False Calumba (Coscinium fenestratum): A Comprehensive Reference
1. Nomenclature and Taxonomic Identity
False calumba is the common English name most consistently applied to
Coscinium fenestratum (Gaertn.) Colebr., a large woody climbing liana in the family
Menispermaceae. The plant is known by many names, including tree turmeric, false calumba, colombo weed, Venivel or Weni wel (Sinhala), Weniwelgeta (Sinhala), Dāru Haridrā or Kāleyaka (Sanskrit), Mara Manjal (Tamil and Malayalam), Haem herb (Thai), and Voer Romiet (Khmer), among others.
The "false calumba" epithet arose because the plant became known in Europe as "false calumba," being used as a substitute for the medicinal herb calumba (Jateorhiza palmata). The distinction is important: true calumba is an East African root, while false calumba is an Asian woody climber sharing some of the same isoquinoline alkaloid chemistry — particularly berberine — but otherwise distinct in origin, morphology, and traditional context. In older materia medica texts, false calumba is referenced as an adulterant in the calumba trade, noted by its "elevated, not depressed" center in cross-section, distinguishing it from authentic calumba slices.
It should be noted that a small number of secondary sources apply the term "false calumba" to Cocculus hirsutus (L.) W.Theob., another Menispermaceae member, but this usage is minority and unconfirmed by pharmacopoeial or major botanical authorities. The authoritative identification of false calumba as Coscinium fenestratum is confirmed by PubChem taxonomy and multiple peer-reviewed botanical reviews.
1.1 Synonyms and Botanical Classification
- Accepted name: Coscinium fenestratum (Gaertn.) Colebr.
- Family: Menispermaceae
- Genus: Coscinium
- Common names (selected): False calumba, tree turmeric, yellow vine, colombo weed, Venivel (Sri Lanka), Hamm (Thai)
1.2 Morphology and Natural Habitat
Coscinium fenestratum is a sturdy woody climber with leathery, shiny leaves and bright yellow sap. It is a large woody climber in the family Menispermaceae, characterized by its yellow-colored stems and wood. This liana grows up to 15 meters in length and inhabits moist deciduous and evergreen forests at altitudes ranging from lowland to 1,200 meters.
Its distribution spans southern India, Sri Lanka, Myanmar, Thailand, Vietnam, the Malay Peninsula, and parts of Indonesia, thriving in wet tropical biomes. More specifically, the distribution of this plant is concentrated in Southeast Asia including Sri Lanka, India, Cambodia, Vietnam, Peninsular Malaysia, Sumatra, West Java, Borneo, northeastern Thailand, and Laos. In India, the main source of C. fenestratum trees is in the Western Ghats region, where it grows in crevices of rocks and trees as a climbing plant.
The plant is dioecious, flowering and fruiting in August to October. The plant takes around 15 years to mature and flower, a biological characteristic with significant implications for its conservation status (see Section 7).
2. Forms and Preparations
Dried root and stem are the important parts of this medicinal plant, and propagation of the Venivel plant is primarily through seeds. The stem is cut into pieces and stored in bottles for future use, and it is commonly used in Sri Lanka to make a herbal drink.
In formal traditional medicine systems, infusion and tincture preparations of the stem are widely used in the traditional Ayurvedic system, and it is used as a tea extract with other herbal ingredients as an immunity booster. The root is used in Sri Lanka as an efficient bitter tonic; it has antiseptic properties that are applied in dressing wounds and ulcers, and it is used as a cure for tetanus. In laboratory and preclinical research settings, preparations have taken the form of aqueous extracts, alcoholic (ethanol or methanol) extracts, and isolated fractions — primarily of the stem and root.
Berberine is extracted from plants rich in this compound, such as Coscinium fenestratum, and then formulated into pharmaceutical forms like tablets, capsules, film-coated tablets, eye drop solutions, and topical powders. The Vietnam Pharmacopoeia contains a monograph on berberine chloride in tablet and film-coated forms, reflecting the importance of Coscinium fenestratum as a raw material source.
