Denigrins A-C: new antitubercular 3,4-diarylpyrrole alkaloids from Dendrilla nigra.

Chemical diversity is vital to antitubercular drug discovery as it ensures a novel bioactivity profile. Marine sponges have so far provided more than 1000 new bioactive molecules. Ethyl acetate extract of the marine sponge Dendrilla nigra on bioactivity-guided screening yielded three new compounds denigrins A-C, with potent antitubercular activity. Spectral and chemical analyses confirmed that these three compounds belong to the 3,4-diaryl pyrrole alkaloid category. The presence of monohydroxy substitution on benzene rings is not very common in lamellarin and related 3,4-diaryl pyrrole alkaloids isolated from marine invertebrates. Among these, denigrin C showed highest potency (minimum inhibitory concentration 4 µg/mL) against Mycobacterium tuberculosis H37Rv.

Rubrolide R: a new furanone metabolite from the ascidian Synoicum of the Indian Ocean.

A new furanone metabolite of the rubrolide family, rubrolide R as diacetate (1), was isolated from a new species of the ascidian Synoicum, besides the known compounds rubrolide A (as diacetate), cadiolide B and prunolide A. The structure of the new rubrolide was elucidated by a study of spectral data. The crude extract and isolated compounds (prunolide A and cadiolide B) showed antiviral activity against the Japanese encephalitis virus. Prunolide A showed cytotoxic activity against breast cancer cell lines at a concentration of < 1 µM.