Browsing by Author "S. Berlinck, Roberto G."
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Item Evaluation of Chemical Diversity in the Exotic Bryozoan Amathia verticillata(Journal of the Brazilian Chemical Society, 2017) dos Santos, Larissa Alessandra; G. Clavico, Etiene E.; L. Parra, Lizbeth Lorena; S. Berlinck, Roberto G.; Ferreira, Antônio Gilberto; Paul, Valerie J.; Crespo Pereira, RenatoThe present investigation tests the effects against feeding by fishes of crude extracts obtained from eleven distinct populations of the bryozoan Amathia verticillata, an invasive species found globally in tropical to warm-temperate waters. Investigation of extracts from 11 populations of A. verticillata led to the identification and quantification of the known indole alkaloid 2,5,6-tribromo-N-methylgramine and isolation and identification of the new indole alkaloid, 2,6-dibromo-N-methylgramine. One extract of A. verticillata from Brazil significantly deterred feeding, while other extracts of A. verticillata from Florida significantly stimulated feeding by fishes, in field assays performed in Brazil. The same extracts of Florida samples showed variable effects on feeding, ranging from attraction to deterrence, in assays carried out in Florida. The absence of broad chemical defenses against feeding by fish suggests that the establishment of A. verticillata as an invasive species into new areas may be due to reasons other than defensive chemistry.Item Isolation, Derivative Synthesis, and Structure−Activity Relationships of Antiparasitic Bromopyrrole Alkaloids from the Marine Sponge Tedania brasiliensis(Journal of Natural Products, 2018) L. Parra, Lizbeth L.; Bertonha, Ariane F.; M. Severo, Ivan R.; C. Aguiar, Anna C.; de Souza, Guilherme E.; Oliva, Glaucius; C. Guido, Rafael V.; Grazzia, Nathalia; Costa, Tábata R.; Miguel, Danilo C.; Gadelha, Fernanda R.; Ferreira, Antonio G.; Hajdu, Eduardo; Romo, Daniel; S. Berlinck, Roberto G.The isolation and identification of a series of new pseudoceratidine (1) derivatives from the sponge Tedania brasiliensis enabled the evaluation of their anti-parasitic activity against Plasmodium falciparum, Leishmania (Leishmania) amazonensis, Leishmania (Leishmania) infantum and Trypanosoma cruzi, the causative agents of malaria, cutaneous leishmaniasis, visceral leishmaniasis and Chagas disease, respectively. The new 3-debromopseudoceratidine (4), 20-debromopseudoceratidine (5), 4-bromopseudoceratidine (6), 19-bromopseudoceratidine (7) and 4,19-dibromopseudoceratidine (8) are reported. New tedamides A – D (9 – 12), with an unprecedented 4-bromo-4-methoxy-5-oxo-4,5-dihydro-1H-pyrrole-2-carboxamide moiety, are also described. Compounds 4 and 5, 6 and 7, 9 and 10, and 11 and 12 have been isolated as pairs of inseparable structural isomers differing in their sites of bromination or oxidation. Tedamides 9+10 and 11+12 were obtained as optically active pairs, indicating an enzymatic formation rather than an artefactual origin. N12-Acetyl pseudoceratidine (2) and N12-formyl pseudoceratidine (3) were obtained by derivatization of pseudoceratidine (1). The anti-parasitic activity of pseudoceratidine (1) led us to synthesize 23 derivatives (16, 17, 20, 21, 23, 25, 27 – 29, 31, 33, 35, 38, 39, 42, 43, 46, 47, 50 and 51) with variations in the polyamine chain and aromatic moiety in sufficient amounts for biological evaluation in anti-parasitic assays. The measured anti-malarial activity of pseudoceratidine (1) and derivatives 4, 5, 16, 23, 25, 31 and 50 provided an initial SAR evaluation of these compounds as potential leads for anti-parasitics against Leishmania amastigotes and against Plasmodium falciparum. The results obtained indicate that pseudoceratidine represents a promising scaffold for the development of new anti-malarial drugs.Item OxaD: A Versatile Indolic Nitrone Synthase from the Marine-Derived Fungus Penicillium oxalicum F30(Journal of the American Chemical Society, 2016) Newmister, Sean A.; Gober, Claire M.; Romminger, Stelamar; Yu, Fengan; Tripathi, Ashootosh; L. Parra, Lizbeth Lorena; Williams, Robert M.; S. Berlinck, Roberto G.; Joullie, Madeleine M.; Sherman, David H.Indole alkaloids are a diverse class of natural products known for their wide range of biological activities and complex chemical structures. Rarely observed in this class are indolic nitrones, such as avrainvillamide and waikialoid, which possess potent bioactivities. Herein the oxa gene cluster from the marine-derived fungus Penicillium oxalicum F30 is described along with the characterization of OxaD, a flavin-dependent oxidase that generates roquefortine L, a nitrone-bearing intermediate in the biosynthesis of oxaline. Nitrone functionality in roquefortine L was confirmed by spectroscopic methods and 1,3-dipolar cycloaddition with methyl acrylate. OxaD is a versatile biocatalyst that converts an array of semisynthetic roquefortine C derivatives bearing indoline systems to their respective nitrones. This work describes the first implementation of a nitrone synthase as a biocatalyst and establishes a novel platform for late-stage diversification of a range of complex natural products.Item Rearranged Terpenoids from the Marine Sponge Darwinella cf. oxeata and Its Predator, the Nudibranch Felimida grahami(Journal of Natural Products, 2017) A. Ramirez, Maria Camila; Gubiani, Juliana R.; L. Parra, Lizbeth L.; C. Santos, Mario F.; Williams, David E.; D. Ferreira, Daiane; T. Mesquita, Juliana; Tempone, Andre G.; Ferreira, Antonio G.; Padula, Vinícius; Hajdu, Eduardo; Andersen, Raymond J.; S. Berlinck, Roberto G.Marine sponges are a rich source of terpenoids with rearranged spongian carbon skeletons. Investigation of extracts from the sponge Darwinella cf. oxeata yielded four new rearranged diterpenoids, oxeatine (2) and oxeatamides H-J (3-5), as well as the known metabolites oxeatamide A (6), oxeatamide A methyl ester (7), and membranolide (1). Oxeatine (2) has a new heterocyclic skeleton, while oxeatamide J (5) has an N-methyl urea group included in a γ-lactam moiety. UPLC-QTOF analysis of the extract obtained from the mantle of the nudibranch Felimida grahami indicated the presence of 1 and 4.