3. Traditional and Historical Use
3.1 Asian Traditional Medicine Systems
Coscinium fenestratum has a long history as a medicinal plant in the various traditional medicines of the region where it grows, including Ayurveda, Unani, and Siddha medicine in India, Sinhala medicine in Sri Lanka, the Kru Khmer healing traditions in Cambodia, and traditional Vietnamese medicine of Thuốc Nam.
The plant holds significant value in traditional medicine systems such as Ayurveda and Siddha, where bitter stem extracts are employed for their purported anti-inflammatory, antiseptic, febrifuge, and tonic properties, often addressing conditions like wounds, ulcers, diabetes, and inflammatory disorders. The plant has been mainly used for treating diabetes mellitus in the traditional Ayurvedic and Siddha systems of medicine.
Traditionally, Oorali tribes and Kaadar tribes of Idukki and Thrissur districts (Kerala, India) have been using the stem of C. fenestratum to treat rheumatism, jaundice, and skin diseases, respectively. In Sri Lanka, the stem is known as Venivel or Weniwelgeta, and it forms a cornerstone of indigenous Sinhala medicine. The root is used in Sri Lanka as an efficient bitter tonic.
The plant is used for a large variety of diseases and conditions, from fevers and diabetes to celiac disease and snake bites. In Thailand, it is a traditional medicine of the northeastern part of Thailand that has become very popularly used; the plant is a woody climbing shrub with a cylindrical stem, and the stem is claimed for balancing blood pressure, being a detoxifying and antidiabetic agent, and for treatment of hypercholesterolemia.
3.2 European Encounter and Use as a Calumba Substitute
The plant's encounter with European pharmacy occurred through the trade in true calumba (Jateorhiza palmata) from Africa. As European demand for calumba root grew, the plant became known in Europe as "false calumba," being used as a substitute for the medicinal herb calumba (Jateorhiza palmata). European apothecaries recognized that the yellow, berberine-rich stem of Coscinium fenestratum from Ceylon (Sri Lanka) and adjacent regions shared bitterness and alkaloid content with the African root it was meant to replace.
In older pharmacognosy texts, the cross-sectional morphology of false calumba stems — with a slightly elevated center — was used as a physical diagnostic criterion to distinguish it from authentic calumba. The plant's role as an adulterant and substitute is documented in classical materia medica literature from the late 18th and 19th centuries.
4. Key Phytochemical Constituents
4.1 Berberine: The Primary Bioactive
The primary bioactive ingredient in Coscinium fenestratum is berberine, but palmatine and jatrorrhizine are also present. The major chemical constituents present in this plant include alkaloids, flavonoids, and steroids; the most important bioactive compound is berberine, which is the most widely studied plant compound.
Berberine is an isoquinoline quaternary alkaloid that imparts the characteristic bright yellow color to the stem and sap. These uses stem from bioactive compounds including berberine and other alkaloids present in the stems. The stem contains berberine, ceryl alcohol, hentriacontane, sitosterol, palmitic acid, oleic acid, and saponin, together with some resinous material.
4.2 Root Alkaloids
Isolation of tertiary alkaloids, including berlambine, dihydroberlambine, and noroxyhydrastinine from the roots has been reported. Additionally, the roots contain many alkaloidal bioactive components, including berlambine, dihydroberlambine, 12,13-dihydro-8-oxo berberine, tetrahydroberberine, oxyberberine, and noroxy hydrastinine.
4.3 Full Phytochemical Profile
A total of 20 compounds, including 4 novel natural products, were identified or tentatively identified for the first time from Coscinium fenestratum in one HPLC-based profiling study. Phytochemical studies have shown that the main alkaloidal constituent of C. fenestratum is berberine, in addition to a smaller amount of protoberberine.
In a 2025 Springer review, a broader panel of phytochemicals was documented from the related Cocculus hirsutus (a distinct plant sometimes also loosely called "false calumba" in South Asian contexts), while for Coscinium fenestratum specifically, the alkaloid profile and some flavonoid and steroid constituents remain the best-characterized portions of the plant chemistry.
5. Established Mechanisms of Action
5.1 AMPK Activation and Glucose Metabolism
The dominant mechanism attributed to Coscinium fenestratum's pharmacological effects — particularly its antidiabetic activity — is routed through its chief constituent, berberine. As an antidiabetic compound, berberine is known to reduce blood glucose levels, increase insulin secretion, and weaken glucose tolerance and insulin resistance by activating the AMPK pathway.
