Isolation and Identification of Alkaloids from Poisons of Fire Salamanders (Salamandra salamandra)

Abstract

Fire salamanders (Salamandra salamandra) are conspicuously colored amphibians secreting a skin poison that contains unique steroid alkaloids such as samandarine (1) and samadarone (2), exhibiting toxic as well as antimicrobial activities. Because of their antipredatory and anti-infectious functions, alkaloids from Salamandra poison are of interest with regard to the threat that the lethal fungus Batrachochytrium salamandrivorans (Bsal) poses to salamanders. Nevertheless, reliable data on the biological activity of Salamandra alkaloids are scarce, in part due to the difficulty to obtain and study those substances. Thus, isolation of pure salamander alkaloids is an important task that might directly contribute to the understanding of Bsal infections. Here we present a noninvasive isolation procedure for samandarine (1) and O-acetylsamandarine (3), as well as for two new alkaloids, O-3-hydroxybutanoylsamandarine (4) and samanone (6), using HPLC. For the first time, high-field NMR data are presented for these alkaloids. Analysis using GC/MS and ESI+-MS, provided important information on the structural variability of these salamander alkaloids.

Toxin variation among salamander populations: discussing potential causes and future directions

“…Since internal standards are not commercially available for these compounds (Knepper et al . 2019), we were not able to verify and correct for this. However, even if the low peak surface areas correspond to much higher biological concentrations, this would not change the observed differences among populations.…”

“…2018; Knepper et al . 2019; Preißler et al . 2019), which will lead to better understanding of their biological activity, we fully believe that S. atra and related species provide a good framework for further ecological and evolutionary studies on amphibian toxins.…”

“…2019); and a new protocol for their isolation (Knepper et al . 2019). The antimicrobial activity of SAMs has also regained attention in the light of the threat imposed by the chytrid fungus Batrachochytrium salamandrivorans (Knepper et al .…”

“…The antimicrobial activity of SAMs has also regained attention in the light of the threat imposed by the chytrid fungus Batrachochytrium salamandrivorans (Knepper et al . 2019). While interspecific variation in SAM profiles has been documented (Vences et al .…”

“…are a group of steroid alkaloids called samandarines (SAMs) (Habermehl 1962(Habermehl , 1971Habermehl & Spiteller 1967;Lüddecke et al 2018). SAMs are neurotoxins with nerve-blocking activity targeting the central nervous system, causing respiratory paralysis and convulsions (Habermehl 1971;Lüddecke et al 2018;Knepper et al 2019) and they seem to be cytotoxic as well (von Byern et al 2017). SAMs also show antimicrobial and antifungal activity (Habermehl & Preusser 1969;Preusser et al 1975;Lüddecke et al 2018;Smith et al 2018), and it was demonstrated that S. salamandra individuals completely deprived of their skin secretions succumb to infections within weeks, unless kept in a sterile environment (Habermehl & Preusser 1969).…”