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Annex B to TOX/2026/36

Updated 13 October 2026

This is a paper for discussion. This does not represent the views of the Committee and should not be cited.

Google Patents describing specific extraction processes for obtaining HCA from G. cambogia were retrieved from publicly available sources and are presented in this Annex to provide additional context on the production of HCA extracts from G. cambogia rinds.

1. In 2022, an application was filed by 주식회사 청안오가닉스 (translates to Cheongan Organics Co., Ltd.) for “A Method Of Extracting Garcinia Cambogia Active Substances Simultaneously Using Imprinted Technique And Extract Thereof” (Publication number: KR20230111319A). This patent describes a molecularly imprinted polymer (MIP) extraction method for selectively isolating HCA. The aim is to create a polymer with binding sites shaped specifically for HCA, then use that polymer to capture and enrich HCA from Garcinia extracts. A simplified workflow is described as follows:

i) Prepare a MIP by mixing HCA with a functional monomer, crosslinker, polymerisation initiator and porogenic solvent. The patenet specifies example ratios of approximately: HCA – 1 molar part, monomer – ≥ 5 molar parts, crosslinker – ≥ 16 molar parts and initiator – ≥ 0.08 molar parts.

ii) Polymerise the mixture – Bulk polymerization to form a solid HCA-imprinted polymer block containing HCA molecules embedded within it

iii) Remove the template (HCA) – Washing the polymer using an extraction solvent consisting of acetic acid:methanol (2:8 v/v) > stirring the polymer in this solvent > then stir again for methanol 10 hours > drying the polymer at 70°C for 1 hour. This leaves behind cavities that are complementary to HCA.

iv) Use the imprinted polymer to extract HCA from G. cambogia.

v) Recover the enriched extract.

2. In 2019, an application was filed by Hunan University of Humanities Science and Technology for “A method for extracting hydroxycitrate from garcinia cambogia fruit (Publication number: CN110590543A). This patent describes a water extraction followed by ethanol fractionation and alkaline salt formation to obtain HCA salts from G. cambogia fruit. A simplified workflow is described as follows:

i) Prepare the raw material - G. cambogia fruit is crushed preferred particle size 30-50 mesh.

ii) Hot water extraction – Add water at a 1:13 to 1:15 (w/v) material-to-liquid ratio (preferred 1:14) > heat at 110-120°C for 10-20 minutes (preferred 115°C for 15 minutes) > cool and filter > retain the filtrate containing dissolved HCA.

iii) Concentrate the extract – A concentrate is obtained by evaporation of the supernatant at 55°C. Concentration factor is 5 times.

iv) First ethanol precipitation – Add ethanol (90-95%) is added to precipitate the pectin at a ratio of 1:1 (v/v). This precipitates unwanted components. The solution is filtered with gauze and centrifuged for 15 minutes to remove pectin. The filtrate is retained.

v) Adjust alcohol concentration – Ethanol (90-95%) is added to the supernatant to adjust the alcohol content to 58-62% (v/v).

vi) Convert HCA to its salt form – An alkali solution (potassium hydroxide: 30-50% w/w or sodium hydroxide) is added to adjust the pH value to 11.5-12.5. HCA forms a salt rather than cyclizing to the lactone.

vii) Recover the product – Filter the precipitated HCA salt > washed with ethanol (95%) three times, then it is washed with ‘absolute’ ethanol twice. The product is placed in a room temperature environment overnight. It is then evaporated under reduced pressure at 60°C, and dried to obtain the final product.

3. In 2017, an application was filed by Wuhan Taiankang Biotechnology Co Ltd, Nanjing Hope-Pharm Co Ltd (Publication number: CN108047029A) for the “Preparation method of the extraction purification hydroxycitric acid from Garcinia cambogia”. The patent describes a process that converts HCA into a calcium salt for purification and then regenerates purified HCA by acidification. The method claimed to extract HCA at 92% purity. A simplified workflow is described as follows:

i) Prepare the raw material – G. cambogia fruit is crushed, is added in alcohol-water solution of 4-10 times of 2%-15% volumetric concentrations. The material is loaded into a multi-stage ‘counter current extraction’ system.

