IngredientsGarcinia atroviridis, known as asam gelugur, asam gelugo, or asam keping (in Malay; Thai: ส้มแขก), is a large rainforest tree ranging from the eastern Himalayas through Myanmar and Thailand to Peninsular Malaysia, Borneo, and Sumatra. The English or common name is "Asam Gelugor," or "Som-Khaek." Local native names in Indonesia include asam gelugor and asam potong; in Thailand: a sa ka lu ko (Malay), som-khaai, ma-khaam khaek, cha muang chang, som-pha-ngum, som-khaek, som-ma-won; and in Malaysia: assam gelugor, boh no, nayo (Semang), asam gelugo, and asam keping.
The species belongs to the tropical family Guttiferae, often known as the Clusiaceae, which consists of 40 genera and over 1,000 species. The genus Garcinia is a commercially important Guttiferae genus with over 400 species found in palaeotropical climates, primarily in Southeast Asia; genus members are mainly small to medium-sized dioecious evergreen fruit trees, occasionally shrubs, with hard wood and abundant latex.
G. atroviridis is a perennial tree growing to a height of more than 10–25 m, with a long hardwood trunk, fluted at the base with dull grey, cracked and fissured or smooth grey bark, and drooping branches; the inner bark produces a little transparent or yellow sap. The leaves are dark green, shiny, long and narrow with a pointed tip and upturned edges. The species is dioecious with male and female flowers on separate trees. The flowers are dark red. The round fruits are borne singly on twig ends, about 7–10 cm in diameter. It has bright red flowers produced singly (female flowers) or in clusters of 10–22 blooms (male flowers).
The tree is native to and extensively distributed in Thailand, Myanmar, Peninsular Malaysia, and India (Assam), and is broadly cultivated in southern Thailand and Myanmar. This species grows wild throughout Peninsular Malaysia but is also widely cultivated, especially in the northern states, owing to its economic and medicinal value. The members of this species grow individually and can be found in humid, mixed lowland forests and up to 600 meters above sea level in the highlands of high rainfall areas in Southeast Asia.
The sun-dried fruits of G. atroviridis are cut into thin slices known as "asam keping" and are sold commercially in this region; these are a popular spice for curries, sour relishes, and fish dressings, and the dried fruit slices are used to provide acidity to cooked foods. Nowadays, som-khaek products are becoming increasingly popular as health foods in Thailand, and a variety of som-khaek goods, such as capsules, fruit slices, and tea, are available in markets. In Malaysia, the young, tender green shoots and leaves are consumed raw or cooked as ulam, or a sour relish.
Garcinia atroviridis, commonly named 'Asam Gelugur' among locals, is extensively used as a flavoring agent to provide a sour sensation, and is also used in many ways to promote health traditionally. The use of dried fruit slices as a culinary souring agent is deeply embedded in the cuisines of Peninsular Malaysia, Thailand, and Indonesia, serving a function analogous to tamarind or dried lime in other regional cuisines.
In the traditional practices of Southeast Asia, G. atroviridis is employed for postpartum medication and to alleviate symptoms such as earache, throat irritation, cough, and pregnancy-related stomach discomfort. In South-East Asia, for the treatment of dandruff, earache, stomach pain associated with pregnancy, and throat irritation, a decoction of G. atroviridis leaves and roots is often used; the dried fruit is used as an expectorant to treat cough, to improve blood circulation, and as a laxative.
The tree is a popular herbal treatment in Southeast Asia, especially Thailand, and is also occasionally cultivated in gardens, and semi-cultivated in the surrounding forest, for its edible fruit.
Multiple plant parts have been employed in traditional medicine. The fruit was sun-dried and sliced for culinary and medicinal use, or prepared as a decoction. The leaves and roots were prepared as decoctions for topical and systemic applications. Som-khaek products have become increasingly popular as health foods in Thailand, and are sold in various forms including capsules, fruit slices, and tea. Contemporary commercial preparations have extended this traditional use into standardized supplements. The Garcinia atroviridis extracts for commercial products are isolated from fruit rind and contain about 50% HCA.