Berberine is known to reduce blood glucose levels, increase insulin secretion, reduce body weight and lipid levels, attenuate glucose tolerance and insulin resistance by activating the 5′-adenosine monophosphate-activated protein kinase (AMPK) pathway, increase glucagon-like peptide-1 (GLP-1) levels, attenuate reactive oxygen species (ROS) production, reverse mitochondrial dysfunction, and suppress inflammation.
More specifically, berberine inhibits α-glucosidase, maltase, and sucrase activities; reduces the expression of a number of adipocyte-specific genes including FAS, SREBP-1, and PPARγ; and reduces oxidative stress and down-regulates pro-inflammatory responses, all resulting in reduced blood glucose and hemoglobin A1c (HbA1c) levels and increased insulin sensitivity.
Research has shown that AMPK activation may not be the sole pathway. Berberine was still effective at stimulating glucose utilization and lactate production even when AMPK activation was blocked by inhibition of AMPK activity, suppression of AMPKα expression by siRNA, and blockade of AMPK pathway by adenoviruses containing dominant-negative forms of AMPKα1/α2, suggesting additional glucose-lowering mechanisms independent of AMPK.
5.2 Antibacterial Mechanisms
Antibacterial activity of Coscinium fenestratum is mainly due to the presence of berberine. The aqueous and alcoholic extracts of the stem exhibited antibiotic and antimicrobial activities. Nair et al. (2005) reported that the antibacterial activity of C. fenestratum is mainly due to the presence of berberine.
5.3 Hypotensive / Vasorelaxant Mechanisms
The extract showed an endothelium-dependent and independent vasorelaxant activity in isolated aortic rings precontracted with phenylephrine and KCl. The capacity of L-NAME, an inhibitor of nitric oxide synthase, to reduce the vasorelaxant action of the extract indicates the involvement of nitric oxide in the plant's blood pressure-lowering effect.
5.4 Antioxidant Mechanisms
The antioxidant activity of Coscinium fenestratum could be due to the presence of berberine and phenolic compounds. Animal studies showed that diabetic rats administered alcoholic extract of Coscinium fenestratum displayed significant increases in enzymatic antioxidants, including catalase, glutathione peroxidase, glutathione synthetase, peroxidase, and superoxide dismutase.
6. Scientific Evidence by Area of Use
It is unclear if all these medicinal uses of C. fenestratum are backed up by science, but laboratory tests have shown that the plant has potent bioactive properties. A critical appraisal of the evidence must distinguish between in vitro, animal, and human data — and acknowledge that for this plant specifically, limited clinical evidence exists for Coscinium fenestratum in humans, with no randomized controlled trials evaluating the plant extract in isolation. Most pharmacological investigations remain confined to in vitro and animal models, leaving the translation of preclinical findings — such as anti-inflammatory, antidiabetic, and hypotensive effects — to human applications unverified through dedicated human studies.
6.1 Diabetes and Blood Glucose Regulation
Evidence strength: Preclinical (animal/in vitro) — no isolated human RCT data.
Hypoglycemic activity was exhibited by the alcoholic stem extract of Coscinium fenestratum for the treatment of diabetes mellitus evaluated in streptozotocin-nicotinamide induced type 2 diabetic rats, and also by the aqueous stem extract in non-insulin dependent diabetic rats.
A PMC-indexed study examined effects in streptozotocin-induced animal models: the anti-hyperglycemic effects of Coscinium fenestratum on plasma glucose levels were studied in both normal and streptozotocin-induced diabetic rats by performing an oral glucose tolerance test (OGTT) with several kinds of sugar, including glucose, maltose, and sucrose. In normal rats, Coscinium fenestratum inhibited the increase of plasma glucose levels in all three kinds of sugar-loaded rats in a dose-dependent manner. In diabetic rats, Coscinium fenestratum significantly decreased plasma glucose levels in glucose- and maltose-loaded rats.
