5,7,8-Trimethyl-benzopyran and 5,7,8-Trimethyl-1,4-benzoxazine Aminoamide Derivatives as Novel Antiarrhythmics against Ischemia-Reperfusion Injury

6-Hydroxy-5,7,8-trimethyl-benzopyran derivatives and 5,7,8-trimethyl-1,4-benzoxazine analogues substituted by the lidocaine pharmacophore aminoamide functionality at C4 of N4, respectively, were synthesized and evaluated against arrhythmias associated with ischemia-reperfusion injury. The antiarrhythmic effect of substitutents at positions C2 and C6 was examined. Six out of the 11 new derivatives, exhibited arrhythmia scores 1.0-1.3 versus the control (4.5 +/- 1.2), which was also reflected to the % premature beats (0.5-3.9), control (13.7 +/- 3.6). Selected compounds were further studied by a conventional microelectrode method. 2-diethylamino-1-(5,7,8-trimethyl-2-phenyl-2,3-dihydro-benzo[1,4]oxazin-4-yl)-ethanotic (50) and the trolox-inspired 4-(2-diethylamino-acetyl)-2,5,7,8-tetramethyl-3.4-dihydro-2H-benzo[1,4]oxazine-2-carboxylic acid ethyl ester (62) Suppress reperfusion arrhythmias and reduce malondialdehyde (MDA) content, leading to a fast recovery of the heart after ischemia-reperfusion. They exhibit combined class IB and class III antiarrhythmic properties, which constitutes them as promising compounds for further studies because, due to their multichannel "amiodarone like" effect, less proarrhythmic complications can be expected.