Endothelium-independent vasorelaxant effect of a Berberis orthobotrys root extract via inhibition of phosphodiesterases in the porcine coronary artery.

BACKGROUND: Berberis orthobotrys Bien ex Aitch. (Berberidaceae) is a plant indigenous of Pakistan that is locally used for the treatment of hypertension. HYPOTHESIS: This study evaluated the vasoactive properties of a Berberis orthobotrys root extract and its fractions, and investigated the role of the endothelium and the underlying mechanism. STUDY DESIGN: An aqueous methanolic extract of Berberis orthobotrys roots was prepared and submitted to a multi-step liquid-liquid fractionation with solvents of increasing polarity. Vascular reactivity of the different fractions was assessed using porcine coronary artery rings either with or without endothelium, and in the presence or absence of specific pharmacological tools. The ability of Berberis orthobotrys extracts to affect phosphodiesterase (PDE) activity was evaluated using a radioenzymatic method and purified phosphodiesterases. RESULTS: The aqueous methanol extract induced similar relaxations in coronary artery rings with and without endothelium, and, amongst the three derived preparations, the butanol fraction (BFBO) was slightly but significantly more effective than the ethyl acetate fraction and the aqueous residue in rings without endothelium. Analysis of the butanol fraction (BFBO) by LC-ELSD-MS indicated the presence of four major isoquinoline alkaloids including berberine. BFBO significantly potentiated the relaxations induced by cyclic GMP- and cyclic AMP-dependent relaxing agonists, and inhibited contractions to KCl, CaCl2, and U46619 in endothelium denuded rings. In contrast, BFBO did not affect relaxations to endothelium-dependent vasodilators. BFBO concentration-dependently inhibited the cyclic GMP-hydrolyzing activity of basal PDE1, calmodulin-activated PDE1 and PDE5, and of cyclic AMP-hydrolyzing activity of PDE3 and PDE4 with IC50 values ranging from 40 to 130µg/ml. CONCLUSION: The butanol fraction of the aqueous methanol extract of Berberis orthobotrys roots induced pronounced endothelium-independent relaxations and inhibited contractile responses by acting directly at the vascular smooth muscle in the coronary artery. Moreover, BFBO potentiated relaxations induced by both cyclic GMP- and cyclic AMP-dependent vasodilators most likely due to its ability to inhibit several vascular PDEs, and in particular PDE4 and PDE5.

Studies on the antihypertensive, antispasmodic, bronchodilator and hepatoprotective activities of the Carum copticum seed extract.

This study describes the antihypertensive, antispasmodic, bronchodilator and hepatoprotective activities of the aqueous-methanolic extract of Carum copticum Benth. seeds (CSE) to rationalize some of its traditional uses. CSE (3-100 mg/kg) caused a dose-dependent fall in arterial blood pressure in anaesthetized rats. In isolated rabbit aorta and jejunum preparations, CSE (0.1-3.0 mg/ml) caused an inhibitory effect on the K+-induced contractions. The calcium channel blocking (CCB) effect was confirmed when CSE shifted the Ca2+ dose-response curves (DRCs) to right similar to verapamil. In isolated guinea-pig tracheal preparations, it caused inhibition of carbachol and K+-induced bronchoconstriction at 0.1-1.0 mg/ml as well as shifted the dose-response curves (DRCs) of carbachol and histamine to the right with suppression of maximum response suggestive of non-specific bronchodilator effect mediated possibly through CCB. Pretreatment of rats with CSE (500 mg/kg orally for 2 days at 12 h intervals) prevented paracetamol (640 mg/kg) and CCl4 (150 ml/kg)-induced rise in serum alkaline phosphatase (ALP) and aminotransferases (AST and ALT). The same dose of CSE was able to prevent the CCl4-induced prolongation in pentobarbital-induced sleeping time in mice confirming its hepatoprotectivity. These results indicate the presence of calcium antagonist(s) in Carum copticum seeds and thus provides sound mechanistic basis for some of their folkloric uses.

Ethnopharmacological evaluation of the anticonvulsant, sedative and antispasmodic activities of Lavandula stoechas L.

Lavandula stoechas L. (Lamiaceae) has been used for a long time in traditional medicine as an anticonvulsant and antispasmodic. The aqueous-methanolic extract of L. stoechas flowers (LS) was studied for its possible anticonvulsant and antispasmodic activities. When tested in mice, LS (600 mg/kg) significantly reduced the severity and increased the latency of convulsions induced by pentylene tetrazole (PTZ). LS likewise reduced PTZ's lethality. LS up to a dose of 600 mg/kg was found devoid of any hypnotic effect in mice, however, animals were found to be dull, calm and relaxed. The sedative effect of the plant extract was confirmed, as it prolonged the pentobarbital sleeping time in mice similar to that of diazepam. In isolated rabbit jejunum preparations, LS caused a dose-dependent (0.1-1.0 mg/ml) relaxation of spontaneous contractions. LS also inhibited K(+)-induced contractions in a similar dose range, thereby suggesting calcium channel blockade. This effect was confirmed when pretreatment of the jejunum preparation with LS produced a dose-dependent shift of the Ca(2+) dose-response curve to the right, similar to the effect of verapamil, a standard calcium channel blocker. These data indicate that the plant extract exhibits anticonvulsant and antispasmodic activities. Its calcium channel blocking property may be mechanistically related to these activities. Its usefulness in folk medicine appears thus to be based on a sound mechanistic background.