An in silico and in vitro study confirmed berberine as the antidiabetic agent: berberine was detected and identified by TLC with an Rf of 0.37 and was found to be responsible for the antidiabetic activity, and the binding energy of berberine in an AutoDock study was −7.84, demonstrating significant antidiabetic properties of the ethanol extract from C. fenestratum seeds. The authors noted, however, that additional research is required to ascertain the potential synergistic or antagonistic effects among various C. fenestratum seed extract constituents.
Regarding the broader berberine literature (which underlies much of the rationale for false calumba's antidiabetic use), biochemical studies have shown that berberine improves insulin sensitivity and insulin secretion; additionally, berberine induces glucose metabolism by activating AMPK signaling and inhibition of inflammation; and a series of studies have demonstrated the antidiabetic potential of berberine at in vitro, preclinical, and clinical trial levels. This body of berberine-specific evidence does not, however, translate directly to validated clinical use of C. fenestratum extract itself.
6.2 Antimicrobial Activity
Evidence strength: In vitro and limited animal data. No human clinical trials.
The aqueous and alcoholic extracts of the stem exhibited antibiotic and antimicrobial activities. Selective inhibitory action on Clostridium tetani was observed at a concentration of 6.25 mg mL⁻¹.
In a study specifically investigating gonorrhea-causing bacteria, bioautographic assay revealed that berberine was the active compound of Coscinium fenestratum against Neisseria gonorrhoeae. The average MIC values of purified berberine against Neisseria gonorrhoeae ATCC 49226 and 11 clinical isolates were 13.51 and 17.66 µg/ml, respectively, while the average MIC value of the crude extract of Coscinium fenestratum against all clinical isolates was about 56.39 µg/ml.
In clinical tests in Vietnam, the extract also showed distinct activity on Staphylococcus aureus and Streptococcus hemolyticus, which may cause inflammation and infection especially in women after childbirth. (Note: this reference appears to describe clinical-setting microbiological testing rather than a controlled human trial.)
6.3 Blood Pressure and Cardiovascular Effects
Evidence strength: Animal studies only. No human RCT data for the whole plant extract.
The present study demonstrates that C. fenestratum extract is effective in reducing blood pressure in anesthetized normotensive rats, with this effect shown to be dose-related and rapid in onset. A 50% ethanolic extract of the stem material has been found to possess hypotensive action in anesthetized dogs, rats, and guinea pigs in a dose-related pattern.
6.4 Antioxidant and Hepatoprotective Effects
Evidence strength: Preclinical only.
Hypotensive and hepatoprotective actions of the plant have been reported. Antioxidant properties have been demonstrated in animal models: diabetic rats treated with the alcoholic extract showed significant restoration of enzymatic antioxidant status. The extracts significantly increased the body weight of rats in one neurotoxicity-focused study. The hepatoprotective activity, while reported, has not been confirmed in human clinical trials.
6.5 Anticancer / Antiproliferative Effects
Evidence strength: In vitro cell-line studies only. No human data.
The methanol and methanol-water extracts of Coscinium fenestratum showed strong and selective antiproliferative activities against two kinds of lung carcinoma cells, A549 and LLC. The methanol extract had an EC50 against LLC cells of 1.65 mg/ml; the methanol-water extract had EC50 values against A549 and LLC cells of 2.88 and 2.84 mg/ml, respectively. The methanol and methanol-water extracts also showed antiproliferative activities against B16-BL6 cells.
Berberine obtained from C. fenestratum has an antiproliferative effect on human non-small cell lung adenocarcinoma (NCI-H838 cell line), colorectal cancer cells, and acute myeloid leukemia (HL-60 cell line). Different cancer cells respond differently to C. fenestratum, and these findings remain confined to laboratory models.
6.6 Anti-Malarial Activity
Evidence strength: In vitro only.
Coscinium fenestratum is widely used as a medicinal plant in many Southeast Asian countries for fever, muscle pain, abdominal pain, inflammation, and malaria. Laboratory screening for anti-malarial activity was conducted in a study of Vietnamese traditional medicinal plants, with methanol and methanol-water extracts evaluated in vitro against chloroquine-resistant Plasmodium falciparum strain FCR-3.
