Antiangiogenic Iridoids from Stachys ocymastrum and Premna resinosa

In this paper, the isolation of one new iridoid glucoside, 6 beta -acetoxyipolamiide ( 1 ), and thirteen ( 2 - 14 ) known congeners from two Lamiaceae species, Stachys ocymastrum and Premna resinosa , leaf extracts is reported. The structural determination of the isolated compounds was performed by mono- and bidimensional NMR spectroscopic analysis as well as MS experiments. The isolates were assayed for their antiangiogenic activity by two in vivo models, zebrafish embryos and chick chorioallantoic membrane assays. The compounds with a significant antiangiogenic activity in both assays were beta -hydroxyipolamiide ( 2 ), ipolamiide ( 3 ), and buddlejoside A (5) ( 8 ). 6- O - alpha - l -(3 ''- O-p -Methoxycinnamoyl-4 ''- O -acetyl)rhamnopyranosyl catalpol ( 13 ) and 6- O - alpha - l -(2 ''- trans -caffeoyl)rhamnopyranosyl catalpol ( 6 ) showed the best antiangiogenic response on blood vessel growth in zebrafish embryos, whereas saccatoside ( 10 ) and 6- O - alpha - l -(2 ''- O - p -methoxycinnamoyl-3 ''- O -acetyl)rhamnopyranosyl catalpol ( 14 ) resulted in a strong reduction of capillary formation in the chorioallantoic membrane assay.