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

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.

Lipophilicity profiling of anthracycline antibiotics by microemulsion electrokinetic chromatography-effects on cardiotoxicity and endotheliotoxicity

Accurate profiling of the lipophilicity of amphoteric compounds might be complex and laborious. In the present work the lipophilicity of 12 anthracycline antibiotics-four parent drugs: doxorubicin, daunorubicin, epidoxorubicin, and epidaunorubicin and eight novel formamidyne derivatives with attached morpholine, hexamethylenoimine or piperidine rings-was determined based on novel approach using MEEKC. In the second stage, lipophilicity was correlated with anthracycline toxicity towards two cell lines. In rat cardiomyoblast cell line (h9c2) a significant correlation between the logP and toxicity was found. The anthracycline lipophilicity was not correlated with toxicity towards the endothelial hybrid cell line (EAhy.926). In conclusion, the lipophilicity of anthracyclines seems to determine their toxicity towards cardiomyoblasts but not on endothelial cells, suggesting a different mechanism of anthracyclines intercellular transport or extrusion in cardiomyoblast and endothelial cells.

Study on the effect of EMD386088, a 5-HT6 receptor partial agonist, in enhancing the anti-immobility action of some antidepressants in rats

The effect of some antidepressants co-administered with EMD386088 in the modified forced swim test in rats was investigated. Additionally, the pharmacokinetics, metabolic stability, and the effect of EMD386088 on P450 cytochromes were determined. Intraperitoneal (i.p.) coadministration of EMD386088 (2.5 mg/kg) and imipramine (15 mg/kg), reboxetine (5 mg/kg), moclobemide (10 mg/kg), or bupropion (10 mg/kg) evoked significant antidepressant-like activity, whereas no effect was observed after joint administration of EMD386088 with s-citalopram (10 mg/kg). Pharmacokinetic in vivo investigation showed a rapid absorption of EMD386088 (2.5 and 5 mg/kg) with t_1/2 = 67 min (t_max = 5 min). Large volume of distribution (V_d/F = 102 L/kg) indicated its penetration into peripheral compartments. The most active coadministration of EMD386088 (2.5 mg/kg) with imipramine (15 mg/kg) resulted in slower absorption of the compound (C_max = 60 min) and decrease in the volume of distribution (V_d/F = 32.2 L/kg). EMD386088 penetrates the blood–brain barrier with a high brain/plasma ratio of about 19 (2.5 mg/kg) and 7.5 for coadministration with imipramine. The in silico and in vitro studies on EMD386088 metabolic stability showed the dehydrogenation of tetrahydropyridine moiety as its main metabolic pathway. EMD386088 did not influence on CYP3A4 activity, and it has been classified as a very weak CYP2D6 inhibitor (IC₅₀ = 2.25 μM). The results obtained from the forced swim test in rats indicate that an activation of 5HT₆ receptor may facilitate antidepressant-like activity of some antidepressants. The pharmacokinetic results suggest that the interaction between EMD386088 and imipramine could not have been pharmacokinetic in nature.

Binding Interactions of Keratin-Based Hair Fiber Extract to Gold, Keratin, and BMP-2

Hair-derived keratin biomaterials composed mostly of reduced keratin proteins (kerateines) have demonstrated their utility as carriers of biologics and drugs for tissue engineering. Electrostatic forces between negatively-charged keratins and biologic macromolecules allow for effective drug retention; attraction to positively-charged growth factors like bone morphogenetic protein 2 (BMP-2) has been used as a strategy for osteoinduction. In this study, the intermolecular surface and bulk interaction properties of kerateines were investigated. Thiol-rich kerateines were chemisorbed onto gold substrates to form an irreversible 2-nm rigid layer for surface plasmon resonance analysis. Kerateine-to-kerateine cohesion was observed in pH-neutral water with an equilibrium dissociation constant (KD) of 1.8 × 10(-4) M, indicating that non-coulombic attractive forces (i.e. hydrophobic and van der Waals) were at work. The association of BMP-2 to kerateine was found to be greater (KD = 1.1 × 10(-7) M), within the range of specific binding. Addition of salts (phosphate-buffered saline; PBS) shortened the Debye length or the electrostatic field influence which weakened the kerateine-BMP-2 binding (KD = 3.2 × 10(-5) M). BMP-2 in bulk kerateine gels provided a limited release in PBS (~ 10% dissociation in 4 weeks), suggesting that electrostatic intermolecular attraction was significant to retain BMP-2 within the keratin matrix. Complete dissociation between kerateine and BMP-2 occurred when the PBS pH was lowered (to 4.5), below the keratin isoelectric point of 5.3. This phenomenon can be attributed to the protonation of keratin at a lower pH, leading to positive-positive repulsion. Therefore, the dynamics of kerateine-BMP-2 binding is highly dependent on pH and salt concentration, as well as on BMP-2 solubility at different pH and molarity. The study findings may contribute to our understanding of the release kinetics of drugs from keratin biomaterials and allow for the development of better, more clinically relevant BMP-2-conjugated systems for bone repair and regeneration.