Isolation of vasodilatory active flavonoids from the traditional remedy Satureja obovata

In the course of screening natural products for smooth muscle relaxant properties, the effects of constituents of Satureja obovata var. obovata (Lamiaceae) on vascular reactivity experiments were studied. Bioassay-guided fractionation led to pure vasodilator compounds, identified by spectroscopic methods as the flavonoids: naringenin, eriodictyol, and luteolin. The relaxant effects induced by different extracts and fractions obtained on KCl (80 mM) and noradrenaline (NA) (10(-6) M) induced contractions on isolated rat aorta were selected as bioassay procedures. The sustained contraction induced by NA (10(-6) M) and K+ (80 mM) were relaxed by luteoline (98.7 +/- 0.7%; 40.30 +/- 2.4%), naringenin (12.41 +/- 1.8%; 3.05 +/- 0.3%), and eriodictyol (67.48 +/- 3.3%; 17.93 +/- 2.1%) each at the dose of 5 x 10(-5)M, respectively.