L-Ascorbic Acid: Metabolism, Biosynthesis, Function

Loewus, Frank A.

doi:10.1016/b978-0-12-675403-2.50009-0

Cited by 32 publications

(30 citation statements)

References 140 publications

(86 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Oxidation of carbon 1 and carbons 2 or 3, and epimerization of carbon 5 represent minimal requirements for this conversion (10,11,14). None of the intermediates involved have been identified although a tentative scheme has been proposed (1 1):…”

mentioning

confidence: 99%

See 1 more Smart Citation

d-Glucosone and l-Sorbosone, Putative Intermediates of l-Ascorbic Acid Biosynthesis in Detached Bean and Spinach Leaves

Saito¹,

Nick²,

Loewus³

1990

Plant Physiol.

Self Cite

View full text Add to dashboard Cite

mentioning

confidence: 99%

“…Evidence of epimerization rests solely on isotopic studies involving overall conversion of glucose to AA (10,13 last step, oxidation of sorbosone to AA, has been described in bean and spinach (15).…”

mentioning

confidence: 99%

d-Glucosone and l-Sorbosone, Putative Intermediates of l-Ascorbic Acid Biosynthesis in Detached Bean and Spinach Leaves

Saito¹,

Nick²,

Loewus³

1990

Plant Physiol.

Self Cite

View full text Add to dashboard Cite

“…In the very high accumulator Halogeton glomeratus, Ca-OA can account for 30Yo ofthe dry weight ofthe plant (10). Glycolic, glyoxylic, and isocitric acids (8) and oxaloacetic (1) and ascorbic (7,13) acids are known to donate carbon to OA in plants. The relative significance of these metabolites as precursors of OA has not been established.…”

mentioning

confidence: 99%

Vacuolar Deposition of Ascorbate-derived Oxalic Acid in Barley

Wagner¹

1981

Plant Physiol.

View full text Add to dashboard Cite

L-11-"4ClAscorbic acid was supplied to detached barley seedings to determine the subcellular location of oxalic acid, one of its metabolic products. Intact vacuoles isolated from protoplasts of labeled leaves contained I'4Cloxalic acid which accounted for about 70% of the intraprotoplast soluble oxalic acid. Tracer-labeled oxalate accounted for 36 and 72%of the "C associated with leaf vacuoles of seedlings labeled for 22 and 96 hours, respectively.OA2 is a widely occurring natural product of plants, yet little is known about its metabolism and function (3,10,15). The amount of OA formed and accumulated in different plant species can vary greatly (3,9,10,14). Moderate to high accumulators, such as spinach and rhubarb, may contain 0.2 to 1% OA (on a fresh weight basis), whereas low accumulators, such as barley and tomato, may contain one-tenth this amount. In the very high accumulator Halogeton glomeratus, Ca-OA can account for 30Yo ofthe dry weight ofthe plant (10). Glycolic, glyoxylic, and isocitric acids (8) and oxaloacetic (1) and ascorbic (7, 13) acids are known to donate carbon to OA in plants. The relative significance of these metabolites as precursors of OA has not been established.Ca-OA, in various crystalline forms, often is observed in plant vacuoles (2). It also has been reported to occur in cytoplasm, in cell walls, and in extracellular spaces. However, ultrastructural observations suggest that extracellular Ca-OA originates in vacuoles (see ref. 4 and references therein). Soluble OA salts are thought to be contained in vacuoles. In the study presented here, vacuolar deposition of OA formed from AA was tested in barley, a low level OA accumulator in which AA to OA conversion has been reported (9). MATERIALS AND METHODSSix 13-day-old seedlings of Hordeum vulgare cv. Moore were cut at soil level and recut under water in preparation for labeling. 70o ethanol. To prepare protoplasts, the leaves were sliced into 1-mm strips and the strips were incubated in a sterile solution containing 1% Cellulysin, 0.5% Macerase (both from Calbiochem), and 0.7 M mannitol. Leaves from 24 plants which had not been labeled were similarly treated to provide carrier protoplasts and vacuoles. Tissues were about 75% digested after incubation at 25 C and in room light for 4 h. After removal of undigested materials, labeled-tissue and carrier-tissue digests were combined and protoplasts were recovered by sedimentation at 500g. Protoplasts (0.4 ml) were washed three times with 40 ml 20 mm Mes-KOH (pH 5.5). One-fifth was removed to be used as a protoplast sample before protoplasts were sedimented from the third wash. The remaining four-fifths was used to prepare vacuoles, essentially as previously described for the preparation oftulip leafvacuoles (12). Vacuoles were released in 0.17 M KH2PO4/K2HPO4 (pH 8.0); Kphosphate), and most residual protoplasts and much of the resulting particulate material were sedimented at 500g. The supernatant was made 17% (w/v) with sucrose by addition of 60%o (w/v) sucrose and this solutio...