6.7 Digestive and Tonic Uses
Evidence strength: Traditional use; no controlled clinical data.
The stem is used for dyspepsia, and as a febrifuge. This use parallels the bitter tonic action attributed to the plant across multiple traditional systems, and aligns with the plant's historical role as a substitute for true calumba — itself a gastrointestinal bitter.
6.8 Human Clinical Evidence: Polyherbal Formulation
Evidence strength: One small open-label RCT — indirect and limited.
One small-scale open-label randomized controlled trial assessed a polyherbal formulation known as Link Samahan®, which includes C. fenestratum stem extract alongside ingredients like Coriandrum sativum, Cuminum cyminum, and others, for its impact on upper respiratory symptoms in 98 healthy volunteers over 3 months. This polyherbal trial does not constitute evidence for C. fenestratum in isolation and cannot be used to attribute outcomes to this plant specifically.
7. Body Systems and Health Areas of Association
Based on traditional use records and preclinical research, Coscinium fenestratum has been associated with the following body systems and health areas:
- Endocrine / Metabolic system: Blood glucose regulation, antidiabetic activity (animal models), lipid modulation attributed to berberine.
- Digestive system: Bitter tonic for dyspepsia; traditional use for gastrointestinal complaints, diarrhea, and as a digestive stimulant.
- Cardiovascular system: Blood pressure reduction, vasorelaxation (animal models), hypotensive activity.
- Immune / Antimicrobial: Antibacterial activity against C. tetani, N. gonorrhoeae, S. aureus, and S. hemolyticus (in vitro).
- Hepatic system: Hepatoprotective and antioxidant effects (animal models); traditional use for jaundice.
- Musculoskeletal system: Traditional use for rheumatism and joint conditions.
- Dermatological: Traditional use for wounds, ulcers, and skin diseases; antiseptic application to wounds.
- Anti-infective / Antipyretic: Widespread traditional use for fevers; traditional use in malaria-endemic regions.
- Oncology (experimental): In vitro antiproliferative activity against multiple cancer cell lines; no human data.
This plant exerts several pharmacological effects including antidiabetic, anticancer, antibacterial, antimalarial, antioxidant, antihypertensive, antiulcer, neuroprotector, and wound healing activities, based on a review of the pharmacological literature — though the evidentiary basis for these effects is predominantly preclinical.
8. Dosage: Forms and Amounts Reported in Studies
No standardized human dose has been established for Coscinium fenestratum extract in isolation. The following doses are drawn exclusively from preclinical and in vitro research as reported in published sources:
- The alcoholic extract of the Coscinium fenestratum stem was administered orally to rats at dosages of 5, 10, and 20 mg/kg body weight, once daily for 14 days in a neurotoxicity study.
- In the acute toxicity test, an oral dose of 5,000 mg/kg of the C. fenestratum extract did not produce mortality or significant changes in the general behavior of animals and gross appearance of internal organs of rats.
- No acute toxicity was detected at the dose of 5 g of Coscinium fenestratum crude extract per kilogram in animal testing related to antimicrobial activity.
- The average MIC values of purified berberine against Neisseria gonorrhoeae ATCC 49226 and 11 clinical isolates were 13.51 and 17.66 µg/ml, respectively, while the average MIC value of the crude extract of Coscinium fenestratum against all clinical isolates was about 56.39 µg/ml in vitro.
- The EC50 of the methanol extract against LLC lung carcinoma cells was 1.65 mg/ml; the methanol-water extract had EC50 values against A549 and LLC cells of 2.88 and 2.84 mg/ml, respectively, in vitro.
No human clinical dosage information specific to Coscinium fenestratum extract has been established in controlled trials. Any dose used in commercial preparations reflects traditional practice or extrapolation, not clinical validation.
9. Safety, Toxicology, and Drug Interactions
9.1 Human Safety Data
No specific side effects have been documented in human clinical trials, as such studies are lacking for C. fenestratum. Regulatory safety review has been conducted at an institutional level: Section 3.9 of the UK Committee on Toxicity's draft scientific opinion addresses the safety of Coscinium fenestratum (root, stem), for which the following information was considered: characterization of the plant, no information on genotoxicity was available, acute toxicity, general toxicity, and neurotoxicity.
