Spiked spiral flag

Spiked Spiral Flag (Costus spicatus): A Comprehensive Reference

1. Identity and Botanical Classification

Spiked Spiral Flag is the common English name most widely applied to Costus spicatus (Jacq.) Sw., a rhizomatous, herbaceous perennial plant belonging to the family Costaceae (order Zingiberales). It is a species of flowering plant in the Costaceae family. The genus Costus is the largest in the family, with about 150 species of mainly tropical distribution. The plant is related to the gingers and was once part of the Zingiberaceae family; however, the Costus species and kin have been reclassified into their own family, Costaceae.

The species C. spicatus is native to the American tropics and is commonly known as spiked alpinia, spiked spiral flag, Indian head ginger, and sour cane. In Spanish and Portuguese, the plant is commonly known as caña de Cristo, caña agria, caña de jabalí, caña de puerco, caña de venado, costo de Arabia, canna de macaco, and canna do brejo. Other English-language common names include insulin plant, insulin flower, painted spiral ginger, sour ginger, spiral flag, spotted spiral ginger, steladder, and stepladder plant.

C. spicatus is native to some islands of the Caribbean, including Dominica, Guadeloupe, Hispaniola, Martinique, and Puerto Rico. There has been some confusion about the native range; Kew Botanical Gardens lists it as also native to Mexico. This rhizomatous herb is further distributed across tropical Mexico, Central America, western South America (Colombia, Ecuador, and Peru), and the Caribbean region, and is also cultivated in India. It is found in tropical and subtropical moist lowland forests, tropical and subtropical moist montane forests, and tropical and subtropical dry forests.

C. spicatus is an evergreen perennial that grows up to 1 m tall, preferring partial shade and well-drained soil. The plant is used as an ornamental, for medicinal purposes, and for erosion control. In botanical literature, it is important to note that Costus woodsonii has often been misidentified as Costus spicatus. The plant should also be distinguished from the closely related Costus pictus D. Don (sometimes called Costus igneus), which shares the common name "spiral flag" and "insulin plant" and is the subject of much overlapping ethnobotanical and pharmacological literature. Costus igneus, also known as Costus pictus, spiral flag, painted spiral ginger, step ladder, fiery costus, or insulin plant, is a plant native to Eastern Brazil that has grown and been consumed widely throughout the world.

2. Traditional and Historical Use

2.1 Mesoamerican and Mexican Traditions

The main uses for this plant in Mexican traditional medicine are to treat diabetes, urinary problems, venereal disease (gonorrhea), as a diuretic, and to treat kidney cancer. Among the Totonac people of Mexico, the plant is employed to address kidney afflictions and hepatitis, with infusions prepared from its leaves and stems. According to the Lacandon Maya, Costus spicatus increases soil fertility, is edible, and is a medicine.

2.2 Caribbean Traditions

In Trinidad, it has been used to treat sexually transmitted infections. In São Tomé, it is known to be used as a diuretic. In Dominican folk medicine, an herbal tea made from the leaves of C. spicatus is used for diabetes (hyperglycemia). Common names in the Antilles include cumani, gengibre cimarron, gengibrillo, canne d'eau, and la canne de rivière.

2.3 South American (Brazilian) Traditions

Costus spicatus Swartz (Costaceae), popularly known as "cana-do-brejo" in Brazil's northeast, is a medicinal plant found in wet coastal forests. In folk medicine, an infusion of the aerial parts is taken to treat inflammation and pain. It is a medicinal plant found in wet coastal forests and is commonly called 'cana-do-brejo' in Brazil.

2.4 Broader Tropical Use

Various species belonging to the genus Costus are used for food, paper, or medicine throughout the American, Asian, and African tropics. C. spicatus young stems are edible. Initially, Costus pictus (the closely related species) was used in traditional medicine because of its diuretic, carminative, and antiseptic properties. The leaves served as a good source for the treatment of diabetes, while rhizomes were used for a wide range of ailments.

2.5 Preparations Used in Traditional Contexts

The fresh leaf can be chewed and consumed without preparation, or the juice can be extracted after crushing and pressing, with a usual dose of one to two fresh leaves per day. The most common preparation is an aqueous infusion-decoction of fresh or dried leaves (one leaf per day), or leaf powder (about 3 g of powder per day, the equivalent of a teaspoon of powder). Preparations typically involve aqueous extracts from rhizomes, boiled or steeped to create teas or infusions for oral consumption, though dosages remain unstandardized across studies. Traditional use incorporates leaves, stems, and rhizomes as a diuretic and tonic.

