(M1530-10-67) Preclinical Pharmacokinetic Study and Lung Penetration of Coumarin Extracted of Zanthoxylum tingoassuiba

Purpose: 6-methoxyseselin (Figure 1) is a coumarin isolated from the Brazilian species Zanthoxylum tingoassuiba [1], [2]. Studies show that this compound can induce potent vasorelaxation and can be used to treat various cardiovascular diseases, including hypertension [3], in addition to antinociceptive, anti-inflammatory, and immunomodulatory properties [2]. Recently, the antiasthmatic properties of 6-methoxyseselin have been demonstrated. When inhaled, it reduced, in a dose-dependent manner, key pathophysiological events of experimental asthma, with similar efficacy to systemic dexamethasone, considered the standard gold drug [4]. These data highlight the potential of 6-methoxyseselin as a candidate for the drug discovery process of new anti-asthmatic drugs. So, we aimed to evaluate this compound's preclinical pharmacokinetics (PK) and pulmonary delivery in mice.

Methods: 6-methoxyseselin was administered to mice (n=40) by inhalation, and intravenous routes at 50 and 15 mg/kg, respectively. Blood samples were collected at times 0.083, 0.25, 0.5, 0.75, 1, 2, and 4 hours after both administrations. All samples were treated and further analyzed by High-Performance Liquid Chromatography with Diode-Array Detection (HPLC-DAD) using a developed and validated bioanalytical method to quantify 6-methoxyseselin in mice’s plasma and lung. The PK parameters were estimated by PKAnalix® v. 2021 R1 (Lixoft, France) following a non-compartmental analysis.

Results: The bioanalytical method for lung and plasma samples shows good linearity (r² >0.999) in the 0.15625 – 5 µg/ml range. The separation of the compound occurred on a C18, with isocratic elution at a 1.0 ml/min flow using a mixture of water and methanol (45:55, v/v) at 228 nm. According to the FDA's Bioanalytical Method Validation guide, accuracy and precision were within intra-day and inter-day acceptance criteria. The samples are considered stable for up to 30 days in the freezer (-20°C). The 6-methoxyseselin plasma PK parameter values of rate of elimination (k_e), half-life (t_1/2), clearance (CL), volume of distribution (Vd), the area under the curve (AUC_total), and mean residence time are (MRT), respectively: 0.23 h^-1, 3.0 h, 3.19 L/h/kg, 8.36 L/kg, 13.9 h.μg/mL, and 4.66 h after intravenous administration and 0.21h^-1, 3.3h, 2.09 L/h/kg, 8.91 L/Kg, 15.8 h.μg/mL, and 4.85 h after inhalation. The lung concentrations of this compound are higher than plasma, with a lung penetration factor of 1.75 and 2.14 and after inhalation and intravenous administration, respectively.

Conclusion: Most parameters did not change significantly between the administration routes, showing favorable pharmacokinetic profiles. The high penetration factors to the lung after both administrations show promising results in using 6-methoxyseselin as a new anti-asthmatic drug. This is the first work to study the pharmacokinetics and pulmonary delivery of 6-methoxyseselin in mice.

References: [1] R. Costa et al., “In vitro antileishmanial and antitrypanosomal activity of compounds isolated from the roots of Zanthoxylum tingoassuiba”, Revista Brasileira de Farmacognosia, vol. 28, ago. 2018, doi: 10.1016/j.bjp.2018.04.013.
[2] R. F. Espírito-Santo et al., “The anti-inflammatory and immunomodulatory potential of braylin: Pharmacological properties and mechanisms by in silico, in vitro and in vivo approaches”, PLoS One, vol. 12, no 6, p. e0179174, 2017, doi: 10.1371/journal.pone.0179174.
[3] W. A. Santos et al., “Braylin induces a potent vasorelaxation, involving distinct mechanisms in superior mesenteric and iliac arteries of rats”, Naunyn Schmiedebergs Arch Pharmacol, vol. 394, no 3, p. 437–446, mar. 2021, doi: 10.1007/s00210-020-01985-0.
[4] R. F. do Espírito-Santo et al., “Inhaled braylin regulates Th2 response and induces relaxant effects in the airway muscles in a model of ovalbumin-induced asthma”, Phytomedicine Plus, vol. 3, no 2, p. 100435, 2023, doi: 10.1016/j.phyplu.2023.100435.

Acknowledgements: Ethical Approval: All procedures were reviewed and approved by the Committee on Ethics in the Use of Animals (CEUA-IGM) of the Oswaldo Cruz Foundation (Fiocruz/ BA) (013-2021). Financial Support and Acknowledgements: This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) – Finance Code 001.

Chemical structure of 6-methoxyseselin