Abstract
Two new capnosane-based diterpenoids, flaccidenol A (
) and 7-
-pavidolide D (
), two new cembranoids, flaccidodioxide (
) and flaccidodiol (
), and three known compounds
to
were characterized from the marine soft coral
, collected off the coast of the island of Pratas. The structures of the new compounds were determined by extensive spectroscopic analyses, including 1D and 2D nuclear magnetic resonance (NMR) spectroscopy, and spectroscopic data comparison with related structures. The rare capnosane diterpenoids were isolated herein from the genus
for the first time. The cytotoxicity of compounds
to
against the proliferation of a limited panel of cancer cell lines was assayed. The isolated diterpenoids also exhibited anti-inflammatory activity through suppression of superoxide anion generation and elastase release in the
-formyl-methionyl-leucyl-phenylalanine/cytochalasin B (fMLF/CB)-stimulated human neutrophils. Furthermore,
and
also exhibited cytotoxicity toward the tested cancer cells, and
could effectively inhibit elastase release. It is worth noting that the biological activities of
are reported for the first time in this paper.