3. Phytochemistry: Key Constituents and Active Compounds

3.1 Overview of Chemical Classes

Phytochemical derivatives of the plant include flavonoids, terpenoids, saponins, steroids, and alkaloids, which are the active constituents that might be contributing to pharmacological effects. The presence of diverse bioactive constituents such as flavonoids, alkaloids, tannins, phenolic compounds, and glycosides contributes to its pharmacological potential. Phytochemical investigation of rhizomes of Costus spicatus has revealed the presence of flavonoids, flavo-sugars, saponins, and sapogenins.

3.2 Specific Compounds Identified by Chromatographic Analysis

The crude extract of Costus spicatus was profiled using high-resolution GC–MS and LC-MS/MS techniques to determine possible bioactive compounds vital to antioxidant activity. A total of 52 and 63 bioactive compounds were detected in GC–MS chromatograms using different solvents (methanol and ethanol) in C. spicatus leaf extracts.

The compounds that occupied the major percentage in the methanolic extract are i-propyl 9-octadecenoate (Z) (5.44%), 13-docosenamide (Z)- (11.31%), gamma-sitosterol (21.72%), stigmasterol (9.25%), methylprednisolone acetate (3.22%), alpha-tocospiro B (3.18%), and 9,19-cyclolanostan-3-olacetate (3 beta) (2.38%).

Bioactive compounds confirmed in both extracts with neuroprotective effects via literature studies include cholestan-3-amine, loliolide, stigmasterol, methylprednisolone acetate, succinimide, fumaric acid, beta-tocopherol, and gamma-tocopherol.

The main metabolite classes identified in extract analysis via LC-DAD-MS were flavonoids, steroidal saponin, and organic acids. Compounds identified include pentonic acid and citric acid.

3.3 Bioactive Polysaccharides

Three polysaccharides—glucans with mean molecular weights of 7.50×10⁵, 4.25×10⁵, and 2.15×10⁵—were isolated from fresh stems of Costus spicatus by fractionation. Chemical and spectroscopic studies indicated that they have a highly branched glucan-type structure composed of α-(1→4)-linked d-glucopyranose residues with (1→3) and (1→6) branching points. These polysaccharides inhibit capillary permeability and demonstrate phagocytosis-stimulating properties.

A similar branched α-glucan was also found in stems of Costus spicatus. These branched α-glucans were biologically active, enhancing phagocytosis in vivo, inhibiting capillary permeability, and exhibiting anti-inflammatory activity.

3.4 Compounds with Antidiabetic Relevance

GC-MS analysis of an aqueous extract of Costus spicatus rhizome revealed the presence of three compounds with a higher binding affinity for all enzymes studied compared to metformin. The compounds interacted with key amino acid residues crucial to the enzymes' activities. Lyxo-d-manno-nononic-1,4-lactone was identified as a potential multi-target inhibitor of PEPCK, α-amylase, β-glucosidase, and FBPase.

3.5 Antimicrobial-Relevant Compounds

The aqueous extract of C. spicatus possessed the highest antioxidant activity for DPPH scavenging activity and lipid peroxidation inhibition assays, whereas the alcoholic aqueous extract showed superior efficacy for hydroxyl radical scavenging activity. A 2024 study using supercritical CO₂ extraction with ultrasound pretreatment of leaves yielded bioactive compounds including linolenic acid (62.52%), palmitic acid, friedelin, and flavonoids, demonstrating antimicrobial activity against Gram-positive bacteria (MIC 62.5–500 µg/mL).

4. Mechanisms of Action

4.1 Anti-inflammatory and Analgesic Mechanisms

The branched α-glucans isolated from stems of Costus spicatus were biologically active: they enhanced phagocytosis in vivo, inhibited capillary permeability, and exhibited anti-inflammatory activity. These polysaccharide-mediated effects on immune cell activity represent one mechanism underlying the plant's anti-inflammatory reputation.

4.2 Antidiabetic Mechanisms

Phyto-compounds from aqueous extract of Costus spicatus rhizome were investigated for their inhibitory activities against PEPCK (phosphoenolpyruvate carboxykinase), α-amylase, β-glucosidase, and fructose-1,6-bisphosphatase as potential novel therapeutic targets for insulin resistance treatment. Inhibition of α-amylase and β-glucosidase would be expected to slow carbohydrate digestion and blunt postprandial glycemia, a mechanism shared by established antidiabetic agents such as acarbose.

