ET743: Chemical analysis of the sea squirt Ecteinascidia turbinata ecosystem

Abstract

The sea squirt Ecteinascidia turbinata produces the powerful drug ET743. In this study Inductively Coupled Plasma–Atomic Emission Spectroscopy (ICP–AES) and Matrix Assisted Laser Desorption Ionization–Mass Spectrometry (MALDI–MS) are systematically used to measure elemental and molecular species in a Florida Keys mangrove ecosystem that contains the sea squirt. ICP–AES is used to measure the concentration of 27 elements down to the parts per billion level in 16 organisms and 3 sediment samples that reside in the mangrove ecosystem including turtle grass, blue crabs, fire sponge, and lettuce slugs. MALDI–MS is used to search for ET743 in these same organisms and sediment samples. A mass spectral feature corresponding to ET743 is identified in the extract of the sea squirt, red mangrove root (Rhizophera mangle), the schoolmaster snapper (Lutjanus griseus), and a sediment sample taken from the ecosystem. We use MALDI–MS to study the impact that various environmental conditions, such as UV light, I2, cation binding (Fe+3, Zn+2, Pb+2, Cu+2), metal oxide nanoparticles (FeO, CuO, TiO2, ZnO, Al2O3), a common mineral (CaCO3), and extremes in acidity (0.1 M HCl, 0.1 M NaOH) have on the ET743 structure. The data provide potential structures (degradation products, metal–ligand complexes, etc.) that might be present in organism or sedimentary extracts that are similar to ET743. We are studying the marine geochemistry of this ecosystem so a broth can be developed and tested for producing this marine natural product.