Studies were conducted to investigate a possible haemolytic effect on rat erythrocytes and spasmolytic activity on rat aorta and guineapig ileum of a methanol extract obtained from roots of Solanum asterophorum (Sast-MeOHR). A sample of blood was collected from fasting Wistar male rats to obtain erythrocyte suspensions. Sast-MeOHR was added to the suspensions at various concentrations and in different preparations and the percentage of haemolysis was calculated. The spasmolytic activity of the Sast-MeOHR extract was also determined on rat aorta and guineapig ileum by relaxation, expressed as reversal percentage of the initial contraction elicited by KCl. Results showed that the extract inhibited the tonic contractions in the guineapig ileum, suggesting that the blockade of calcium influx was through voltage-activated calcium channels, as these channels are responsible for maintaining this contractile response. The Sast-MeOHR extract caused no damage to the membrane of erythrocytes at concentrations that showed spasmolytic activity on guineapig ileum. Thus, it appeared that Sast-MeOHR probably had low or no in vivo toxicity.

Leptohyptis macrostachys, previously known as Hyptis macrostachys Benth., is used in folk medicine to relieve the symptoms of asthma, cough, and bronchitis. Recently, we showed that the ethanol extract obtained from Leptohyptis macrostachys has selective spasmolytic activity on guinea pig ileum. Therefore, the aim of this study was to characterize the spasmolytic mechanism of this extract, investigated whether it presents toxicological and antidiarrheal activities. Therefore, the crude ethanolic extract of Leptohyptis macrostachys was analyzed by high-performance liquid chromatographicdiode array detection (HPLC-DAD). The spasmolytic effect was evaluated on guinea pig ileum, toxicological activity using rats and antidiarrheal activity using male and female mice. In HPLC-DAD analysis, Rosmarinic acid (5.44%) was the most abundant phenolic compound, being considered as a chemical marker. The spasmolytic potency of the extract on histamine-induced contraction was reduced in the presence of 1 mM TEA + , a selective big-conductance K + channels blocker (BK Ca). The extract produces a dosedependent antidiarrheal activity, inhibiting equipotently defecation frequency and liquid stool formation. In addition, the extract has inhibited in a dose-dependent manner both castor oil-induced intestinal transit and intestinal fluid content. Thus, the spasmolytic activity of the extract involves positive modulation of BK Ca and its antidiarrheal activity is related to inhibition of intestinal motility and secretion.