Antiarrhythmic, hypotensive and α1-adrenolytic properties of new 2-methoxyphenylpiperazine derivatives of xanthone.

The main goal of this study was to assess antiarrhythmic and hypotensive activity of new 2-methoxyphenylpiperazine derivatives of xanthone. In order to better understand mechanism of action of studied compounds, their abilities to antagonize the increase in blood pressure elicited by adrenaline, noradrenaline and methoxamine, as well as the antagonistic properties for α1-adrenoceptors on isolated rat aorta were evaluated. Therapeutic antiarrhythmic activity was investigated in an adrenaline-induced model of arrhythmia. Hypotensive activity in normotensive rats was evaluated after oral administration. Influence on blood vasopressor response and α1-adrenoceptors in rat thoracic aorta was evaluated to determine if the observed cardiovascular effects could be related to α1-adrenolytic properties. Tested compounds produced antiarrhythmic and hypotensive activity. The most active compound was MH-99 - (R,S)-4-(2-hydroxy-3-(4-(2-methoxyphenyl)piperazine-1-yl)propoxy)-9H-xanthen-9-one hydrochloride. All studied compounds showed α1-adrenolytic properties in the in vivo and in vitro tests. The results indicate that the new valuable compounds with antiarrhythmic and hypotensive activity might be found in the group of xanthone derivatives. Further pharmacological utility of these compounds should be investigated.