M. Itoigawa, K. Takeya, H. Furukawa
Nov 1, 1990
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Archives internationales de pharmacodynamie et de therapie
Abstract
The structure-activity relationship of a novel natural substance murrayaquinone-A and related compounds, was studied by evaluating their positive inotropic potencies on guinea-pig papillary muscle in Krebs-Henseleit solution. Among the selected eight compounds, menadione and plumbagin (aromatic methyl-p-quinone) induced a potent triphasic inotropic response, as reported previously for murrayaquinone-A. The order of potency of these active compounds was: plumbagin (pD2 = 6.40) greater menadione (pD2 = 5.70) greater than murrayaquinone-A (pD2 = 5.27). Demethyl derivatives of aromatic methyl-p-quinones (carbazolequinone, 1,4-naphthoquinone and 2-hydroxy-1,4-naphthoquinone) and methyl-benzoquinones (co-enzyme Q10 and 2-methyl-1,4-benzoquinone) did not produce any positive inotropic effect. It is concluded that the presence of the aromatic methyl-p-quinone skeleton is essential for the development of an inotropic response. A common mechanism for this positive inotropic effect is suggested by the fact that in all cases it was triphasic in nature and inhibited in anoxic conditions or by 2,4-dinitrophenol and dicumarol.