Laggera pterodonta: A Comprehensive Reference
1. Identity, Taxonomy, and Botanical Description
Scientific Name and Synonyms
Laggera pterodonta (DC.) Benth. belongs to the family Asteraceae, and is chiefly distributed in China, India, and Africa. Its full taxonomic designation is Laggera pterodonta (DC.) Sch. Bip. ex Oliv., reflecting the original description by De Candolle and subsequent treatments by Schultz Bipontinus and Oliver. The genus Laggera, belonging to the Asteraceae family, has about 20 species, which are distributed mainly in tropical Southeastern Asia and Africa.
Common Names and Folk Designations
The plant is known in China as Choulingdan, a name that references its stimulous odor. In Nigeria, the plant is used widely in ethnomedicine and is referred to in the context of pediatric treatment. Laggera pterodonta (DC) Sch. Bip belonging to the family Asteraceae/Compositae is a robust herb that grows up to 1.70 m in height. It is viscid and strongly aromatic. The plant is recognizable by its toothed stem wings, whereas they are entire in other species, and by its basal leaves larger than higher ones.
Geographic Distribution
It is widely distributed in tropical and subtropical regions of Africa and Asia, including parts of East and West Africa, China, and India. More specifically, the plant is distributed widely in Southwestern China, especially in Sichuan and Yunnan Provinces. Studies have documented the plant's presence in Nigeria, Benin, Côte d'Ivoire, Cameroon, and across sub-Saharan Africa.
Botanical Description
Laggera pterodonta (DC.) Benth. is a traditional Chinese medicine. It is a perennial herb in the daisy family (Asteraceae/Compositae). The aerial parts — leaves, stems, and flowers — are the primary plant materials collected for medicinal and phytochemical use.
2. Traditional and Historical Use
Traditional Chinese Medicine
For centuries, Laggera pterodonta, a Chinese herbal medicine, has been widely employed for treating respiratory infectious diseases. L. pterodonta has been used as a traditional herbal medicine in China to treat a series of diseases, such as influenza, sore throats, bronchitis, and malaria. The aerial part of Laggera pterodonta has been widely used in China as a folk medicine for several centuries to ameliorate some inflammatory ailments, arthritis, and hepatitis and as anti-viral agents.
Laggera pterodonta (DC.) Benth is a medicinal plant that is widely used in Traditional Chinese Medicine, especially in Yunnan province, and has been used to treat influenza, pharyngolaryngitis, and bronchitis. L. pterodonta is one of commonly used antiviral TCM materials. Its crude extract has been developed into several drug formulations for antiviral use in China.
African Ethnomedicine
Laggera pterodonta is a reputable ethnomedicinal plant in Nigeria for the treatment of pediatric malaria and inflammations. In Nigeria the fresh aerial part of the plant is used for the treatment of pediatric malaria. For this purpose the fresh aerial part of the plant is pounded and water added, filtered, and the filtrate is drunk and the residue is rubbed all over the body.
Most species of the genus Laggera are often used in traditional and folk medicines for the treatment of jaundice, inflammation, leukemia, removing phlegm, bronchitis, and bacterial diseases. Laggera pterodonta is used by four of five ethnic groups surveyed in the mountainous area of Xishuangbanna, Southwest China, attesting to its broad cross-cultural recognition as a medicinal and aromatic plant. Most informants believed that plants with strong smells can drive away hematophagous invertebrates, and many plants used by more than one ethnic group were common aromatic plants, including Laggera pterodonta.
Traditional Preparations
Initially, the medicinal use of plants was restricted to direct use as herbal mixtures, teas, concoctions, decoctions, or functional foods taken for their medicinal value. In the Chinese folk tradition, the aerial parts of the plant are typically collected, dried, and then processed into decoctions or liquid mixtures. In Nigerian traditional practice, as noted above, fresh material is pounded and extracted with water before oral administration. The plant has been used as folk medicine since ancient times because it has antibacterial properties and anti-inflammatory effects and has been used as a cure for bronchitis, angina, malaria, and influenza.
