Stachytarpheta cayennensis

Identity: Botanical Description, Nomenclature, and Natural Source

Scientific Name and Taxonomy

Stachytarpheta cayennensis (Rich.) Vahl is the accepted scientific name for this species of flowering plant. It belongs to the genus Stachytarpheta within the family Verbenaceae, a group of mostly tropical and subtropical herbs, shrubs, and trees known for their often showy flowers. The genus name Stachytarpheta derives from the Greek stachys (spike) and tarphys (thick or dense), alluding to the plant's dense, spike-like inflorescences. The specific epithet cayennensis refers to Cayenne, the capital of French Guiana.

Notable synonyms recorded in botanical literature include Verbena cayennensis Rich., Stachytarpheta urticifolia Sims, Abena cayennensis (Rich.) Hitchc., Valerianoides cayennensis (Rich.) Kuntze, Verbena dichotoma Ruiz & Pav., and Zappania cayennensis (Rich.) Mirb.

Common Names

In English, the plant is known by many common names, including blue snakeweed, Cayenne snakeweed, dark-blue snakeweed, bluetop, nettle-leaf porterweed, rattail, rough-leaf false vervain, blue rat's tail, Brazilian tea, Cayenne vervain, false verbena, joee, nettleleaf velvetberry, and Cayenne porterweed. Names in other languages include honagasō (Japanese), gervão-urticante (Brazilian Portuguese), piche de gato and rabo de zorro (Spanish), herbe à chenille, herbe bleue, and queue de rat (French), ōi or ōwī (Hawaiian), sakura or ouchung (Chuukese), and tiāki (Māori). In Brazil it is also called gervão.

Botanical Description and Habitat

Stachytarpheta cayennensis is a perennial herbaceous subshrub or shrub in the Verbenaceae family, native to southern Mexico, Central America, South America, and the Caribbean, characterized by its erect, branched stems reaching 0.4–2.5 meters in height, opposite ovate to oblong leaves with serrate margins measuring 2–10 cm long, and distinctive long, slender, spike-like inflorescences up to 45 cm that bear small blue, purple, or white flowers. It has an upright, branching stem, sometimes with a woody base. The leaves are oppositely arranged, with blades up to 8 to 10 centimeters long, oval in shape with sharply toothed edges, and rough-textured or wrinkly on the upper surfaces. The flowers are deep purple-blue to lavender with pale centers, and white-flowered plants are also known. The flowers last a single day before wilting.

Widely introduced and naturalized in tropical and subtropical regions worldwide, including parts of Africa, Asia, the Pacific Islands, Australia, and the Indian Ocean islands, this species thrives in disturbed habitats such as roadsides, pastures, grasslands, forest margins, and waste areas, often at elevations from sea level to 1,800 meters in seasonally dry tropical biomes.

Relationship to Closely Related Species

Stachytarpheta cayennensis is frequently confused with the closely related S. jamaicensis (L.) Vahl and S. angustifolia (Mill.) Vahl. The increasing demand for herbal products necessitates the standardization of medicinal plants, particularly those that are closely related and often misidentified. A comparative study successfully established unique diagnostic characters, physicochemical properties, and chemical evaluations of S. cayennensis and S. angustifolia, providing essential standards for their identification and potential inclusion in the West African herbal pharmacopoeia. Diagnostic microscopic characters unique to S. cayennensis in differentiating it from S. angustifolia include a glandular trichome with unicellular head, higher stomata number (adaxial 7.2, abaxial 17.0), higher stomata index (adaxial 24.7, abaxial 39.0), lower stomata size (adaxial 15.8 × 3.6 µm, abaxial 16.4 × 4.2 µm), and lower trichome length (adaxial 255.9 µm, abaxial 237.5 µm).

