What is PRL-8-53?

PRL-8-53 (methyl 3-[2-[benzyl(methyl)amino]ethyl]benzoate hydrochloride, also called PRL 8-53 and m-[2-(benzylmethylamino)ethyl]benzoic acid methyl ester; CAS 51352-87-5 for the hydrochloride) is a synthetic small molecule built on a phenethylamine core: a benzene ring carrying a methyl ester at the meta (3-) position, joined by a two-carbon chain to a tertiary nitrogen that bears one methyl group and one benzyl group. It belongs to a patented series of substituted aminoethyl meta-benzoic acid esters and is catalogued with cholinergic and nootropic research compounds. PRL-8-53 is not a peptide and not an amino acid, even though many searches call it a “PRL 8-53 peptide.” Its chemistry comes from two functional groups: a basic tertiary amine that forms the hydrochloride salt, and an aromatic methyl ester.

The compound was introduced in a 1974 note in Experientia by N. R. Hansl, who listed affiliations at Creighton University and Pacific Research Laboratories (Hansl, 1974, Experientia 30:271–272). The matching patent claims the free base as one member of a 19-claim ester series and makes it by acid hydrolysis of a trifluoromethyl precursor followed by esterification with methanol, giving a white crystalline hydrochloride that melts at 150–151 °C (Hansl, US 3,870,715, Example 1). What PRL-8-53 does at the receptor level is less well mapped: the source documents classify the series as cholinergic, but no receptor binding constant (K_i) or enzyme IC₅₀ for PRL-8-53 appears in the indexed literature.

Batch-verified at Modern Aminos, PRL-8-53 is supplied in one laboratory format:

• 10 mg dry-fill capsules, 60 units per capsule bottle

Laboratories building cholinergic and monoamine-pathway reference panels often place PRL-8-53 next to other public reference listings such as BPAP, Bromantane, and L-THP, as well as Noopept, Phenylpiracetam Hydrazide, and Sunifiram. For a closer look at why searches call PRL-8-53 a peptide when it is not one, see Is PRL-8-53 a Peptide? A Methyl Benzoate Ester Explained.

Chemical and Molecular Data for PRL-8-53

Identity fields are drawn from PubChem CID 70700868 and CID 39989, with UNII codes from the FDA Global Substance Registration System as listed in PubChem; identity and quantity results come from the lot certificate in the Certificate of Analysis tab.

What are the Mechanisms of Action?

The biochemical targets and pathway logic of PRL-8-53 in laboratory research include:

• Phenethylamine scaffold with a meta methyl ester: PRL-8-53 is a 2-phenylethylamine whose ring carries a methoxycarbonyl group at position 3 and whose nitrogen carries N-methyl and N-benzyl groups, which makes it a tertiary amine (PubChem CID 39989). The pairing of a basic amine with an aromatic ester is the structural theme of the whole patented series (Hansl, US 3,870,715).
• Cholinergic classification in the source documents: The patent describes the substituted aminoethyl meta-benzoic acid esters as cholinergic agents, and the 1974 Experientia note introduces the hydrochloride as a new type of CNS-active compound (Hansl, US 3,870,715; Hansl, 1974). Neither source names a receptor subtype or reports a binding constant, so PRL-8-53 is a classified but molecularly uncharacterized cholinergic reference compound.
• Acid-addition salt chemistry: The tertiary nitrogen accepts a proton to form acid-addition salts. The patent isolates PRL-8-53 as the hydrochloride by adding HCl in ether and regenerates the free base with alkali hydroxide (Hansl, US 3,870,715, Example 1). PubChem lists one hydrogen-bond donor for the hydrochloride and none for the free base, with three acceptors in each (PubChem CID 70700868).
• Computed physicochemical descriptors: For the free base, PubChem computes XLogP3 3.6, a topological polar surface area of 29.5 Ų, 7 rotatable bonds, and 21 heavy atoms (PubChem CID 39989). These values describe a lipophilic amine with a small polar surface, which is useful context when choosing solvents and chromatographic conditions.
• Structure-activity handles in the patent series: The same patent claims analogs that swap the methyl ester for ethyl, n-propyl or t-butyl esters, replace the benzylmethylamino group with benzylethylamino, diethylamino, morpholino, piperidino or N-methylpiperazino groups, or add an α-methyl or β-methoxy group to the side chain (Hansl, US 3,870,715, claims 3–19). That makes PRL-8-53 a natural parent compound for ester- and amine-variation SAR work.
• Synthetic origin of the ester: The patented route builds the side chain from m-trifluoromethylbromobenzene by a Grignard reaction with ethylene oxide, converts the alcohol to a chloride with thionyl chloride, couples it with benzylmethylamine, and then turns the CF₃ group into a carboxylic acid with concentrated sulfuric acid before methanol esterification. The patent credits the relative inertness of the CF₃ group for letting the Grignard step work (Hansl, US 3,870,715).

What Does Published Research Show for PRL-8-53?

Peer-reviewed and patent literature on PRL-8-53 and its free base centers on synthesis, salt chemistry, and compound-series classification:

• Founding report (Experientia / PubMed): Hansl introduced 3-(2-benzylmethylaminoethyl)benzoic acid methyl ester hydrochloride as a new type of CNS-active compound in a two-page 1974 note (PubMed 4824605).
• Patent synthesis and salt isolation (US 3,870,715): Sulfuric acid hydrolysis of N-benzyl-N-methyl-3-trifluoromethylphenethylamine, methanol esterification, and HCl/ether precipitation give the hydrochloride, recrystallized from methanol/ether and isoamyl alcohol/ether, melting at 150–151 °C (US 3,870,715).
• Analog series and claims (US 3,870,715): Nineteen claims cover ester variants (ethyl, n-propyl, t-butyl), amine variants (benzylethyl, diethyl, methylisopropyl, morpholino, piperidino, N-methylpiperazino), and side-chain α-methyl and β-methoxy variants, with PRL-8-53’s free base named in claim 3 (US 3,870,715).
• Receptor-level data gap: Neither founding document reports a receptor subtype, K_i, EC₅₀, or IC₅₀, and no later binding study for PRL-8-53 is indexed in PubMed. Descriptions of specific dopaminergic or serotonergic receptor actions are not backed by a primary binding dataset.
• Chemical Directory & Structure Verification (PubChem / GSRS): Hydrochloride CAS 51352-87-5, CID 70700868, InChIKey HLBBSWSJLPLPRU-UHFFFAOYSA-N, UNII 2P77XL8HV7, 319.8 g/mol; free base CAS 51352-88-6, CID 39989, InChIKey IGJQEMHBYKNIQR-UHFFFAOYSA-N, UNII BM2TE2XHK6, 283.4 g/mol.
• Analytical Quality: Why chromatographic testing matters for reference materials is covered in Modern Aminos’ note on HPLC testing.

How does PRL-8-53 compare to other compounds?

To map cholinergic, monoamine, and structure-class reference tools, researchers compare PRL-8-53 against other laboratory compounds, including several available at Modern Aminos:

Frequently Asked Questions (FAQs)