4.3 Nephroprotective Mechanisms

PCSL (polyphenol-rich extract of Costus spicatus leaves) showed significant (p < 0.05) nephroprotective potential against cisplatin-induced nephrotoxicity in HEK cells. Moreover, in vivo studies revealed significant (p < 0.05) amelioration in serum biochemical markers and antioxidant enzymes against cisplatin-induced nephrotoxicity. The antilithiatic (kidney stone prevention) activity has been associated with inhibition of crystal growth and aggregation.

4.4 Antioxidant Mechanisms

The plant's antioxidant capacity is attributed to its polyphenol and tocopherol content. The aqueous extract possesses notable DPPH free-radical scavenging and lipid peroxidation inhibition activity. Stigmasterol, beta-tocopherol, and gamma-tocopherol—major identified constituents—are known to contribute to oxidative stress attenuation.

5. Scientific Evidence by Area of Use

5.1 Renal Protection and Diuresis

Several ethnobotanical studies have suggested diuretic and renoprotective effects of C. spicatus, but until recently no published data had validated this traditional use. A 2020 preclinical study sought to fill this gap: the study investigated the diuretic and nephroprotective effects of C. spicatus in Wistar rats and assessed its antilithiatic activity by in vitro crystallization. The study showed that extract from Costus spicatus (ESCS) has important nephroprotective effects against rhabdomyolysis-induced acute kidney injury in rats. Moreover, the plant extract exerted a dose-dependent antilithiatic effect, reducing both crystal growth and aggregation in urine samples from healthy humans. The data were interpreted as supporting the traditional use of C. spicatus for the treatment of kidney diseases.

A separate study published in a Springer journal examined the nephroprotective effects further: Costus spicatus (spiked spiralflag ginger) is traditionally utilized for antidiabetic, antihyperlipidemic, diuretic, antimicrobial, and anticancer properties. The study tested the nephroprotective effect of the polyphenol-rich extract of Costus spicatus leaves (PCSL) using preclinical models, including the HEK cell line and Wistar albino rats against cisplatin-induced toxicity.

Evidence strength: Evidence for renal/diuretic effects is preclinical only (rodent models and in vitro crystallization studies). No controlled human clinical trials have been published on these endpoints. The antilithiatic work with human urine samples is in vitro, not a clinical trial.

5.2 Blood Glucose and Antidiabetic Activity

Costus spicatus (Insulin plant) rhizome has been used in folkloric medicine to treat diabetes mellitus and other associated pathological manifestations. Alloxan, dexamethasone, and streptozotocin-induced diabetic rat models, as well as in vitro studies, have shown that this plant extract possesses antidiabetic properties.

A study modeling antidiabetic efficacy in histopathological analysis showed significant β-cell regeneration in treated groups, particularly at the higher dose, indicating the potential of Costus pictus to restore pancreatic function. The study highlights the therapeutic efficacy of Costus pictus in managing hyperglycemia and mitigating metabolic dysfunctions associated with diabetes. The plant's antioxidant and anti-inflammatory properties likely contribute to its beneficial effects.

In silico work published in PMC revealed that GC-MS analysis of an aqueous extract of Costus spicatus rhizome identified three compounds with higher binding affinity for all enzymes studied than metformin, with Lyxo-d-manno-nononic-1,4-lactone identified as a potential multi-target inhibitor with reasonable pharmacokinetic properties and no significant predicted toxicity.

In Dominican folk medicine, an herbal tea made from the leaves of C. spicatus is used for diabetes (hyperglycemia). Despite these signals, further studies are needed to understand the detailed mechanisms of action, optimize dosing, and evaluate clinical efficacy in humans.

Evidence strength: Preliminary. Antidiabetic evidence consists predominantly of animal (rodent) models and in silico (computational docking) analyses. No published randomized controlled trials in humans on C. spicatus for glycemic control were identified in the peer-reviewed literature.

