Araguspongines K and L, new bioactive bis-1-oxaquinolizidine N-oxide alkaloids from Red Sea specimens of Xestospongia exigua

In addition to the previously reported (+)-araguspongine A, (+)-araguspongine C, (+)-araguspongine D, (-)-araguspongine E, and (+)-xestospongin B, two new N-oxide araguspongines, (+)-araguspongine K and (+)-araguspongine L, are described here. Their structures were established on the basis of spectral analyses including (1)H-(15)N HMBC. The promising in vitro antimalarial and antituberculosis activities of araguspongine C are reported.