Description
Summary Abstract
IPAM (Indolepropionamide; 3-Indolepropionamide; amide of indole-3-propionic acid (IPA); CAS 5814-95-9 for parent IPA; MW ~187.24 g/mol for amide form; L-023) is the primary amide derivative of indole-3-propionic acid, a tryptophan catabolite produced predominantly by Clostridium sporogenes and related gut microbiota species. IPA and its amide congeners act as ligands for the pregnane X receptor (PXR) — a nuclear receptor governing intestinal barrier gene expression and xenobiotic defense — and the aryl hydrocarbon receptor (AhR), a key transcriptional regulator of mucosal immune homeostasis. Structurally, indolepropionamide is among the most potent free-radical scavengers identified in the tryptophan indole metabolome, exceeding melatonin in hydroxyl-radical quenching capacity in some assay systems. The compound reduces synthesis of the pro-inflammatory transcription factor NF-κB and associated cytokines (TNF-α, IL-6), attenuates NLRP3 inflammasome activation, and enhances neurotrophic factor expression in CNS models. Ongoing research positions IPA and its amide forms as gut-brain axis mediators with relevance to metabolic, inflammatory, and neurodegenerative research contexts.
Clinical Indications
Preclinical and observational research implicates indolepropionamide and its parent acid IPA in the following areas of investigation:
- Gut Epithelial Barrier Integrity and IBD: PXR activation by IPA upregulates claudin-1 and other tight-junction proteins, reinforcing intestinal permeability defense; low plasma IPA is observed in IBD cohorts, supporting the barrier-protective mechanism as therapeutically relevant.
- Metabolic and Hepatic Inflammation: In the METSIM cohort study (Tuomainen et al., 2018; PMID 30053918), higher circulating IPA levels were independently associated with reduced risk of type 2 diabetes and non-alcoholic fatty liver disease, positioning IPA as a metabolically protective microbiome-derived signal.
- Neuroprotection and Cognitive Function: IPA crosses the blood-brain barrier and boosts central kynurenic acid (KYNA) levels — a neuroprotective tryptophan metabolite — while independently suppressing hippocampal neuroinflammation and protecting against amyloid-β-associated synaptic loss in preclinical neurodegeneration models (PMID 40942152).
- Antioxidant Defense: Indolepropionamide and IPA are potent free-radical scavengers; the indole ring system quenches hydroxyl, peroxyl, and superoxide radicals in a manner comparable to or exceeding melatonin in selected assay conditions, relevant to oxidative stress-driven pathology research.
Contraindications
- CYP Enzyme Induction Risk: PXR activation by IPA congeners can upregulate CYP3A4 and related cytochrome P450 enzymes, potentially altering the pharmacokinetics of co-administered drugs with narrow therapeutic windows metabolized by CYP3A4.
- Pregnancy: PXR agonism has been reported to affect placental drug transport and steroid metabolism; data on safety during pregnancy are insufficient to establish a risk profile.
- Tryptophan Metabolism Disorders: Individuals with documented disorders of tryptophan metabolism (e.g., Hartnup disease, pyridoxine-dependent epilepsy) may exhibit unpredictable responses to indole metabolite supplementation.
Mechanism of Action (MOA)
Indolepropionamide exerts its biological effects through three principal molecular mechanisms spanning the gut, liver, and CNS:
Pregnane X Receptor (PXR) Agonism
IPA and its amide derivatives bind and activate the pregnane X receptor (PXR; NR1I2) in intestinal epithelial cells and hepatocytes. PXR activation induces claudin-1 and other tight-junction scaffold genes, reinforcing intestinal epithelial barrier function. Simultaneously, hepatic PXR activation modulates xenobiotic detoxification via CYP3A4/MDR1 induction — a dual role that positions PXR agonists as both barrier-protective and metabolic regulators.
Aryl Hydrocarbon Receptor (AhR) Activation
The indole scaffold of IPA activates the aryl hydrocarbon receptor (AhR) — a ligand-activated transcription factor governing mucosal immune homeostasis, IL-22 production by innate lymphoid cells (ILC3s), and T-regulatory cell differentiation. AhR activation by microbiota-derived indoles, including IPA, suppresses Th17-type inflammation while promoting tolerogenic immune responses in the gut mucosa, constituting a key gut-brain immune axis signaling mechanism.
Free-Radical Scavenging and NF-κB Inhibition
The bicyclic indole ring system confers potent hydrogen-atom transfer (HAT) antioxidant capacity to IPA and indolepropionamide, enabling direct scavenging of hydroxyl radicals, peroxyl radicals, and reactive nitrogen species. Downstream, IPA reduces NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) activation and decreases synthesis of TNF-α, IL-6, and NLRP3 inflammasome components — an anti-inflammatory profile relevant to both peripheral tissue and CNS inflammatory research contexts.
Gut-Brain Axis — Kynurenic Acid Modulation
IPA administered orally or absorbed from gut microbiota elevates central kynurenic acid (KYNA) levels — a kynurenine pathway metabolite that antagonizes NMDA receptors and α7 nicotinic acetylcholine receptors, exerting neuroprotective effects. This gut-to-brain tryptophan signaling axis, documented by Schwarcz and colleagues, suggests that IPA-class metabolites function as microbiome-derived neuroprotective signals capable of modifying the central kynurenine/kynurenic acid ratio in a therapeutically relevant manner.
Key Features & Specifications
Defining characteristics of IPAM as a gut-microbiome-derived tryptophan metabolite:
Chemical Analysis
| Property | Specification Reference Data |
|---|---|
| IUPAC Name | 3-(1H-indol-3-yl)propanamide |
| CAS Number (parent IPA) | 830-96-6 (indole-3-propionic acid); 5814-95-9 (alternative IPA registry) |
| Molecular Formula (amide) | C11H12N2O |
| Molecular Weight (amide) | ~188.23 g/mol |
| Synonyms | Indolepropionamide; 3-Indolepropionamide; IPA amide; Indole-3-propionamide |
| Parent Compound | Indole-3-propionic acid (IPA) — primary gut microbiota tryptophan catabolite |
| Form / Variation | Liquid formulation (L-023) — $44.00 |
Storage, Safety, and Handling
Storage Protocol
Store liquid IPAM formulation at 2–8 °C, protected from light; indole compounds are susceptible to photo-oxidation. Avoid repeated freeze-thaw cycling of the liquid preparation. For long-term archival, aliquoting into smaller volumes at −20 °C is recommended. The compound should be inspected for discoloration (yellow-to-brown color change indicates oxidative degradation of the indole chromophore) before each use.
Handling & Compliance
Handle with standard laboratory PPE (nitrile gloves, safety glasses). As a PXR agonist, indolepropionamide has the potential to induce CYP3A4 and MDR1 expression, which may modulate concurrent pharmacological experimental conditions involving CYP3A4-substrate drugs. This compound is not listed on the WADA Prohibited List. Standard institutional biosafety procedures for small-molecule research compounds apply.