PRL-8-53

1 Identity

Non-peptide small molecule. A benzoic acid methyl ester bearing a meta ethylene linker to a tertiary benzyl(methyl)amine: one basic nitrogen, no stereocenter, no amide bond of any kind, and a hydrolytically labile ester that is the principal degradation site. It sits in this catalog because the market sells it beside peptides, not because it shares any chemistry with them. which is indexed to both salt states by different sellers. Not a peptide and not an abbreviation of one. The '8-53' is a laboratory series number, not a residue range. Do not confuse with PRL-8-147 or with prolactin ('PRL'), an unrelated protein whose abbreviation collides with this name in search.

Sequence

None, and none can exist. There are no amino acids and no peptide bond in this molecule. The full structural name is methyl 3-{2-[benzyl(methyl)amino]ethyl}benzoate. Any document offering a sequence, an amino-acid analysis, a net peptide content or an endotoxin figure for this article has run a peptide template against a small molecule and was not read by whoever signed it.

Molecular formula

C18H21NO2 (free base) and C18H22ClNO2 (monohydrochloride). Both are in current commerce under the one product name and the one CAS number, so the formula is not fully specified until the salt state is declared.

Average mass

Average mass 283.371 Da for the free base (C18H21NO2) and 319.829 Da as the monohydrochloride formula weight (C18H22ClNO2), on IUPAC 2021 abridged conventional atomic weights. The pre-2021 table (C 12.0107, H 1.00794, N 14.0067, O 15.9994, Cl 35.453) returns 283.365 and 319.826 exactly for the same two formulas. Neither figure is wrong; the catalog standardizes on the IUPAC 2021 abridged table and states the basis on the face of every mass. The 36.46 Da gap between the two salt states is 12.9 percent of the article's mass and it is a content-calculation difference on every lot, not a labeling nicety.

Monoisotopic mass

283.15723 Da neutral free base; [M+H]+ 284.16451; [M+Na]+ 306.14645. A plus or minus 5 ppm identity window on the protonated ion is plus or minus 0.0014 Da. Electrospray never observes the salt: a hydrochloride dissociates in solution and the measured ion is the protonated free base at 284.1645, so 319.83 is a formula weight and not a mass any instrument reports. For completeness the neutral monoisotopic mass of the C18H22ClNO2 formula unit is 319.13391, a number that has a use in gravimetric calculation and no use in a mass spectrum.

Salt / variant note

The headline confusable is invisible to mass spectrometry at any resolution. The ortho (2-) and para (4-) positional isomers of the benzoate ring are plausible synthetic contaminants and plausible substitutions; they carry the identical formula C18H21NO2, the identical 283.15723 monoisotopic mass and the identical [M+H]+ 284.16451, and only 1H and 13C NMR against a reference spectrum, or chromatographic co-elution against a certified standard, distinguishes them. A certificate whose entire identity section is a mass number has not established which isomer is in the bottle. Salt axis, live in the market right now: free base C18H21NO2 at 283.371 against monohydrochloride C18H22ClNO2 at 319.829, a 12.9 percent content difference, with one seller shipping the hydrochloride and another describing the free base under the same product name and the same CAS. The remainder of the field separates by arithmetic: the hydrolyzed free acid 3-{2-[benzyl(methyl)amino]ethyl}benzoic acid, C17H19NO2, average 269.344, monoisotopic 269.14158, [M+H]+ 270.14886 - the moisture-driven degradant and the stability-indicating impurity; the ethyl ester homolog C19H23NO2, average 297.398, monoisotopic 297.17288, [M+H]+ 298.18016, exactly 14.02 Da heavy and the classic outcome of the wrong alcohol in the esterification; the des-benzyl secondary amine methyl 3-[2-(methylamino)ethyl]benzoate, C11H15NO2, average 193.246, monoisotopic 193.11028, [M+H]+ 194.11756, the incompletely benzylated intermediate; and the N-oxide C18H21NO3, average 299.370, monoisotopic 299.15214, [M+H]+ 300.15942, plus 15.995 Da on air exposure of a tertiary amine. Presentation axis, which is where the article actually differs in commerce: one seller ships 60 capsules of 10 mg rather than a neat substance, and a capsule certificate describes a formulation with excipients, so it cannot be received against a substance specification at all.

2 Class & testing panel

Form

Single article

Testing panel

P6 — panel definition

3 Primary sources & evidence

The index reports the design and provenance of the literature, not a conclusion about effect.

Published literature exists and it is very small. The human record is a single study from 1978 in 47 male participants, authored by the compound's originator and never independently replicated in the forty-eight years since. Around it sits a thin animal literature from the same laboratory and the same period. What does not exist: any modern pharmacokinetic characterization, any formal toxicology or genotoxicity package, any regulatory review in any jurisdiction, any registered clinical trial, and any active non-human research program. The originating patent, US 3,872,119, has long since expired, which is a fact about the patent term and not about the chemistry. Literature volume by study type is printed at the head of the research page so a reader sees the size of the base before reading a word of it.

4 Storage & specification

Storage

White to off-white crystalline solid, salt state as declared, tightly closed amber glass with in-pack desiccant, 15-25 degrees C, protect from moisture. The ester is the labile feature and hydrolysis is the degradation pathway, so moisture control governs; refrigeration is neither required nor specified, and a cold humid cabinet with repeated door openings would be worse than a controlled room-temperature one.

Shelf life

Provisional 24-month retest interval at 15-25 degrees C, pending this company's own three-lot ICH Q1A-format study - long-term at 25 degrees C / 60 percent RH and accelerated at 40 degrees C / 75 percent RH - with the hydrolysis-derived benzoic acid at 269.344 tracked as the stability-indicating impurity and Karl Fischer water trended alongside it. That study replaces the assumed interval at the 12-month data point. The interval is shortened on data and never extended without a completed dataset.