Mechanism of vasorelaxant activity of a fraction of root extract of <i style="">Sesamum indicum</i> Linn.

Abstract

The petroleum ether soluble fraction (SIPE) of the root extract of <i style="">S. indicum</i> was evaluated for the vasorelaxant activity using isolated rat aorta. SIPE up to 180 µg/ml concentration significantly inhibited phenylephrine- and KCl-induced contraction to the extent of 98.13 ± 6.37 and 70.19 ± 3.43% respectively in isolated rat aorta in a concentration dependent manner. The vasorelaxant activity was not blocked by propranolol (10 µM), atropine (1 µM) indomethacin (10 µM) and glibenclamide (10 µM). Influence of SIPE on phenylephrine-induced contractions in aortic preparations in absence of functional endothelium and on pre-incubating the tissue with L-NAME (300 µM) or methylene blue (10 µM) was also studied. SIPE at 180 µg/ml concentration could elicit partial relaxation in presence of L-NAME or methylene blue to the extent of 34.26 ± 6.13 and 25.66 ± 10.95% respectively. However, in absence of functional endothelium, SIPE exhibited little relaxation to the extent of 6.70 ± 4.87%. These studies revealed that the vasorelaxant activity of SIPE was chiefly mediated through endothelium-dependent pathway.