3. Phytochemistry: Key Constituents and Active Compounds
Overview of Chemical Diversity
Over 150 bioactive compounds — including flavonoids, sesquiterpenoids, phenolics, alkaloids, and essential oils — have been identified in L. pterodonta and contribute to its diverse pharmacological effects. Previous studies have shown that the main chemical constituents in L. pterodonta are volatile oils, sesquiterpenes, and flavonoids. Additional compound classes include phenolic acids, phenylpropanoids, steroids, and glucosides.
Sesquiterpenoids
Among the compounds isolated, sesquiterpenoids and flavonoids are the main types. Most sesquiterpenoids of L. pterodonta have a eudesmane skeleton and possess a wide range of pharmacological activities. Eudesmane derivatives and flavones are the characteristic class of secondary metabolites from the genus Laggera, which are usually regarded as significant chemotaxonomic markers for Laggera.
Key sesquiterpenoids isolated from L. pterodonta include:
- Pterodontic acid — a eudesmane-type sesquiterpene that has received the most intensive pharmacological attention, particularly for its antiviral and anti-inflammatory activities.
- Pterodondiol and pterodontriol B — also eudesmane-type sesquiterpenes with documented antibacterial activity.
- Pterodontoside A — a sesquiterpene glucoside.
- 1β-Hydroxy pterodontic acid — a hydroxylated sesquiterpenoid.
Eleven compounds have been obtained from L. pterodonta, identified as 6-O-beta-D-glucopyranosyl-carvotanacetone, pterodontic acid, 1beta-hydroxy pterodontic acid, pterodontoside A, pterodondiol, pterodontriol B, 5-hydroxy-3,4',6,7-tetramethoxyflavone, artemitin, chrysosplenetin B, quercetin, and beta-sitosterol.
For instance, pterodontriol A, pterodontic acid, and ilicic acid have inhibitory effects on tumor cells. Pterodontic acid has an anti-inflammatory effect as observed by decreasing xylene-induced ear edema in mice.
A 2021 study isolated two novel norsesquiterpenoids: norpterodonols A and B are two undescribed norsesquiterpenoid derivatives. Nuclear magnetic resonance spectroscopy and mass spectrometry analysis revealed that two eudesmane-type sesquiterpene compounds — pterodontic acid and pterodondiol — were identified as particularly active components.
Flavonoids
Ten compounds have been isolated and elucidated including 3,4',5-trihydroxy-6,7-dimethoxyflavone, 3,3',5-trihydroxy-4',6,7-trimethoxyflavone, chrysosplenetin B, 5-hydroxy-4',7-dimethoxyflavanone, 5,7,4'-trihydroxy-3,3'-dimethoxyflavone, artemitin, quercetin, pinostrobin, luteolin, and apigenin.
Of particular interest is 3,5-dihydroxy-6,7,3',4'-tetramethoxyflavone (DHTMF), a polymethoxyflavone isolated from Laggera pterodonta, which is a herbal medicine used to treat cancer in the Chinese folk. Chrysosplenetin and absinthin demonstrate notable antioxidant activity.
Essential Oil Composition
Essential oils of L. pterodonta are rich in oxygenated monoterpenes and sesquiterpenes, especially 2,5-dimethoxy-p-cymene and γ-eudesmol, which are key to its therapeutic potential. Most of the essential oils or volatile oils of Laggera plants are rich sources of oxygenated monoterpenes and sesquiterpenes. Among the oxygenated monoterpenes, the aromatic ether 2,5-dimethoxy-p-cymene (thymohydroquinone dimethyl ether) is the most abundant compound in many geographic samples. In Côte d'Ivoire specimens, 98.9% of the whole composition of the oil was identified with a high amount of 2,5-dimethoxy-p-cymene (78.9%). The other significant components were α-humulene (6.2%), (E)-β-caryophyllene (1.7%), thymyl methyl oxide (1.7%), α-phellandrene (1.5%), p-cymene (1.2%), and 10-epi-γ-eudesmol (1.0%).