Common Forms and Preparations

The plant is used in several physical forms depending on the tradition and intended use. The leaves are the most commonly employed part, though roots, stems, and whole plants are also used. Preparations documented in ethnobotanical sources include water-based decoctions and infusions (teas), poultices, baths, tinctures, and alcoholic or aqueous extracts used in laboratory and clinical research settings. The root, stems and leaves are used as a decoction in a bath to remedy grippe, headache, and fractures. In scientific investigations, preparations have typically been produced as methanolic, ethanolic, aqueous, ethyl acetate, hexane, butanol, and dichloromethane extracts of dried or fresh leaf material.

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Traditional and Historical Use

Latin America and the Caribbean

The leaves are used in folk medicine as infusion and decoction for several disorders, such as inflammation, pain, fever, hepatic and renal disorders, helminthiasis, constipation, hypertension, stress, and diabetes. Several Latin American peoples recognize extracts of the plant as a treatment to ease the symptoms of malaria. The boiled juice or a tea made from the leaves or the whole plant is taken to relieve fever and other symptoms.

In Caribbean practices, leaf decoctions are employed to treat dysentery, while root teas address malaria; infusions help manage hypertension, and poultices from the leaves are applied to wounds. Additionally, chewed leaves serve as a remedy for thrush and toothache, with the plant also used for colds, diarrhea, and skin infections.

The Créoles use the leaf tea for dysentery, while the Kofans in northwest Amazonia drink a decoction of the plant to relieve stomach pains. Indigenous peoples of Peru use the plant for diabetes, and the Wayãpi and Palikur Indians in Guyana use the plant in baths to relieve colds and headaches.

In Brazil, the plant is known as gervão and enjoys a particularly long history of medicinal use. The plant is used traditionally as anti-allergic, bronchodilatory, digestion-stimulating, antacid, and antidiarrheal; as a pain-relieving, antispasmodic, and anti-inflammatory agent; for liver protection and detoxification; and as a cellular protective, antioxidant, antimicrobial, anticonvulsant, and sedative agent.

The common name "Brazilian tea" attests to a longstanding practice of preparing the aerial parts as a beverage infusion. The leaves are described as astringent, cholagogue, and purgative in classical accounts of Caribbean and South American plant use.

West Africa and Nigeria

In African traditional medicine, particularly in Nigeria, the leaves are used as a sedative and anxiolytic for insomnia and anxiety, as well as for inflammation, pain, fever, hepatic and renal disorders, and helminthiasis. In Ghana, the extracts of the leaves of Stachytarpheta cayennensis are employed in traditional medicine for the management of mental illness.

External Applications

The plant is also used externally to treat wounds and toothache. Poultices and baths prepared from the leaves and roots are documented across multiple cultures of the Caribbean and South America for skin conditions, fractures, and fevers.

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Key Constituents and Active Compounds

Iridoid Glycosides

Ipolamiide and verbascoside were isolated as the main constituents of Stachytarpheta cayennensis in a previous study. It is also considered to be most rich in iridoid glycosides, mainly ipolamiide and lamiide; phenylethanoid glycosides such as jinoside-D, martinoside (martynoside), acetoside, iso-acetoside, and leucosceptoside-A. Arylpropanoid glycosides found are verbascoside and isoverbascoside.

Previous studies have identified numerous compounds isolated from different parts of Stachytarpheta cayennensis, each with its unique chemical structure and potential bioactivities, including ipolamiide, isoverbascoside, 6β-hydroxyipolamide, verbascoside, apigenin, stigmasterol glucoside, and betulinic acid. A novel compound, nnenoside-B, isolated from the leaves of S. cayennensis, showed absorption peaks with characteristic bands at Vmax 2980 cm⁻¹ and 2750 cm⁻¹.

Flavonoids and Polyphenolics

A flavonoid in gervâo called scutellarein has been documented with cardioprotective, anti-inflammatory, and antiviral actions. Another flavonoid found in gervâo called hispidulin is also found in verbena and vervain and is considered one of the main "active" chemicals in all three plants. Hispidulin has been reported to have anti-asthmatic, bronchodilator, and antispasmodic properties; liver detoxifying actions; and helps to normalize sticky blood.

