3β,3′β-Dimethylxestospongin C, a NewBis-1-Oxaquinolizidine Alkaloid from the Palauan SpongeXestospongiasp

3β,3′β-Dimethylxestospongin C, a NewBis-1-Oxaquinolizidine Alkaloid from the Palauan SpongeXestospongiasp 9′-Epi-3β,3′β-dimethylxestospongin C, a New Macrocyclic Diamine Alkaloid from the Hainan SpongeNeopetrosia exigua 9′<i>-Epi</i>-3<i>β</i>,3′<i>β</i>-dimethylxestospongin C, a New Macrocyclic Diamine Alkaloid from the Hainan Sponge<i>Neopetrosia exigua</i> A New Quinolizidine Alkaloid from the Papua New Guinean Sponge Xestospongia exigua A New Quinolizidine Alkaloid from the Papua New Guinean Sponge <i>Xestospongia exigua</i> Two New Alkaloids from Xestospongia sp., a New Caledonian Sponge Two New Alkaloids from Xestospongia sp., a New Caledonian Sponge Bis-1-oxaquinolizidines from the Sponge Haliclona exigua Araguspongines K and L, New Bioactive Bis-1-oxaquinolizidine <i>N</i>-Oxide Alkaloids from Red Sea Specimens of <i>Xestospongia </i><i>e</i><i>xigua</i> Araguspongines B, C, D, E, F, G, H, and J, new vasodilative bis-1-oxaquinolizidine alkaloids from an Okinawan marine sponge, Xestospongia sp.