The essential oils of leaves and flowers from Cameroon were characterized by a high percentage of oxygenated sesquiterpenes (30–80%) and thymol derivatives (4–50%). The major components in these oils were γ-eudesmol (17–45%), α-eudesmol (4–15%), 2,5-dimethoxy-p-cymene (4–50%), and juniper camphor (4–12%).
All leaf essential oil samples contained 2,5-dimethoxy-p-cymene, α-humulene, and (E)-β-caryophyllene among the main components. Other components allowed differentiation into two groups: sabinene and germacrene D for Group I; 10-epi-γ-eudesmol and eudesm-7(11)-en-4α-ol for Group II. This geographic variation in essential oil composition is well documented and should be considered when comparing biological activity data across different studies.
In North-Central Nigeria, the aerial part hydrodistillate contained 23 components, of which n-Triacontane was the major constituent (~43%). Other major volatile constituents included dimethoxydurene (~9%), caryophyllene oxide (~7%), linoleoyl chloride (~7%), oleic acid (~4%), and gamma-Eudesmol (~4%). This markedly different profile from Asian and West African specimens underscores the intraspecific chemical variability of the species.
Other Compound Classes
Fourteen compounds have been isolated from the aerial parts, including six sesquiterpenoids, five flavonoids, one lignan, and two pyrrole alkaloids. Pyrrole alkaloids may serve as potential chemotaxonomic markers for L. pterodonta and could be used to distinguish among species of Compositae.
A further investigation led to the isolation of twenty-one compounds, including nine sesquiterpenoids, four flavonoids, four triterpenoids, and four glucosides.
Twelve secondary metabolite classes have been detected in all plant parts: carbohydrates, terpenes, flavonoids, phenols, tannins, phlobatannins, sterols, alkaloids, volatile oil, balsams, resins, and chlorogenic acid.
4. Mechanisms of Action
Antiviral Mechanisms
Pterodontic acid can suppress the activation of the NF-κB signaling pathway and the export of viral ribonucleoprotein (RNP) complexes from the nucleus. In addition, it can significantly attenuate expression of the pro-inflammatory molecules IL-6, MIP-1β, MCP-1, and IP-10 induced by human influenza A virus (H1N1), and similarly downregulate expression of cytokines and chemokines induced by avian influenza A virus (H9N2). This in vitro antiviral activity is most probably associated with inhibiting the replication of influenza A virus by blocking nuclear export of viral RNP complexes, and attenuating the inflammatory response by inhibiting activation of the NF-κB pathway.
Pterodontic acid can inhibit Retinoic acid inducible gene-I (RIG-I) expression at the mRNA and protein level at 100 μg/ml; it can also inhibit Tumor Necrosis Factor-related Apoptosis-inducing Ligand/Fas Ligand (TRAIL/FasL) expression in mRNA level at 100 μg/ml; cleaved caspase 3/7, p-NF-κB, and p-ERK were all suppressed in protein level by pterodontic acid at 100 μg/ml.
Western blot analysis verified that the active component C8 (containing pterodontic acid and pterodondiol) inhibited Toll-like receptor 7, myeloid differentiation primary response protein 88, and tumor necrosis factor receptor-associated factor 6 expression, in addition to p65 phosphorylation, at concentrations of 100 or 150 µg/ml. An indirect immunofluorescence assay demonstrated that C8 may inhibit p65/NF-κB nuclear translocation. Additionally, C8 prevented an increase in cytokine mRNA expression, including IL-1β, IL-6, IL-8, and MCP-1.
The sesquiterpene-rich fraction acts on the early stage of virus replication (0–6 h). It inhibited the p38/MAPK pathway and then inhibited the NF-κB pathway and COX-2. The fraction also prevented the increased expression of cytokines and chemokines.
