N-phenyl and N-benzyl substituted succinimides: Preclinical evaluation for their antihypertensive effect and underlying mechanism.

The study was designed to investigate the antihypertensive potential of 2-(2, 5-dioxo-1-phenylpyrrolidin-3-yl)-3-(4-isopropylphenyl)-2-methylpropanal (Comp-1) and 2-(1-benzyl-2,5-dioxopyrrolidin-3-yl)-3-(4-isopropylphenyl)-2-methylpropanal (Succ-5) in rats. The study results showed that, just like nifedipine (the standard reference drug), the test compounds, Comp-1 (at doses of 15 and 20 mg/kg) and Succ-5 (at a dose of 20 mg/kg) had significant antihypertensive effect against deoxycorticosterone acetate-salted rats. The test compounds maintained the level of cardiac markers troponin I and creatinine kinase myocardial bands (CK-MB) in serum, and modulate the oxidative stress markers Glutathione s-transferase (GST) activity, reduced glutathione (GSH), catalase levels, and lipid peroxidation (LPO). These compounds also reduced the expression of inflammatory markers, including cyclooxygenase-2 (COX-2) and tumor necrosis factor alpha (TNF-α) in heart tissues. Furthermore, in the ex-vivo study, the test substances relaxed the contractions induced by phenylephrine (PE) and potassium (K+). Vasodilation was endothelium-independent because the test substances showed nearly the same effect in aortic rings with intact endothelium, denuded endothelium, and with L-NAME pretreatment. The test compounds shifted the calcium curve to the right, i.e., contraction was inhibited and decreased the maximal response. This study demonstrated the antihypertensive, anti-inflammatory, antioxidant, and vasodilate effects of the test compounds. In addition, the results supported the phenomenon of calcium channel blockades responsible for vasodilation.