A novel dihydropyridine with 3-aryl meta-hydroxyl substitution blocks L-type calcium channels in rat cardiomyocytes

Rationale: Dihydropyridines are widely used for the treatment of several cardiac diseases due to their blocking activity on L-type Ca²⁺ channels and their renowned antioxidant properties. Methods: We synthesized six novel dihydropyridine molecules and performed docking studies on the binding site of the L-type Ca²⁺ channel. We used biochemical techniques on isolated adult rat cardiomyocytes to assess the efficacy of these molecules on their Ca²⁺ channel-blocking activity and antioxidant properties. The Ca²⁺ channel-blocking activity was evaluated by confocal microscopy on fluo-3AM loaded cardiomyocytes, as well as using patch clamp experiments. Antioxidant properties were evaluated by flow cytometry using the ROS sensitive dye 1,2,3 DHR. Results: Our docking studies show that a novel compound with 3-OH substitution inserts into the active binding site of the L-type Ca²⁺ channel previously described for nitrendipine. In biochemical assays, the novel meta-OH group in the aryl in C4 showed a high blocking effect on L-type Ca²⁺ channel as opposed to para-substituted compounds. In the tests we performed, none of the molecules showed antioxidant properties. Conclusions: Only substitutions in C2, C3 and C5 of the aryl ring render dihydropyridine compounds with the capacity of blocking LTCC. Based on our docking studies, we postulate that the antioxidant activity requires a larger group than the meta-OH substitution in C2, C3 or C5 of the dihydropyridine ring.