Silicic acid

From Wikipedia, the free encyclopedia

Annual mean sea surface silicic acid for the World Ocean. Data from the World Ocean Atlas 2001.
Annual mean sea surface silicic acid for the World Ocean. Data from the World Ocean Atlas 2001.

Silicic acid is a general name for a family of chemical compounds of the element silicon, hydrogen, and oxygen, with the general formula [SiOx(OH)4-2x]n. Some simple silicic acids have been identified in very dilute aqueous solution, such as metasilicic acid (H2SiO3), orthosilicic acid (H4SiO4, pKa1=9.84, pKa2=13.2 at 25° C), disilicic acid (H2Si2O5), and pyrosilicic acid (H6Si2O7); however in the solid state these probably condense to form polymeric silicic acids of complex structure.

Silicic acids may be formed by acidification of silicate salts (such as sodium silicate) in aqueous solution. When heated they lose water to form silica gel, an active form of silicon dioxide.

In the oceans, silicon exists primarily as orthosilicic acid (H4SiO4), and its biogeochemical cycle is regulated by the group of algae known as the diatoms. These algae polymerise the silicic acid to so-called biogenic silica, used to construct their cell walls (called frustules).

Continuing research of the correlation of aluminium and Alzheimer's disease has in the last few years included the use of silicic acid in beverages[1][2][3], due to its abilities to both reduce aluminium uptake in the digestive system as well as cause renal excretion of aluminium.

Orthosilicic acid is the form predominantly absorbed by humans and is found in numerous tissues including bone, tendons, aorta, liver and kidney. Compelling data suggest that silica is essential for health although no RDI has been established. However, deficiency induces deformities in skull and peripheral bones, poorly formed joints, reduced contents of cartilage, collagen, and disruption of mineral balance in the femur and vertebrae. [4]

Choline-stabilized orthosilicic acid is bioavailable nutritional supplement. It has been shown to stimulate collagen type 1 synthesis and osteoblastic differentiation in human osteoblast-like cells in vitro[5], improve hair tensile strength[6], have positive effect on skin surface and skin mechanical properties, and on brittleness of hair and nails[7], abate brittle nail syndrome[8], partially prevent femoral bone loss in the aged ovariectomized rat model[9], and increase collagen concentration in calves [10].

[edit] References

  1. N. N. Greenwood, A. Earnshaw, Chemistry of the Elements, 2nd ed., Butterworth-Heinemann, Oxford, UK, 1997.
  2. R. K. Iler, The Chemistry of Silica, Wiley, New York, 1979.
  1. ^ Exley C, Korchazhkina O, Job D, Strekopytov S, Polwart A, Crome P (2006). "Non-invasive therapy to reduce the body burden of aluminium in Alzheimer's disease". J. Alzheimers Dis. 10 (1): 17–24; discussion 29–31. PMID 16988476. 
  2. ^ González-Muñoz MJ, Peña A, Meseguer I (2008). "Role of beer as a possible protective factor in preventing Alzheimer's disease". Food Chem. Toxicol. 46 (1): 49–56. doi:10.1016/j.fct.2007.06.036. PMID 17697731. 
  3. ^ Gonzalez-Muñoz MJ, Meseguer I, Sanchez-Reus MI, et al (2008). "Beer consumption reduces cerebral oxidation caused by aluminum toxicity by normalizing gene expression of tumor necrotic factor alpha and several antioxidant enzymes". Food Chem. Toxicol. 46 (3): 1111–8. doi:10.1016/j.fct.2007.11.006. PMID 18096288. 
  4. ^ Martin KR (2007). "The chemistry of silica and its potential health benefits". J Nutr Health Aging 11 (2): 94–7. PMID 17435951. 
  5. ^ Reffitt DM, Ogston N, Jugdaohsingh R, et al (2003). "Orthosilicic acid stimulates collagen type 1 synthesis and osteoblastic differentiation in human osteoblast-like cells in vitro". Bone 32 (2): 127–35. doi:10.1016/S8756-3282(02)00950-X. PMID 12633784. 
  6. ^ Wickett RR, Kossmann E, Barel A, et al (2007). "Effect of oral intake of choline-stabilized orthosilicic acid on hair tensile strength and morphology in women with fine hair". Arch. Dermatol. Res. 299 (10): 499–505. doi:10.1007/s00403-007-0796-z. PMID 17960402. 
  7. ^ Barel A, Calomme M, Timchenko A, et al (2005). "Effect of oral intake of choline-stabilized orthosilicic acid on skin, nails and hair in women with photodamaged skin". Arch. Dermatol. Res. 297 (4): 147–53. doi:10.1007/s00403-005-0584-6. PMID 16205932. 
  8. ^ Scheinfeld N, Dahdah MJ, Scher R (2007). "Vitamins and minerals: their role in nail health and disease". J Drugs Dermatol 6 (8): 782–7. PMID 17763607. 
  9. ^ Calomme M, Geusens P, Demeester N, et al (2006). "Partial prevention of long-term femoral bone loss in aged ovariectomized rats supplemented with choline-stabilized orthosilicic acid". Calcif. Tissue Int. 78 (4): 227–32. doi:10.1007/s00223-005-0288-0. PMID 16604283. 
  10. ^ Calomme MR, Vanden Berghe DA (1997). "Supplementation of calves with stabilized orthosilicic acid. Effect on the Si, Ca, Mg, and P concentrations in serum and the collagen concentration in skin and cartilage". Biol Trace Elem Res 56 (2): 153–65. doi:10.1007/BF02785389. PMID 9164661. 
 This inorganic compound-related article is a stub. You can help Wikipedia by expanding it.