Dodeca-2E,4E-dienoic Acid Isobutylamide: A Comprehensive Reference
1. Identity and Chemical Characterization
Names and Identifiers
Dodeca-2(E),4(E)-dienoic acid isobutylamide is known by several synonyms, including (2E,4E)-N-isobutyldodeca-2,4-dienamide, 2,4-Dodecadienamide, N-(2-methylpropyl)-, (2E,4E)-, and the informal designation Dienamide A2. In experimental literature it is frequently abbreviated as DDI (from its common name) or designated A2 (in the landmark Raduner et al. receptor-binding series) or A15 (in the Gulledge et al. mast-cell series) — these reflect the same compound identified by different research groups using different numbering conventions. Its CAS Registry Number is 24738-51-0.
ChEBI classifies (2E,4E)-N-isobutyl-2,4-dodecadienamide as a fatty amide. It is recorded in that database as having a role as a metabolite. Its molecular formula is C16H29NO and its molecular weight is 251.41 g/mol. Structurally, it consists of a straight-chain twelve-carbon fatty acid backbone bearing two conjugated trans double bonds at the 2- and 4-positions (E,E geometry), with the carboxyl terminus forming an amide bond with isobutylamine (N-(2-methylpropyl) group).
Classification Within the Alkylamide Family
Alkamides (alkylamides), along with other compound classes such as caffeic acid derivatives, polysaccharides, and glycoproteins, are believed to contribute to Echinacea's immunostimulatory and anti-inflammatory properties. Alkamides are structurally similar to anandamide, an endogenous ligand of cannabinoid (CB) receptors and an integral component of the endocannabinoid system that plays a key role in immune-inflammatory responses. Dodeca-2E,4E-dienoic acid isobutylamide is distinguished from the more abundant tetraene alkylamides (dodeca-2E,4E,8Z,10E/Z-tetraenoic acid isobutylamides) by the absence of the additional double bonds at the 8- and 10-positions, giving it a simpler diene structure.
Natural Source and Botanical Distribution
Dodeca-2(E),4(E)-dienoic acid isobutylamide (also known as Kalecide) is a naturally occurring metabolite in Echinacea, one of the most widely used traditional herbal medicines. Both Echinacea purpurea (E. purpurea) and Echinacea angustifolia (E. angustifolia) are commonly utilized in the production of teas, extracts, tinctures, and various over-the-counter products. In total, seventeen alkamides have been identified in E. purpurea, and dodeca-2(E),4(E)-dienoic acid isobutylamide is one of them.
Quantification in E. purpurea aerial parts and roots places dodeca-2E,4E-dienoic acid (the parent acid moiety) at approximately 0.06 ± 0.05 mg/g dry weight, making it a minor constituent relative to the principal tetraene pair, which totals approximately 1.44 ± 1.00 mg/g dry weight. Within E. angustifolia, high-speed countercurrent chromatography isolation of root material yielded dodeca-2E,4E-dienoic acid isobutylamide at 3.2 mg at 99% purity — confirming its presence but lower abundance relative to the tetraene isomers (38.9 mg at 97% purity in the same isolation run).
The amides of E. purpurea root have mainly a 2,4-dienoic unit such as dodeca-2E,4E,8Z,10E-tetraenoic acid isobutylamide, whereas those of E. angustifolia root favor a monoenoic structure such as dodeca-2E-ene-8,10-diynoic acid isobutylamide. Dodeca-2E,4E-dienoic acid isobutylamide occupies an intermediate structural position between these two profiles and is found in both species.
Common Forms and Preparations
In Echinacea purpurea, the predominant alkamide is the tetraene pair; in isolated form, these closely related alkylamide compounds appear as off-white crystalline solids with a low melting point. The compounds should be handled at low temperatures or in a manner that minimizes heat exposure to prevent melting, and alkamides are susceptible to oxidative degradation, making it essential to limit their exposure to air.