show abstract

Section: Model Fitting From Response Surface Methodologymentioning

confidence: 99%

“…This can possibly be attributed to the fact that AA is not trapped within the plant cell wall. AA is synthesized in the plant cytosol (Loewus, 1980) and is distributed into the chloroplasts, vacuole, and apoplast of the plant cell (Rautenkranz et al, 1994).Y 2 = 138.3 -70.7 X 1 -0.104 X 2 + 2.30 X 3 + 24.1 X 1 X 1 -0.000017 X 2 X 2 + 0.005 X 3 X 3 + 0.0374 X 1 X 2 -1.69 X 1 X 3 + 0.00565 X 2 X 3TPC values of the extracts ranged from 48.46 to 105.78 mg GAE/g with the highest values observed with the experimental design when 1.5% solvent volume with 300 mg/L enzyme concentration and 15 h reaction time is applied. ANOVA for the response variable TPC (Table 4) indicated that the regression model for TPC was significant (p<0.05) and did not exhibit any lack of fit.…”

mentioning

confidence: 99%

Bioactive rich extracts from Terminalia ferdinandiana by enzyme-assisted extraction: A simple food safe extraction method

Chaliha¹,

Williams²,

Edwards³

et al. 2017

J. Med. Plants Res.

View full text Add to dashboard Cite

A food grade compatible enzyme assisted extraction (EAE) technique for extracting bioactive compounds from freeze-dried Kakadu plum puree was evaluated. To optimise the extraction, a central composite rotatable design (CCRD) was conducted and effects of solvent concentration, enzyme concentration and time of reaction on extracted levels of free ellagic acid (fEA), ascorbic acid (AA) and total phenolic content (TPC) were determined. In the extracts, concentration of fEA ranged from 53.6 to 266.6 mg/100 g dry weight (DW) of Kakadu plum puree; AA 63.7 to 112.1 mg/100 g DW and TPC levels of 73.23 to 104.74 mg of gallic acid equivalent (GAE)/g. Extraction yield of fEA ranged from 10.3 to 51.3%. The model was found to be suitable for extraction of fEA -an important bioactive compound with documented antimicrobial properties from Kakadu plum fruit. A solvent (propylene glycol) concentration of 1.5% (w/w), enzyme (pectolytic enzymes) concentration of 300 mg/L and extraction time of 15 h was ascertained as optimum for the fEA extraction delivering a yield of 51.3%. The extraction method described here facilitates the provision of a simple, cost effective food-grade compatible extract that by-passes the need for organic solvents thereby obtaining an EA-rich aqueous extract with enhanced biological activities. This simple extraction method can also be applied to other EA rich plant material like pomegranate and peel of many common fruits which are generated as food processing by-products and can be easily adopted by numerous industries.Key words: Central composite rotatable design, ellagic acid, enzyme assisted extraction, Kakadu plum fruit, Terminalia ferdinandiana. INTRODUCTIONA species of Terminalia endemic to Australia -Terminalia ferdinandiana Exell, Combretaceae, commonly known as Kakadu plum, has a significant history as a food source and traditional medicine by the Australian aboriginal *Corresponding author. E-mail: mridusmita.chaliha@uqconnect.edu.au. Tel: (617) 3276-6007. Fax: (617) 3276-9591.Author(s) agree that this article remain permanently open access under the terms of the Creative Commons Attribution License 4.0 International License population for centuries. Fruits are consumed to cure headaches and to alleviate the symptoms of colds and flu while the pounded fruit is used as an antiseptic and a soothing balm for aching limbs (Konczak et al., 2010). Kakadu plum grows across large areas of Australia: Western Australia, to the south of Broome and Northern Territory, near the Arnhem Land and the Gulf area in the east, covering a range of environmental conditions (Wrigley, 1988).Kakadu plum is a rich source of polyphenolic compounds for example ellagic acid (EA) and its hydrolysable tannin, ellagitannin (Konczak et al., 2014;Williams et al., 2014). EA and its derivatives are present at high levels in many Terminalia plants (Pfundstein et al., 2010) and are reported to be responsible for their perceived health promoting and biological activities (Dhanani et al., 2015). Konczak et al. (2014) reported free EA (...

show abstract

L-Ascorbic Acid: Metabolism, Biosynthesis, Function

Cited by 32 publications

References 140 publications

d-Glucosone and l-Sorbosone, Putative Intermediates of l-Ascorbic Acid Biosynthesis in Detached Bean and Spinach Leaves

d-Glucosone and l-Sorbosone, Putative Intermediates of l-Ascorbic Acid Biosynthesis in Detached Bean and Spinach Leaves

Vacuolar Deposition of Ascorbate-derived Oxalic Acid in Barley

Bioactive rich extracts from Terminalia ferdinandiana by enzyme-assisted extraction: A simple food safe extraction method

Contact Info

Product

Resources

About