Hydroxycitric acid

Hydroxycitric acid
Hydroxycitric acid.png
Preferred IUPAC name
1,2-Dihydroxypropane-1,2,3-tricarboxylic acid
Other names
Hydroxycitrate (anion name)
3D model (JSmol)
Molar mass208.12 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]

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