In consumer products, dodeca-2E,4E-dienoic acid isobutylamide is not commercially prepared as an isolated pure compound for human consumption. Instead, it is present as a component of broad-spectrum Echinacea preparations. Both E. purpurea and E. angustifolia are commonly utilized in the production of teas, extracts, tinctures, and various over-the-counter products. Ethanolic extraction (typically 60% ethanol) concentrates lipophilic alkylamides more effectively than aqueous extraction, while purely aqueous preparations (teas) contain substantially reduced alkylamide content.
2. Traditional and Historical Use
Indigenous North American Use
Echinacea angustifolia was widely used by North American Indigenous peoples as folk medicine, with archaeological evidence dating back to the 18th century. The nine Echinacea species were most widely used — both historically and currently — by Native Americans of the Great Plains for medicinal purposes. Echinacea angustifolia has been described as the most widely used medicinal plant of the Plains Indians in North America, used by at least 15 tribes for a variety of ailments, including coughs, colds, inflammation, snakebite, sore throats, toothache, worms, and as a painkiller.
Traditional use included external application for insect bites, burns, and wounds; chewing of roots for throat and tooth infections; and internal use for cough, pain, snake bites, and stomach cramps. Some Plains tribes used Echinacea for cold symptoms. The Kiowa used it for coughs and sore throats, the Cheyenne for sore throats, the Pawnee for headaches, and many tribes, including the Lakota, used it as a pain medication.
There is also an extensive ethnobotanical record of Echinacea use for management of pain — for example, toothache by the Niitsitapi (Blackfoot First Nation), arthritis by the Tsestho'e (Cheyenne tribes), and rheumatism or burns by the Šakówiŋ (Dakota and Lakota First Nations).
The E. purpurea species of Echinacea was originally discovered by Native Americans in North America, who used the plant medicinally for respiratory tract infections, tooth pain, and snakebite. While documentation of specific molecular constituents such as dodeca-2E,4E-dienoic acid isobutylamide was obviously absent in historical contexts, the preparations used — particularly root chewing and ethanolic extracts — are now known to deliver this alkylamide along with related congeners.
Entry into Western Herbal Medicine and European Phytopharmacy
Early European settlers noticed the Indigenous uses of Echinacea and began to develop their own uses. According to Wallace Sampson, its modern use for the common cold began when a Swiss herbal supplement maker was told that Echinacea was used for cold prevention by Native American tribes who lived in the area of South Dakota. By the start of the 20th century it was the most common herbal remedy in America. Commercial cultivation began in Germany in the late 1930s, and in Switzerland in 1950, by A. Vogel.
Soon chemists and pharmacologists began the task of identifying potentially active ingredients and their properties, including alkylamides, cichoric acid, echinacoside, ketoalkenes, and polysaccharides. Extracts appeared to exhibit immunostimulant properties and were mainly promoted for the prevention and treatment of colds, influenza, and sepsis. The purpose of the preparations — internal administration for immune support, particularly of the respiratory tract — mirrors the traditional use categories recorded by Indigenous peoples.
Preparation Methods in Tradition
The tribes used physical applications to treat wounds, burns, and insect bites; chewed the roots to treat toothache and throat infections; and ingested the plants to treat pain, coughs, stomach cramps, and snake bites. Root chewing is particularly relevant to the alkylamide profile: the lipophilic alkylamides, including dodeca-2E,4E-dienoic acid isobutylamide, are more soluble in partially alcoholic media than in pure water, meaning that oral mucosa contact with chewed roots and ethanol-based tinctures would deliver this compound more efficiently than hot-water teas.