5.3 Antinociceptive (Pain-Relieving) and Anti-inflammatory Activity

A study published in the journal Pharmaceutical Biology examined these properties directly: The methanol extract obtained from the leaves of Costus spicatus (MECs) was evaluated for antinociceptive and anti-inflammatory activities. Analgesic and anti-inflammatory activities were studied by measuring nociception through acetic acid, formalin, and hot-plate tests, while inflammation was induced by carrageenan. All experiments were conducted with experimental animals. Following oral administration, MECs (100, 200, and 400 mg/kg) significantly reduced the number of writhes in the writhing test and the number of paw licks during phases 1 and 2 of the formalin test when compared to the control group.

Previous pharmacological studies that used different preparations of C. spicatus have reported analgesic and anti-inflammatory effects.

Evidence strength: Preclinical only. All analgesic and anti-inflammatory studies available are conducted in rodent models using oral gavage administration. No human trials exist.

5.4 Antimicrobial and Antifungal Activity

Antifungal and antimicrobial activities of C. spicatus have been reported. Characterization of extracts of Costus spicatus has permitted identification of compounds with antimicrobial activity including N-[4-bromo-n-butyl]-2-piperidone and 4-nitro-1H-imidazol, as well as compounds with antifungal activity such as 2H-pyran-2-one and 5-methyl-2-furfural. Costus spicatus possesses antimicrobial properties, and both the extract obtained by maceration and the extract obtained with hexane demonstrated the inhibitory capacity against evaluated microorganisms.

For the closely related Costus speciosus, a BMC Complementary Medicine study found: Based on fractionation results, two active sesquiterpenoids, costunolide and eremanthin, were isolated from the hexane extract. Both compounds were tested against bacteria and fungi using the micro broth dilution method; both the compounds inhibited the tested fungi but not the bacteria.

There is also evidence of antiprotozoal activity in several extracts of the Costus genus.

Evidence strength: In vitro only. Antimicrobial studies are exclusively laboratory-based (agar diffusion, broth dilution). No human clinical studies on infections have been conducted.

5.5 Antioxidant Activity

The aqueous extract of C. spicatus possessed the highest antioxidant activity for DPPH scavenging activity and lipid peroxidation inhibition assays, whereas the alcoholic aqueous extract showed superior efficacy for hydroxyl radical scavenging activity. The presence of polyphenols, tocopherols, and phenolic acids provides a plausible phytochemical basis for these findings. These antioxidant effects are proposed as contributing mechanisms to the plant's observed cytoprotective, nephroprotective, and antidiabetic properties in preclinical models.

Evidence strength: In vitro only. Antioxidant assays are laboratory-based. Clinical relevance in humans is undetermined.

5.6 Neuroprotective Potential

In silico molecular docking found that four compounds from C. spicatus exhibited promising binding affinities with predicted binding sites on alpha-synuclein. Notably, Androsta [17-16-b] furan-5′-imine, 4′-methylene-3-methoxy-N-cyclohexyl- showed the highest docking interaction score of −7.4, indicating a strong binding affinity. These findings suggest that this plant may possess neuroprotective properties, warranting further investigation.

Evidence strength: Highly preliminary; in silico (computational) only. No cell-based, animal, or human studies on neuroprotective endpoints have been published for this species.

5.7 Antiprotozoal Activity

Several extracts of Costus spicatus with antiprotozoal activity have been identified. This work contributes to validating some traditional uses and opens subsequent investigations on active compound isolation and identification.

Evidence strength: Preliminary; in vitro only. Results have not been confirmed in animal models or human trials.

6. Body Systems and Health Areas Associated with Costus spicatus

• Renal / Urinary system: Diuresis, nephroprotection, antilithiatic (kidney stone inhibition), urinary tract infections — among the best-supported in preclinical literature.
• Metabolic / Endocrine system: Blood glucose regulation, antidiabetic and anti-hyperglycemic activity — predominantly preclinical evidence via rodent models and in silico studies.
• Immune / Inflammatory system: Anti-inflammatory activity, phagocytosis enhancement via glucan polysaccharides — evidence from in vitro and rodent studies.
• Musculoskeletal / Nervous system (pain): Antinociceptive (analgesic) activity — preclinical rodent studies only.
• Microbiology / Infectious disease: Antibacterial, antifungal, and antiprotozoal effects — exclusively in vitro.
• Neurological system: Neuroprotective potential based on computational docking only — no wet-lab confirmation.
• Antioxidant / Cytoprotective: DPPH and hydroxyl radical scavenging, lipid peroxidation inhibition — in vitro.
• Reproductive / Sexual health: Traditional use for sexually transmitted infections; no pharmacological validation specific to reproductive endpoints for C. spicatus has been identified in the peer-reviewed literature.