Anti-Inflammatory Mechanisms
The anti-inflammatory effect of the total flavonoids of Laggera pterodonta (TFLP) was evaluated with various in vivo models of both acute and chronic inflammation. In the acute inflammation tests, TFLP significantly inhibited xylene-induced mouse ear oedema, carrageenan-induced rat paw oedema, and acetic acid-induced mouse vascular permeability. In the carrageenan-induced rat pleurisy model, TFLP efficiently suppressed inflammatory exudate and leukocyte migration, reduced the serum levels of lysozyme (LZM) and malondialdehyde (MDA), increased the activity of serum superoxide dismutase (SOD), and also decreased the contents of total protein, nitric oxide (NO), and prostaglandin E2 (PGE2) in the pleural exudates. In the chronic inflammation experiment, TFLP inhibited cotton pellet-induced rat granuloma.
Compounds isolated from L. pterodonta were evaluated for their inhibitory effects on nitric oxide (NO) production in LPS-induced RAW 264.7 macrophages, and compounds 8, 10, 16, 18, 20, 21, and 23 were shown to have obvious anti-inflammatory effects.
Hepatoprotective and Antioxidant Mechanisms
Although Laggera pterodonta as a folk medicine has been widely used for several centuries to ameliorate some inflammatory ailments including hepatitis in China, the hepatoprotective and antioxidative effects were only formally studied comparatively recently. The hepatoprotective effect of total phenolics from L. pterodonta (TPLP) against CCl4-, D-GalN-, TAA-, and t-BHP-induced injury was examined in primary cultured neonatal rat hepatocytes. TPLP inhibited the cellular leakage of two enzymes, hepatocyte ASAT and ALAT, caused by these chemicals and improved cell viability. Moreover, TPLP afforded much stronger protection than the reference drug silibinin.
Pro-Apoptotic Mechanisms (Anticancer)
DHTMF suppressed K562R cell viability in both time- and dose-dependent manners. DHTMF combined with imatinib enhanced the inhibitory effects and apoptosis in K562R cells compared with DHTMF alone. DHTMF alone and in combination with imatinib significantly decreased the mitochondrial membrane potential and increased the levels of cleaved caspase-9, caspase-7, caspase-3, and PARP in K562R cells. This indicates activation of the intrinsic (mitochondrial) apoptosis pathway.
5. Scientific Evidence by Area of Use
5.1 Respiratory Tract Infections and Influenza
Human / Clinical Evidence
Laggera pterodonta, a traditional Chinese medicine, has been commonly used in respiratory tract infections for more than hundreds of years without any randomized controlled trials to evaluate its efficacy and safety — until the trial by Shang et al. A double-blind, randomized-controlled trial was conducted in three tertiary hospitals of Kunming, China. A total of 133 acute bronchiolitis children with an initial episode of wheezing were randomly assigned to a control mixture or Laggera pterodonta mixture. All recruited patients were given three doses of the mixture every 24 h for 5 days. Clinical symptoms and responses including adverse events in both groups were assessed, and laboratory tests were done at enrolment and then after 120 h. Significantly more hospitalized children fulfilled the discharge criteria at 96 h and 120 h in the Laggera pterodonta mixture group compared to the control group (97% vs 75.8%, P < 0.001 and 98.5% vs 89.4%, P = 0.03), respectively.
The authors concluded that Laggera pterodonta mixture is effective and safe to be prescribed in hospitalized children with acute bronchiolitis. This remains, to date, the most directly applicable human clinical trial of L. pterodonta as a therapeutic agent.
Evidence strength: The Shang et al. (2017) trial constitutes moderate-quality clinical evidence from a single double-blind RCT in a pediatric population. It was conducted in one country's hospitals and has not been independently replicated at the same scale.
Preclinical Evidence — Influenza
It has been reported that the extracts and flavonols from L. pterodonta exhibited antiviral activities against respiratory syncytial virus (RSV), herpes simplex type I (HSV-I), herpes simplex type II (HSV-II), and enterovirus 71 (EV71), respectively. Further experiments exhibited that pterodontic acid can suppress the activation of the NF-κB signal pathway and export of viral RNP complexes from the nucleus. In addition, it can significantly attenuate expression of the pro-inflammatory molecules IL-6, MIP-1β, MCP-1, and IP-10 induced by human influenza A virus (H1N1) and similarly downregulate expression of cytokines and chemokines induced by avian influenza A virus (H9N2). Pterodontic acid might be a potential antiviral agent against influenza A virus.
