Discovery of antiasthmatic natural products from Mexican medicinal plants

Diseases such as asthma and COPD (chronic obstructive pulmonary disease) involve bronchoconstriction of airways. Several natural products and medicinal plants have shown the ability to produce relaxation of airway smooth muscle. The flavones gnaphaliin A and B were identified as tracheal smooth muscle relaxant active principles from the n-hexane extract of Gnaphalium liebmannii Sch. Bp ex Klatt (family Asteraceae). The main relaxant mechanism of action of these flavones is the inhibition of PDEs with a preference to inhibit the degradation of cGMP. The docking study suggested that these flavones bind with high specificity to the same binding site of sildenafil at PDE type 5. The content of gnaphaliins varies widely with the particular Gnaphalium species. On the other hand the alkaloid berberine (as carbonate) was identified as one of the active relaxant principles in the dichloromethane extract from the aerial parts of Argemone ochroleuca (Papaveraceae). The relaxant effect of berberine on tracheal muscle is due to its antagonistic effect on muscarinic acetylcholine receptors. Tymol has been identified as active principle in other Mexican medicinal plants and aqueous extracts of Bougainvillea glabra potentiates the relaxant effect of salbutamol and ipratropium.

Acknowledgements: This work was supported by grant of Dirección General de Asuntos del Personal Académico DGAPA-UNAM IN210112.