The main plant chemicals in gervâo include: apigenol-7-glucuronide, alpha-spinasterol, gamma-amino butyric acid, chlorogenic acid, citral, dopamine, friedelin, geraniol, hentriacontane, hispidulin, ipolamiide, luteolol-7-glucuronide, n-dotriacontane, n-nonacosane, n-pentriacontane, n-tetratriancontane, n-triacontane, n-tritriacontane, salicylic acid, scutellarein, stachytarphine, stigmasterol, tarphetalin, ursolic acid, and verbascoside.

Antioxidant Phenolic Content

Chemical analysis of bioactive compounds yielded higher total phenolic content (2511 ± 3.14 µg gallic acid equivalents/g) and total flavonoid content (604 ± 0.5 µg quercetin equivalents/g) in S. cayennensis, which also corresponds to higher antioxidant activity with IC₅₀ = 127.3 ± 1.72 µg/mL. Total phenolic contents were relatively high in the ethyl acetate fraction and crude extract, while total flavonoid contents were also higher in the ethyl acetate fraction and crude extract.

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Established Mechanisms of Action

Anti-inflammatory Mechanisms

The iridoid ipolamiide and the phenylethanoid glycoside acteoside, isolated from the active fraction of S. cayennensis, showed inhibitory effect on histamine- and bradykinin-induced contractions of guinea-pig ileum. These compounds also showed in vivo anti-inflammatory activity when administered orally to rats, mainly in the fourth hour after administration of the phlogistic agent (70.22% and 93.99%, respectively). These results indicate that S. cayennensis shows anti-inflammatory properties which seems to be due, at least partly, to the inhibition of bradykinin and histamine.

In the 2006 study by Penido et al., published in the Journal of Ethnopharmacology, chromatographic analysis of the crude ethanolic extract (SC01) revealed high concentrations of the iridoid ipolamiide, whereas a second ethanolic extract (SC02) presented the arylpropanoid verbascoside as a major constituent. The oral administration of SC01 (100 mg/kg) into Swiss mice failed to inhibit paw oedema and pleural exudation induced by carrageenan and zymosan, whereas SC02 (100 mg/kg, p.o.) inhibited oedema and protein extravasation in all instances. Both extracts inhibited total leukocyte accumulation into the pleural cavity 4 and 24 h after intrathoracic injection of carrageenan, due to the inhibition of neutrophil and mononuclear cell influx, whereas only SC02 was able to inhibit leukocyte mobilization induced by zymosan.

CNS / Sedative and Anxiolytic Mechanisms

Flumazenil blocked the effect of the leaves of Stachytarpheta cayennensis on rearing, locomotion, and the elevated plus maze, suggesting that GABA receptors are involved in the observed sedative and anxiolytic activities. The study also found opioid receptors to be involved in the sedative activity of the leaves of Stachytarpheta cayennensis.

The methanolic extract, the butanol, and aqueous fractions possess sedative activity, while the ethylacetate fraction possesses stimulant property. The anxiolytic effect was found in both the aqueous fraction and the butanol fraction but not in the main methanol extract and also not in the ethylacetate fraction.

Gamma-amino butyric acid (GABA) is itself listed among the identified plant constituents (see above), suggesting a potential direct substrate-related mechanism in addition to receptor modulation.

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Scientific Evidence by Area of Use

1. Anti-inflammatory and Antinociceptive Activity

Evidence type: In vitro and animal (rodent) studies; no human clinical trials identified.