An active component (C8) isolated from Laggera pterodonta was evaluated. Nuclear magnetic resonance spectroscopy and mass spectrometry analysis revealed two eudesmane-type sesquiterpene compounds: pterodontic acid and pterodondiol. C8 was demonstrated to have a broad-spectrum effect against different influenza viruses, including human and avian influenza viruses, with a half maximal inhibitory concentration value of 19.9–91.4 µg/ml.
Pterodontic acid (a eudesmane-type sesquiterpene isolated from L. pterodonta) displays excellent selective antiviral activity to H1N1 subtype of influenza A virus. The antiviral activity of pterodontic acid was relatively close to that of post-marketed ribavirin.
Network pharmacology, molecular docking, and simulation were conducted to screen candidate targets associated with AKT and NF-κB. A series of experiments provided evidence that LP treatment in H3N2-infected mice can reduce pro-inflammatory cytokine levels (TNF-α, IL-6, IL-1β, and MCP-1) while increasing T cells (CD3+, CD4+, and CD8+).
Evidence strength: The antiviral evidence is predominantly preclinical (in vitro cell-culture and animal models). The single human RCT concerns bronchiolitis (primarily RSV-associated) rather than influenza specifically. No large-scale, independently replicated human trial of L. pterodonta against influenza has been published.
5.2 Anti-Inflammatory Activity
The anti-inflammatory effect of the total flavonoids of Laggera pterodonta (TFLP) was evaluated with various in vivo models of both acute and chronic inflammation. In the acute inflammation tests, TFLP significantly inhibited xylene-induced mouse ear oedema, carrageenan-induced rat paw oedema, and acetic acid-induced mouse vascular permeability. These are standard rodent pharmacological screening models; evidence is preclinical only.
Experimental validation in a mice model provided evidence that L. pterodonta treatment in H3N2-infected mice can reduce pro-inflammatory cytokine levels (TNF-α, IL-6, IL-1β, and MCP-1).
Evidence strength: Anti-inflammatory evidence is entirely preclinical (in vivo rodent models and in vitro macrophage assays). No dedicated human trial of L. pterodonta for inflammatory conditions has been identified in the peer-reviewed literature.
5.3 Antimicrobial and Antifungal Activity
Compounds pterodontic acid and pterodondiol showed moderate activity against bacteria including Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus subtilis, Mycobacterium phlei, and Bacillus species.
Methanol extracts of the aerial part of the plant showed antituberculosis activity against Mycobacterium bovis (MIC = 625 μg/mL).
The essential oil of L. pterodonta, which has high 2,5-dimethoxy-p-cymene (36.75%) content, displayed moderate activity against some Gram-negative bacteria, such as Enterobacter aerogenes (MIC = 0.125 mg/mL) and Enterococcus faecalis (MIC = 0.5 mg/mL).
Regarding antifungal activity, six eudesmane-type sesquiterpenes were isolated from L. pterodonta and their antifungal activity against six plant-pathogenic fungal species was evaluated: Phytophthora nicotianae, Fusarium oxysporum, Alternaria alternata, Gloeosporium fructigenum, Colletotrichum fructicola, and Botrytis cinerea. The results showed that the six compounds exhibited varying degrees of inhibitory effects. Compound 1 showed the strongest antifungal effect in a dose-dependent way, with EC₅₀ values of 12.56, 51.29, and 47.86 μg/mL against P. nicotianae, F. oxysporum, and G. fructigenum, respectively.
Evidence strength: All antimicrobial and antifungal evidence is preclinical (in vitro assays). No clinical studies in humans have been identified. The antifungal targets studied to date are primarily plant pathogens rather than human pathogens.
