Relaxant effects of Peperomia hispidula (Sw.) A. Dietr. on isolated rat tracheal rings

Peperomia hispidula (Sw.) A. Dietr. is used in Mexican traditional medicine for treating respiratory illnesses such as asthma. The latter disorder results from an excessive and inappropriate constriction of airway smooth muscle. The aim of the present study was to evaluate the relaxant activity of P. hispidula on isolated rat tracheal rings contracted with carbachol. The methyleugenol was identified as the main active constituent in the dichloromethane extract. To explore the possible mechanism of action, concentration-response curves were constructed in the presence and absence of propranolol (3 μM), indomethacin (10 μM), glibenclamide (1 μM), and L-NAME (300μM), finding that neither reduced methyleugenol-induced smooth muscle relaxation. In conclusion, P. hispidula herein displayed relaxant activity on rat tracheal rings. The effect of methyleugenol, was probably not related to the activation of β2-adrenoceptors, prostaglandins, K+ATP channels or nitric oxide

Actividad relajante de Hyptis suaveolens en anillos aislados de tráquea de cobayo

El asma es una enfermedad crónica cuya sintomatología incluye la dificultad respiratoria, que se debe a la restricción del flujo de aire. Esto se atribuye a la contracción del músculo liso bronquial por diversos mediadores inflamatorios.  Desafortunadamente, en la mayoría de los pacientes las terapias existentes no han logrado un control adecuado de la sintomatología, por lo que es necesaria la búsqueda de nuevas opciones.  Hyptis suaveolens es utilizada en el estado de Chiapas, México, para tratar el asma, sin embargo, esta actividad no ha sido corroborada científicamente. Por lo que el objetivo de la presente contribución fue determinar la actividad relajante de Hyptis suaveolens en el modelo de anillos aislados de tráquea de cobayo. Los extractos de hexano, diclorometano y metanol de la planta se prepararon por maceración. El extracto de mayor actividad se separó por cromatografía en columna para encontrar la fracción más activa. Se determinó la participación de los receptores β2 adrenérgicos y muscarínicos, mediante curvas concentración-respuesta a partir de los siguientes tratamientos: la subfracción activa de Hyptis suaveolens (56-177 µg/mL) e isoproterenol (3-170 µM) en ausencia y presencia de propranolol (0.3 µM), y carbacol (1x10-16-0.01 M) en ausencia y presencia de la subfracción activa (100 y 177 µg/mL) o de atropina (0.3 y 3 µM). El extracto de diclorometano fue el más activo (p<0.05), y su subfracción más activa (F4´) tuvo una CE50 de 91.19 ± 1.83 µg/mL. El efecto relajante de F4´ no fue inhibido por propranolol. F4´ se comportó como un antagonista competitivo de los receptores muscarínicos (p<0.01).  En conclusión, Hyptis suaveolens ejerce actividad relajante sobre anillos aislados de tráquea de cobayo. Una subfracción activa del extracto de diclorometano actuó como antagonista competitivo sobre los receptores muscarínicos, pero los receptores β2 adrenérgicos no participaron en su mecanismo de acción

First Evidence of Gastroprotection by Schinus molle: Roles of Nitric Oxide, Prostaglandins, and Sulfhydryls Groups in Its Mechanism of Action

Schinus molle is a plant traditionally used in Mexico to treat gastric disorders. However, no scientific evidence has been reported on its gastroprotective effect. The aim of the current contribution was to conduct a bioassay-guided study on S. molle to evaluate its gastroprotective activity in a model of Wistar rats given ethanol orally to induce gastric lesions. The hexane and dichloromethane extracts from the tested plant showed over 99% gastroprotection at a dose of 100 mg/kg. From the hexane extract, two of the three fractions (F1 and F2) afforded over 99% gastroprotection. The F1 fraction was subjected to column chromatography, which revealed a white solid. Based on the ESI-MS analysis, the two main compounds in this solid were identified. The predominant compound was probably a triterpene. This mixture of compounds furnished about 67% gastroprotection at a dose of 100 mg/kg. Pretreatment with L-NAME, indomethacin, and NEM was carried out to explore the possible involvement of nitric oxide, prostaglandins, and/or sulfhydryl groups, respectively, in the gastroprotective activity of the white solid. We found evidence for the participation of all three factors. No antisecretory activity was detected (tested by pylorus ligation). In conclusion, evidence is herein provided for the first time of the gastroprotective effect of S. molle

Gastroprotection of Calein D against Ethanol-Induced Gastric Lesions in Mice: Role of Prostaglandins, Nitric Oxide and Sulfhydryls

Peptic ulcers are currently treated with various drugs, all having serious side effects. The aim of this study was to evaluate the gastroprotective activity of calein D (from Calea urticifolia), a sesquiterpene lactone with a germacrane skeleton. Gastric lesions were induced in mice by administering ethanol (0.2 mL) after oral treatment with calein D at 3, 10 and 30 mg/kg, resulting in 13.15 &#177; 3.44%, 77.65 &#177; 7.38% and 95.76 &#177; 2.18% gastroprotection, respectively, to be compared with that of the control group. The effect found for 30 mg/kg of calein D was not reversed by pretreatment with NG-nitro-l-arginine methyl ester (l-NAME, 70 mg/kg, ip), indomethacin (10 mg/kg, sc) or N-ethylmaleimide (NEM, 10 mg/kg, sc). Hence, the mechanism of action of calein D does not involve NO, prostaglandins or sulfhydryl compounds. Calein D was more potent than carbenoxolone, the reference drug. The findings for the latter are in agreement with previous reports