Synephrine activity

On comparing the activities of the five compounds for which numerical estimates are available in all three assays (synephrine, octopamine, phenylethanolamine, norepinephrine and tyramine) the rank orders of potency in the three systems are Crayfish, 1,2,3t4,5 Cockroach, 2,1,3,4,5 Locust 1,2,3t5,4. This indicates a basic similarity in the responses of these preparations. In each case it was found that ring hydroxylation of the phenylethylamine nucleus was not essential for activity, although p-hydroxylation does yield the best activity. This is particularly evident in the crayfish study where a-MAMBA (a-methylaminomethyl benzyl alcohol), the analog of synephrine which lacks ring substitution, was one of the most active compounds tested, and 3-phenylethanolamine, the corresponding analog of OA, is almost as active as OA. The base compound for this series, phenylethylamine, also shows appreciable activity, but only in the crayfish assay. 

In 1937 Arnow showed that tyrosine could be converted into DOPA by ultraviolet radiation51 and that the DOPA produced in this manner was subsequently destroyed by further irradiation, the solutions becoming red-brown in color (presumably due to the formation of dopachrome).51 In 1939 Konzett and Weis reported that the blood pressure-raising effect of adrenaline solutions was lost on ultraviolet irradiation and that the solutions became colored and fluorescent the initial red color fades to reddish yellow.62 This phenomenon suggests the initial formation of adrenochrome, followed by its isomerization to adrenolutin, both of these compounds being virtually void of pressor activity. Similarly to the radiation-induced hydroxylation of tyrosine mentioned above, synephrine was first... 

Synephrine One isomer has 60 times more pressor activity 173... 

Synephrine is a sympathomimetic agent with mainly direct effects on a-adren-ergic receptors. It has been used to treat hypotension and also as an ocular decongestant (389). It occurs in tangerines (Table II) in concentrations high enough to be physiologically active (119). 

Basic and advanced life-support measures should be instituted as indicated. Gastric decontamination may be performed depending on the specific drug involved, the patient s symptomatology, and the history of the ingestion. Activated charcoal may be used to adsorb ephedrine, synephrine, and/or caffeine. 

Receptor Activated by synephrine Binding relative to norephinephrine Reference Clinical hemodynamic response to receptor activation (23)... 

Brown CM, McGrath JC, Midgley JM, et al. Activities of octopamine and synephrine stereoisomers on alpha-adrenoceptors. Br J Pharmacol 1988 93 417 -29. 

Jordan R, Midgley JM, Thonoor CM, Williams CM. Beta-adrenergic activities of octopamine and synephrine stereoisomers on guinea-pig atria and trachea. J Pharm Pharmacol 1987 39(9) 752-754. 

Synephrine, the N-methylated analog of OA, completely blocked uptake at this concentration. The two imidazolines, naphazoline and XAMI, were somewhat effective as uptake blockers (20-30% inhibition), comparable to DCDM and DDCDM. The tricyclic antidepressant desipramine, a known amine uptake blocker in vertebrates, showed good potency in the cockroach system, as originally described by Evans (21). Finally, the N-chloroethyl benzylamine derivative, xylamine, has been described as a potent, specific and irreversible inhibitor of norepinephrine uptake in mammals (25). It was an active inhibitor of uptake in the cockroach preparation. 

Synephrine, as a potential substrate for NAT, showed considerable inhibition, but naphazoline and XAMI were inactive. Desipramine proved to be quite effective as an inhibitor of NAT, but the most active compound in this group was xylamine. More detailed study of the inhibition by this compound gave an IC50 of less than 1 uM (without preincubation with the enzyme before addition of the substrate) and showed that the inhibition was progressive and... 

Phenylephrine (neo-synephrine, others) is a selective receptor agonist it activates receptors only at much higher concentrations. The drug causes marked arterial vasoconstriction during intravenous infusion. Phenylephrine also is used as a nasal decongestant and as a mydriatic in various nasal and ophthalmic formulations (see Chapter 63 for ophthalmic uses). 

Brown C.M., J.C. McGrath, and J.M. Midgley. 1988. Activities of octapamine and synephrine stereoisomers on alpha-adrenoreceptors. Br. J. Pharmacol. 93 417-429. 

Storage Hygroscopic store in cool, dry place keep tightly closed protect from moisture Uses Photoinitiator prod, of paracetamol, synephrine pharmaceutical active Manuf./Dlsthb. Advanced Synthesis Tech. http //www. advancedsynthesis. com, Aldrich http //www.sigma-aidrich.com-, Alfa Chem http //www.aifachem.homepage.com, Biddle... 

Considering that, studies have been developed to establish the toxicological profile of p-synephrine. The acute administration of C. aurantium extract (2.5 % p-synephrine) and p-synephrine produced reduction in locomotor activity, gasping, exophthalmia, piloerection, and salivation, corroborating to the hypothesis that p-synephrine acts not only in p3-adrenoreceptors but also in other adrenergic receptors. However, all the effects were reversible and persisted for 3 h. The adrenergic stimulation alerts for the same possible side effects of p-synephrine and C. aurantium [78]. The subchronic toxicity of Citrus aurantium extract and p-synephrine were also determined and indicated a low subchronic toxicity in mice but a possible alteration in the oxidative metabolism [79]. 

Neo-Synephrine is the active ingredient in some nose sprays used to reduce swelling of nasal membranes. Identify the functional groups in the structure of Neo-Synephrine. 

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