title: Pipa carvalhoi skin secretion profiling: absence of peptides and identification of kynurenic acid as the major constitutive component.
abstract: The presence of peptides has been identified in all African pipid genera; nevertheless, little is known about skin secretion of South American frog genus Pipa. Skin secretion from captive and wild Pipa carvalhoi were obtained in the presence or absence of norepinephrine stimulation. The <10 kDa fraction was analyzed by liquid chromatography and mass spectrometry, searching for peptides. Chromatographic profiles show the presence of a major component in this secretion, regardless of the stimulation method (norepinephrine or mechanical stimulation) and the origin of the animal (captivity or wild), as well as in the absence of any stimulus. The general mass distribution profile in P. carvalhoi skin secretion shows numerous components below 800 Da. Moreover, no peptide could be identified, regardless of the chromatographic approach. The major component was purified and identified as kynurenic acid, an L-tryptophan derivative. P. carvalhoi does not secrete peptides as toxins in its skin. In addition, we here report that kynurenic acid is the main component of P. carvalhoi skin secretion. Although no biological activity was associated with kynurenic acid, we propose that this molecule is a pheromone that signals the presence of a co-specific in the shady environment in which this animal lives. In this study we demonstrate the absence of peptidic toxins in the skin secretion of P. carvalhoi, a break of paradigm in the pipid family.
authors.affiliation: Laboratório de Bioquímica e Biofísica, Instituto Butantan, Av Vital Brasil 1500, São Paulo, SP, 05503-900, Brazil.
authors.forename: Douglas Oscar Ceolin
authors.initials: DO
authors.lastname: Mariano
authors.affiliation: Instituto de Química - Universidade de São Paulo, Av. Prof. Lineu Prestes, 748, Sala 1115, Bloco 11 térreo, São Paulo, SP 05508-000, Brazil.
authors.forename: Lydia Fumiko
authors.initials: LF
authors.lastname: Yamaguchi
authors.affiliation: Laboratório de Biologia Celular, Instituto Butantan, Av Vital Brasil 1500, São Paulo, SP 05503-900, Brazil.
authors.forename: Carlos
authors.initials: C
authors.lastname: Jared
authors.affiliation: Laboratório de Biologia Celular, Instituto Butantan, Av Vital Brasil 1500, São Paulo, SP 05503-900, Brazil.
authors.forename: Marta Maria
authors.initials: MM
authors.lastname: Antoniazzi
authors.affiliation: Laboratório de Bioquímica e Biofísica, Instituto Butantan, Av Vital Brasil 1500, São Paulo, SP, 05503-900, Brazil.
authors.forename: Juliana Mozer
authors.initials: JM
authors.lastname: Sciani
authors.affiliation: Instituto de Química - Universidade de São Paulo, Av. Prof. Lineu Prestes, 748, Sala 1115, Bloco 11 térreo, São Paulo, SP 05508-000, Brazil.
authors.forename: Massuo Jorge
authors.initials: MJ
authors.lastname: Kato
authors.affiliation: Laboratório de Bioquímica e Biofísica, Instituto Butantan, Av Vital Brasil 1500, São Paulo, SP, 05503-900, Brazil. Electronic address: daniel.pimenta@butantan.gov.br.
authors.forename: Daniel Carvalho
authors.initials: DC
authors.lastname: Pimenta
mesh_terms: D000818:Animals; D001001:Anura / Q000378:metabolism*; D055598:Chemical Phenomena; D007736:Kynurenic Acid / Q000378:metabolism*; D012867:Skin / Q000378:metabolism*
chemical_list: D007736:Kynurenic Acid
keywords: Anura; Granular glands; Kynurenic acid; Pipa carvalhoi; Pipidae; Xenopus laevis