Hypotensive Effect of O-Methylisothalicberine, A Bisbenzylisoquinoline Alkaloid Isolated from Berberis chilensis on Normotensive Rats

Abstract

O-Methylisothalicberine (O-MI) is a bisbenzylisoquinoline alkaloid isolated from Berberis chilensis, structurally similar to alkaloids previously described in the literature as calcium antagonists of natural origin (berbamine, tetrandrine, antioquine, 7-O-demethylisothalicberine and others). O-MI caused a significant reduction of mean arterial pressure (MAP) in normotensive anaesthetized rats. Doses of 1.0; 2.5; 5.0; 7.5 and 10.0 mg/kg were administered via the femoral vein. MAP was reduced by 5.8%; 10.1%; 35.6%; 67.9% and 60.5% respectively. The onset of hypotensive action was 5 s after 5 mg/kg i.v. and the effect lasted for about 120 s. O-MI exhibited an LD50 of 5 mg/mL towards the brine shrimp (Artemia salina). © 1997 by John Wiley & Sons, Ltd. Phytother. Res. 11, 246–248, 1997