Phytic acid

Phytic acid
IUPAC name (1r,2R,3S,4s,5R,6S)-cyclohexane-1,2,3,4,5,6-hexayl hexakis[dihydrogen (phosphate)]
Identifiers
CAS number	83-86-3 Y
PubChem	890
ChemSpider	16735966 Y
UNII	7IGF0S7R8I Y
ChEBI	CHEBI:17401 Y
Jmol-3D images	Image 1
SMILES [C@@H]1([C@@H]([C@@H]([C@@H]([C@H]([C@@H]1OP(=O)(O)O)OP(=O)(O)O)OP(=O)(O)O)OP(=O)(O)O)OP(=O)(O)O)OP(=O)(O)O
InChI InChI=1S/C6H18O24P6/c7-31(8,9)25-1-2(26-32(10,11)12)4(28-34(16,17)18)6(30-36(22,23)24)5(29-35(19,20)21)3(1)27-33(13,14)15/h1-6H,(H2,7,8,9)(H2,10,11,12)(H2,13,14,15)(H2,16,17,18)(H2,19,20,21)(H2,22,23,24)/t1-,2-,3-,4+,5-,6- Y Key: IMQLKJBTEOYOSI-GPIVLXJGSA-N Y InChI=1/C6H18O24P6/c7-31(8,9)25-1-2(26-32(10,11)12)4(28-34(16,17)18)6(30-36(22,23)24)5(29-35(19,20)21)3(1)27-33(13,14)15/h1-6H,(H2,7,8,9)(H2,10,11,12)(H2,13,14,15)(H2,16,17,18)(H2,19,20,21)(H2,22,23,24)/t1-,2-,3-,4+,5-,6- Key: IMQLKJBTEOYOSI-GPIVLXJGBP
Properties
Molecular formula	C6H18O24P6
Molar mass	660.04 g mol−1
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Phytic acid (known as inositol hexakisphosphate (IP6), or phytate when in salt form) is the principal storage form of phosphorus in many plant tissues, especially bran and seeds.^[1] Phytate is not digestible to humans or nonruminant animals, however, so it is not a source of either inositol or phosphate if eaten directly. Morever, it chelates and thus makes unabsorbable certain important minor minerals such as zinc and iron, and to a lesser extent, also macro minerals such as calcium and magnesium.

Catabolites of phytic acid are called lower inositol polyphosphates. Examples are inositol penta- (IP5), tetra- (IP4), and triphosphate (IP3).

Contents 1 Significance in agriculture 2 Food science 3 Therapeutic uses 4 Biological and physiological roles 5 See also 6 References

Significance in agriculture

Phosphorus and inositol in phytate form are not, in general, bioavailable to nonruminant animals because these animals lack the digestive enzyme phytase required to remove phosphate from the inositol in the phytate molecule. On the other hand, ruminants readily digest phytate because of the phytase produced by rumen microorganisms.^[2]

In most commercial agriculture, nonruminant livestock, such as swine, fowl, and fish,^[3] are fed mainly grains, such as maize, and legumes, such as soybeans. Because phytate from these grains and beans is unavailable for absorption, the unabsorbed phytate passes through the gastrointestinal tract, elevating the amount of phosphorus in the manure.^[2] Excess phosphorus excretion can lead to environmental problems, such as eutrophication.^[4]

The bioavailability of phytate phosphorus can be increased by supplementation of the diet with the enzyme phytase.^[5] Also, viable low-phytic acid mutant lines have been developed in several crop species in which the seeds have drastically reduced levels of phytic acid and concomitant increases in inorganic phosphorus.^[6] However, reported germination problems have hindered the use of these cultivars thus far.

The use of sprouted grains will reduce the quantity of phytic acids in feed, with no significant reduction of nutritional value.^[7]

Phytates also have the potential to be used in soil remediation, to immobilize uranium, nickel and other inorganic contaminants.^[8]

Food science

Phytic acid is found within the hulls of nuts, seeds, and grains.^[1] In-home food preparation techniques can reduce the phytic acid in all of these foods. Simply cooking the food will reduce the phytic acid to some degree. More effective methods are soaking in an acid medium, lactic acid fermentation, and sprouting.^[9]

Phytic acid has a strong binding affinity to important minerals, such as calcium, magnesium, iron, and zinc. When a mineral binds to phytic acid, it becomes insoluble, precipitates and will be nonabsorbable in the intestines. This process can therefore contribute to mineral deficiencies in people whose diets rely on these foods for their mineral intake, such as those in developing countries.^[10][11] Contrary to that, one study correlated decreased osteoporosis risk with phytic acid consumption.^[12] It also acts as an acid, chelating the vitamin niacin, the deficiency of which is known as pellagra.^[13] In this regard, it is an antinutrient, despite its possible therapeutic effects (see below). For people with a particularly low intake of essential minerals, especially those in developing countries, this effect can be undesirable.

