Non-conventional Lignans: Coumarinolignans, Flavonolignans, and Stilbenolignans

Begum, S.; Sahai, Mahendra; Ray, Arnab

doi:10.1007/978-3-7091-0140-7_1

Cited by 34 publications

(48 citation statements)

References 112 publications

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“…However, the biosynthesis of flavanolignans in plants is not well understood. The final reaction step is likely to proceed through the oxidative coupling of flavonoid and coniferyl alcohol catalyzed by a peroxidase (Begum et al, 2010). Our work strongly supports that CYP93G1 catalyzes an essential step in the generation of tricin nucleus for O-linked flavanolignan and glycoside formation in rice.…”

Section: Cyp93b11) Involved In Root Nodulationsupporting

confidence: 71%

Cytochrome P450 93G1 Is a Flavone Synthase II That Channels Flavanones to the Biosynthesis of Tricin O-Linked Conjugates in Rice

et al. 2014

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Flavones are a major class of flavonoids with a wide range of physiological functions in plants. They are constitutively accumulated as C-glycosides and O-linked conjugates in vegetative tissues of grasses. It has long been presumed that the two structural modifications of flavones occur through independent metabolic routes. Previously, we reported that cytochrome P450 93G2 (CYP93G2) functions as a flavanone 2-hydroxylase (F2H) that provides 2-hydroxyflavanones for C-glycosylation in rice (Oryza sativa). Flavone C-glycosides are subsequently formed by dehydratase activity on 2-hydroxyflavanone C-glycosides. On the other hand, O-linked modifications were proposed to proceed after the flavone nucleus is generated. In this study, we demonstrate that CYP93G1, the closest homolog of CYP93G2 in rice, is a bona fide flavone synthase II (FNSII) that catalyzes the direct conversion of flavanones to flavones. In recombinant enzyme assays, CYP93G1 desaturated naringenin and eriodictyol to apigenin and luteolin, respectively. Consistently, transgenic expression of CYP93G1 in Arabidopsis (Arabidopsis thaliana) resulted in the accumulation of different flavone O-glycosides, which are not naturally present in cruciferous plants. Metabolite analysis of a rice CYP93G1 insertion mutant further demonstrated the preferential depletion of tricin O-linked flavanolignans and glycosides. By contrast, redirection of metabolic flow to the biosynthesis of flavone C-glycosides was observed. Our findings established that CYP93G1 is a key branch point enzyme channeling flavanones to the biosynthesis of tricin O-linked conjugates in rice. Functional diversification of F2H and FNSII in the cytochrome P450 CYP93G subfamily may represent a lineage-specific event leading to the prevalent cooccurrence of flavone C-and O-linked derivatives in grasses today.

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Section: Cyp93b11) Involved In Root Nodulationsupporting

confidence: 71%

Cytochrome P450 93G1 Is a Flavone Synthase II That Channels Flavanones to the Biosynthesis of Tricin O-Linked Conjugates in Rice

et al. 2014

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“…Furthermore, the obtained spectral data for the known isolated compounds were consistent with the reported literature; they were unambiguously identified as jatrophadiketone (1) [11], β.sitosterol (2) [12,13], curcuson D (3) [14], curcuson C (4) [14], naringenin (5) [15], β.sitosterol glucoside (6) [16], spruceanol (7) [17], propacin (8) [18,19], cleomiscosin B (9) [18,19], cleomiscosin A (10) [18,19], apigenin (11) [20], uracil (12) [21,22,23], cynaroside (13) [24], linarin (14) [25,26], hovetricoside C (16) [27], N-methyltryptamine (17) [28], N-methyltyramine (19) [29], hordenine (20) [30], hordenine HCL (21) and N-methyltyramine HCL (22) [compounds 21 and 22 were identical to the standard samples (Sigma-Aldrich, USA), as shown by 1 H NMR and TLC. ].…”

Section: Structure Elucidationsupporting

confidence: 77%

Phytochemical and Biological Investigation of <em>Jatropha pelargoniifolia</em> Root Native to the Kingdom of Saudi Arabia