5.4 Hepatoprotective Activity
Although Laggera pterodonta has been widely used for several centuries to ameliorate hepatitis in China, formal laboratory studies are limited. The hepatoprotective effect of total phenolics from L. pterodonta (TPLP) against CCl4-, D-GalN-, TAA-, and t-BHP-induced injury was examined in primary cultured neonatal rat hepatocytes. TPLP inhibited the cellular leakage of hepatocyte ASAT and ALAT caused by these chemicals and improved cell viability. Moreover, TPLP afforded much stronger protection than the reference drug silibinin.
Evidence strength: Hepatoprotective evidence is limited to a single in vitro hepatocyte study. No animal studies or clinical trials in humans have been published on this endpoint.
5.5 Anticancer Activity
3,5-Dihydroxy-6,7,3',4'-tetramethoxyflavone (DHTMF) is a polymethoxyflavone isolated from Laggera pterodonta that is used to treat cancer in Chinese folk medicine. In an earlier study, DHTMF demonstrated good antiproliferative activities against a number of cancer cell lines and induced the apoptosis of CNE cells in vitro in a time- and dose-dependent manner while exhibiting low cytotoxicity in the two normal cell lines Vero and EVC304.
DHTMF suppressed K562R (imatinib-resistant chronic myeloid leukemia) cell viability in both time- and dose-dependent manners. DHTMF combined with imatinib enhanced the inhibitory effects and apoptosis in K562R cells. DHTMF alone and in combination with imatinib significantly decreased the mitochondrial membrane potential and increased the levels of cleaved caspase-9, caspase-7, caspase-3, and PARP in K562R cells.
The flavonoid 5,7,3',4'-tetramethoxy-3-hydroxyflavone displayed potent antitumor efficacy in vitro, as validated by the MTT assay.
Evidence strength: All anticancer evidence is strictly preclinical, based on cell line studies. No animal studies or human clinical trials have been conducted on the anticancer properties of L. pterodonta constituents.
5.6 Insecticidal and Repellent Activity
Preliminary studies have indicated that the ethanol extract of L. pterodonta exhibits contact toxicity against aphids (Aphis gossypii) and East Asian locusts (Locusta migratoria manilensis), while petroleum ether extracts showed inhibitory effects against Colletotrichum gloeosporioides.
Multiple ethnic groups in Xishuangbanna, Southwest China use Laggera pterodonta as an aromatic plant to repel hematophagous invertebrates.
Evidence strength: Preclinical and ethnobotanical only. No controlled human trials on repellent use.
5.7 Antioxidant Activity
Phytochemical constituents of L. pterodonta, including chrysosplenetin and absinthin, demonstrate notable antioxidant activity. The total phenolics fraction (TPLP) was also evaluated for DPPH radical scavenging activity in the context of the hepatoprotection study noted above.
Evidence strength: Preclinical (in vitro assays) only. No human trials.
6. Body Systems and Health Areas
Based on the peer-reviewed literature, L. pterodonta has been investigated in connection with the following body systems and health areas:
- Respiratory system: As a traditional herbal medicine, L. pterodonta has long been used as ethnomedicine to treat bronchitis, pneumonia, and epidemic influenza. One human RCT supports its use in acute bronchiolitis in children.
- Immune system / inflammatory response: Multiple preclinical studies document inhibition of NF-κB, COX-2, p38/MAPK, and production of pro-inflammatory cytokines including IL-6, TNF-α, and IL-1β.
- Hepatic system: Traditionally used for hepatitis in China; in vitro data supports hepatoprotective and antioxidant effects of total phenolics.
- Hematological / oncological: In vitro studies on leukemia cell lines (CML K562R) and other cancer cell lines show apoptosis induction via the intrinsic pathway.
- Antimicrobial applications: Demonstrated activity against both bacteria and fungi in vitro, including some drug-resistant organisms.
- Gastrointestinal tract: Traditionally used for gastrointestinal disturbances; limited formal preclinical evidence.
- Integumentary system / wounds: Traditional topical use for skin complaints documented ethnographically.