3. Key Constituents, Chemical Context, and Mechanisms of Action
Position Among Echinacea Alkylamides
The most recent comprehensive alkylamide overview by Mudge et al. (2011) utilized UFLC-DAD-MS analysis and identified 24 total alkylamides in the roots of E. purpurea and E. angustifolia, including 15 of the 17 previously reported in E. purpurea, and 22 in E. angustifolia. Of the identified alkylamides in E. purpurea to date, only a few have been investigated for pharmacological activity, primarily numbers 8 and 9 (the dodeca-2E,4E,8Z,10E(Z)-tetraenoic acid isobutylamides), as well as three other alkylamides found in higher concentrations in Echinacea roots: undeca-2E-ene-8,10-diynoic acid isobutylamide, dodeca-2E-ene-8,10-diynoic acid isobutylamide, and dodeca-2E,4E-dienoic acid isobutylamide.
Cannabinoid Receptor Binding (CB2 and CB1)
The alkylamides dodeca-2E,4E,8Z,10Z-tetraenoic acid isobutylamide (A1) and dodeca-2E,4E-dienoic acid isobutylamide (A2) bind to the CB2 receptor more strongly than the endogenous cannabinoids. The Ki values of A1 and A2 (CB2 ~60 nM; CB1 >1500 nM) were determined by displacement of the synthetic high-affinity cannabinoid ligand [3H]CP-55,940. This represents highly selective CB2 binding with ~25-fold selectivity over CB1 at the tested concentrations.
Molecular modeling suggests that alkylamides bind in the solvent-accessible cavity in CB2, directed by H-bonding and π–π interactions. In a screen with 49 other pharmacologically relevant receptors, it could be shown that A1 and A2 specifically bind to CB2 and CB1.
The CB1 and CB2 receptors are heptahelical G-protein-coupled receptors with different distributions: the CB1 receptors are highly expressed in the central nervous system (CNS) with low to moderate expressions in the periphery, while the CB2 receptor expression is high in the immune system, but with much lower and more restricted distribution in the CNS. The strong, preferential binding to CB2 over CB1 is pharmacologically significant because it predicts predominantly peripheral immunomodulatory activity without the central psychoactive effects associated with CB1 activation.
Cytokine Modulation via CB2-Dependent and CB2-Independent Pathways
A1 and A2 elevated total intracellular Ca2+ in CB2-positive but not in CB2-negative promyelocytic HL60 cells, an effect that was inhibited by the CB2 antagonist SR144528. At 50 nM, A1, A2, and the endogenous cannabinoid anandamide up-regulated constitutive interleukin (IL)-6 expression in human whole blood in a seemingly CB2-dependent manner.
A1, A2, anandamide, the CB2 antagonist SR144528, and also the non-CB2-binding alkylamide undeca-2E-ene,8,10-diynoic acid isobutylamide all significantly inhibited lipopolysaccharide-induced tumor necrosis factor α, IL-1β, and IL-12p70 expression (5–500 nM) in a CB2-independent manner. This indicates that the compound acts on at least two distinct molecular pathways simultaneously.
N-alkylamides act in concert and exert pleiotropic effects modulating the endocannabinoid system by simultaneously targeting the CB2 receptor, endocannabinoid transport, and degradation. In addition to selectively binding and activating CB2 receptors, certain Echinacea alkylamides can modulate endocannabinoid system (ECS) activity through effects on endocannabinoid metabolism and transport.
Dodeca-2E,4E-dienoic acid isobutylamide exerts immunomodulatory effects down-regulating the gene expression and reducing the protein plasmatic levels of pro-inflammatory cytokines such as IL-6, TNF-α, and IL-8, and up-regulating the expression of anti-inflammatory molecules such as IL-10.
PPARγ Activation and Metabolic Signaling
Dodeca-2(E),4(E)-dienoic acid isobutylamide (DDI), an alkamide derived from the plant Echinacea purpurea, promotes adipocyte differentiation and activates peroxisome proliferator-activated receptor γ (PPARγ), which is associated with enhanced insulin sensitivity. An ethanolic extract of E. purpurea and its constituent dodeca-2(E),4(E)-dienoic acid isobutylamide have exhibited PPARγ activation.
The expressions of PPARγ and C/EBPα in adipocytes treated with dodeca-2(E),4(E)-dienoic acid isobutylamide were significantly higher than in control cells. These results suggest that dodeca-2(E),4(E)-dienoic acid isobutylamide appears to be responsible for EEEP (ethanol extract of E. purpurea)-enhanced adipocyte differentiation.
