Pharmacological properties of novel bicyclic isoquinoline analogs in isolated guinea pig atria, trachea and in human platelets: relationship to trimetoquinol

Synthesis and in vitro platelet aggregation and TP receptor binding studies on bicyclic 5,8-ethanooctahydroisoquinolines and 5,8-ethanotetrahydroisoquinolines

Eighteen novel bicyclic 1-substituted benzyl octahydro- and tetrahydroisoquinolines were synthesized and evaluated for human thromboxane A(2)/prostaglandin H(2) (TP) receptor affinity and antagonism of TP receptor-mediated platelet aggregation. In both cases, potency depended more on the presence of methoxy groups on the 1-benzyl moiety than on nitrogen substitution or extent of oxidation of the isoquinoline ring system. The most potent of the bicyclic compounds retained the 5,8-ethanooctahydroisoquinoline ring structure of the parent molecule (1) and required the 3,4,5-trimethoxybenzyl substitution pattern found in the well-characterized tetrahydroisoquinoline antiplatelet agent trimetoquinol. Differences in nitrogen substituent SAR were noted between the mono-methoxylated compounds and the 3,4,5-trimethoxybenzyl derivatives.

Assessment of the intraocular pressure-lowering activity of bicyclic derivatives of 1-substituted benzyloctahydroisoquinoline

In our study of IOP-lowering agents, we have synthesized several bicyclic analogs of 1-benzyloctahydroisoquinoline. The target molecules were synthesized in an eleven-step process. Structures were proved through spectrometry, elemental analysis and, in selected cases, high resolution mass spectrometry. The final products were secondary or tertiary amines containing a 1-benzyl moiety substituted at the p-position with a methoxy, methyl or chloro group. All target molecules were analyzed in 1% solution in distilled water in normotensive rabbits. After topical administration, IOP was monitored in both eyes for up to seven hours. The 1-p-methoxybenzyl molecule 2 was the most active, and caused a maximal IOP drop of 8.8 +/- 1.9 (n = 7) mm Hg in the ipsilateral eye at 4 hours post-administration, with only partial recovery at seven hours. All other compounds tested either showed very weak activity (3-6) or were inactive (1). All compounds produced a contralateral effect, and 5 induced rebound ocular hypertension. We conclude that selected tertiary bicyclic 1-p-methoxybenzyl-octahydroisoquinolines, particularly N-methylated structures, exhibit a significant IOP-lowering effect in normotensive rabbits.