Browsing by Author "L. Parra, Lizbeth Lorena"
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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 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.