The most extensively published pharmacological activity of S. cayennensis is its anti-inflammatory effect. In a foundational 1998 study by Schapoval et al. (Journal of Ethnopharmacology, 60: 53–59), intraperitoneal pretreatment with alcoholic and n-butanolic extracts of dried leaves at doses ranging from 100 to 200 mg/kg significantly inhibited carrageenan-induced edema formation. The active extracts were fractionated and monitored with the same bioassay. The iridoid ipolamiide and the phenylethanoid glycoside acteoside, isolated from the active fraction, showed inhibitory effect on histamine- and bradykinin-induced contractions of guinea-pig ileum. The compounds also showed in vivo anti-inflammatory activity when administered orally to rats mainly in the fourth hour after the administration of the phlogistic agent (70.22% and 93.99%, respectively). These results indicate that S. cayennensis shows anti-inflammatory properties which seems to be due, at least partly, to the inhibition of bradykinin and histamine.

The 2006 Penido et al. study further refined these findings: SC02 inhibited LPS-induced total leukocyte, neutrophil, and eosinophil accumulation in the pleural cavity, whereas SC01 selectively inhibited neutrophil influx. In addition, the data indicate that extract SC02 presents important anti-ulcerogenic activity, since it inhibited diclofenac-induced (100 mg/kg, p.o.) gastric ulcers.

Strength of evidence: Preliminary; confined to rodent and in vitro models. No randomized controlled trials (RCTs) in humans exist for this indication.

2. Gastroprotective and Antidiarrheal Activity

Evidence type: Animal studies (rats and mice); no human clinical data identified.

Almeida et al. (1995) demonstrated antidiarrheal effects of Stachytarpheta cayennensis in rats. Further studies performed by Vela et al. (1997, 2004) showed the laxative and anti-ulcer properties of Stachytarpheta cayennensis, due to the efficient reduction of gastric acidity and stomach protection it provides.

The extract and fractions of Stachytarpheta cayennensis possessed both antibacterial and antispasmodic effects, confirming the claimed use in folkloric medicine for wound healing and gastrointestinal ulceration. The study aimed to investigate the antimicrobial activity of the methanol leaf extract and its fractions, as well as the antispasmodic effects on acetylcholine- and histamine-induced contractions on isolated guinea pig ileum.

Strength of evidence: Preliminary; based on animal and isolated tissue models only. Consistent with traditional use, but no human studies available.

3. Sedative and Anxiolytic Activity

Evidence type: Animal study (mice), published in a peer-reviewed journal (African Journal of Traditional, Complementary and Alternative Medicines, 2013, PMC3847405).

The leaves are used ethnomedicinally in Nigeria and other parts of the world for insomnia and anxiety among other uses. The investigations sought scientific evidence for the ethnomedicinal use of the leaves for the management of insomnia and anxiety as well as the neural mechanisms for these activities. The sedative and anxiolytic effects of the extracts of the leaves of Stachytarpheta cayennensis were examined in this study. The methanolic extract (5–50 mg/kg, i.p.) as well as the ethylacetate (10–50 mg/kg, i.p.), butanol, and aqueous fractions (5–50 mg/kg, i.p.) of the extract were examined. Sedation was assessed as reduced novelty-induced rearing (NIR), reduced spontaneous locomotor activity (SLA), and increased pentobarbitone-induced sleeping time (PIST) in mice.

Opioid receptors were found to be implicated in the sedative activity. This study provided scientific validation for the traditional use of S. cayennensis leaves in managing insomnia and anxiety, shedding light on their mechanisms of action.

Strength of evidence: Mechanistically informative preclinical data in mice; no human RCTs. The identification of GABAergic and opioid receptor involvement is a notable finding but requires human translation.

4. Antimalarial / Antiplasmodial Activity

Evidence type: Animal studies (mice) and in vitro assays against Plasmodium falciparum; no human clinical trials identified.

S. cayennensis (Verbenaceae) is traditionally used in west and central Africa as a malaria remedy. A study was undertaken to evaluate antiplasmodial activity of S. cayennensis leaf fractions and to isolate and identify some active constituents. Solvent portions and ethyl acetate column fractions were investigated in early infection in mice against both chloroquine-sensitive (HB3) and chloroquine-resistant (FCM29) P. falciparum. Compounds isolated from active fractions were identified based on their spectroscopic data and evaluated for antioxidant and heme biomineralization inhibitory activity.

