Panapophenanthrin, a Rare Oligocyclic Diterpene from Panus strigellus.

During the course of our search for biologically active secondary metabolites from fungal cultures, a new oligocyclic diterpenoidal derivative, panapophenanthrin (1), was isolated from Panus strigellus. In addition, two known metabolites, panepophenanthrin (2) and dihydrohypnophilin (3), were also obtained. The chemical structures of the isolated compounds were elucidated based on extensive 1D and 2D NMR spectral analyses together with high-resolution electrospray ionization mass spectrometry (HR-ESI-MS). The absolute configuration was determined through TDDFT-ECD calculations. All of the compounds were assessed for their antimicrobial and cytotoxic activities. Compounds 1 and 3 showed moderate to weak activities in the performed antimicrobial assays, while compound 1 exhibited potent cytotoxic activity against the mammalian cell lines mouse fibroblast (L929) and human endocervical adenocarcinoma (KB3.1).

Identification of angular naphthopyrones from the Philippine echinoderm Comanthus species as inhibitors of the NF-κB signaling pathway.

The redox-sensitive nuclear factor kappa-B (NF-κB) signaling pathway is an important cellular pathway often misregulated in various cancer cells. Therefore, blockade of NF-κB signaling in cancer cells presents a promising strategy and enormous effort has been invested to identify potent and specific inhibitors. The aim of this study was the identification of new compounds derived from marine organisms that act as NF-κB inhibitors and to identify their mechanism of action. In the present work a bioassay-guided investigation of a Philippine specimen of the marine echinoderm Comanthus sp. yielded ten compounds evenly divided into anthraquinones and naphthopyrones. From these compounds only two naphthopyrones, comaparvin and 6-methoxycomaparvin exhibited noteworthy inhibitory activity against tumor necrosis factor-alpha (TNF-α) induced NF-κB activation in rat hepatoma cells and human breast cancer cells. Comaparvin at concentrations between 50µM and 100µM reduces chymotrypsin-like proteasomal activity, blocks nuclear translocation of NF-κB and effectively inhibits TNF-α induced IκB phosphorylation suggesting a role of this compound in targeting IκB kinase (IKK). Furthermore, comaparvin sensitized cancer cells to apoptotic effects mediated by the pro-inflammatory cytokine TNF-α. These results correlate with downregulation of TNF-α induced expression of protective NF-κB target genes like MnSOD, XIAP or A20. In conclusion we identified the naphthopyrone comaparvin isolated from the marine echinoderm Comanthus sp. as a new inhibitor of the NF-κB signaling pathway acting by targeting both proteasome function and IκB phosphorylation likely by direct inhibitory effect on IKKß activity.

Dibromopyrrole alkaloids from the marine sponge Acanthostylotella sp.

Fourteen dibromopyrrole alkaloids were isolated from the marine sponge Acanthostylotella sp. collected in Indonesia. In addition to the known compounds 4,5-dibromo-N-(methoxy-methyl)-1H-pyrrole-2-carboxamide (7), 4,5-dibromo-1H-pyrrole-2-carboxamide (8), mukanadin D (9), (+/-)-longamide B methyl ester (10), (+/-)-longamide B (11), (+/-)-longamide (12), 3,4-dibromo-lH-pyrrole-2-carboxamide (13), 2-cyano-4,5-dibromo-1H-pyrrole (14), six compounds were isolated that proved to be new natural products including acanthamides A-D (1-4), methyl 3,4-dibromo-1H-pyrrole-2-carboxylate (5) and 3,5-dibromo-1H-pyrrole-2-carboxylic acid (6). The structures of the new compounds were unequivocally identified based on one and two dimensional NMR and on HRFTMS as well as by comparison with the literature.