Phenol biosynthesis in higher plants. Gallic acid.
Ontology highlight
ABSTRACT:
SUBMITTER: Dewick PM
PROVIDER: S-EPMC1184696 | biostudies-other | 1969 Jul
REPOSITORIES: biostudies-other
Similar Datasets
Project description:Vitamin B6 is an essential metabolite in all organisms. It can act as a coenzyme for numerous metabolic enzymes and has recently been shown to be a potent antioxidant. Plants and microorganisms have a de novo biosynthetic pathway for vitamin B6, but animals must obtain it from dietary sources. In Escherichia coli, it is known that the vitamin is derived from deoxyxylulose 5-phosphate (an intermediate in the nonmevalonate pathway of isoprenoid biosynthesis) and 4-phosphohydroxy-l-threonine. It has been assumed that vitamin B6 is synthesized in the same way in plants, but this hypothesis has never been experimentally proven. Here, we show that, in plants, synthesis of the vitamin takes an entirely different route, which does not involve deoxyxylulose 5-phosphate but instead utilizes intermediates from the pentose phosphate pathway, i.e., ribose 5-phosphate or ribulose 5-phosphate, and from glycolysis, i.e., dihydroxyacetone phosphate or glyceraldehyde 3-phosphate. The revelation is based on the recent discovery that, in bacteria and fungi, a novel pathway is in place that involves two genes (PDX1 and PDX2), neither of which is homologous to any of those involved in the previously doctrined E. coli pathway. We demonstrate that Arabidopsis thaliana has two functional homologs of PDX1 and a single homolog of PDX2. Furthermore, and contrary to what was inferred previously, we show that the pathway appears to be cytosolic and is not localized to the plastid. Last, we report that the single PDX2 homolog is essential for plant viability.
| S-EPMC1224648 | biostudies-literature
Project description:1. [2-(14)C]Mevalonate was incorporated into squalene and the major phytosterols of pea and maize leaves; it was also incorporated into compounds belonging to the 4,4-dimethyl and 4alpha-methyl steroid groups and which may be possible phytosterol intermediates. 2. l-[Me-(14)C]Methionine was incorporated into the major sterols and also into the 4,4-dimethyl and 4alpha-methyl steroid groups. No radioactivity was detected in squalene. 3. Under anaerobic conditions incorporation of [2-(14)C]-mevalonate into the non-saponifiable lipid of pea leaves was drastically decreased but radioactive squalene was accumulated. 4. Cycloartenol, 24-methylenecycloartanol, 24-methylenelophenol, 24-ethylidenelophenol, fucosterol, beta-sitosterol, stigmasterol and campesterol have been identified by gas-liquid chromatography in pea leaves. 5. The significance of these results in connexion with phytosterol biosynthesis and the introduction of the alkyl group at C-24 into phytosterols is discussed.
| S-EPMC1265065 | biostudies-other
Project description:Anhydrous 3,4,5-trihy-droxy-benzoic acid, C(7)H(6)O(5), is essentially planar, with its non-H atoms exhibiting mean and maximum deviations from coplanarity of 0.014 and 0.0377?(5)?Å, respectively. The C-C-C-OH torsion angle about the bond linking the carboxyl group to the benzene ring is -0.33?(10)°. In the crystal, the -COOH groups form centrosymmetric hydrogen-bonded cyclic dimers [graph set R(2) (2)(8)] and the phenolic -OH groups participate in both intra- and inter-molecular hydrogen bonds, forming a three-dimensional network structure.
| S-EPMC3051435 | biostudies-literature
Project description:Gallic acid (GA), a key intermediate in the synthesis of plant hydrolysable tannins, is also a primary anti-inflammatory, cardio-protective agent found in wine, tea, and cocoa. In this publication, we reveal the identity of a gene and encoded protein essential for GA synthesis. Although it has long been recognized that plants, bacteria, and fungi synthesize and accumulate GA, the pathway leading to its synthesis was largely unknown. Here we provide evidence that shikimate dehydrogenase (SDH), a shikimate pathway enzyme essential for aromatic amino acid synthesis, is also required for GA production. Escherichia coli (E. coli) aroE mutants lacking a functional SDH can be complemented with the plant enzyme such that they grew on media lacking aromatic amino acids and produced GA in vitro. Transgenic Nicotiana tabacum lines expressing a Juglans regia SDH exhibited a 500% increase in GA accumulation. The J. regia and E. coli SDH was purified via overexpression in E. coli and used to measure substrate and cofactor kinetics, following reduction of NADP(+) to NADPH. Reversed-phase liquid chromatography coupled to electrospray mass spectrometry (RP-LC/ESI-MS) was used to quantify and validate GA production through dehydrogenation of 3-dehydroshikimate (3-DHS) by purified E. coli and J. regia SDH when shikimic acid (SA) or 3-DHS were used as substrates and NADP(+) as cofactor. Finally, we show that purified E. coli and J. regia SDH produced GA in vitro.
| S-EPMC3057006 | biostudies-literature
Project description:In plants, the shikimate pathway provides aromatic amino acids that are used to generate numerous secondary metabolites, including phenolic compounds. In this pathway, shikimate dehydrogenases (SDH) 'classically' catalyse the reversible dehydrogenation of 3-dehydroshikimate to shikimate. The capacity of SDH to produce gallic acid from shikimate pathway metabolites has not been studied in depth. In grapevine berries, gallic acid mainly accumulates as galloylated flavan-3-ols. The four grapevine SDH proteins have been produced in Escherichia coli In vitro, VvSDH1 exhibited the highest 'classical' SDH activity. Two genes, VvSDH3 and VvSDH4, mainly expressed in immature berry tissues in which galloylated flavan-3-ols are accumulated, encoded enzymes with lower 'classical' activity but were able to produce gallic acid in vitro The over-expression of VvSDH3 in hairy-roots increased the content of aromatic amino acids and hydroxycinnamates, but had little or no effect on molecules more distant from the shikimate pathway (stilbenoids and flavan-3-ols). In parallel, the contents of gallic acid, β-glucogallin, and galloylated flavan-3-ols were increased, attesting to the influence of this gene on gallic acid metabolism. Phylogenetic analysis from dicotyledon SDHs opens the way for the examination of genes from other plants which accumulate gallic acid-based metabolites.
