Comparative Effect of Free Vanillin and Vanillin‐Loaded Nanoemulsion in Airways of Rodents

ABSTRACT Vanillin (4‐hydroxy‐3‐methoxybenzaldehyde) is a phenolic aldehyde compound found in the plants of the genus Vanilla . This substance is widely used as a flavouring in the world, used in the food even pharmaceutical industries. Some studies have reported pharmacological activities such as antitumor, antinociceptive, anti‐inflammatory and neuroprotective activities. This study aimed to investigate the spasmolytic, antitussive, expectorant and anti‐asthmatic effects of vanillin in rodents. The spasmolytic activity of vanillin was assayed in isolated rat tracheas that were contracted with carbachol or KCl. The in vivo effects were evaluated in mouse models of citric acid‐induced cough, phenol red dosage in bronchoalveolar lavage and ovalbumin‐induced asthma. The maximal relaxing effect promoted by vanillin in isolated rat trachea was greater in contractions induced by KCl 60 mM than by carbachol (10 μM). In calcium‐free media, this effect was significantly reduced during CCh‐induced contractions. Vanillin at doses of 10, 30 or 100 mg/kg reduced the number of inflammatory cells in bronchoalveolar lavage and the number of coughs in mice after treatment. The effect of vanillin may be related to the opioid receptor, as the antitussive effect was abolished in the presence of 0, 4 mg/kg naloxone. The vanillin‐loaded nanoemulsions exhibited expectorant activity. The present study showed that vanillin may be responsible for these anti‐asthmatic, antitussive and spasmolytic effects.