Bioactive flavonoids from the leaves of Lawsonia alba (Henna)

Three new flavonoids, lawsochrysin ( 1 ), lawsochrysinin ( 2 ), and lawsonaringenin ( 3 ) were isolated from the leaves of Lawsonia alba Lam. along with four flavonoids 3′,4′-dimethoxy flavone ( 4 ), 7-hydroxy flavone ( 5 ), 3,3′,4′,7-tetrahydroxy flavanone ( 6 ) and rhoifolin ( 7 ) hitherto unreported from this genus. Their structures were elucidated on the basis of spectroscopic evidences. Compounds ( 3 ) and ( 6 ) showed a good urease inhibition activity IC 50 = 139.1 ± 0.77 and 184.53 ± 0.61 μM respectively, ( 6 ) also showed a DPPH radical scavenging activity with IC 50 = 33.83 μM.