ii) Extract HCA – Extract with dilute aqueous ethanol solution (examples include 2% to 15% ethanol in water) > continue counter-current extraction for several hours (5 h in one example) > filter to obtain the crude extract containing hydroxycitric acid.

iii) Form calcium hydroxycitrate salt – Transfer the extract to a neutralization vessel > add calcium hydroxide solution > adjust pH to approximately 7.5 > heat to about 85°C and stir for around 2 hours > cool and centrifuge > wash the precipitate to obtain crude calcium hydroxycitrate.

iv) Purify the calcium hydroxycitrate salt – Suspend the crude calcium hydroxycitrate in deionized water > heat to about 100°C for approximately 1 hour > cool and centrifuge again > recover a purified calcium hydroxycitrate intermediate.

v) Regenerate HCA – Transfer the purified calcium hydroxycitrate to an acidification vessel > add water > add dilute sulfuric acid gradually to obtain a pH of 4.0-5.5 > the calcium salt is converted back to free HCA while calcium sulfate is formed and removed.

vi) Decolourise and concentrate – Remove insoluble materials > decolourise the solution (using adsorbent activated carbon) > concentrate the HCA solution.

vii) Crystallise and product recovery – refine and crystallise the HCA > centrifuge the crystals > HCA is dried - drying vacuum degree is stated as 0.05-0.1MPa, vacuum drying temperature is 28-32°C > milled and blend the final product.

4. In 2016, an application was filed by 주식회사 코씨드바이오팜 (translates to
Coseed Biopharm Co., Ltd.) for “Method of High Yield Extraction of Hydroxycitric Acid from Garcinia cambogia with Response Surface Methodology” (Publication number: KR101781365B1).  The patent focuses on optimising extraction conditions to maximise the recovery of HCA from G. cambogia using statistical design and response surface methodology (RSM). A simplified workflow is described as follows:

i) Select extraction variables – Ethanol concentration in the extraction solvent, extraction temperature, raw material to solvent ratio. These variables were systematically optimised using RSM and a Box-Behnken experimental design.

ii) Prepare the extraction solvent – Use an aqueous ethanol extraction solvent.

iii) Extract HCA from G. cambogia – Extraction solvent is 0.96% ethanol in water, extraction temperature of 80°C, solvent to material ratio of 1:4.65 dried ground G. cambogia fruit and solvent.

iv) Analyse HCA yield – HCA concentration is measured after extraction > regression analysis and RSM are used to determine the effect of each extraction parameter and identify the optimum conditions.

5. In 2015, an application was filed by an ‘Individual’ for ”Method for extracting and purifying hydroxycitric acid from garcinia cambogia” (Publication number: CN104725218A). The patent describes a calcium salt purification process for producing high-purity HCA from G. cambogia fruit. The method uses precipitation as calcium hydroxycitrate, followed by acidification, decolorization, concentration, and crystallization. A simplified workflow is described as follows:

i) Extract G. cambogia – crushed G. cambogia fruit (primarily the rind/pericarp) is added into a multi-function extractor with deionised water (10, 8, or 6 times the raw material quantity) this is heated to 60-90°C. Solutions are collected at 1, 1.5 and 2 hours, when the immersion liquid has a pH of 5.6, extraction is stopped. The solution is heated to 80-90°C for 30 minutes and allowed to settle for 4-6 hours.

ii) Neutralise the extract – The solution is filtered. The collected filtrate is heated to 60-80°C, calcium hydroxide is added whilst stirring to form HCA calcium (insoluble). Calcium hydroxide is added and heated to 90-100°C for 30-60 minutes, the pH is maintained at 6-7.

iii) Wash and desalt the calcium hydroxycitrate – The solution is poured into a settling bath, the supernatant liquid is pumped, the sediment is centrifuged. The HCA calcium is hot washed at 80-90°C.

iv) Acid hydrolysis and purification – Potassium permanganate (1-2%) is dripped per 20 mL of washing, sulphuric acid (5-10%) is added to the HCA calcium solution and boiled for 3-5 hours.

v) Decolourise and concentrate – Solution is decolourised by adding activated charcoal, this results in obtaining a colourless liquid. The HCA solution is concentrated under reduced pressure, evaporated to a proportion of 1.10-1.20. At this stage the HCA concentrate is described as a crude product.

