New flavonoids with multiple bronchodilator activity pathways from L. (Pers.) growing in Saudi Arabia.

Total extract of () expressed potent bronchodilator effect in isolated Guinea pigs' tracheal muscles. Fractionation of total extract ( using liquid-liquid technique followed by bronchodilator testing indicated that the activity was trapped to the chloroform (CHCl) soluble fraction. Phytochemical study of the CHCl fraction guided by bronchodilator activity led to the isolation of 7 active flavones of which compounds (Tephroapollin G), (Acetyltephroapollin C), (4''-Dehydroxytephroapollin E), and (Tephroapollin F) were new. Structures were identified using relevant spectroscopic tools including optical rotations and CD data. Compounds , , and lanceolatin A () behaved like papaverine by inhibiting carbachol (CCh) as well as high potassium (K)-mediated contractions at equivalent concentrations with varied potencies whereas (-)-Tephroapollin G () selectively inhibited CCh-mediated contractions but was not found active against high K. -Tephroapollin F () and (-)-Pseudosemiglabrin () in contrast were significantly more potent to abolish CCh induced contraction when compared with high K similar to dicyclomine. Papaverine like dual phosphodiesterase enzyme Ca ion inhibitory activities of and were confirmed indirectly by the bolster of the isoprenaline curves against CCh to the left whereas Ca inhibitory effect of and - was confirmed by the rightward deflection of Ca concentration-response curves (CRCs) towards right with quashing of the maximum response in same fashion like verapamil. Moreover, compounds and at lower concentrations showed selective blockade of muscarinic receptor similar to atropine. Oral administration of the , CHCl and to guinea pigs significantly protected against bronchospasm induced by 0.2 % histamine aerosol .