Inhibition of Mast Cell Activation
Echinacea species produce many fatty acid amides referred to as alkylamides, which can inhibit cytokine, chemokine, and prostaglandin production from macrophages and T cells. Alkylamides are thought to contribute to the anti-inflammatory activity of E. purpurea extracts by inhibiting production of inflammatory mediators. More specifically, the goal of a key study was to evaluate the effects of the alkylamide dodeca-2E,4E-dienoic acid isobutylamide (A15) on mast cells, which are important mediators of allergic and inflammatory responses, and to investigate the mechanism of alkylamide inhibition of mast cell activation.
COX-2 Inhibition
Echinacea alkylamides have been shown to inhibit TNF-α expression via cannabinoid CB2 receptor activation and to inhibit COX-2 (cyclooxygenase-2) activity. COX-2 is a key enzyme in the biosynthesis of pro-inflammatory prostaglandins, and its inhibition represents an additional mechanism through which dodeca-2E,4E-dienoic acid isobutylamide may contribute to anti-inflammatory effects.
Macrophage-Mediated Inflammatory Mediator Inhibition
The alkylamides undeca-2Z,4E-diene-8,10-diynic acid isobutylamide, dodeca-2E,4E,8Z,10E/Z-tetraenoic acid isobutylamide, dodeca-2E,4E-dienoic acid isobutylamide, and undeca-2E-ene-8,10-diynoic acid isobutylamide from E. purpurea suppressed production of TNF-α and PGE2 from RAW 264.7 macrophage-like cells infected with the H1N1 influenza A strain PR/8/34 (Cech et al., 2010). Dodeca-2E,4E-dienoic acid isobutylamide was especially effective at inhibiting production of these mediators and also strongly inhibited production of G-CSF, CCL2/MCP-1, CCL3/MIP-1α, and CCL5/RANTES.
4. Scientific Evidence by Area
4.1 Immunomodulation and Anti-Inflammatory Activity
Evidence type: Predominantly in vitro (cell-based), with some ex vivo human whole-blood data. No clinical trials isolating this specific compound.
Raduner et al. (2006) demonstrated that dodeca-2E,4E-dienoic acid isobutylamide (A2) binds to the CB2 receptor more strongly than the endogenous cannabinoids, with Ki values of approximately 60 nM (CB2) and >1500 nM (CB1), determined by displacement of [3H]CP-55,940. This study — published in the Journal of Biological Chemistry — used radioligand binding assays, receptor screen panels covering 49 pharmacological receptors, and Ca2+ mobilization assays in human cell lines. The findings established this compound as a selective CB2 ligand with nanomolar affinity, representing a milestone in understanding the mechanism of Echinacea alkylamide activity.
At 50 nM, A2 (dodeca-2E,4E-dienoic acid isobutylamide) up-regulated constitutive IL-6 expression in human whole blood in a seemingly CB2-dependent manner. This ex vivo human whole-blood model provides a degree of translational relevance beyond pure cell culture, though it cannot be equated with clinical endpoint evidence.
Echinacea alkylamides demonstrate multi-target behavior: nanomolar-affinity CB₂ activation dampens TNF-α and IL-6, whereas partial TLR4 antagonism re-balances Th1/Th2 cytokine bias, potentially complementing conventional immunosuppression.
Evidence strength: The immunomodulatory mechanism is well-characterized at the molecular level through robust in vitro and ex vivo studies. However, no clinical trials have been conducted with isolated dodeca-2E,4E-dienoic acid isobutylamide as a single agent. Clinical evidence is available for whole Echinacea preparations, but the individual contribution of this specific alkylamide to clinical outcomes cannot be separated from the mixture.
4.2 Antiviral Activity (Respiratory Viruses)
Evidence type: In vitro only.