vi) Refine and crystallise – In a closed reactor with methyl alcohol (7-10 times the amount of crude HCA), the crude HCA product is slowly added, 3-5% of ‘gac’ is also added, the reaction mixture is slowly stirred and heated to 70 ± 2°C for 1 hour. Reactor is set to the following conditions: pressure 0.06-0.08 MPa and temperature 50 ± 2°C. When the initial concentration is halved, the temperature is set below 30°C, the mixture is stirred for 12-16 hours to form crystals.

vii) Recover the final product – The wet crystals are centrifuged, transferred into a drying machine set at 0.06-0.08 MPa and temperature of 40-60°C to dry for 2.5 hours. The dried material is pulverised for 30 minutes (rotating speed of 2r/min).

6.      In 2009, an application was filed by Vittal Mallya Scientific Research Foundation for ‘High Purity (-) Hydroxycitric Acid Metal Salt Derivatives and Method of Preparation of the Same’ (Publication number: US20100152488A1). The method claimed to extract HCA at 98% purity. A simplified workflow is described as follows:

i) Dried rinds of the fruits of G. cambogia are cut into small pieces and extracted into boiling water for 6-10 hours three times. The combined extracts are evaporated to get a syrupy mass.

ii) ‘Sufficient quantity’ of acetone/methanol and their analogues like methyl ethyl ketone, isobutyl methyl ketone/ethyl alcohol/isopropyl alcohol/butyl alcohol as such or in different proportions added to remove pectin and other insoluble matter. After filtration, the filtrate is concentrated to get a viscous mass.

iii) The viscous mass is repeatedly extracted with diethyl ether, di isopropyl ether, methyl tertiary butyl ether/butyl acetate, isopropyl acetate, ethyl acetate and on evaporation of organic layer yielded crude lactone. The crude lactone upon crystallization from solvents like diethyl ether, ethyl acetate, acetonitrile with petroleum ether in different proportions gives pure crystals of (−)-HCA lactone.

iv) Prepare HCA metal salts – The purity of the product is confirmed by subjecting to HPLC. The pure crystalline lactone has been dissolved in water and treated with stoichiometric quantities of alkali viz., sodium hydroxide, potassium hydroxide, calcium carbonate, potassium carbonate, magnesium carbonate and other IA and IIA group metal carbonates/hydroxides. These solutions when spray dried or precipitated with ethyl alcohol to get corresponding metal salts of (−)-HCA.

v) The (−)-HCA lactone has also been prepared from commercially available calcium/sodium/potassium salts and their solutions of hydroxycitric acid.

7. In 1999, an application was filed by Department of Science and Technology of Ministry of Science and Technology India for ‘Convenient method for the large scale isolation of garcinia acid’ (Publication number: US6147228A). The patent describes a large-scale, chromatography-free process for isolating optically pure Garcinia acid (HCA) from the fruit rinds of G. cambogia, G. indica, or G. atroviridis. The yield is reported to be 5-10% of the weight of the dried fruit rinds. A simplified workflow is described as follows:

i) Aqueous extraction – Fruit rinds are cut into small pieces > soaked in boiling water for 10 to 20 hours > extraction repeated several times > combined aqueous extracts are concentrated to a syrup.

ii) Pectin removal – Methanol, ethanol or butanol is added to the concentrated aqueous extract > pectin precipitates and is removed by filtration > the filtrate is reconcentrated to give a pectin-free syrup.

iii) Conversion to alkali hydroxycitrate salt – The syrup is made alkaline using potassium hydroxide at elevated temperature > alcohol (methanol, ethanol or butanol) is added > two layers form >the lower layer containing the alkali HCA salt is collected > the salt is washed repeatedly with aqueous alcohol. iv) Regeneration of HCA – The purified alkali salt is neutralised with a mineral acid > the resulting solution is concentration to obtain a Garcinia acid rich-concentrate.

v) Removal of inorganic impurities – The concentrate is triturated with acetone, ether or methanol > inorganic salts precipitate and are removed by filtration > the filtrate is concentrated to obtain crude HCA.

vi) Recrystallisation – Crude HCA is recrystallised from acetone, methanol, ethanol, chloroform, dichloroethane or suitable solvent mixtures.