Propranolol glycol

Side-chain metabolism of propranolol: involvement of monoamine oxidase and aldehyde reductase in the metabolism of N-desisopropylpropranolol to propranolol glycol in rat liver.[Pubmed:11489433]

Comp Biochem Physiol C Toxicol Pharmacol. 2001 Aug;129(4):361-8.

The further metabolism of N-desisopropylpropranolol (NDP), a side-chain metabolite of propranolol (PL), was investigated in isolated rat hepatocytes. Propranolol glycol (PGL) was generated from NDP as a major metabolite. Naphtetrazole (NTE), a potent inhibitor of monoamine oxidase (MAO), significantly retarded the disappearance of NDP from the incubation medium, suggesting the involvement of MAO in the deamination of NDP to an aldehyde intermediate. In a reaction mixture of rat liver mitochondria and cytosol with NADPH, phenobarbital, a specific inhibitor of aldehyde reductase, and 4-nitrobenzaldehyde (4-NBA), a substrate inhibitor of aldehyde reductase, decreased the formation of PGL from NDP. 4-NBA was a competitive inhibitor of the enzyme responsible for the PGL formation. The optimal pH for the formation of PGL from NDP in the reaction mixture was approximately 8.0. Based on these results, we propose the possibility that, in the rat liver, MAO catalyzes the oxidative deamination of NDP to an aldehyde intermediate and the formed aldehyde intermediate is subsequently reduced to PGL by aldehyde reductase. Furthermore, the enantioselective metabolism of NDP to PGL was examined. In isolated rat hepatocytes, the amount of PGL formed from S-NDP [S(-)-form of NDP] was larger than that of PGL formed from R-NDP [R(+)-form of NDP].

Regioisomeric products of propranolol metabolism. The monomethyl ethers of 3,4-dihydroxypropranolol and of 3,4-dihydroxypropranolol glycol.[Pubmed:2898336]

Drug Metab Dispos. 1988 Mar-Apr;16(2):217-21.

Regioisomeric monomethyl ethers of the 3,4-catechol of propranolol (1) and its 3-aryloxypropane-1,2-diol (glycol) metabolite were prepared to prove the structures of these putative products of oxidative metabolism. The ring regioisomer 4-methoxy-3-hydroxypropranolol (3) was prepared from 1-acetoxy-3-acetyl-4-methoxynaphthalene (8). Baeyer-Villiger oxidation was the key step in converting the 3-acetyl functionality to the desired 3-naphthol. The ring regioisomer 4-hydroxy-3-methoxypropranolol (4) was prepared from 3-methoxy-1,4-dihydroxynaphthalene (13) by selective 1-O-acylation with trimethylacetyl chloride. 4-O-Benzylation, followed by hydrolysis, and side chain elaboration afforded the 4-O-benzyl ether of 4. Similar methods afforded glycols 5 and 6, with the side chain obtained by osmium tetroxide oxidation of an O-allyl group. GC/MS analysis using the trifluoroacetyl derivatives of these known standards showed both 3 and 4 were metabolites of 1 in the rat. From a single dose study in man, 4 was identified as a minor urinary metabolite, and both regioisomeric glycol metabolites 5 and 6 were observed. In addition, another regioisomeric hydroxymethoxyglycol metabolite was found.

Comparative studies with the enantiomers of the glycol metabolite of propranolol and their effects on the cardiac beta-adrenoceptor.[Pubmed:2886586]

J Pharm Pharmacol. 1987 May;39(5):378-83.

The two enantiomers ((R)- and (S)-) of Propranolol glycol, a metabolite of propranolol, have been synthesized, and their effects upon the beta-adrenoceptor studied by two methods. The ability of these compounds to antagonize the inotropic actions of isoprenaline was examined on spontaneously beating rat atrial preparations. Also, the effects of these enantiomers upon the binding of [3H]dihydroalprenolol to beta-receptors in rat cardiac ventricular membranes was studied. Experiments with the atria indicated that the (S)-glycol was a reversible competitive antagonist of isoprenaline with a potency approximately one thousand times lower than that of (+/-)-propranolol. In contrast, the (R)-glycol appeared to act as an irreversible antagonist, producing complex dose-response curves. The effects of these compounds to cause displacement of alprenolol binding were consistent with the organ bath data. The interaction of the (S)-glycol with the beta-receptor binding site was reversible (Ki of 27.6 +/- 4.2 microM) but less potent than that of (+/-)-propranolol (Ki of 0.99 +/- 0.07 nM). On the other hand, pretreatment of ventricular membranes with the (R)-glycol, followed by extensive washing techniques, resulted in alprenolol binding which did not regain control values, providing further evidence for an irreversible effect upon the beta-receptor. The possible significance of these pharmacological actions of the two enantiomers is discussed in terms of the in vivo metabolic pathways for propranolol.

Synthesis of nano-sized stereoselective imprinted polymer by copolymerization of (S)-2-(acrylamido) propanoic acid and ethylene glycol dimethacrylate in the presence of racemic propranolol and copper ion.[Pubmed:27040217]

Mater Sci Eng C Mater Biol Appl. 2016 Jun;63:247-55.

A new chiral functional monomer of (S)-2-(acrylamido) propanoic acid was obtained by reaction of (l)-alanine with acryloyl chloride. The resulting monomer was characterized by FT-IR and HNMR and then utilized for the preparation of chiral imprinted polymer (CIP). This was carried out by copolymerization of (l)-alanine-derived chiral monomer and ethylene glycol dimethacrylate, in the presence of racemic propranolol and copper nitrate, via precipitation polymerization technique, resulting in nano-sized networked polymer particles. The polymer obtained was characterized by scanning electron microscopy and FT-IR. The non-imprinted polymer was also synthesized and used as blank polymer. Density functional theory (DFT) was also employed to optimize the structures of two diasterometric ternary complexes, suspected to be created in the pre-polymerization step, by reaction of optically active isomers of propranolol, copper ion and (S)-2-(acrylamido) propanoic acid. Relative energies and other characteristics of the described complexes, calculated by the DFT, predicted the higher stability of (S)-propranolol involved complex, compared to (R)-propranolol participated complex. Practical batch extraction test which employed CIP as solid phase adsorbent, indicated that the CIP recognized selectively (S)-propranolol in the racemic mixture of propranolol; whereas, the non-imprinted polymer (NIP) showed no differentiation capability between two optically active isomers of propranolol.