At a dose of 2.5 mg/kg, compounds I–III significantly (P < 0.05) suppressed infection by 54.91–88.95%. Compound III also displayed strong antioxidant effect (EC₅₀ = 0.05 mg/ml) comparable to equivalent concentrations of ascorbic acid (EC₅₀ = 0.03 mg/ml), whereas compound I elicited stronger inhibitory effect (67.93%) on heme biomineralization than compound III (38.67%). The compounds were identified as apigenin (I), stigmasterol glucoside (II), and verbascoside (III). The findings showed that S. cayennensis leaves contain antiplasmodial-active compounds which show potential for further development.

In a separate in vivo study, the ethanolic leaf extract of Stachytarpheta cayennensis (90–270 mg/kg/day) was screened for blood schizonticidal activity against chloroquine-sensitive Plasmodium berghei berghei in mice. The schizonticidal effect during early and established infections was investigated. Stachytarpheta cayennensis (90–270 mg/kg/day) exhibited significant (P < 0.05) blood schizonticidal activity both in the 4-day early infection test and in established infection, with a considerable mean survival time comparable to that of the standard drug chloroquine (5 mg/kg/day). The leaf extract possesses significant (P < 0.05) antiplasmodial activity, which confirms its use in folkloric medicine for the treatment of malaria.

Specifically, the chemosuppression levels were 64.6%, 77.42%, and 78.2% for doses of 90, 180, and 270 mg/kg/day, respectively. The chemosuppression produced by the extract was significant (P < 0.05) compared to control and comparable to that of the standard drug chloroquine (5 mg/kg/day) with a chemosuppression of 87.8%.

Strength of evidence: Promising preclinical data in rodents and in vitro against drug-resistant parasites. No human trials. Active compounds (apigenin, verbascoside, stigmasterol glucoside) have been identified, adding mechanistic plausibility.

5. Immunomodulatory Activity

Evidence type: Animal and in vitro study (BMC Complementary Medicine and Therapies, 2014; PMC4195953).

The methanol extract of S. cayennensis (MESC) exhibited 64.21% inhibition of delayed-type hypersensitivity response (DTHR) at 500 mg/kg dose and evoked 139.64% of phagocytic stimulation at 100 µg/ml dose. MESC also significantly (P < 0.05) showed dose-related stimulation of humoral immunity and a highest percentage leucocyte mobilization of 10.15% at 250 mg/kg dose. Artesunate offered a non-significant phagocytic stimulation while the combined effect of artesunate and MESC exhibited significant (P < 0.05) dose-dependent phagocytic stimulation with a highest value of 393.77% at 100 µg/ml.

Strength of evidence: Animal and in vitro only. The synergistic effect with artesunate is of pharmacological interest but is not confirmed in humans.

6. Antimicrobial Activity

Evidence type: In vitro agar diffusion studies.

Organisms used in one study were clinical isolates of Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella paratyphi, Candida albicans, and Aspergillus niger. The extract and fractions exhibited dose-dependent inhibition against all the bacteria tested, but also exhibited insignificant antifungal activity against Candida albicans and Aspergillus niger. The extract and fractions possessed both antibacterial and antispasmodic effects, confirming the claimed use in folkloric medicine for wound healing and gastrointestinal ulceration.

Strength of evidence: In vitro only; antibacterial activity appears stronger than antifungal activity in this experimental model. Human data are absent.

7. Antioxidant Activity

Evidence type: In vitro assays.

The antioxidant and antidiabetic activities of extracts and solvent fractions of S. cayennensis give credence to their traditional use as food and medicine. In addition, in silico and in vitro antidiabetic assessment of ipolamiide was performed. The total phenolic and flavonoid contents are among the highest reported for closely related species in the genus, which correlates with measurable free-radical scavenging capacity.

