Chemical investigation of the hexane extract of the sponge Diacarnus megaspinorhabdosa provided a series of new norterpene derivatives including three norditerpene cyclic peroxides, diacarperoxides A, B, and C (1 to 3), four norsesterterpene cyclic peroxides, diacarperoxides D to G (4 to 7), and the acyclic norsesterterpene diacardiol A (8). In addition, known norterpene peroxide congeners were also isolated, which included a known norsesterterpene cyclic peroxide (9), nuapapuin A methyl ester (10), epimuqubilin B (11), methyl-2-epinuapapuinoate (12), and methyl diacarnoate A (13). The structures of the new compounds were established on the basis of one- and two-dimensional NMR spectroscopic studies (H, C, COSY, HMQC, HMBC, and ROESY) as well as by mass spectrometric analyses. The relative configuration of chiral centers at C-2, C-3, and C-6 was assigned by established empirical rules. All compounds were evaluated for their cytotoxic properties in vitro using several human as well as murine cancer cell lines.
Ibrahim, S. R. M., Ebel, R., Wray, V., Müller, W. E. G., Edrada-Ebel, R., & Proksch, P. (2008). Diacarperoxides, norterpene cyclic peroxides from the sponge Diacarnus megaspinorhabdosa. Journal of Natural Products, 71(8), 1358-1364. https://doi.org/10.1021/np800102u