Berlinck, R.G.S., Ogawa, C.A., Almeida, A.M.P., Sanchez, M.A.A., Costa, L.V., Malpezzi, E.L.A., Freitas, J.C., Hajdu, E., “Chemical and Pharmacological Characterization of Halitoxin from Amphimedon viridis (Porifera) from the Southeastern Brazilian Coast”, Comparative Biochemistry and Physiology, 115C, 155-163 (1996).

Abstract: The halitoxin complex from the marine sponge Amphimedon viridis, collected in the São Sebastião channel (southeastern Brazilian coast), was isolated by gel-filtration chromatography on Sephadex LH-20. Spectroscopic data (1H, 13C and 2D-NMR) of halitoxin from A. viridis indicated that it has the same two alkylpyridine monomers composition of the previously isolated halitoxin from Amphimedon compressa (as Haliclona rubens). Nevertheless, analysis by High Performance Gel Permeation Chromatography indicated that the halitoxin complex of A. viridis has a lower molecular weight (500, 2000 and 5000 Da; the major component corresponding to the fraction of 2000 Da MW) when compared to the previously isolated halitoxin complex from A. compressa. Some pharmacological properties of the halitoxin complex from A. viridis were evaluated in terms of lethality, antimitosis, hemolysis and neurotoxicity. The possible chemotaxonomic value of alkyl pyridine alkaloids is discussed.

Chehade, C.C., Dias, R.L.A., Berlinck, R.G.S., Ferreira, A.G., Costa, L.V., Rangel, M., Malpezzi, E.L.A., Freitas, J.C. and Hajdu, E., “1,3-Dimethylisoguanine, a New Purine from the Marine Sponge Amphimedon viridis, Journal of Natural Products, 60, 729-731 (1997).

Abstract: A new purine, 1,3-dimethylisoguanine (1), has been isolated from the marine sponge Amphimedon viridis and identified by analysis of spectroscopic data. Compound 1 increased the contractions obtained by transmural electrical stimulation in the guinea pig longitudinal muscle/myenteric plexus in a dose-dependent manner.

Gambardella, M.T.P., Dias, R.L.A., Chehade, C.M.M., Berlinck, R.G.S., “1,3-Dimethylisoguanine trihydrate”, Acta Crystallographica, C55, 1585-1587 (1999).

Abstract: The title compound, isolated from the marine sponge Amphimedon viridis, crystallizes with three molecules of water, C7H9N5O.3H2O The water molecules are involved in four hydrogen bonds with 1,3-dimethylisoguanine, having N…O distances 3.010(3), 2.857(3), 2.762(3) and 2.810(3) angstroms. The molecules are linked together through four water-water hydrogen bonds, having O..O distances 2.812(3), 2.739(2), 2.784(3) and 2.796(3) angstroms.

Related paper (review)

Almeida, A.M.P., Berlinck, R.G.S., Hajdu, E., “Alcalóides Alquilpiridínicos de Esponjas Marinhas”, Química Nova, 20, 170-185 (1997).

Abstract: The chemistry of alkylpyridine alkaloids originating from marine sponges is comprehensively reviewed, with emphasis on their natural occurrence, methods for isolation, spectroscopic characterization, biological activities and chemical synthesis. A likely chemotaxonomic role is suggested, as markers for sponges of the Order Haplosclerida (Demospongiae).