H. Martin Garraffo

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Herein we review what is known about the chemical ecology of poison frogs with a focus on dendrobatid poison frogs. While five anuran families are known to have an alkaloid-derived chemical defense, the dendrobatids have been studied in greatest detail and provides chemical ecologists with a complex model system for understanding how chemical defenses(More)
GC-MS analysis of single-skins of ten Melanophryniscus rubriventris toads (five collections of two toads each) captured during their breeding season in NW Argentina has revealed a total of 127 alkaloids of which 56 had not been previously detected in any frog or toad. Included among these new alkaloids are 23 new diastereomers of previously reported(More)
Seventy skins of three mantellid frog species from Madagascan swamp-forest habitats, Mantella aurantiaca, M. crocea, and M. milotympanum, were individually examined for skin alkaloids using GC/MS. These poison frogs were found to differ significantly in their alkaloid composition from species of Mantella originating from non-flooded rainforest in eastern(More)
A short synthesis of the postulated structure for indolizidine alkaloid 259B with the hydrogens at C5 and C9 entgegen has been achieved with complete control of stereochemistry at C5. Both diastereoisomers at C8 were obtained, but neither proved to be the natural product. The comparison of the mass and FTIR spectral properties of the synthetic compounds to(More)
BACKGROUND The 5,8-disubstituted indolizidines constitute the largest class of poison-frog alkaloids. Some alkaloids have been shown to act as noncompetitive blockers at nicotinic acetylcholine receptors but the proposed structures and the biological activities of most of the 5,8-disubstituted indolizidines have not been determined because of limited(More)
We previously reported that the synthetic quinolizidine 1-epi-207I is a relatively selective blocker of alpha7 nicotinic acetylcholine receptors. We now synthesized the analogous poison frog alkaloids 233A, 235U, and 251AA, and investigated the biological activities at two major types of neuronal nicotinic receptors. Electrophysiological study showed that(More)
BACKGROUND The 5,8-disubstituted indolizidines are the largest class of poison-frog alkaloids found in anuran skin, and are of considerable interest because of their inhibitory effects on the neuronal nicotinic acetylcholine receptors. Many synthetic strategies for the construction of this nucleus have been reported: however, a flexible route has not been(More)
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