Enantioselective LC/ESI-MS/MS analysis and pharmacokinetic and tissue distribution study of (2RS)-1-(7-methoxy-1H-indol-4-yloxy)-3-(2-(2-methoxyphenoxy)ethylamino)-propan-2-ol in rats

A preliminary metabolites identification of a novel compound with β-adrenolytic activity

BACKGROUND

The identification of main metabolites and assessment of renal excretion of a novel compound with β-adrenolytic activity (2RS)-1-(1H-indol-4-yloxy)-3-((2-(2-methoxyphenoxy)ethyl)amino)propan-2-ol, briefly called (RS)-9 or 2F109, were studied in vivo in rat serum, urine, faeces, liver, intestine, lungs and kidneys, and in vitro in rat liver microsomes.

METHODS

Structures of the metabolites have been developed by comparing the high-resolution product ion mass spectra of metabolites and the parent compound based on the differences in mass values of main fragments. Quantitative analysis of (RS)-9 was done using a system of liquid chromatography coupled with a triple quadrupole mass spectrometer API 2000. Identification studies of predicted metabolites were made by a high-resolution mass spectrometer LTQ XL Orbitrap Discovery and using a Roxy^™ system, for online electrochemical mimicry of oxidative metabolism by cytochrome P450s connected to QTRAP 5500.

RESULTS

For (RS)-9 (m/z 357.2084) phase I metabolites derived from oxidation process: hydroxyl derivatives (m/z 373.2470) and dihydroxyl derivatives (m/z 389.4318), and phase II metabolites: N-methylated compound (m/z 371.1612), O-glucuronide (m/z 533.5118), and sulfate (m/z 437.2350) were identified.

CONCLUSION

(RS)-9 was extensively metabolised to several phase I and II metabolites, and renal excretion was a minor route in its elimination.

Binding of new aminopropan-2-ol compounds to bovine serum albumin, α1-acid glycoprotein and rat serum using equilibrium dialysis and LC/MS/MS

BACKGROUND

The binding of three new aminopropan-2-ol compounds briefly called 2F109, ANBL and TWo8 with potential cardiovascular activity to bovine serum albumin (BSA), α1-acid glycoprotein (AGP) and to rat serum was studied. The chemical structures of these compounds are related to carvedilol. They possess an antiarrhythmic and hypotensive activity, and β- and α-adrenolytic mechanism of action. All analogues are weak bases with pKa values 8.65, 8.85 and 8.26 for 2F109, ANBL and TWo8, respectively, and they possess lipophilic character (log P > 1.9584).

METHODS

The extent of protein binding was determined using equilibrium dialysis in the range 2.5 - 900 μM, and 2.5 - 300 μM for binding of investigated compounds to BSA and AGP, respectively, and the quantitative measurement was done by LC/ESI-MS/MS assay.

RESULTS

The studied compounds bound to a single class of binding sites on BSA which was characterized by low affinity (Kd for 2F109 = 8.49 x 10(-5) M, for ANBL= 1.92 x 10(-5) M, and for TWo8 = 1.71 x 10(-5) M) and low capacity (n = 0.53 for 2F109, 0.132 for ANBL and 0.13 for TWo8). The binding of 2F109, ANBL and TWo8 to AGP revealed one class of binding sites, with moderate affinity (Kd for 2F109 = 4.67 x 10(-6) M, for ANBL = 3.48 x 10(-5) M, and for TWo8 = 1.13 x 10(-5) M) and higher capacity (n = 2.21 for 2F109, 2.76 for ANBL and 2.28 for TWo8).

CONCLUSION

The obtained data indicate that 2F109, ANBL and TWo8 moderately bind to BSA (34.2 - 71.2%) with low capacity (Ka = 6.21 x 10(3) - 7.61 x 10(3)M(-1)) and strongly bind to AGP (71.5 - 85.5%) with moderate affinity (Ka = 7.94 x 10(4) - 4.73 x 10(5)M(-1)).