| S-EPMC4892741 | biostudies-literature
Project description:A technique involving solid-phase extractions and polyethylene h.p.l.c. suitable for the routine compositional analysis of the total protochlorophyllide pool of plants is described. The resynthesis kinetics of the individual components of the pool have been studied in briefly illuminated etiolated tissue of wheat (Triticum aestivum) and cucumber (Cucumis sativus) during subsequent redarkening. The data are interpreted in terms of a precursor-product relationship between the di- and mono-vinyl analogues of protochlorophyllide during their reaccumulation in darkness. The interconversion is assumed to be catalysed by an 8-vinyl reductase, which shows greater activity in wheat than in cucumber. Analyses of the redox state of the nicotinamide nucleotide of the pool during the process are compatible with NADPH as the cofactor of the putative reductase.
| S-EPMC1132460 | biostudies-other
Project description:IN THE TITLE COMPOUND (SYSTENATIC NAME: 3,4,5-trihy-droxy-benzoic acid pyridine monosolvate), C(5)H(5)N·C(7)H(6)O(5), the gallic acid mol-ecule is essentially planar (r.m.s deviation = 0.0766?Å for non-H atoms) and is linked to the pyridine mol-ecule by an O-H?N hydrogen bond. An intra-molecular O-H?O hydrogen bond occurs in the gallic acid mol-ecule. The gallic acid and pyridine mean planes make a dihedral angle 12.6?(3)°. Inter-molecular O-H?O and O-H?N hydrogen bonding involving the hy-droxy and carboxyl groups and the pyridine mol-ecule, and ?-? inter-actions between inversion-related pyridines [centroid-centroid distance = 3.459?(6)?Å] and between pyridine and benzene rings [centroid-centroid distance = 3.548?(6)?Å], lead to a three-dimensional network in the crystal.
| S-EPMC3247482 | biostudies-literature
Project description:The biosynthetic pathway of L-tartaric acid, the form most commonly encountered in nature, and its catabolic ties to vitamin C, remain a challenge to plant scientists. Vitamin C and L-tartaric acid are plant-derived metabolites with intrinsic human value. In contrast to most fruits during development, grapes accumulate L-tartaric acid, which remains within the berry throughout ripening. Berry taste and the organoleptic properties and aging potential of wines are intimately linked to levels of L-tartaric acid present in the fruit, and those added during vinification. Elucidation of the reactions relating L-tartaric acid to vitamin C catabolism in the Vitaceae showed that they proceed via the oxidation of L-idonic acid, the proposed rate-limiting step in the pathway. Here we report the use of transcript and metabolite profiling to identify candidate cDNAs from genes expressed at developmental times and in tissues appropriate for L-tartaric acid biosynthesis in grape berries. Enzymological analyses of one candidate confirmed its activity in the proposed rate-limiting step of the direct pathway from vitamin C to tartaric acid in higher plants. Surveying organic acid content in Vitis and related genera, we have identified a non-tartrate-forming species in which this gene is deleted. This species accumulates in excess of three times the levels of vitamin C than comparably ripe berries of tartrate-accumulating species, suggesting that modulation of tartaric acid biosynthesis may provide a rational basis for the production of grapes rich in vitamin C.
| S-EPMC1459401 | biostudies-literature
Project description:Gallic acid (GA) is well known for its antioxidant and hepatoprotective activity, though its effectiveness is restricted due to rapid metabolism and elimination. To overcome these problems, gallic acid-phospholipid complex was prepared and the effect of phospholipid complexation was investigated on carbon tetrachloride (CCl4)-induced oxidative damage in rat liver. The complex significantly reduced the hepatic marker enzymes in rat serum and restored the antioxidant enzyme levels with respect to CCl4-induced group (P < 0.05 and P < 0.01). Also, the complex improved the pharmacokinetics of GA by increasing the relative bioavailability and elimination half-life. The study therefore suggests that phospholipid complexation has enhanced the therapeutic efficacy of GA which may be due to its improved absorption and increased bioavailability in rat serum.
| S-EPMC3755146 | biostudies-other
Project description:1. Chloroplasts and mitochondria were isolated by aqueous and non-aqueous cell-fractionation techniques. In a variety of higher plants the mitochondrial DNA bands in a caesium chloride gradient at 1.706g.cm.(-3), whereas chloroplastal DNA has a buoyant density of 1.697g.cm.(-3). 2. In total cellular DNA of moderate molecular weight, the chloroplastal DNA is found within the Gaussian distribution of the nuclear DNA and is not resolved as a satellite. 3. Both chloroplastal DNA and mitochondrial DNA from lettuce renature rapidly. 4. The kinetic complexity of mitochondrial DNA is > 10(8) daltons. 5. Chloroplastal DNA is made up from fast and slow renaturing sequences with kinetic complexities of 3x10(6) and 1.2x10(8) daltons respectively. 6. From the discrepancy between analytical and kinetic complexity it is concluded that chloroplastal DNA is extensively reiterated.
| S-EPMC1187784 | biostudies-other