(R)-α-Benzyl-proline methyl ester hydrochloride

Optically pure (R)-(-)-m-trimethylacetoxy-alpha-[(methylamino)methyl]benzyl alcohol hydrochloride was synthesized by the following sequence: (R)-(-)-phenylephrine was condensed with acetone in the presence of calcium carbide to give an oxazolidine derivative and then treated with thallous ethoxide in ether followed by trimethylacetyl chloride to yield the phenolic ester. Finally, the oxazolidine ring was cleaved by one equivalent of hydrogen chloride in ethanol. Condensation of phenylephrine with benzaldehyde, with or without solvents, gave either 1,1,2-trimethyl-4,6-dihydroxy-1,2,3,4-tetrahydroisoquinoline or a mixture of side-chain oxazolidine and the tetrahydroisoquinoline. Condensation of epinephrine with opianic acid in pyridine also gave a tetrahydroisoquinoline only. When applied on rabbit eyes, the prodrug (R)-(-)-m-trimethylacetoxy-alpha[(methylamino)methyl]benzyl alcohol hydrochloride exhibited an unexpected, three times higher mydriatic activity than the corresponding racemic prodrug and was 15 times more active than the parent, (R)-(-)-phenylephrine.

(+)-Dapoxetine hydrochloride, (R)-Etodolac; Abatacept, ABT-510, Adalimumab, Agatolimod sodium, Alemtuzumab, Alvocidib hydrochloride, Aminolevulinic acid methyl ester, Aripiprazole, AS01B, AS02B, AS02V, Azacitidine; Becatecarin, Bevacizumab, Bevirimat, Bortezomib, Bremelanotide; CAIV-T, Canfosfamide hydrochloride, CHR-2797, Ciclesonide, Clevidipine; Darbepoetin alfa, Decitabine, Degarelix acetate, Dendritic cell-based vaccine, Denosumab, Desloratadine, DMXB-Anabaseine, Duloxetine hydrochloride, Dutasteride; Ecogramostim, Eicosapentaenoic acid/docosahexaenoic acid, Eletriptan, Enzastaurin hydrochloride, Erlotinib hydrochloride, Escitalopram oxalate, Etoricoxib, Everolimus, Ezetimibe, Ezetimibe/simvastatin; Ferumoxytol, Fesoterodine fumarate, Fulvestrant; Gefitinib, GM-CSF DNA, GSK-690693; H5N1 avian flu vaccine, Hepatitis B hyperimmunoglobulin, Human Fibroblast Growth Factor 1, Hypericin-PVP; Icatibant acetate, Iclaprim, Immunoglobulin intravenous (human), Ipilimumab, ISS-1018; L19-IL-2, Lapuleucel-T, Laropiprant, Liposomal doxorubicin, LP-261, Lumiracoxib, LY-518674; MDV-3100, MGCD-0103, Mirabegron, MyoCell; NASHA/Dx, Niacin/laropiprant; O6-Benzylguanine, Ocrelizumab, Olmesartan medoxomil, Omalizumab; P-276-00, Paclitaxel nanoparticles, Paclitaxel nanoparticles, Padoporfin, Paliperidone, PAN-811, Pegaptanib octasodium, Pegfilgrastim, Pemetrexed disodium, PF-00299804, Pimecrolimus, Prasugrel, Pregabalin; Reolysin, Rimonabant, Rivaroxaban, Rosuvastatin calcium; Satraplatin, SCH-697243,Selenite sodium, Silodosin, Sorafenib, Sunitinib malate; Talarozole, Taxus, Temsirolimus, Tocilizumab, Tolevamer potassium sodium, Tremelimumab, TTP-889; Uracil; V-260, Valsartan/amlodipine besylate, Vardenafil hydrochloride hydrate, Varenicline tartrate, Varespladib, Vitespen, Voclosporin, VX-001; Xience V; Zotarolimus-eluting stent.

Background: Previous reports suggest that 5-hydroxytryptamine might play a role in the antidepressant actions of (R,S)-ketamine. However, its role in the antidepressant actions of (R)-ketamine, which is more potent than (S)-ketamine, is unknown. This study was conducted to examine whether 5-hydroxytryptamine depletion affects the antidepressant actions of (R)-ketamine in a chronic social defeat stress model. Methods: An inhibitor of 5-hydroxytryptamine synthesis, para-chlorophenylalanine methyl ester hydrochloride (300 mg/kg, twice daily for 3 consecutive days), or vehicle was administered to control and chronic social defeat stress-susceptible mice. Levels of 5-hydroxytryptamine and its metabolite, 5-hydroxyindoleacetic acid, in mouse brain regions were measured using high-performance liquid chromatography. Furthermore, antidepressant effects of (R)-ketamine (10 mg/kg) in the vehicle- and para-chlorophenylalanine methyl ester hydrochloride-treated susceptible mice were assessed using tail suspension test and 1% sucrose preference test. Results: para-Chlorophenylalanine methyl ester hydrochloride treatment caused marked reductions of 5-hydroxytryptamine and 5-hydroxyindoleacetic acid in the brain regions of control and chronic social defeat stress susceptible mice. In the tail suspension test, (R)-ketamine significantly attenuated the increased immobility time in the chronic social defeat stress-susceptible mice with or without 5-hydroxytryptamine depletion. In the sucrose preference test (2 and 5 days after a single dose), (R)-ketamine significantly enhanced reduced sucrose consumption in the chronic social defeat stress-susceptible mice with or without 5-hydroxytryptamine depletion. Conclusions: These findings show that 5-hydroxytryptamine depletion did not affect the antidepressant effects of (R)-ketamine in a chronic social defeat stress model. Therefore, it is unlikely that 5-hydroxytryptamine plays a major role in the antidepressant actions of (R)-ketamine.