Binding of calcium with phytic acid depends on pH.^[14]

"Probiotic lactobacilli, and other species of the endogenous digestive microflora, as well, are an important source of the enzyme phytase which catalyses the release of phosphate from phytate and hydrolyses the complexes formed by phytate and metal ions or other cations, rendering them more soluble, ultimately improving and facilitating their intestinal absorption"^[15]

Ascorbic acid (vitamin C) can reduce phytic acid effects on iron.^[16]

Food sources of Phytic Acid ^{[17] [18] [19][20]}

Food	[% minimum dry]	[% maximum dry]
Linseed	2.15	2.78
Sesame seeds flour	5.36	5.36
Almonds	1.35	3.22
Brazilnuts	1.97	6.34
Coconut	0.36	0.36
Hazelnut	0.65	0.65
Peanuts	0.95	1.76
Walnut	0.98	0.98
Corn	0.75	2.22
Oat	0.42	1.16
Oat Meal	0.89	2.40
Brown rice	0.84	0.99
Polished rice	0.14	0.60
Wheat	0.39	1.35
Wheat flour	0.25	1.37
Wheat germ	0.08	1.14
Whole wheat bread	0.43	1.05
Beans, pinto	2.38	2.38
Chickpeas	0.56	0.56
Lentils	0.44	0.50
Soybeans	1.00	2.22
Tofu	1.46	2.90
Soy beverage	1.24	1.24
Soy protein concentrate	1.24	2.17
New potato	0.18	0.34
Spinach	0.22	NR

Food sources of Phytic Acid (fresh weight)^[18]

Food	[% minimum fresh weight]	[% maximum fresh weight]
Taro	0.143	0.195
Cassava	0.114	0.152

Therapeutic uses

Phytic acid may be considered a phytonutrient, providing an antioxidant effect.^[1][21] Phytic acid's mineral binding properties may also prevent colon cancer by reducing oxidative stress in the lumen of the intestinal tract.^[22] Researchers now believe phytic acid, found in the fiber of legumes and grains, is the major ingredient responsible for preventing colon cancer and other cancers.^[1][23]

In vitro studies using a cell culture model have suggested phytic acid may have a neuroprotective effect by chelating iron.^[24] Similar types of cell-culture studies have found phytic acid significantly decreased apoptotic cell death induced by 1-methyl-4-phenylpyridinium. Phytic acid, at least in rodents, is known to cross the blood-brain barrier,^[25] and so, there is a strong possibility that neuroprotection occurs in vivo as well.

Phytic acid's chelating effect may serve to prevent, inhibit, or even cure some cancers by depriving those cells of the minerals (especially iron) they need to reproduce.^[1] The deprivation of essential minerals like iron would, much like other systemic treatments for cancers, also have negative effects on noncancerous cells.

A randomized, controlled trial in breast cancer patients showed no effect on chemotherapy-induced anemia or tumor markers, but the patients reported subjectively feeling better.^[26]

Phytic acid is one of few chelating therapies used for uranium removal.^[27]

It has been shown to be a required cofactor for YopJ, a toxin from Yersinia pestis.^[28] It is also a required cofactor for the related toxin AvrA from Salmonella typhimurium^[28] as well as Clostridium difficile Toxin A and Toxin B.

As a food additive, phytic acid is used as a preservative, as E391.^[29]

Biological and physiological roles

In seeds and grains, phytic acid and its metabolites have several important roles. Most notably, phytic acid functions as a phosphorus store, as an energy store, as a source of cations and as a source of myoinositol (a cell wall precursor). Phytic acid is the principal storage forms of phosphorus in plant seeds.^[30]

In animal cells, myoinositol polyphosphates are ubiquitous, and phytic acid (myoinositol hexakisphosphate) is the most abundant, with its concentration ranging from 10 to 100 uM in mammalian cells, depending on cell type and developmental stage.^[31][32] The interaction of phytic acid with specific intracellular proteins has been investigated in vitro, and these interactions have been found to result in the inhibition or potentiation of the physiological activities of those proteins.^[33][34] The best evidence from these studies suggests an intracellular role for phytic acid as a cofactor in DNA repair by nonhomologous end-joining.^[33] Other studies using yeast mutants have also suggested intracellular phytic acid may be involved in mRNA export from the nucleus to the cytosol.^[35] There are still major gaps in the understanding of this molecule, and the exact pathways of phytic acid and lower inositol posphate metabolism are still unknown. As such, the exact physiological roles of intracellular phytic acid are still a matter of debate.^[36]

See also

• Phytase
• Phytochemicals

References