Pharmacological basis for the medicinal use of morus alba in gut and airways disorders

Crude extract of Morus alba at 100 mg/kg exhibited protective effect against castor oil-induced diarrhea in mice. In isolated rabbit jejunum, M. alba (0.3-10 mg/mL) inhibited the spontaneous contractions and caused glibenclamide-sensitive inhibition of low K⁺ (20 mM)-induced contractions, with mild effect on high K⁺ (80 mM). Similarly, cromakalim caused inhibition of low K⁺, but not of high K⁺, while verapamil did not differentiate in its inhibitory effect on two concentrations of K⁺. M. alba (3.0-30 mg/kg) caused suppression of carbachol (100 µg/kg)-induced increase in inspiratory pressure of anaesthetized rats. In guinea-pig trachea, M. alba completely inhibited low K⁺ contractions, with partial effect on high K⁺. M. alba (0.3-1.0 mg/mL) caused leftward shift of isoprenaline-induced inhibitory concentration response curves, like papaverine. These results indicate that M. alba possesses a combination of K_ATP channel opening, weak Ca⁺⁺-antagonist and phosphodiesterase inhibitory mechanisms, which explain its medicinal use in hyperactive gut and airways disorders.