A parallel EFSA-level assessment of berberine-containing plant preparations is relevant: a genotoxicity concern for berberine was identified in in vitro assays; the toxicity profiles of preparations of the other plant species raise concerns, and with insufficient data, no safe intake can currently be established for any of these berberine-containing plant preparations.
9.2 Berberine-Derived Safety Concerns
Because berberine is the principal bioactive of false calumba, the known safety profile of isolated berberine is directly relevant. The high berberine content raises concerns for gastrointestinal disturbances (e.g., nausea, diarrhea) or hypotension at elevated doses, analogous to isolated berberine effects.
Some individuals may experience side effects such as nausea, vomiting, headaches, dizziness, tachycardia (rapid heart rate), and low blood pressure with berberine.
9.3 Neurotoxicity Signal
One animal study raises a specific neurotoxicity concern: a study to observe the effect of Coscinium fenestratum stem on neurotoxicity and neurobehavior was carried out in various brain areas of an animal model. The alcoholic extract was administered orally to rats at dosages of 5, 10, and 20 mg/kg body weight, once daily for 14 days. The extracts induced neurotoxicity in the cerebra of treated animals at these doses. The interpretation and human relevance of this finding require further investigation.
9.4 Drug Interactions
Key limitations include the scarcity of long-term toxicity data, absence of human pharmacokinetic and safety trials, and variability in extract composition due to wild sourcing, complicating standardization and risk assessment. Potential herb-drug interactions, particularly with antihypertensives or CYP3A4 substrates via berberine, remain uncharacterized.
Based on known berberine pharmacology, berberine can interact with medications; the riskiest combinations are with diabetes drugs, blood pressure medicines, heart rhythm medications including digoxin, statins, and blood thinners, and it may also affect antibiotics, antifungals, and sedatives. These interactions are inferred from the berberine constituent rather than confirmed specifically for whole-plant Coscinium fenestratum preparations.
9.5 Acute Toxicity (Animal)
In acute animal toxicity testing, an oral dose of 5,000 mg/kg of the C. fenestratum extract did not produce mortality or significant changes in the general behavior of animals and gross appearance of internal organs of rats, suggesting a wide acute margin of safety in rodent models — though subchronic and chronic toxicity data in humans remain absent.
10. Conservation Status
The growing demand for false calumba as a source of berberine, combined with slow plant growth, has driven significant wild population decline. Due to destructive collection, overexploitation, and habitat loss, the plant is on the verge of extinction in the wild. It is categorized as critically endangered in India, vulnerable in Vietnam, and indeterminate in Sri Lanka and Malaysia.
Its critically endangered status is due to overexploitation of the plant for the supply of the raw drug market and its relatively slow growth rate, which results in depletion of species in the wild. Because of the growing populations and industrialization of Asia, the demand for Coscinium fenestratum has increased manifold in the last decades, decimating the natural populations. Coscinium fenestratum is assessed as Data Deficient (DD) on the IUCN Red List, reflecting a lack of sufficient quantitative data globally, though national-level assessments in key range states classify it as critically endangered.
The C. fenestratum plant species has not been cultivated at scale. However, most of its populations have been heavily exploited in their natural habitats. The 15-year minimum growth time to flowering creates a significant regeneration bottleneck that amplifies the impact of overharvesting.
11. Summary of Evidence Quality
Although widely used in traditional medicines, only a few studies have been performed related to chemical constituents. Most of the biological activity evaluations were carried out using in vitro evaluation methods and only a few studies were carried out in animal models. In the future, properly designed in vivo and clinical studies are necessary to evaluate the pharmacological activities along with bioassay-guided studies to isolate and identify the active constituents.
In summary, the pharmacological rationale for false calumba's traditional uses is biologically plausible and supported by consistent preclinical evidence, primarily mediated through berberine. However, the absence of controlled human clinical trials for the whole-plant extract, the neurotoxicity signal in animal studies, the EFSA-level safety concern about establishing a safe intake for berberine-containing preparations, and the plant's critically endangered status in key habitats all constitute important factors for any evaluation of this ingredient's role in modern dietary supplements.
References
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