Hydroxycitric acid

Hydroxycitric acid
Names
IUPAC name
1,2-dihydroxypropane-1,2,3-tricarboxylic acid
Other names
Hydroxycitrate
Identifiers
3D model (JSmol)
ChemSpider
Properties
C6H8O8
Molar mass 208.12 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Hydroxycitric acid (HCA) is a derivative of citric acid that is found in a variety of tropical plants including Garcinia cambogia and Hibiscus subdariffa.[1]

There are four isomers, (+)- and (-)-hydroxycitric acid, and (+)- and (-)-allo-hydroxycitric acid. The (-)-hydroxycitric acid isomer is the one found in Garcinia.[2]

Biological effects

(-)-HCA is a competitive inhibitor of ATP citrate lyase, which converts citrate into oxaloacetate and acetyl CoA.[2] The reverse of this conversion is a step in the citric acid cycle.

Laboratory and animal studies of HCA have produced results that indicate a potential for modulation of lipid metabolism.[3] However, a clinical study has demonstrated that HCA has no effect in terms of weight loss or reduction of fat mass.[4] A meta-analysis published in 2010 revealed that gastrointestinal adverse effects were twice as likely for users of hydroxycitric acid. The use of HCA is contraindicated in patients suffering Colitis or Inflammatory Bowel Disease.[5]

One isomer of HCA, known as (2S,3R)-HCA, inhibits pancreatic alpha-amylase and intestinal alpha-glucosidase, leading to a reduction in carbohydrate metabolism in vitro.[1] In a study in Zucker rats, which are genetically predisposed to obesity, Garcinia cambogia extract containing HCA showed that high doses led to significant suppression of epididymal fat accumulation, but also had high testicular toxicity.[6] However, this study has been criticized because of possible contamination of the HCA used and various design flaws.[7][8]

Researchers at the University of Houston reported hydroxycitrate is capable of dissolving calcium oxalate crystals, a component of human kidney stones. This is an unusual effect because it is rare for a crystal to dissolve while in a supersaturated growth solution. The researchers believe the effect could lead to the development of new drugs for human kidney stones.[9]

References

  1. 1 2 Yamada T, Hida H, Yamada Y (2007). "Chemistry, physiological properties, and microbial production of hydroxycitric acid". Appl. Microbiol. Biotechnol. 75 (5): 977–82. PMID 17476502. doi:10.1007/s00253-007-0962-4.
  2. 1 2 Jena et al 2002, Chemistry and Biochemistry of (−)-Hydroxycitric Acid from Garcinia, Journal of Agricultural and Food Chemistry 50(1):10-22
  3. ↑ Shara M, Ohia SE, Yasmin T, et al. (2003). "Dose- and time-dependent effects of a novel (−)-hydroxycitric acid extract on body weight, hepatic and testicular lipid peroxidation, DNA fragmentation and histopathological data over a period of 90 days". Mol. Cell. Biochem. 254 (1–2): 339–46. PMID 14674714. doi:10.1023/A:1027358106407.
  4. ↑ Heymsfield SB, Allison DB, Vasselli JR, Pietrobelli A, Greenfield D, Nunez C (1998). "Garcinia cambogia (hydroxycitric acid) as a potential antiobesity agent: a randomized controlled trial". JAMA. 280 (18): 1596–600. PMID 9820262. doi:10.1001/jama.280.18.1596.
  5. ↑ Igho O, Shao K, Rachel P, Barbara W, Edzard E (2011). "The Use of Garcinia Extract Hydroxycitric Acid as a Weight loss Supplement: A Systematic Review and Meta-Analysis of Randomised Clinical Trials". J Obes. 2011 (622): 849. PMC 3010674 Freely accessible. PMID 21197150. doi:10.1155/2011/509038.
  6. ↑ Saito M, Ueno M, Ogino S, Kubo K, Nagata J, Takeuchi M (2005). "High dose of Garcinia cambogia is effective in suppressing fat accumulation in developing male Zucker obese rats, but highly toxic to the testis". Food Chem. Toxicol. 43 (3): 411–9. PMID 15680676. doi:10.1016/j.fct.2004.11.008.
  7. ↑ Madhusudan Soni Burdock Group (2005). "Garcinia cambogia toxicity is misleading". Food and Chemical Toxicology. 43 (11): 1683–1684. PMID 15993998. doi:10.1016/j.fct.2005.05.011.
  8. ↑ Hayamizu, K; Tomi, H; Kaneko, I; Shen, M; Soni, MG; Yoshino, G (2008). "Effects of Garcinia cambogia extract on serum sex hormones in overweight subjects". Fitoterapia. 79 (4): 255–61. PMID 18316163. doi:10.1016/j.fitote.2007.12.003.
  9. ↑ Chung J, Granja I, Taylor M, Mpourmpakis G, Asplin J. "Molecular modifiers reveal a mechanism of pathological crystal growth inhibition". Nature. doi:10.1038/nature19062.
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