The occurrence of defensive alkaloids in non-integumentary tissues of the Brazilian red-belly toad Melanophryniscus simplex (Bufonidae)

Author(s)

Grant, Taran ^[1] ; Colombo, Patrick ^[2] ; Verrastro, Laura ^[3] ; Saporito, Ralph A. ^[4]

Affiliation

^[1] Univ Sao Paulo, Dept Zool, Inst Biociencias, BR-05422970 Sao Paulo - Brazil

^[2] Pontificia Univ Catolica Rio Grande do Sul, Lab Sistemat Vertebrados, Fac Biociencias, BR-90619900 Porto Alegre, RS - Brazil

^[3] Univ Fed Rio Grande do Sul, Lab Herpetol, Dept Zool, Inst Biociencias, BR-91540000 Porto Alegre, RS - Brazil

^[4] John Carroll Univ, Dept Biol, University Hts, OH 44118 - USA

• Document type: Journal article
• Source: Chemoecology; v. 22, n. 3, p. 169-178, SEP 2012.
• Web of Science Citations: 16

Abstract

The red-belly toads (Melanophryniscus) of southern South America secrete defensive alkaloids from dermal granular glands. To date, all information on Melanophryniscus alkaloids has been obtained by extraction from either skins or whole organisms; however, in other amphibians, tetrodotoxins, samandarines, and bufadienolides have been detected in both skin and other organs, which raise the possibility that lipophilic alkaloids may occur in non-integumentary tissues in Melanophryniscus as well. To test this hypothesis, we studied the distribution of alkaloids in the skin, skeletal muscle, liver, and mature oocytes of the red-belly toad M. simplex from three localities in southern Brazil. Gas chromatography and mass spectrometry of skin extracts from 11 individuals of M. simplex resulted in the detection of 47 alkaloids (including isomers), 9 unclassified and 38 from 12 known structural classes. Each alkaloid that was present in the skin of an individual was also present in the same relative proportion in that individual's skeletal muscle, liver, and oocytes. The most abundant and widely distributed alkaloids were the pumiliotoxins 251D, 267C, and 323A, 5,8-disubstituted indolizidines 207A and 223D, 5,6,8-trisubstituted indolizidine 231B, 3,5-disubstituted pyrrolizidines cis-223B and cis- and trans-251K, and izidine 211C. We report the first record of piperidines in Melanophryniscus, bringing the total number of alkaloid classes detected in this genus to 16. Alkaloid composition differed significantly among the three study sites. The functional significance of defensive chemicals in non-integumentary tissues is unknown. (AU)

• FAPESP's process: 08/50928-1 - Speciation of frogs in high-altitude environments
• Grantee: Célio Fernando Baptista Haddad
• Support Opportunities: Research Projects - Thematic Grants