title: New hemiketal steroid from the introduced soft coral Chromonephthea braziliensis is a chemical defense against predatory fishes.
abstract: Recent studies show that chemical defenses in the exotic soft coral Chromonephthea braziliensis Ofwegen (Nephtheidae, Alcyonacea) can be one of the reasons for the success of this introduced species. We report for the first time the detailed composition of the monohydroxylated sterol fraction and a new hemiketal steroid, 23-keto-cladiellin-A, isolated from the unpalatable hexane extract from C. braziliensis. Bioassay-guided fractionation of this extract revealed that this hemiketal steroid exhibits potent feeding deterrent properties against a natural assemblage of fishes at the natural concentration. The major sterol fraction, containing the monohydroxylated sterols, was inactive in the bioassay. The results suggest that this active molecule may be driving the observed success of the invasion of this soft coral along the Brazilian Atlantic coast.
authors.affiliation: Departamento de Ecologia, IBRAG, Universidade do Estado do Rio de Janeiro, Rua São Francisco Xavier 524, PHLC Sala 220, 20.559-900, Rio de Janeiro, Brazil. bgfleury@uol.com.br
authors.forename: Beatriz G
authors.initials: BG
authors.lastname: Fleury
authors.forename: Bruno G
authors.initials: BG
authors.lastname: Lages
authors.forename: Jussara P
authors.initials: JP
authors.lastname: Barbosa
authors.forename: Carlos R
authors.initials: CR
authors.lastname: Kaiser
authors.forename: Angelo C
authors.initials: AC
authors.lastname: Pinto
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000737:chemistry* / Q000502:physiology*; D004777:Environment; D005399:Fishes / Q000502:physiology*; D011235:Predatory Behavior / Q000502:physiology*; D013256:Steroids / Q000032:analysis* / Q000302:isolation & purification* / Q000494:pharmacology; D013261:Sterols / Q000737:chemistry
chemical_list: C532128:23-keto-cladiellin-A; D013256:Steroids; D013261:Sterols