7. Dosage Forms and Reported Dosages

The medicinal parts of Costus plants commonly called "insulin plants" are especially the leaves, and to a lesser extent the stems and rhizomes, and the essential oil of the whole plant.

The following dosages or forms have been documented in the scientific or patent literature:

• Fresh leaf: chewed and consumed without preparation; juice can be extracted after crushing and pressing, with a usual dose of one to two fresh leaves per day.
• Aqueous infusion-decoction: one fresh or dried leaf per day, or leaf powder of approximately 3 g per day (the equivalent of a teaspoon of powder).
• In rodent antinociceptive studies, oral doses of 100, 200, and 400 mg/kg of methanol extract were tested.
• In streptozotocin-induced diabetic rat studies involving the related species Costus pictus, doses of approximately 50 to 200 mg/kg/day were used. The corresponding proposed dose for humans in patent documentation was approximately 500 mg/day to 2000 mg/day of an extract. (These figures are from patent literature involving Costus pictus and are not derived from completed human clinical trials.)
• Described dosage forms in patent filings include capsule, tablet, granule, sachet, powder, paste, ointment, infusion, injection, ampoule, solution, suspension, emulsion, pill, and sustained-release formulations.

Note on standardization: Dosages remain unstandardized across studies. No regulatory body (FDA, EMA, WHO) has established a formal recommended daily intake or therapeutic dose for Costus spicatus, and the plant is not included in major pharmacopeial monographs (USP, European Pharmacopoeia, WHO monographs) as of the time of writing.

8. Safety Considerations and Potential Interactions

8.1 Acute Toxicity Data

The only published acute toxicity data available in the peer-reviewed literature relates primarily to the closely related species Costus pictus (which shares the common name). The lethal dose of Costus pictus D. Don methanolic leaf extract was fixed as greater than 2000 mg/kg body weight in Wistar rats. No obvious change was observed in feeding habits, weight, hematology, biochemical parameters, or histopathology. The methanolic leaf extract of Costus pictus D. Don was observed to be apparently safe when given orally in albino Wistar rats.

8.2 Chronic Toxicity and Hepatotoxicity Concerns

A study on a different species of the Costus genus—Costus afer Ker Gawl—reported that the aqueous extract of its leaves may cause potential hepatotoxicity for chronic use of more than 28 days, but was non-toxic to the kidneys of the male albino Wistar rat. No equivalent chronic toxicity study specifically in C. spicatus in humans has been published. The longer-term side effects of this plant are largely unknown. More research is needed.

8.3 Drug Interactions

Taking herbal Costus may interact with other medications, including potential contraindications with concurrently used drugs. Caution is advised due to potential interactions with anti-diabetic medications, and contraindications during pregnancy or lactation are noted, despite preclinical data showing no acute toxicity up to 2000 mg/kg. Because C. spicatus extracts have demonstrated hypoglycemic activity in animal models, concurrent use with insulin or oral hypoglycemic agents (e.g., metformin, sulfonylureas) may theoretically potentiate blood glucose lowering, though this interaction has not been formally characterized in human studies.

8.4 Absence of Human Safety Studies

There is no available safety study in the literature for Costus species use in humans that provides rigorous pharmacovigilance data. The evidence base for safety in humans therefore consists of anecdotal traditional use over generations rather than formal clinical safety trials. Formal evidence of hepatotoxicity, nephrotoxicity, or reproductive harm in C. spicatus specifically does not currently exist in the peer-reviewed literature, but the absence of evidence should not be conflated with evidence of absence, given the very limited human research conducted.

8.5 Pregnancy and Lactation

Contraindications during pregnancy or lactation are noted in available documentation, consistent with general caution regarding unstudied botanicals in these populations.

8.6 Regulatory Status

These plants are not yet part of the pharmacopeias of Western medicine and have not been evaluated or approved by the U.S. Food and Drug Administration (FDA), the European Medicines Agency (EMA), or subject to a positive monograph from the Committee on Herbal Medicinal Products (HMPC). Costus spicatus is listed on Brazil's National List of Medicinal Plants of Interest to the SUS (RENISUS), which is the National List of Medicinal Plants of Interest to the SUS (Renisus), a Brazilian government framework that identifies candidate plants for further research and possible integration into the public health system, but does not constitute a drug approval.