Previous studies have identified various organic acids in the fruits of G. atroviridis, including ascorbic acid, citric acid, malic acid, tartaric acid, hydroxycitric acid, pentadecanoic acid, nonadecanoic acid, dodecanoic acid, 1′,1″-dibutyl methyl hydroxycitrate, and 2-(butoxycarbonylmethyl)-3-butoxycarbonyl-2-hydroxy-3-propanolide. The most pharmacologically studied of these is (−)-hydroxycitric acid (HCA).
The fruit has been found to contain (−)-hydroxycitric acid (HCA) and flavonoids that have been shown to possess remarkable hypolipidemic effects, promoting weight reduction by reducing lipogenesis and enhancing glycogen formation. In mammals, HCA is an important metabolic regulator of obesity and lipid disorders. HCA, the main acid found in G. atroviridis fruits, has been demonstrated to be a competitive inhibitor of ATP (adenosine 5′-triphosphate) citrate lyase (ACL). This enzyme assists in catalyzing the extramitochondrial cleavage of citrate to oxaloacetate and acetyl coenzyme A (CoA).
HCA has been shown to be a competitive inhibitor of ATP citrate lyase. Moreover, HCA increases hepatic glycogen synthesis, which helps produce a longer-lasting neurosignal from the liver to the brain, indicating satiety and thus prolonging appetite suppression.
(−)-Hydroxycitric acid, a derivative of citric acid found in fruit rinds of some Garcinia species, especially G. indica, G. atroviridis, and G. cambogia, is widely used in pharmaceutical products to improve exercise performance and weight loss.
Terpenoids, namely garcinol and isogarcinol, have also been identified in G. atroviridis fruits. Garcinol (also known as camboginol) is a polyisoprenylated benzophenone that has been associated with anticancer and antioxidant properties in other Garcinia species.
Camboginol, a prenylated xanthone, has been detected in G. atroviridis fruits. The presence of xanthones can contribute to the therapeutic effect of this plant extract. Xanthones are simple three-membered ring compounds that have very diverse biological profiles depending on their various structures, such as antihypertensive, antioxidative, antithrombotic, and anticancer activities.
Sesquiterpenoids such as α-humulene, β-caryophyllene alcohol, and (−)-β-caryophyllene have been found in these fruits. Phytochemical analysis of essential oils extracted from G. atroviridis leaves found that the oils were found to contain 64% (E)-β-farnesene and 19% β-caryophyllene.
The fruits are reported to contain saturated fatty acids such as pentadecanoic (15:0), octadecanoic (18:0, stearic acid), nonadecanoic (19:0), and dodecanoic (12:0, lauric acid) acids.
Numerous studies have shown that consumption of HCA suppresses appetite and lowers the production of cholesterol and fatty acids. HCA reduces appetite, lipogenesis, and body weight by inhibiting an enzyme involved in fat storage in adipose tissue. The inhibition of ATP citrate lyase is the foundational mechanism: by blocking extramitochondrial acetyl-CoA production, HCA limits the substrate available for de novo fatty acid and cholesterol synthesis.
The most directly relevant human trial involving G. atroviridis specifically was conducted in Thailand. In this study, subjects received either HCA from G. atroviridis or placebo; all subjects were recommended a similar diet with 1,000 kcal/day, and the trial lasted for 2 months. At baseline, the mean BMI of the treatment group was 27.5 ± 0.2 kg/m² and 26.7 ± 0.5 kg/m² for placebo. The HCA group lost significantly more weight (2.8 vs. 1.4 kg, p < 0.05) and at a greater rate than the placebo group; the decrease in body weight was due to a loss of fat storage, as evidenced by a significant decrease in triceps skin fold thickness. On a short-term basis, HCA from Garcinia atroviridis was effective for weight management.
