Lc-ms applications in chemical ecology: Analysis of natural products in amphibian skin and milkweed plants

The primary focus of this project was to identify the characteristic chemical compounds produced by amphibian skin microbes in response to the presence of the fungal pathogen Batrachochytrium dendrobatidis (Bd) . Accordingly, a nonlethal swabbing technique was developed that is compatible with reverse-phase liquid chromatography (LC) followed by UV-Visible spectroscopy and mass spectrometry (MS) analysis. This method was validated via a pilot study using frogs from Bioko Island (Africa) and optimized through several projects investigating metabolite profiles in amphibian communities. A secondary project utilized MS experiments (including Q1, precursor ion, and multiple reaction monitoring scans) to identify pyrrolizidine alkaloid (PA) compounds in the parts of milkweed plants. Major findings include identification of PAs in the nectar of Parsonsia alboflavescens, as well as detection of PAs in Echites umbellatus. This was the first documentation of PAs in the nectar of any Apocynaceae species and the first finding of PAs in Echites umbellatus.