Further classification of skin alkaloids from neotropical poison frogs (dendrobatidae), with a general survey of toxic/noxious substances in the amphibia

Daly, John W.; Myers, Charles W.; Whittaker, Noel F.

doi:10.1016/0041-0101(87)90265-0

Cited by 390 publications

(297 citation statements)

References 151 publications

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“…Alkaloids have been well studied in the dendrobatid poison frog Oophaga [formerly Dendrobates (20)] pumilio (21)(22)(23). More than 30 years of research with this species throughout its natural geographic range has resulted in the detection of Ͼ230 alkaloids from 21 different structural classes (R.A.S., M.A.D., P. Jain, H.M.G., T.F.S., and J.W.D., unpublished data); many of these alkaloids are shared with other poison frogs.…”

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confidence: 99%

Oribatid mites as a major dietary source for alkaloids in poison frogs

Saporito

Donnelly²,

Norton³

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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Alkaloids in the skin glands of poison frogs serve as a chemical defense against predation, and almost all of these alkaloids appear to be sequestered from dietary arthropods. Certain alkaloid-containing ants have been considered the primary dietary source, but dietary sources for the majority of alkaloids remain unknown. Herein we report the presence of ≈80 alkaloids from extracts of oribatid mites collected throughout Costa Rica and Panama, which represent 11 of the ≈24 structural classes of alkaloids known in poison frogs. Forty-one of these alkaloids also occur in the dendrobatid poison frog, Oophaga pumilio , which co-occurs with the collected mites. These shared alkaloids include twenty-five 5,8-disubstituted or 5,6,8-trisubstituted indolizidines; one 1,4-disubstituted quinolizidine; three pumiliotoxins; and one homopumiliotoxin. All but the last of these alkaloid classes occur widely in poison frogs. In addition, nearly 40 alkaloids of unknown structure were detected in mites; none of these alkaloids have been identified in frog extracts. Two of these alkaloids are homopumiliotoxins, five appear to be izidines, four appear to be tricyclics, and six are related in structure to poison frog alkaloids that are currently unclassified as to structure. Mites are common in the diet of O. pumilio , as well as in the diets of other poison frogs. The results of this study indicate that mites are a significant arthropod repository of a variety of alkaloids and represent a major dietary source of alkaloids in poison frogs.

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mentioning

confidence: 99%

Oribatid mites as a major dietary source for alkaloids in poison frogs

Saporito

Donnelly²,

Norton³

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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160

181

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“…In addition, the great majority of alkaloid-containing amphibians are characterized by vivid colours of probable aposematic function, often covering the entire body although sometimes restricted to the ventral or dorsal side. Representatives of more than 80 other genera of frogs screened contained no alkaloids [3,7,8], confirming that these compounds are restricted to only a small number of lineages.…”

Section: Introductionmentioning

confidence: 81%

“…Single skins of the frogs were extracted with methanol. This extract was either directly used for GC-MS analysis or the alkaloids were separated from neutrals according to a described procedure [3]. Alkaloids were identified by comparison of mass spectra and gas chromatographic retention times with those of reference samples and are named with codes consisting of the nominal molecular weight and an identifying letter, both in bold face [3,7].…”

Section: Methodsmentioning

confidence: 99%

“…These include amines, peptides, proteins and steroids that appear to be largely produced de novo by the amphibians [3,4], thereby differing from alkaloids, another class of toxins present in some amphibians. Only the steroidal samandarine alkaloids of European salamanders are apparently biosynthesized by them [3,5], while the origin of water-soluble alkaloids (tetrodotoxins; present in some bufonid and brachycephalid toads, at least one dendrobatid frog, and some newts) remains unclarified although symbiotic micro-organisms might be involved [4,6]. On the contrary, lipid-soluble alkaloids are taken up to an overwhelming extent with prey and then sequestered into specialized skin glands [6].…”

Section: Introductionmentioning

confidence: 99%

“…A negative alkaloid screening for the genus Eleutherodactylus has been reported [3], probably referring to South or Central American species of the Terrarana clade that today are considered to belong to other genera [10]. Eleutherodactylids includes two subfamilies, four genera and five subgenera, and their distribution is centred in the Caribbean region.…”

Section: Introductionmentioning

confidence: 99%

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Discovery of skin alkaloids in a miniaturized eleutherodactylid frog from Cuba

et al. 2010

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Four phylogenetically independent lineages of frogs are currently known to sequester lipid-soluble skin alkaloids for which a dietary source has been demonstrated. We report here a remarkable fifth such instance, in Eleutherodactylus iberia and Eleutherodactylus orientalis , two species of miniaturized frogs of the family Eleutherodactylidae from Cuba. Six pumiliotoxins and two indolizidines were found in E. iberia , one of the smallest frogs in the world and characterized by a contrasting colour pattern for which we hypothesize an aposematic function. Analyses of stomach content indicated a numerical prevalence of mites with an important proportion of oribatids—a group of arthropods known to contain one of the pumiliotoxins detected in E. iberia . This suggests that miniaturization and specialization to small prey may have favoured the acquisition of dietary skin alkaloids in these amphibians.

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Serous gland dimorphism in the skin ofMelanophryniscus stelzneri (Anura: Bufonidae)

et al. 1998

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Two serous gland types (I and II) in the skin of the Argentine toad Melanophryniscus stelzneri were discovered using light and electron microscopy. Glands of the two types differ in several traits: features of the products (both mature and immature), organelles involved in biosynthesis, and paths of serous maturation. No consistent differences, however, were detected between the myoepithelial sheaths encircling the secretory units. Type I glands manufacture vesicles containing a single dense body with a repeating substructure and conform to the fundamental secretory line of bufonid skin, a secretory line involved in biosynthesis of steroids. Type II glands synthesize granules of varying densities and seem to belong to a line of glands that secrete proteinaceous products. The occurrence of the two serous gland types in Melanophryniscus stelzneri is discussed in a comparison with current literature on the morphofunctional characteristics of anuran poison glands, which perform both regulative and defensive roles. It is suggested that di‐ or polymorphism in serous glands is an adaptive trait that allows differential release of active molecules on the body surface. J. Morphol. 237:19–32, 1998. © 1998 Wiley‐Liss, Inc.

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Further classification of skin alkaloids from neotropical poison frogs (dendrobatidae), with a general survey of toxic/noxious substances in the amphibia

Cited by 390 publications

References 151 publications

Oribatid mites as a major dietary source for alkaloids in poison frogs

Oribatid mites as a major dietary source for alkaloids in poison frogs

Discovery of skin alkaloids in a miniaturized eleutherodactylid frog from Cuba

Serous gland dimorphism in the skin ofMelanophryniscus stelzneri (Anura: Bufonidae)

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