This study was included in a broader systematic review and meta-analysis. The aim of this systematic review was to examine the efficacy of Garcinia extract/HCA as a weight reduction agent using data from randomized clinical trials (RCTs). Twenty-three eligible trials were identified and twelve were included; nine trials provided data suitable for statistical pooling. The meta-analysis revealed a small, statistically significant difference in weight loss favouring HCA over placebo (MD: −0.88 kg; 95% CI: −1.75, −0.00). G. cambogia was the main source of HCA in most studies, with Garcinia atroviridis being the source of HCA in one included study.
Evidence strength: The RCTs suggest that Garcinia extracts/HCA can cause short-term weight loss. However, the clinical effect size is small, most of the evidence base is drawn from G. cambogia rather than G. atroviridis specifically, and the optimal dose remains undefined.
Researchers investigated the phytochemical composition, safety profiles, and antioxidant and antiobesity effects of methanolic extracts of G. atroviridis (MeGa) in obese female rats; repeated dose toxicity studies were conducted according to OECD guidelines; upon sacrifice, haematological, biochemical, lipid profile, and serum-based metabolomics analyses were performed to evaluate metabolic expression changes and their related pathways. After 9 weeks of treatment, MeGa-treated obese rats had lower weight gain and better lipid profiles (cholesterol and triglyceride), which correlated with the altered metabolic pathways involved in the metabolism of lipid (glycerophospholipid) and biosynthesis of unsaturated fatty acid.
HCA and flavonoids found in G. atroviridis have been shown to possess remarkable hypolipidemic effects, promoting weight reduction by reducing lipogenesis and enhancing glycogen formation. In the obese rat model described above, treatment with the methanolic extract improved both cholesterol and triglyceride levels after 9 weeks. Clinical evidence derived from the HCA systematic review also identified lipid changes; however, gastrointestinal adverse events were twice as common in the HCA group compared with placebo in one included study.
A study examining fruit polysaccharides found additional anti-obesity and hypertension-related mechanisms. The potential of G. atroviridis fruit polysaccharides (GAP) in inhibiting lipase and angiotensin converting enzyme was investigated; the GAP was optimized using microwave-deep eutectic solvent-assisted extraction. The GAP showed a high molecular weight and viscosity as well as high branching size, which may have a greater ability to form complex structures that can inhibit targeted enzyme activities; these large structures can physically block the access of enzymes to their substrate. The extracted GAP showed inhibition of pancreatic lipase (79.41%) in vitro. This is a preclinical, in-vitro finding and has not been confirmed in human trials.
Studies have demonstrated that G. atroviridis extracts or constituents exert their antioxidant potential by scavenging free radicals or by inhibiting the various molecular targets involved in oxidative stress production. The ethanolic fruit extract exhibited antioxidant properties, scavenging DPPH• and ABTS•+ radicals and chelating copper. These findings are from in vitro assays, and their in vivo relevance in humans has not been established in clinical trials specific to G. atroviridis.
A study evaluated the antimicrobial potential of G. atroviridis fruit extracts; the ethanolic fruit extracts showed potent antimicrobial activity against S. aureus ATCC 25923, L. monocytogenes ATCC 19112, S. enterica ser. Typhimurium ATCC 14028, and E. coli ATCC 43895, and the researchers concluded that the extracts can be used as a natural preservative for reducing the microbial population. This evidence is preclinical and in vitro. No human clinical trials have been published evaluating the antimicrobial efficacy of G. atroviridis preparations.
G. atroviridis works against inflammation by inhibiting PGE2 and NO. The xanthone content can contribute to the therapeutic effect of this plant extract; xanthones have diverse biological profiles depending on their various structures, including antihypertensive, antioxidative, antithrombotic, and anticancer activities. These are preclinical, in vitro, or animal findings. No published human clinical trials specifically assess G. atroviridis as an anti-inflammatory agent.
