Investigação farmacológica da nanoemulsão contendo β-Mirceno para o tratamento problemas respiratórios

Abstract

β-Myrcene is a monoterpene possessing anti-inflammatory, antioxidant, and antinociceptive properties. This study aimed to develop a myrcene-containing nanoemulsion (NEMC), evaluate its acute toxicity, and investigate the spasmolytic, antitussive, antiasthmatic, and expectorant effects of myrcene or the myrcene-containing nanoemulsion. NEMC was formulated using the spontaneous emulsification method. This involved adding an aqueous phase, consisting of a phosphate buffer solution, to an organic phase. The organic phase was composed of medium-chain triglyceride oil, myrcene, and surfactants in varying proportions, under constant stirring and at room temperature. The size and polydispersity index of the nanoemulsion were determined. This study was approved by the Ethics Committee on Animal Use of the Federal University of Vale do São Francisco (CEUA-UNIVASF), registered under No. 0002/270121. Preclinical acute toxicity was evaluated according to OECD guidelines. Each animal received a single oral dose of 2,000 mg/kg of NEMC and was observed at 30, 60, 120, 180, and 360 minutes, and every 24 hours for 14 days. Motor behavior and muscle relaxation in mice were assessed using open-field and rotarod tests. The spasmolytic activity on isolated rat tracheal smooth muscle was evaluated in an organ bath under carbachol or KCl-induced contractions. Antitussive activity was assessed using the citric acid-induced cough method. The antitussive activity of inhaled myrcene was also investigated. Expectorant activity was determined by quantifying phenol red. Antiasthmatic activity was evaluated using an ovalbumin (OVA)-induced asthma model. NEMC exhibited a size of 97.37±5.844 nm and a polydispersity index (PDI) of 0.2387±0.01810. Acute toxicity tests (2000 mg/kg, oral administration) showed no mortality or significant changes in physiological parameters. In experimental models, β-myrcene (75 mg/kg) did not affect motor coordination (open-field and rotarod tests) and induced modest relaxation (10.41±5.11% under carbachol contraction; 19.48±5.12% under KCl contraction) in isolated rat trachea. In its nanoemulsified form, NEMC (75 mg/kg) significantly reduced citric acid-induced cough frequency (55.62±16.48% vs. 121.2±9.41% of control; p < 0.05), with a mechanism involving GABAergic and opioid pathways, and potassium channels. Both formulations demonstrated expectorant activity, increasing phenol red secretion in bronchoalveolar lavage (NEMC: 3.38±0.29 µg/mL vs. 1.93±0.11 µg/mL for saline). In the ovalbumin-induced asthma model, NEMC significantly reduced the migration of inflammatory cells, confirming its antiasthmatic effect. These results indicate that the nanoemulsion preserves the pharmacological properties of β-myrcene, offering advantages in terms of bioavailability. Both formulations exhibited antitussive, expectorant, and anti-inflammatory effects, highlighting their therapeutic potential for respiratory diseases, particularly asthma and associated conditions. The study reveals the nanoemulsion as a promising strategy for delivering lipophilic compounds.