Strength of evidence: Preliminary in vitro data only.

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Body Systems and Health Areas of Association

• Central Nervous System: Sedative and anxiolytic properties mediated through GABAergic and opioid receptor pathways; traditional use for insomnia, anxiety, and mental illness.
• Immune System: Immunomodulatory effects including stimulation of phagocytic activity, humoral immunity, and modulation of delayed-type hypersensitivity responses.
• Musculoskeletal/Inflammatory: Anti-inflammatory and antinociceptive effects documented in animal models; inhibition of histamine- and bradykinin-mediated pathways.
• Gastrointestinal System: Antidiarrheal, antispasmodic, gastroprotective (anti-ulcer), laxative, and gastric acid-reducing effects; traditional use for constipation, dysentery, stomach pain, and ulcers.
• Infectious Disease / Parasitology: Antiplasmodial activity against both chloroquine-sensitive and chloroquine-resistant P. falciparum; antibacterial activity against clinical pathogens; traditional use for malaria and helminthiasis.
• Hepatic/Renal Systems: Traditional use for hepatic and renal disorders; liver-protective effects attributed to antioxidant constituents including verbascoside and betulinic acid.
• Cardiovascular/Metabolic: Traditional use for hypertension and diabetes; the plant extract's hypotensive and hypoglycemic potential has been noted in ethnobotanical records, though these remain under-investigated scientifically.
• Respiratory System: Traditional use for coughs, colds, and asthma-like symptoms, with hispidulin noted as a bronchodilatory and antispasmodic constituent.

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Dosage Forms and Dosages Reported in Studies

The following dosages are reported only as documented in specific peer-reviewed studies and should not be interpreted as therapeutic recommendations:

• For sedative and anxiolytic studies in mice: methanolic extract at 5–50 mg/kg (i.p.), ethylacetate fraction at 10–50 mg/kg (i.p.), and butanol and aqueous fractions at 5–50 mg/kg (i.p.).
• For in vivo antiplasmodial studies in mice: ethanolic leaf extract at 90–270 mg/kg/day.
• For antiplasmodial compound studies in mice: isolated compounds (apigenin, stigmasterol glucoside, verbascoside) at a dose of 2.5 mg/kg.
• For anti-inflammatory studies: oral administration of 100 mg/kg ethanolic extract (SC01 and SC02) in Swiss mice.
• For anti-inflammatory studies: intraperitoneal pretreatment with alcoholic and n-butanolic extracts at doses ranging from 100 to 200 mg/kg.
• For immunomodulatory studies: methanol extract at 500 mg/kg (for DTHR inhibition) and 100 µg/ml in vitro (for phagocytic stimulation), with leucocyte mobilization assessed at 250 mg/kg.

No standardized dosages for human use have been established by any pharmacopeia or regulatory authority. No human clinical dose-finding studies are available in the published literature.

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Safety Considerations

Acute Toxicity

In one immunomodulatory study, the LD₅₀ of the methanol extract of S. cayennensis (MESC) was estimated to be greater than 5,000 mg/kg, since there were no lethality and signs of acute intoxication after 48 h observation.

In contrast, in the antimalarial study by Okokon et al. (2008), the extract (500–1,000 mg/kg) produced physical signs of toxicity such as writhing, gasping, palpitation, decreased respiratory rate, body and limb tone, and death depending on the dose. All mice treated with 4,000 mg/kg dose of the extract and above died. The i.p. LD₅₀ of the extract in mice was calculated to be 938.08 mg/kg. The divergence between these LD₅₀ values across studies reflects differences in route of administration (i.p. vs. oral), extraction method, and species, and illustrates the importance of these variables in toxicological interpretation.

Subchronic / Repeated-Dose Toxicity

The many pharmacological potentials of Stachytarpheta cayennensis, especially in managing central nervous system disorders, hypertension, diabetes, and infections, have made it a subject of abuse, necessitating the need to ascertain its safety. A study investigated the toxic effects of the leaf extract of S. cayennensis in rats following acute and 28-day repeated doses in male and female rats, using OECD 423 and 407 Test guidelines, respectively.