The in vitro antitumour-promoting, cytotoxic, and antioxidant activities of two ester derivatives of garcinia acid — previously isolated from the fruits of G. atroviridis — were examined. Based on the inhibition of Epstein-Barr virus early antigen (EBV-EA) activation, compound 1 (IC50: 70 μM) showed much higher (8-fold) antitumour-promoting activity than compound 2 (IC50: 560 μM). Both compounds were nontoxic towards CEM-SS (human T-lymphoblastic leukemia) cells (CD50 > 100 μM), Raji (human B-lymphoblastoid) cells (CD50 > 600 μM), and brine shrimp (LD50 > 300 μM). Although the antitumour-promoting activity was moderate compared with the known antitumour promoter genistein, its non-toxicity suggests potential as chemopreventive agents.
In research on essential oils, a study investigated the anti-proliferative effect of essential oil extracted from leaves of G. atroviridis (EO-L) against the PANC-1 human pancreatic cancer cell line; the IC50 and selective index (SI) values of EO-L were determined as 78 µg/mL and 1.23, respectively; combination index analysis revealed moderate synergism between EO-L and 2-deoxy-D-glucose treatments. This preliminary study demonstrated the potential cytotoxic effect of EO-L to induce 50% cell death in a human breast cancer cell line (MCF-7) at a concentration of 71 µg/mL.
Evidence strength: All anticancer evidence for G. atroviridis is in vitro or cell-line based. There are no human clinical trials evaluating its efficacy in cancer treatment or prevention.
A study aimed to identify the bioactive compounds and evaluate the antidiabetic and cytotoxic potential of G. atroviridis fruit aqueous crude extract; the extract demonstrated promising inhibitory potential. In vitro studies have examined inhibition of α-glucosidase (an enzyme targeted in type 2 diabetes management), and xanthones have the ability to inhibit α-glucosidase according to recent studies. Extracts derived from G. atroviridis fruits have exhibited a range of biological activities, including anti-diabetic effects, as documented in preclinical work. No human clinical trials have been published assessing G. atroviridis specifically for glycemic control.
The G. atroviridis fruit extract exhibited antioxidant properties, scavenging DPPH• and ABTS•+ radicals and chelating copper. It inhibited cellular tyrosinase activity and melanin content in stimulated B16F10 cells, downregulating TYR, TRP-1, phosphorylated CREB, CREB, and MITF proteins along with transcription levels of MITF, TYR, and TRP-2. These findings are preclinical (cell-culture based) and network pharmacology investigations; no human trials exist for this application.
Garcinia extract products currently available in the market are manufactured as conventional oral liquid, tablet, and capsule dosage forms, designed to be taken three times a day to deliver a dose of 1,500–2,800 mg.
In the systematic review of HCA-containing Garcinia RCTs, the dosage of HCA used across included studies ranged from 1 g to 2.8 g daily; the optimal dose of HCA is currently unknown. A nonlinear, significant (P < .05) correlation between the dosage of HCA and body weight loss was found.
The one clinical trial conducted specifically with G. atroviridis-derived HCA administered the supplement to obese women in Thailand for 2 months alongside a 1,000 kcal/day diet, resulting in 2.8 kg weight loss in the treatment group versus 1.4 kg in placebo.
Som-khaek products in Thailand are sold in various forms including capsules, fruit slices, and tea. No pharmacopeial or officially approved dosage monograph has been established for G. atroviridis specifically by authorities such as the WHO, European Pharmacopoeia, or USP as of the available literature.
Researchers investigated the phytochemical composition, safety profiles, and antioxidant and antiobesity effects of methanolic extracts of G. atroviridis in obese female rats; repeated dose toxicity studies were conducted according to the OECD guidelines. MeGa was found to be nontoxic in both male and female rats with an oral lethal dose (LD50) of 2,000 mg/kg.
Despite many studies reporting on the antioxidant and weight reduction properties of the leaves and fruit extracts of G. atroviridis, no comprehensive study is available on the safety of GA extracts according to standard guidelines such as good laboratory practice and OECD. Although herbs are derived from nature, their safety is not guaranteed, and some may have unexpected adverse effects, including acute liver injury and fatal herb–drug interaction. Many herbal products lack scientific evidence on their safety profiles and their respective mechanisms of action before they are marketed.
