(1) Post-Graduate Program in Pharmaceutical Sciences, University of Sorocaba, Uniso, Rodovia Raposo Tavares, km 92.5, Zip code 18023-000, Sorocaba, SP, Brazil.
(2) Pharmacy Graduate Course, University of Sorocaba, Uniso, Rodovia Raposo Tavares, km 92.5, Zip code 18023-000, Sorocaba, SP, Brazil.
(3) Chemistry Graduate Course, University of Sorocaba, Uniso, Rodovia Raposo Tavares, km 92.5, Zip code 18023-000, Sorocaba, SP, Brazil.
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Mikania laevigata Schultz Bip. Ex Baker, popularly known as guaco, had its use approved as a phytomedicine bronchodilator by Brazilian regulatory agency, since exerts a trachea relaxation which is attributed to coumarin, the main biomarker of guaco. The role of diaphragm muscle in the respiration face to guaco extract was investigated comparatively to salbutamol and coumarin, aiming to verify the better extract from nonpolar to polar extracts of M. laevigata.
A validated experimental model of mouse phrenic nerve-diaphragm (PND) preparation was used. The diaphragm aids in breathing contracting muscle fibers, so we sought a facilitatory effect on these different extracts based on their polarity. An inconvenience for studying substances of different polarities is become them soluble in water, since the biological preparation is maintained in a nutritive solution. We selected polyethylene glycol 400 (PEG400) and dimethyl sulfoxide (DMSO) as solubilizers, while coumarin and salbutamol were used as reference in diaphragm muscle preparation.
Among hexane, dichloromethane, ethyl acetate and methanolic extracts from guaco only hexane and ethyl acetate showed a facilitatory effect. Between the solubilizing agents, PEG400 causes lesser influence on contractile response than DMSO, although the latter has major absorptivity to coumarin than PEG400.
In this study, we argue the influence of solubilizers on the coumarin and salbutamol roles, in PND preparation, while the better extracts from guaco were selected for explaining the involvement of diaphragm muscle in the use of guaco as bronchodilator.
Under these perspectives we conclude that hexane and ethyl acetate extracts of M. laevigata contains substances, including coumarin, that participate in therapeutical efficacy of guaco on the pulmonary diseases.