7. Dosage Forms and Reported Dosages
No internationally standardized dosage for Laggera pterodonta has been established by a pharmacopeial body or regulatory health authority. The following dosages appear in the peer-reviewed literature:
- Clinical trial (bronchiolitis, children aged 3–24 months): L. pterodonta mixture was administered as three doses every 24 h for 5 days in hospitalized children. The specific dosage per administration was not stated in the available abstract.
- In vitro studies (pterodontic acid): Pterodontic acid was tested at a concentration of 100 μg/ml in cell-based assays for immune regulation and antiviral activity.
- In vitro studies (C8 fraction): C8 (containing pterodontic acid and pterodondiol) demonstrated broad-spectrum antiviral effects with a half maximal inhibitory concentration (IC₅₀) value of 19.9–91.4 µg/ml against different influenza viruses.
- Antifungal sesquiterpenes: Compound 1 (an eudesmane-type sesquiterpene) showed EC₅₀ values of 12.56, 51.29, and 47.86 μg/mL against specific plant-pathogenic fungi.
- Antibacterial essential oil: The essential oil displayed moderate antibacterial activity with MIC values of 0.125 mg/mL against Enterobacter aerogenes and 0.5 mg/mL against Enterococcus faecalis.
- Antituberculosis extract: Methanol extracts of the aerial part showed antituberculosis activity against Mycobacterium bovis at MIC = 625 μg/mL.
The primary dosage forms documented in the literature and traditional practice include:
- Aqueous decoctions and liquid mixtures (traditional Chinese medicine and Nigerian folk medicine)
- Ethanol and methanol extracts (for pharmacological testing)
- Volatile/essential oil obtained by hydrodistillation
- Standardized fractions (sesquiterpene fraction, total flavonoids, total phenolics) used in preclinical experiments
- Isolated pure compounds (pterodontic acid, DHTMF) for mechanistic studies
8. Safety Considerations
Clinical Trial Safety Data
Laggera pterodonta has been commonly used in respiratory tract infections for more than hundreds of years. In the double-blind randomized controlled trial, the investigators concluded that Laggera pterodonta mixture is effective and safe to be prescribed in hospitalized children with acute bronchiolitis. Adverse events were assessed throughout the trial, though specific adverse event rates are not detailed in the available abstract.
Evidence of Toxicity from Extract Studies
Pharmacological activities of the crude L. pterodonta extracts have been evaluated, and the studied activities include acute toxicity testing, suggesting that formal acute toxicity profiling has been performed in preclinical settings, though detailed LD₅₀ or NOAEL values are not reported in the available published summaries.
DHTMF demonstrated good antiproliferative activities against a number of cancer cell lines while exhibiting low cytotoxicity in the two normal cell lines Vero and EVC304. This is preliminary reassurance of selectivity for the polymethoxyflavone constituent, but applies only in vitro.
Geographic Variability and Standardization
A notable safety-relevant issue is the documented intraspecific chemical variability of L. pterodonta depending on geographic origin. Reports published on the volatile oil of L. pterodonta from different countries and on different parts of this plant show variation and little similarity in major chemical compositions. This means that preparations sourced from different regions may have substantially different phytochemical profiles, making quality standardization essential for any therapeutic application.
Pyrrole Alkaloid Considerations
Pyrrole alkaloids isolated from L. pterodonta may serve as potential chemotaxonomic markers for the species. Pyrrolizidine alkaloids (PAs), which occur in numerous members of the Asteraceae family, are a recognized class of hepatotoxic compounds; however, the specific pyrrole alkaloids identified from L. pterodonta in the available literature are described as chemotaxonomic markers, and their specific toxicological profiles as isolated from this species have not been detailed in the sources surveyed here.
Absence of Regulatory Monographs
No monograph for Laggera pterodonta has been published by the WHO, the European Medicines Agency (EMA), the European Scientific Cooperative on Phytotherapy (ESCOP), the German Commission E, the United States Pharmacopeia (USP), or the European Pharmacopoeia as of the available literature. It is not listed as an ingredient reviewed by the NIH Office of Dietary Supplements. Its use in the West primarily occurs outside formal regulatory frameworks.
References
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