Probing Anti-Proliferative 24-Homoscalaranes from a Sponge Lendenfeldia sp.

In the current study, an NMR spectroscopic pattern-based procedure for probing scalarane derivatives was performed and four new 24-homoscalaranes, lendenfeldaranes A−D (1− 4), along with three known compounds, 12α-acetoxy-22-hydroxy-24-methyl-24-oxoscalar-16-en- 25-al (5), felixin F (6), and 24-methyl-12,24,25-trioxoscalar-16-en-22-oic acid (7) were isolated from the sponge Lendenfeldia sp. The structures of scalaranes 1−7 were elucidated on the basis of spectroscopic analysis. Scalaranes 1−7 were further evaluated for their cytotoxicity toward a series of human cancer cell lines and the results suggested that 5 and 7 dominated in the anti- proliferative activity of the extract. The 18-aldehyde functionality was found to play a key role in their activity.