Abstract
Continuing chemical investigation of the Red Sea sponge
sp. led to the isolation of four new 3,4-
-3,19-dinorspongian diterpenoid lactones, secodinorspongins A-D (
-
), along with a classical spongian diterpenoid lactone, sponginolide (
). The chemical structures, including the absolute configurations of these compounds, were elucidated using the extensive spectroscopic study composed of 1D and 2D NMR data analyses, and a comparison between calculated-electronic-circular-dichroism (ECD) and experimental-circular-dichroism (CD) spectra. A plausible biosynthetic pathway of
-
was also proposed. Furthermore, the cytotoxicity, antibacterial and anti-inflammatory activities of
-
were evaluated. Compound
was found to exhibit inhibitory activity against the growth of
(
), and
and
exhibited suppression of superoxide-anion generation and elastase release in fMLF/CB-induced human neutrophils.