title: Antiprotozoal and antioxidant alkaloids from Alternanthera littoralis.
abstract: Five alkaloids, in addition to hydroxytyrosol and uridine, were isolated from aerial parts of Alternanthera littoralis P. Beauv. Among the isolated compounds, alternamide A was an unusual tricyclic alkaloid with a bridged benzoazepine core. All isolated alkaloids have a catechol moiety, indicating a possible common biosynthetic route. Their structures were established by 1D and 2D NMR spectroscopy in combination with extensive tandem MS experiments by collisional induced dissociation (CID). The antiprotozoal activity of the isolated compounds was assayed against trypomastigote forms of Trypanosoma cruzi and amastigotes of Leishmania amazonensis. Alternamine A was the most active compound, reducing markedly the viability of both parasites. Antioxidant capacities evaluated by ORACFLassay showed that the isolated alkaloids (mainly alternamide B) contributed to the high activity recorded for the ethanolic crude extract; possibly, the catechol moiety present in all structures plays a central role in this result.
authors.affiliation: DeMpSter Mass Spectrometry Group, Superior Institute of Health Sciences, Amazonas State University - UEA, 69055-010 Manaus, AM, Brazil; Department of Plant Biology, PPG BTPB and PPG BV, Institute of Biology, University of Campinas - UNICAMP, 13083-970 Campinas, SP, Brazil. Electronic address: hectorkoolen@gmail.com.
authors.forename: Hector H F
authors.initials: HH
authors.lastname: Koolen
authors.affiliation: Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo - USP, 05508-000 São Paulo, SP, Brazil.
authors.forename: Elizabeth M F
authors.initials: EM
authors.lastname: Pral
authors.affiliation: Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo - USP, 05508-000 São Paulo, SP, Brazil.
authors.forename: Silvia C
authors.initials: SC
authors.lastname: Alfieri
authors.affiliation: Department of Plant Biology, PPG BTPB and PPG BV, Institute of Biology, University of Campinas - UNICAMP, 13083-970 Campinas, SP, Brazil.
authors.forename: Jane V N
authors.initials: JV
authors.lastname: Marinho
authors.affiliation: Department of Plant Biology, PPG BTPB and PPG BV, Institute of Biology, University of Campinas - UNICAMP, 13083-970 Campinas, SP, Brazil.
authors.forename: Alessandra F
authors.initials: AF
authors.lastname: Serain
authors.affiliation: Department of Plant Biology, PPG BTPB and PPG BV, Institute of Biology, University of Campinas - UNICAMP, 13083-970 Campinas, SP, Brazil.
authors.forename: Alvaro J
authors.initials: AJ
authors.lastname: Hernández-Tasco
authors.affiliation: Department of Plant Biology, PPG BTPB and PPG BV, Institute of Biology, University of Campinas - UNICAMP, 13083-970 Campinas, SP, Brazil.
authors.forename: Nathalia L
authors.initials: NL
authors.lastname: Andreazza
authors.affiliation: Department of Plant Biology, PPG BTPB and PPG BV, Institute of Biology, University of Campinas - UNICAMP, 13083-970 Campinas, SP, Brazil.
authors.forename: Marcos J
authors.initials: MJ
authors.lastname: Salvador
mesh_terms: D000470:Alkaloids / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D027703:Amaranthaceae / Q000737:chemistry*; D000975:Antioxidants / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D000981:Antiprotozoal Agents / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D001938:Brazil; D002396:Catechols / Q000737:chemistry; D007891:Leishmania / Q000187:drug effects; D019906:Nuclear Magnetic Resonance, Biomolecular; D014349:Trypanosoma cruzi / Q000187:drug effects
chemical_list: D000470:Alkaloids; D000975:Antioxidants; D000981:Antiprotozoal Agents; D002396:Catechols; C034221:catechol
keywords: Alkaloids; Alternanthera littoralis; Amaranthaceae; Antioxidant activity; Antiprotozoal activities; Catechol