2 research outputs found
Callyspongiolide, a Cytotoxic Macrolide from the Marine Sponge <i>Callyspongia</i> sp.
A novel
macrolide, callyspongiolide, whose structure was determined
by comprehensive analysis of the NMR and HRMS spectra, was isolated
from the marine sponge <i>Callyspongia</i> sp. collected
in Indonesia. The compound features a carbamate-substituted 14-membered
macrocyclic lactone ring with a conjugated structurally unprecedented
diene-ynic side chain terminating at a brominated benzene ring. Callyspongiolide
showed strong cytotoxicity against human Jurkat J16 T and Ramos B
lymphocytes
Pro-Apoptotic and Immunostimulatory Tetrahydroxanthone Dimers from the Endophytic Fungus Phomopsis longicolla
Four tetrahydroxanthone dimers (<b>1</b>ā<b>4</b>) and four biogenetically related monomers
(<b>5</b>ā<b>8</b>), including the new derivatives <b>4</b>ā<b>6</b>, were isolated from the endophyte Phomopsis
longicolla. The absolute configurations of <b>2</b>ā<b>4</b> were established for the first time by TDDFT
electronic circular dichroism calculations, and that of phomoxanthone
A (<b>1</b>) was revised by X-ray crystallography. Phomoxanthone
A (<b>1</b>) showed the strongest pro-apoptotic activity when
tested against a panel of human cancer cell lines, including cisplatin-resistant
cells, whereas it was up to 100-fold less active against healthy blood
cells. It was also the most potent activator of murine T lymphocytes,
NK cells, and macrophages, suggesting an activation of the immune
system in parallel to its pro-apoptotic activity. This dual effect
in combating cancer cells could help in fighting resistance during
chemotherapy. Preliminary structureāactivity studies of isolated
compounds and derivatives obtained by semisynthesis (<b>9a</b>ā<b>11</b>) hinted at the location of the biaryl axis
and the presence of acetyl groups as important structural elements
for the biological activity of the studied tetrahydroxanthones