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.