9. Taxonomic and Nomenclatural Notes

Researchers and consumers encountering "spiked spiral flag" in supplement contexts should be aware of significant taxonomic complexity in the Costus genus. The name "spiral flag" or "spiked spiral flag" is applied variably to C. spicatus, C. pictus, and C. igneus, which are distinct biological species with partially overlapping but not identical phytochemical profiles and pharmacological data. The family Costaceae consists of four genera and about 200 species. Much published pharmacological literature labeled "insulin plant" or "spiral flag" may refer to Costus pictus D. Don rather than C. spicatus Jacq. Sw., and the two should not be assumed interchangeable when evaluating scientific evidence or selecting a preparation. Additionally, in botanical literature, Costus woodsonii has often been misidentified as Costus spicatus, adding a further layer of potential confusion in both folk and scientific sources.

10. Summary of Evidence Quality

• Traditional use: Well-documented across multiple cultures (Mexican, Totonac Maya, Lacandon Maya, Caribbean, Brazilian) for urinary, antidiabetic, anti-inflammatory, and antimicrobial purposes.
• Phytochemistry: Reasonably well characterized via GC-MS and LC-MS/MS in recent studies; major classes include flavonoids, sterols (stigmasterol, gamma-sitosterol), tocopherols, steroidal saponins, organic acids, and bioactive polysaccharides (branched α-glucans).
• Mechanisms of action: Plausible mechanistic hypotheses for most traditional uses, supported by in vitro and in silico data; no clinical mechanism-of-action studies in humans.
• Clinical (human) evidence: Currently absent. All pharmacological evidence is from in vitro cell assays, rodent models, or computational studies. No peer-reviewed randomized controlled trial or observational study in humans with defined endpoints has been published for Costus spicatus.
• Safety: Acute animal toxicity data suggests relative safety at doses tested in rodents; long-term human safety is uncharacterized.

References

• University of Texas at El Paso — Herbal Safety: Spiral Ginger (Costus spicatus)
• Manimaran et al. (2025). "Current Perspectives in Detection of Bioactive Compounds From Costus spicatus Through GC–MS and LC-MS/MS: Antioxidant Properties and In Silico Analysis for Industrial Applications." Biochemistry Research International. PMC11753854.
• Nephroprotective and antilithiatic activities of Costus spicatus (Jacq.) Sw. — Journal of Ethnopharmacology, 2020. ScienceDirect.
• Evaluation of the inhibitory potentials of selected compounds from Costus spicatus (Jacq.) rhizome towards enzymes associated with insulin resistance in polycystic ovarian syndrome: an in silico study. PMC8611123.
• Bioactive polysaccharides from Costus spicatus. Carbohydrate Polymers, 2002. ScienceDirect.
• Antinociceptive and anti-inflammatory effects of Costus spicatus in experimental animals. Pharmaceutical Biology, 2010. Taylor & Francis.
• Nephroprotective effect of polyphenol-rich extract of Costus spicatus in cisplatin-induced nephrotoxicity in Wistar albino rats. 3 Biotech, 2022. Springer.
• Nephroprotective effect of polyphenol-rich extract of Costus spicatus in cisplatin-induced nephrotoxicity in Wistar albino rats. PMC9314513.
• Current and potential future biological uses of Saussurea costus (Falc.) Lipsch: A comprehensive review. ScienceDirect, 2024.
• Costus pictus — transition from a medicinal plant to functional food: A review. ScienceDirect, 2021.
• A review on the bioactive compounds, medicinal uses and pharmacological significance of Costus igneus. ScienceDirect, 2026.
• Evaluation of Safety Profile of Costus pictus D. Don Methanolic Leaf Extract on Albino Wistar Rats. Biomedical and Pharmacology Journal, 2023.
• Evaluating the therapeutic efficacy, tolerability, and safety of an aqueous extract of Costus speciosus rhizome in acute pharyngitis and acute tonsillitis: A pilot study. PMC4549600.
• Antimicrobial activity of sesquiterpene lactones isolated from traditional medicinal plant, Costus speciosus. PMC3348003.
• Wikipedia: Costus spicatus.
• A Literature Review of Anti-Diabetic Medicinal Plant Properties (Costus species). Journal of Biomedical Research & Environmental Sciences, 2021.
• Phytomania: Costus Insulin Plants — Herbal Medicine overview.
• Healthline: Costus Igneus — Side Effects of the Insulin Plant for Diabetes Treatment.