posted on 2024-03-02, 21:21authored byLaurence
K. Jennings, Navdeep Kaur, Maria C. Ramos, Fernando Reyes, Maggie M. Reddy, Olivier P. Thomas
The chemical diversity of annelids,
particularly those belonging
to the class Sipuncula, remains largely unexplored. However, as part
of a Marine Biodiscovery program in Ireland, the peanut worm Phascolosoma granulatum emerged as a promising source of
unique metabolites. The purification of the MeOH/CH2Cl2 extract of this species led to the isolation of six new linear
guanidine amides, named phascolosomines A–F (1–6). NMR analysis allowed for the elucidation
of their structures, all of which feature a terminal guanidine, central
amide linkage, and a terminal isobutyl group. Notably, these guanidine
amides were present in unusually high concentrations, comprising ∼3%
of the dry mass of the organism. The primary concentration of the
phascolosomines in the viscera is similar to that previously identified
in linear amides from sipunculid worms and marine fireworms. The compounds
from sipunculid worms have been hypothesized to be toxins, while those
from fireworms are reported to be defensive irritants. However, screening
of the newly isolated compounds for inhibitory bioactivity showed
no significant inhibition in any of the assays conducted.