Although previous research suggests that the alkylamides present in Echinacea may be responsible for reducing the symptoms associated with the common cold or flu through their immunomodulatory activity, the roles of specific alkylamides and their targets have not been well-elucidated or established. One study tested the antiviral and cytokine regulatory activity of various specific alkylamides that are present predominantly in Echinacea root extracts and found that dodeca-2E,4E-dienoic acid isobutylamide had potent antiviral activity against rhinovirus (the causative agent of most common colds) and influenza virus, as well as potent inhibition of IL-8 cytokine production.
Dodeca-2E,4E-dienoic acid isobutylamide displayed potent inhibition of both rhinovirus and influenza virus, as well as IL-8 expression, suggesting this alkylamide could be further investigated as a potential therapeutic for both the common cold and flu. The study published in Molecules (MDPI, 2025) used viral plaque assays with HeLaH1 and MCDK cell lines to measure viral replication.
Seventeen extracts and 4 alkylamides were tested for the ability to inhibit production of cytokines, chemokines, and PGE2 from RAW 264.7 macrophage-like cells infected with the H1N1 influenza A strain PR/8/34. The alkylamides undeca-2Z,4E-diene-8,10-diynic acid isobutylamide, dodeca-2E,4E,8Z,10E/Z-tetraenoic acid isobutylamide, dodeca-2E,4E-dienoic acid isobutylamide, and undeca-2E-ene-8,10-diynoic acid isobutylamide suppressed production of TNF-α and PGE2 from infected cells. Dodeca-2E,4E-dienoic acid isobutylamide was especially effective at inhibiting production of these mediators and also strongly inhibited production of G-CSF, CCL2/MCP-1, CCL3/MIP-1α, and CCL5/RANTES.
Evidence strength: These results are exclusively from cell culture and animal macrophage models. While the antiviral and cytokine-suppressive activity in vitro is notable, the translational value to clinical antiviral therapy cannot be assessed without human pharmacokinetic and clinical data specifically for this isolated compound. Evidence at this stage is preliminary in vitro only.
4.3 Mast Cell Stabilization and Allergy-Related Activity
Evidence type: In vitro (primary mast cell cultures and mast cell lines).
A study evaluated the effects of an ethanolic E. purpurea root extract and the alkylamide dodeca-2E,4E-dienoic acid isobutylamide (A15) on mast cells, which are important mediators of allergic and inflammatory responses. Inhibition of mast cell activation may help explain the traditional use of Echinacea. A15 was evaluated for its effects on degranulation, calcium influx, cytokine and lipid mediator production using bone marrow-derived mast cells (BMMCs) and the transformed rat basophilic leukemia mast cell line RBL-2H3, using enzymatic assays, fluorimetry, ELISAs, and microscopy. This study (Gulledge et al., Journal of Ethnopharmacology, 2018) represents the most direct investigation of dodeca-2E,4E-dienoic acid isobutylamide's effect on allergy-relevant cell types.
Evidence strength: Preliminary, in vitro only. No human allergy clinical data exist for this isolated compound.
4.4 Glucose Metabolism and Insulin Sensitivity
Evidence type: In vitro cell models (3T3-L1 adipocytes).
Investigators assessed whether DDI may increase glucose uptake through activation of the insulin signaling pathway in 3T3-L1 adipocytes. DDI increased insulin-stimulated glucose uptake, and expression and translocation of glucose transporter 4 (GLUT4) in adipocytes treated with sub-optimal levels of insulin. Additionally, DDI enhanced Akt phosphorylation, whereas phosphoinositide 3-kinase/Akt inhibitors suppressed DDI-induced glucose uptake. These results suggest that DDI may improve insulin sensitivity through the activation of Akt signaling, which leads to enhanced glucose uptake. This study was published in Molecular and Cellular Biochemistry (2017).
Echinacea purpurea has been shown to have anti-diabetic activities; for example, it activates peroxisome proliferator-activated receptor γ (PPARγ) and increases insulin-stimulated glucose uptake.
