New quinoline alkaloids from Ruta chalepensis

The roots of Ruta chalepensis, collected from the northern Saudi desert, yi elded two new quinoline alkaloids, namely, 2-{6'-(2H-benzo[d]1 ",3 "-dioxol en-5 "-yl)hexyl}-hydroquinolin-4-one (1) and 2-{6'-(2H-benzo[d]1 ",3 "-diox olen-5 "-yl)hexyl}-4-methoxy-quinoline (2). Nine previously reported alkalo ids, dictamnine, pteleine, skimmianine, rutacridone, isogravacridonechlorin e, maculosidine, graveoline, graveolinine, and 4-methoxy-1-methyl-2(1H)-qui nolinone, and coumarins, chalepensin, and umbelliferone were also isolated. Structure elucidations were based primarily on 1D and 2D NMR analyses and chemical transformations. Antimicrobial activity of these compounds is disc ussed.