A significant and well-documented safety concern exists within the Garcinia genus, predominantly attributed to the closely related species Garcinia cambogia (now formally reclassified as Garcinia gummi-gutta). More than 200 adverse events of liver injury resulting from Garcinia consumption have been identified in published review. A total of 34 case reports of Garcinia hepatotoxicity indicated one death and nine liver transplants, with 17 cases receiving CIOMS/RUCAM scores that indicated possible to highly probable causality due to Garcinia dietary supplements; in one case, causality was confirmed by rechallenge.
Garcinia toxicity was consistent with drug-induced liver injury and included elevated serum liver enzymes alanine aminotransferase (ALT) and aspartate aminotransferase with a high ratio of ALT to alkaline phosphatase. Proposed mechanisms of toxicity include genetic predisposition to immune-mediated reactions involving the human leucocyte antigen HLA-B*35:01 allele, induction of hepatocyte oxidative stress and inflammation, and hepatocyte apoptosis caused by the active constituent, hydroxycitric acid, which inhibits mitochondrial ATP-citrate lyase.
Most adverse events reported in Garcinia surveillance databases were related to hepatotoxicity (increased serum liver enzymes, upper abdominal pain, jaundice, and hepatitis) or central nervous system disorders resembling serotonin syndrome (anxiety, headache, and increased heart rate).
It is important to note that the hepatotoxicity literature is largely based on G. cambogia/G. gummi-gutta, and the applicability to G. atroviridis specifically is not established in equivalent depth. Nevertheless, since both species contain HCA and are used in similar supplement formats, the mechanistic concern is pharmacologically relevant.
In vitro experiments showed that the combination of Garcinia cambogia with montelukast (a leukotriene receptor antagonist) greatly reduced cell viability, increased intracellular ROS levels, and affected cytoplasmic Nrf2 expression, suggesting an impairment of antioxidant and cytoprotective defenses. The results support safety concerns about Garcinia-containing supplements and shed light on possible mechanisms underpinning hepatotoxicity. This specific interaction has not been studied for G. atroviridis, but the shared HCA content makes the pharmacological concern relevant across species.
In the broader systematic review of HCA clinical trials, gastrointestinal adverse events were twice as common in the HCA group compared with placebo in one included study. The duration of studies is a limiting factor for long-term safety assessment: given the short duration of studies involving the use of HCA, it is unclear how safe this dietary supplement is on the intermediate and long term.
Clinical case reports of liver injury associated with Garcinia dietary supplements prompted the United States Pharmacopeia (USP) to revise the USP Garcinia family of dietary ingredient monographs to include a cautionary statement regarding potential risk of liver damage. No such specific monograph for G. atroviridis has been published by the WHO, EMA, or EFSA as of the available literature.
G. atroviridis has a long history of curing a variety of diseases, but only a few pharmacological studies have been done to date to support these claims. The extracts or bioactive constituents from G. atroviridis have demonstrated various therapeutic functions — including antioxidant, antimicrobial, anticancer, anti-inflammatory, antihyperlipidemic, and anti-diabetic — in laboratory research. However, the vast majority of this evidence derives from in vitro cell-culture systems, animal models, or computational studies such as molecular docking. Human clinical trial evidence specific to G. atroviridis is limited to a single randomized controlled trial for weight management conducted in Thailand, plus participation in a broader meta-analysis of Garcinia-derived HCA. The overall quality and quantity of clinical evidence for this specific species is insufficient to draw firm conclusions about efficacy for any therapeutic indication beyond short-term modest weight loss support. Further research, particularly large-scale randomized controlled trials with well-defined extracts, standardized doses, and long-term safety monitoring, is needed.
Health conditions that Asam gelugor may help support.
Body systems that Asam gelugor may help support.
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