Evidence strength: Preliminary cell-culture data only. No human or animal in vivo studies have been conducted with isolated dodeca-2E,4E-dienoic acid isobutylamide assessing glycemic outcomes. These findings are mechanistically interesting but of unproven clinical relevance.
4.5 Pain Modulation
Evidence type: Mechanistic/receptor binding; animal data for related alkylamides; historical ethnobotanical parallel.
Recent research has revealed a relevant new mechanism of pain management by Echinacea mediated by alkylamides acting at the cannabinoid (CB) receptors. Given the well-established roles of CB2 receptor agonism in peripheral pain modulation — particularly in inflammatory pain models — the selective CB2 binding of dodeca-2E,4E-dienoic acid isobutylamide provides a plausible mechanistic framework for the traditional analgesic uses of Echinacea. However, while the ethnobotanical record documents use by multiple nations for conditions including arthritis and rheumatism, no clinical analgesic trials have been conducted with this isolated compound.
Evidence strength: Mechanistic basis is reasonable given the CB2 receptor profile, but direct human analgesic evidence for this specific compound is absent.
5. Body Systems and Health Areas
- Immune System: Alkamides from Echinacea, including dodeca-2E,4E-dienoic acid isobutylamide, have documented immunomodulatory and anti-inflammatory activities. These effects are mediated through CB2 receptor binding, cytokine modulation (down-regulation of TNF-α, IL-1β, IL-12, IL-6, IL-8; up-regulation of IL-10), COX-2 inhibition, and mast cell stabilization.
- Respiratory Tract: Today, Echinacea products are primarily promoted as a dietary supplement for the common cold and other respiratory tract infections, based on the idea that certain species of Echinacea may stimulate the immune system. Dodeca-2E,4E-dienoic acid isobutylamide has demonstrated antiviral activity against rhinovirus and influenza virus in vitro.
- Endocannabinoid System: The compound selectively engages CB2 receptors (Ki ~60 nM) with high selectivity over CB1, placing it functionally within the endocannabinoid system with predominantly peripheral immune-modulatory consequences.
- Metabolic / Endocrine System: PPARγ activation and enhancement of Akt-mediated glucose uptake in adipocytes link this compound to pathways relevant to insulin sensitivity and carbohydrate metabolism, though these relationships have only been demonstrated in cell models.
- Skin: Some Echinacea products may be promoted for topical use (application to the skin) for various skin problems, like eczema. Alkylamides' anti-inflammatory and mast-cell-stabilizing activities have been proposed as relevant mechanisms for topical applications, though again specific clinical evidence for isolated dodeca-2E,4E-dienoic acid isobutylamide is lacking.
6. Pharmacokinetics and Bioavailability
Oral Bioavailability of Alkylamides as a Class
It has been demonstrated that alkylamides are the only Echinacea compounds that after oral administration showed high bioavailability. According to the human pharmacokinetic studies reviewed in the EMA reports, the alkylamides from E. purpurea and E. angustifolia show good oral bioavailability with rapid absorption and measurable plasma concentration within 20–60 minutes post-ingestion.
Alkylamides were rapidly absorbed and were measurable in plasma 20 minutes after tablet ingestion and remained detectable for up to 12 hours. The maximal concentrations for the sum of alkylamides in human plasma were reached within 2.3 hours post-ingestion and averaged 336 ± 131 ng/mL plasma. The authors concluded that alkylamides from Echinacea preparations were orally bioavailable and their pharmacokinetics supported the three times daily regimen already recommended for Echinacea.
Detectability of Dodeca-2E,4E-dienoic Acid Isobutylamide Specifically in Plasma
In a pharmacokinetic study using a single oral 2.5 mL dose of 60% ethanolic extract from E. angustifolia roots in healthy volunteers, dodeca-2E,4E-dienoic acid isobutylamide was not detected in serum (limit of detection being 3 pg/mL). This is a critical finding: despite being pharmacologically active in vitro, this specific compound — at the concentrations delivered by that particular preparation — fell below the limit of detection in circulating blood. Other alkylamides from the same dose were measurable, including the undeca-2E/Z-ene-8,10-diynoic acid isobutylamides (1.87 ng/mL) and dodeca-2E,4E,8Z-trienoic acid isobutylamide (2.1 ng/mL).
