Alkaloids and Polyacetylenes from Hippobroma longiflora with Antiangiogenesis Properties.

Four new alkaloids, hippobrines A-D ( 1 - 4 ), along with three new polyacetylenes, hippobrenes A-C ( 5 - 7 ), were isolated from Hippobroma longiflora . Compounds 1 - 3 possess an unprecedented carbon skeleton. All of the new structures were determined by analyzing their mass and NMR spectroscopic data. The absolute configurations of 1 and 2 were confirmed by single-crystal X-ray analyses, and the absolute configurations of 3 and 7 were deduced using their ECD spectra. Plausible biogenetic pathways of 1 and 4 were proposed. In regard to bioactivities, all compounds ( 1 - 7 ) exhibited weak antiangiogenic activity against human endothelial progenitor cells, with IC 50 values ranging from 21.1 ± 1.1 to 44.0 ± 2.3 μg/mL.