Aati¹,

Gamal²,

Kayser³

2018

Preprint

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Extensive phytochemical and chromatographic analysis of different root fractions of Jatropha pelargoniifolia Courb. (Euphorbiaceae) resulted in the isolation and identification of 22 distinct secondary metabolite compounds. Two new compounds, 6-hydroxy-8-methoxycoumarin-7-O-β-D-glycopyranoside and (3-(2-(methylamino) ethyl)-1H-indol-2-yl) methanol, were isolated and identified for the first time from a natural source. In addition, other known compounds, such as hovetricoside C and Nmethyltryptamine were isolated from Euphorbiaceae, and hordenine, Nmethyltyramine, their salts, cynaroside and linarin were identified in Jatropha spp. for the first time. Some isolated metabolites, such as β-sitosterol, β-sitosterol glucoside, curcusons D and C, naringenin, apigenin, cleomiscosins B and A, spruceanol, propacin, jatrophadiketone, and uracil were previously identified in various Jatropha species. The structures of the isolated compounds were determined using different spectroscopic techniques. The anti-inflammatory, antinociceptive, antipyretic, and antioxidant activities were evaluated for some adequately available isolated compounds. Compounds showed significant antinociceptive activity compared with the standard analgesic drug indomethacin. The edema size was significantly reduced (p< 0.05-0.001) in the animals treated with low doses (5 and 10 mg/kg) of the isolated compounds compared with those treated with a high dose (100 mg/kg) of standard anti-inflammatory drug (phenylbutazone). Furthermore, all tested compounds showed a significant (p< 0.05-0.001) reduction in the rectal temperature of hyper-thermic mice.

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“…Here, we define flavonolignols as 49-Ob-linked coupling products of a flavone and one or more phenylpropanoids. This term is in analogy with the existing term flavonolignan that is used for the lowmolecular-mass compounds composed of flavonoid and lignan moieties (Begum et al, 2010) and the term oligolignol that is used for oligomers of canonical monolignols (Morreel et al, 2004(Morreel et al, , 2010b. The fact that some flavonolignols were found without further decoration with sugars and their lack of optical activity suggest that these might be considered as lignin oligomers (Lan et al, 2015(Lan et al, , 2016a.…”

Section: Chs-deficient Plants Have An Altered Phenolic Metabolismmentioning

confidence: 99%

Silencing CHALCONE SYNTHASE in Maize Impedes the Incorporation of Tricin into Lignin and Increases Lignin Content

et al. 2016

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Lignin is a phenolic heteropolymer that is deposited in secondary-thickened cell walls, where it provides mechanical strength. A recent structural characterization of cell walls from monocot species showed that the flavone tricin is part of the native lignin polymer, where it is hypothesized to initiate lignin chains. In this study, we investigated the consequences of altered tricin levels on lignin structure and cell wall recalcitrance by phenolic profiling, nuclear magnetic resonance, and saccharification assays of the naturally silenced maize (Zea mays) C2-Idf (inhibitor diffuse) mutant, defective in the CHALCONE SYNTHASE Colorless2 (C2) gene. We show that the C2-Idf mutant produces highly reduced levels of apigenin-and tricin-related flavonoids, resulting in a strongly reduced incorporation of tricin into the lignin polymer. Moreover, the lignin was enriched in b-b and b-5 units, lending support to the contention that tricin acts to initiate lignin chains and that, in the absence of tricin, more monolignol dimerization reactions occur. In addition, the C2-Idf mutation resulted in strikingly higher Klason lignin levels in the leaves. As a consequence, the leaves of C2-Idf mutants had significantly reduced saccharification efficiencies compared with those of control plants. These findings are instructive for lignin engineering strategies to improve biomass processing and biochemical production.

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Non-conventional Lignans: Coumarinolignans, Flavonolignans, and Stilbenolignans

Cited by 34 publications

References 112 publications

Cytochrome P450 93G1 Is a Flavone Synthase II That Channels Flavanones to the Biosynthesis of Tricin O-Linked Conjugates in Rice

Cytochrome P450 93G1 Is a Flavone Synthase II That Channels Flavanones to the Biosynthesis of Tricin O-Linked Conjugates in Rice

Phytochemical and Biological Investigation of <em>Jatropha pelargoniifolia</em> Root Native to the Kingdom of Saudi Arabia

Silencing CHALCONE SYNTHASE in Maize Impedes the Incorporation of Tricin into Lignin and Increases Lignin Content

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