Gustavo Valencia del Toro

Spasmolytic effect of Alternanthera repens on isolated rat ileum

Abstract Context: Alternanthera repens (L.) Kuntze (Amaranthaceae) is widely used in Mexican traditional medicine for the treatment of gastrointestinal disorders that are mainly related to diarrhea. Objective: The aim of the present study was to investigate the spasmolytic effect of hexane (Hx), methanol (Me) and aqueous (Aq) extracts as well as chromatographic Me fractions (F1–F6) of A. repens in rat ileum. Materials and methods: Dried and powdered aerial parts were used to obtain the extracts. The rat ileum preparations were incubated in Tyrode’s solution gassed (95% O2–5% CO2) at 37 °C. The effect on the contractile response of isolated ileum was evaluated by obtaining cumulative concentration–response curves to CaCl2, KCl, 5-HT and acetylcholine in the absence and presence of different doses of Aq (0.56–2.09 mg/mL), Me (0.24–0.91 mg/mL) and Hx (0.24–0.91 mg/mL) extracts, as well as six Me fractions of 0.66 mg/mL (F1 to F6). Results: The A. repens Me (0.24 mg/mL) caused an inhibitory response of the Ca2+-induced contractions, with IC50 values of 0.18 ± 0.061 and 0.67 ± 0.061 mM in the presence and absence of the Me, respectively. Me fractions F2 to F4 presented a significant inhibitory effect (F(3,8) = 60.17, p = 0.0001), causing a reduction in the CaCl2-induced contractions and shifting the Ca2+ (0.39 to 1.81 mM) concentration–response curves to the right. With respect to the effect on 5-HT-induced contractions, IC50 values Hx extract (0.24 mg/mL) were 5.44 ± 0.08 × 10−6 M and 3.38 ± 0.07 × 10−6 M in the presence and absence of the Hx, respectively. Discussion and conclusion: The spasmolytic effects induced by Me and Me fractions of A. repens may involve a serotonergic and Ca2+ influx blockade mechanisms, which may justify the use of A. repens extracts as an effective traditional treatment against diarrhea.