The reported peak plasma concentration Cmax values for alkylamides varied between studies from 0.04 ng/mL for E. purpurea alkylamides (Goey et al., 2012) to over 300 ng/mL for E. purpurea/E. angustifolia alkylamides (Matthias et al., 2005). The EMA highlighted that these discrepancies are likely due to differences in the alkylamide profiles between Echinacea species, extract concentrations, analytical methods, and study design.
Metabolic Pathways
In incubations with human liver microsomes and selective inhibitors, CYP2E1 was found to be principally responsible for producing the dominant hydroxylation product, whereas CYP2C9 was the principal source of the epoxides and CYP1A2 was responsible for the dealkylation product. These metabolic pathways for Echinacea alkylamides as a class are relevant to understanding the possibility of drug interactions.
Food Effects
The effect of the absence of food on alkylamide oral availability was examined in subjects who ingested Echinacea tablets following an overnight fast. No differences were observed for the disposition of individual or total alkylamides in the fasted versus the fed subjects.
7. Dosage Forms and Reported Dosages
Dodeca-2E,4E-dienoic acid isobutylamide has not been studied in isolation in human clinical or pharmacokinetic trials at defined doses. All dosage information pertains to mixed Echinacea preparations of which this alkylamide is a minor constituent.
- In the Matthias et al. pharmacokinetic study, volunteers received Echinacea orally as 4 tablets, each containing 675 mg of Echinacea purpurea root and 600 mg of Echinacea angustifolia root.
- In a softgel capsule pharmacokinetic and immunological study, 10 mg of Echinacea angustifolia lipophilic extract (containing the relevant alkylamides, primarily the tetraene) was given in a single oral administration to 10 human volunteers.
- A two-way crossover comparative bioavailability study involved liquid preparation (mixture of E. purpurea root at 300 mg/mL and E. angustifolia root at 200 mg/mL extracted in 60% ethanol) and tablet preparation (E. purpurea root 675 mg/tablet and E. angustifolia root 600 mg/tablet).
N-alkylamides have been shown to reach nM plasma concentrations in humans despite their relatively moderate bioavailability, and depending on the initial dose, potentially bioactive concentrations can be reached. The nanomolar CB2 binding affinity of dodeca-2E,4E-dienoic acid isobutylamide (~60 nM Ki) is at least theoretically consistent with bioactive concentrations being achievable from pharmacologically relevant Echinacea doses, though this has not been confirmed for this specific compound in published plasma detection studies.
8. Safety Considerations and Interactions
General Tolerability of Echinacea Alkylamide-Containing Preparations
Adverse events reported during clinical trials following administration of Echinacea spp. mono-preparations were generally mild and mostly without causality. Due to published long-term studies with continuous ingestion of different Echinacea preparations up to 6 months with no reported toxicological concerns, Echinacea can be recommended also for long-term use.
CYP Enzyme Interactions
Neither Echinaforce nor the alkylamides produced any significant changes in the steady-state CYP3A4 mRNA levels. In contrast, treatment with 50 μM rifampicin resulted in a 3.8-fold up-regulation over the vehicle control. The authors concluded that Echinaforce is unlikely to affect CYP3A4 transcriptional levels, even at concentrations which can inhibit the enzymatic activity of CYP3A4, and their data provides further evidence for the lack of interactions between Echinacea and conventional drugs.
In pharmacokinetic herb-drug interaction studies performed in vivo, no significant inhibitions of human CYP2D6 and CYP3A4 isoforms have been found after the administration of standardized E. purpurea preparations. However, contradictory results exist in studies using liver microsomes. Accordingly, there is conflicting evidence about whether echinacea interacts with some drugs metabolized by the liver, and there are theoretical reasons to suspect that echinacea might interact with immunosuppressants or caffeine.
