a substrate delay time of 6 h after IPTG induction. Finally, the efficiency of eriodictyol conversion from P2&3-carrying strains fed naringin was up to 57.67 ± 3.36%. The same strategy was used to produce catechin and caf-feic acid, and the highest conversion efficiencies were 35.2 ± 3.14 and 32.93 ± 2.01%, respectively. In this paper, the catalytic activity of HpaBC on dihydrokaempferol and kaempferol was demonstrated for the first time. This study demonstrates a feasible method for efficiently synthesizing in vivo B-ring dihydroxylated flavonoids, such as catechins, flavanols, dihydroflavonols and flavonols, in a bacterial expression system.
Oxidative Transformation of Leucocyanidin by Anthocyanidin Synthase from Vitis vinifera Leads only to Quercetin
Zhang, Jia-Rong,Trossat-Magnin, Claudine,Bathany, Katell,Delrot, Serge,Chaudière, Jean
, p. 3595 - 3604 (2019/03/29)
Anthocyanidin synthase from Vitis vinifera (VvANS) catalyzes the in vitro transformation of the natural isomer of leucocyanidin, 2R,3S,4S-cis-leucocyanidin, into 2R,4S-flavan-3,3,4-triol ([M + H]+, m/z 323) and quercetin. The C3-hydroxylation product 2R,4S-flavan-3,3,4-triol is first produced and its C3,C4-dehydration product is in tautomeric equilibrium with (+)-dihydroquercetin. The latter undergoes a second VvANS-catalyzed C3-hydroxylation leading to a 4-keto-2R-flavan-3,3-gem-diol which upon dehydration gives quercetin. The unnatural isomer of leucocyanidin, 2R,3S,4R-trans-leucocyanidin, is similarly transformed into quercetin upon C3,C4-dehydration, but unlike 3,4-cis-leucocyanidin, it also undergoes some C2,C3-dehydration followed by an acid-catalyzed hydroxyl group extrusion at C4 to give traces of cyanidin. Overall, the C3,C4-trans isomer of leucocyanidin is transformed into 2R,4R-flavan-3,3,4-triol (M + 1, m/z 323), (+)-DHQ, (-)-epiDHQ, quercetin, and traces of cyanidin. Our data bring the first direct observation of 3,4-cis-leucocyanidin- and 3,4-trans-leucocyanidin-derived 3,3-gem-diols, supporting the idea that the generic function of ANS is to catalyze the C3-hydroxylation of its substrates. No cyanidin is produced with the natural cis isomer of leucocyanidin, and only traces with the unnatural trans isomer, which suggests that anthocyanidin synthase requires other substrate(s) for the in vivo formation of anthocyanidins.
