In Vitro Antispasmodic Activity of Peracetylated Penstemonoside, Aucubin and Catalpol

A. V. Ortiz de Urbina; M. L. Martín; B. Fernández; L. San Román; L. Cubillo

doi:10.1055/s-2006-959561

Planta Medica, Table of Contents

Planta Med 1994; 60(6): 512-515
DOI: 10.1055/s-2006-959561

Papers

In Vitro Antispasmodic Activity of Peracetylated Penstemonoside, Aucubin and Catalpol

A. V. Ortiz de Urbina¹ , M. L. Martín¹ , B. Fernández¹ , L. San Román¹ , L. Cubillo²

¹Laboratorio de Farmacognosia y Farmacodinamia, Departamento de Fisiología y Farmacología, Facultad de Farmacia, Universidad de Salamanca, E-37007 Salamanca, Spain
²Departamento de Química Orgánica, Facultad de Químicas, Universidad de Salamanca, E-37008 Salamanca, Spain

Abstract

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Abstract

In vitro, the peracetates of penstemonoside, aucubin and catalpol, iridoids isolated from Parentucellia latifolia, antagonize the uterine muscular contractions induced by acetylcholine and calcium, in a similar way to papaverine. The antagonism is non-competitive against acetylcholine (pD₂′ values: 5.60 for the peracetates of penstemonoside, 5.74 for aucubin, 5.59 for catalpol, and 5.32 for papaverine) and competitive against calcium (pA₂ values: 6.60 for the peracetates of penstemonoside, 6.34 for aucubin, 6.48 for catalpol, and 6.23 for papaverine). The two components, phasic and tonic, of the response of the vas deferens to potassium are reduced by the three iridoids. The reduction is similar for both phases. The antispasmodic activity of the three iridoids, similar to papaverine, is related to an inhibiting effect of extracellular calcium, intracellular or both.

Key words

Penstemonoside - aucubin - catalpol - iridoids - Parentucellia latifolia (L.) Caruel - Scrophulariaceae - antispasmodic activity

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