Plants oxalates

Calcium oxalate (723) occurs as the monohydrate (whewellite, the thermodynamically stable form under ambient conditions (724)), the dihydrate (weddellite) in plant calcium stores and in sap, or the trihydrate (725). Calcium oxalate also plays a structural role in plants. Oxalate, for example from excessive amounts of rhubarb or spinach, inhibits absorption of Ca2+ from the GIT precipitation of calcium oxalate is the reason for the toxicity of oxalates. Calcium oxalate may also occur in man, where it can appear as minute star-shaped crystals in the urine. It is the main constituent of the majority of urinary calculi in man (726,727). The relationships between dietary calcium... 

OXALIC ACID ORIGINALLY CAME FROM THE WOOD SORREL PLANT— OXAL/S. NOW IT IS MADE ARTIFICIALLY. 

A synthetic coupled cycle of calcium and carbon through the oxalate-carbonate pathway is shown in Fig. 12.8. Atmospheric CO2 is fixed by the plants through photosynthesis to produce biomass. Inside the plant, oxalate crystals form. In addition, fungal mycelium may also accumulate oxalate. Mainly in the form of calcium oxalate (COM or COD), this carbon pool is used by oxalotrophic bacteria as a carbon, energy and electron source. The transformation of oxalate can occur in the soil... 

During plutonium reconversion in a reprocessing plant, oxalate supernatant is normally generated during plutonium precipitation by oxalic acid as plutonium oxalate. This is further converted into plutonium oxide. This waste solution will have the following composition uranium (U) 5 gm dm , plutonium (Pu) 25 mg dm, mthenium (Ru ° ) 0.0032 mCi dm, cesium (Cs ) 0.003 mCi dm , nitric acid 3 M, and H2C2O4 0.1 M. 

Oxalate is found in plants, animals, and in humans. Oxalate content of plants is, compared to that of animals and humans, much higher. The calcium oxalate found in plants can even account for a large amount of their total calcium. Plant oxalate is the main regulator of calcium concentrations in plant tissues, an important factor in plants defense (against herbivores), and in heavy metal tolerance [2]. In contrast to these important roles that have been dedicated to oxalate in plants, in... 

Oxalic acid is poisonous and occurs naturally in a number of plants including sorrel and begonia It is a good idea to keep houseplants out of the reach of small children who might be tempted to eat the leaves or berries... 

Astcracantha longifolia Ness (Aeanthacese). This plant, formerly named Hygrophila spinosa, contains an alkaloid, C10H12O3N4, m.p. 216-7°, which forms an oxalate, m.p. 221-2°, and a sulphate, m.p. 210-1°, and may be a purine derivative (Basu and Lai, Qtiart. J. Pharmacol., 1947, 20, 38). 

C17-0116. Oxalic acid, a diprotic carboxylic acid found in many plants, including rhubarb, is an effective stain remover. Consider the following diagram to be a small section of an aqueous solution of oxalic acid ... 

Plant material fractionation. The detailed steps of isolation and separation of oligosaccharide fractions were described earlier [10]. Pectin was separated by boiling the cell walls in 0.5 M ammonium-oxalate buffer, pH 5.2 at 100 C for Ih. The dialyzed solution of pectin was hydrolyzed with 0.15M HCl for 3h at 100 C. Neutralized and desalted hydrolysate was loaded to the column (lx90cm) filled with biogel TSK HW-40 (Toyo Soda, Japan) equilibrated and eluted with 50mM sodium acetate (pH 5.2) at a rate of 0.3ml/min. In all fractions (1ml) the sugars were determined by o-toluidine method (Resnikov et al., 1982) and fraction IP was collected as shown on Figure 1. 

The uptake and biotransformation of benzene from soil and the atmosphere has been studied in a nnmber of plants. It was shown that in leaves of spinach Spinacia oleraced) the label in -benzene was fonnd in mnconic, fnmaric, snccinic, malic, and oxalic acids, as well as in specific amino acids, and that an enzyme preparation in the presence of NADH or NADPH prodnced phenol (Ugrekhelidze et al. 1997). 

Li H-Q, 1 Matsuda, Y Eujise, A Ichiyama (1999) Short-chain acyl-CoA-dependent production of oxalate from oxaloacetate by Burkholderia glumae, a plant pathogen which causes grain rot and seedling rot of rice via oxalate production. J Biochem 126 243-253. 

Root exudation of extraordinary high amounts of specific carboxy lutes (e.g ci-u-ate, malate. oxalate, pbytosiderophores) in response to nutritional deficiency stress or Al toxicity in some plant species cannot simply be attributed to diffusion processes. The controlled release of these compounds, involved in mobilization of mineral nutrients and in detoxification of Al. may be mediated by more specific mechanisms. Inhibitory effects by exogenous application of various anion chan-... 

Aluminium toxicity is a major stress factor in many acidic soils. At soil pH levels below 5.0, intense solubilization of mononuclear A1 species strongly limits root growth by multiple cytotoxic effects mainly on root meristems (240,241). There is increasing evidence that A1 complexation with carboxylates released in apical root zones in response to elevated external Al concentration is a widespread mechanism for Al exclusion in many plant species (Fig. 10). Formation of stable Al complexes occurs with citrate, oxalate, tartarate, and—to a lesser extent— also with malate (86,242,243). The Al carboxylate complexes are less toxic than free ionic Al species (244) and are not taken up by plant roots (240). This explains the well-documented alleviatory effects on root growth in many plant species by carboxylate applications (citric, oxalic, and tartaric acids) to the culture media in presence of toxic Al concentrations (8,244,245) Citrate, malate and oxalate are the carboxylate anions reported so far to be released from Al-stressed plant roots (Fig. 10), and Al resistance of species and cultivars seems to be related to the amount of exuded carboxylates (246,247) but also to the ability to maintain the release of carboxylates over extended periods (248). In contrast to P deficiency-induced carboxylate exudation, which usually increases after several days or weeks of the stress treatment (72,113), exudation of carboxylates in response to Al toxicity is a fast reaction occurring within minutes to several hours... 

I. Aluminium-induced specilic. secretion of oxalic acid from root tips. Plant Phvsiol. 7/7 745 (1998). 

Aliphatic compounds Several water-soluble simple organic acids and alcohols are cannon plant and soil constituents. They include methanol, ethanol, n-propanol and butanol (40), and crotonic, oxalic, formic, butyric, lactic, acetic and succinic acids (41, 42), all of which inhibit seed germination or plant growth. Under aerobic conditions, however, aliphalic acids are metabolized in the soil and therefore, should not be considered a major source of allelopathic activity (40). 

Bioinorganic materials Carbonated hydoxyapatite in mammals silica or calcium oxalate in weeds Provide structural support to the body Bones, teeth, and shell in animals phytolithes in plants about 5... 

Oxalate Ca(C00)2H20 Ca(C00)2-2H20 Whewellite 1 Weddellite I " Insect eggs Vertebrate stones. .Abundant in plants Deterrent Cytoskeleton Ca store... 

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