Immunosuppressant Drug Interactions
Echinacea may make immunosuppressant medications such as tacrolimus (Prograf®) or cyclosporine (Gengraf®, Neoral®, or Sandimmune®) less effective. This concern stems from the immunomodulatory activity of alkylamides, including dodeca-2E,4E-dienoic acid isobutylamide, which by activating CB2 receptors and modulating cytokine expression could theoretically counteract pharmacological immunosuppression.
Some studies suggest that Echinacea could decrease plasma levels, affect therapeutic efficacy, or cause adverse effects with some anticancer drugs.
Autoimmune Conditions — Reassessment of Historical Contraindications
The contraindications in cases of autoimmune diseases and immune-suppression are questionable, since lipophilic Echinacea preparations containing alkamides suppress cellular immune responses, and beneficial effects in autoimmunity have been reported. This is a nuanced finding: alkylamide-rich (lipophilic) preparations, rather than stimulating immunity uniformly, appear to have immunomodulatory (bi-directional) effects that may differ from earlier assumptions of simple immunostimulation.
Pregnancy and Lactation
Some studies of the use of solid or liquid extracts of E. purpurea and E. angustifolia suggest it is possibly safe for up to 7 days during the first trimester of pregnancy, though consultation with a healthcare provider is advised. Little is known about whether it is safe to use Echinacea while breastfeeding. Although there has been some impact reported on embryonic angiogenesis in mice, no association with an increased risk for major or minor malformations during organogenesis was found in a literature review.
Anticancer Drug Interactions
In HIV-infected patients, co-administration with etravirine was found to be safe and well tolerated. In a large population-based study, use of Echinacea was associated with a slight increase in diastolic blood pressure.
Oxidative Stability
Alkamides are susceptible to oxidative degradation, making it essential to limit their exposure to air. This property is relevant to the shelf-life and potency of preparations containing dodeca-2E,4E-dienoic acid isobutylamide, and supports the use of standardized, well-preserved extracts rather than non-standardized products.
9. Evidentiary Summary and Limitations
Dodeca-2E,4E-dienoic acid isobutylamide is a chemically well-characterized minor alkylamide constituent of E. purpurea and E. angustifolia, with a clearly defined molecular identity, CAS registration, and confirmed presence in commercial Echinacea preparations. At the mechanistic level, it is among the most pharmacologically interesting Echinacea alkylamides: it binds CB2 receptors with greater affinity than the endogenous cannabinoid anandamide, modulates a broad array of pro- and anti-inflammatory cytokines through both CB2-dependent and CB2-independent mechanisms, inhibits COX-2 activity, stabilizes mast cells, and activates PPARγ to promote insulin-sensitizing signaling in adipocytes. This multi-target profile is mechanistically coherent and well documented in peer-reviewed research.
However, several important limitations define the current state of evidence. First, all pharmacological studies have been conducted using in vitro cell models or ex vivo human whole-blood assays; no clinical trials have tested this isolated compound. Second, specific plasma pharmacokinetic data for this compound following oral Echinacea administration are incomplete, with at least one published study failing to detect it above the limit of quantification — raising questions about the achievable plasma concentrations after typical oral doses. Third, the majority of available clinical evidence concerns whole Echinacea preparations, from which the independent contribution of this particular minor alkylamide cannot be deconvoluted. Fourth, despite many different preparations and hundreds of publications, no exact identification of a truly active ingredient in Echinacea has been established.
In summary, dodeca-2E,4E-dienoic acid isobutylamide is a biologically active natural compound with a well-established molecular pharmacology, a coherent mechanistic basis for the traditional anti-inflammatory and immune-supportive uses of its source plants, and preliminary but promising in vitro evidence across multiple health-relevant pathways. The translation of these findings to demonstrated human clinical benefit for this compound specifically remains an open and active research question.
References
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