The findings of this study, published in a peer-reviewed journal and indexed in PubMed Central (PMC7588336), were notably concerning: histological assessment revealed evidence of liver and kidney toxicities, and recovery was incomplete, as signs of toxicities were still evident after 21 days of recovery. Therefore, the extract is potentially harmful to vital organs with evidence of sex-differential adverse effects and non-reversible forms of toxicity, especially with repeated usage, necessitating the need to avoid indiscriminate use.

Genotoxicity

The leaf extract treatment induced chromosomal aberrations and micronuclei (MNC) formations in Allium cepa root tip cells that were significant (p < 0.05) compared to the control group. The leaf extract treatment further induced cell death, ghost cells, cell membrane damage, and binucleated cells. These results suggest that the leaf extract of Stachytarpheta cayennensis possesses cytotoxic and genotoxic effects on A. cepa.

This genotoxicity signal, while derived from a plant bioassay model rather than mammalian cells, is a precautionary finding that researchers have highlighted alongside the histopathological organ toxicity data.

Incompletely Characterized Toxicity Profile

Despite the documented pharmacological potentials, the toxicity profile of the plant remains largely unexplored. The traditional use of the leaf of S. cayennensis in the management of insomnia has made this plant a subject of abuse, necessitating the need to establish its safety profile. No studies on drug–drug interactions in humans or animals have been identified in the peer-reviewed literature. Given the documented GABAergic and opioid receptor activity, theoretical additive effects with CNS depressants (such as benzodiazepines, opioids, or barbiturates) represent a plausible but unstudied concern. Given the antiplasmodial activity and evidence of synergy with artesunate in animal models, herb–drug interactions with standard antimalarial agents may also be relevant but remain unstudied in humans.

Absence of Regulatory Status

As of the available literature, Stachytarpheta cayennensis has not been assessed or approved by any major international pharmacopeia (European Pharmacopoeia, USP, WHO), nor evaluated by the European Medicines Agency (EMA) or the U.S. National Center for Complementary and Integrative Health (NCCIH) as a medicinal herb. The species and its extracts are not included in Commission E monographs or ESCOP monographs. It features in the West African subregion's traditional medicine sphere but lacks formal pharmacopeial standardization.

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Summary of Evidence Status

The entire body of scientific evidence for Stachytarpheta cayennensis consists of in vitro assays, animal pharmacology (predominantly in mice and rats), and ethnobotanical surveys. No randomized controlled trials, cohort studies, or any other form of human clinical evidence has been identified in the peer-reviewed literature for any of its attributed uses. The preclinical evidence is pharmacologically coherent with traditional uses in the areas of anti-inflammation, antiplasmodial activity, sedation/anxiolysis, and gut protection, and active compounds responsible for several of these effects have been chemically identified and characterized. However, the gap between preclinical promise and clinically validated efficacy is substantial, and the subchronic toxicity findings — particularly evidence of hepatic and renal injury in rodent studies — underscore that safety for human use remains an open question requiring systematic investigation.

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References

• Penido C, et al. "Anti-inflammatory and anti-ulcerogenic properties of Stachytarpheta cayennensis (L.C. Rich) Vahl." Journal of Ethnopharmacology 104(1–2): 225–233. 2006. ScienceDirect.
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• Okokon JE, Ettebong E, Antia BS. "In vivo antimalarial activity of ethanolic leaf extract of Stachytarpheta cayennensis." Indian Journal of Pharmacology 40(3): 111–113. 2008. PubMed Central PMC2792606.
• Okoye TC, et al. "Immunomodulatory effects of Stachytarpheta cayennensis leaf extract and its synergistic effect with artesunate." BMC Complementary and Alternative Medicine 14: 376. 2014. PubMed Central PMC4195953.
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