Sborník abstraktů 2010 - Fakulta chemická - Vysoké učení technické ...

Biotransformation of arsenic in
marine organisms - degradation of
arsenosugars in decomposing algae
Jana Navrátilová
Faculty of Chemistry, Brno University of Technology,
Institute of Food Science and Biotechnology, 612 00 Brno, Czech Republic,
xcnavratilovaj@fch.vutbr.cz
The biotransformation of arsenic compounds in marine organisms have been
discussed extensively because marine organisms can accumulate high arsenic concentrations.
An important role in arsenic cycling in marine ecosystems play marine
macroalgae. In general, arsenic in marine macroalgae is present as dimethylarsenoribosides,
while in animals the most abundant arsenic species is arsenobetaine.
Dimethylated arsenoribosides are considered likely precursors to arsenobetaine.
Arsenosugars in marine algae can occur at concentration exceeding 50 mg As kg-1
dry mass.
Arsenosugars are synthetised in alga from arsenate what is the main arsenic
species in seawater. That process is considered be a detoxification mechanism. An
important fact is the chemical similarity of arsenic and phosphorus, arsenate may
follow the same metabolic pathways in organisms as phosphorus, and interfere in
phosphorus metabolism.
The transformation of organoarsenicals during the natural decomposition of
brown kelp Ecklonia radiata was followed using HPLC/ICPMS. Ecklonia radiata
contains most of its arsenic as dimethylarsenoribosides (glycerol, phosphate, sulfonate
are dominant macroalgae species). The oxo-arsenosugars originally present
in Ecklonia degraded first to dimethylarsinoylethanol (DMAE), and then to dimethylarsinate
(DMA) and inorganic arsenic. The rate of degradation and the proportions
of degradation products depended on the extent of contact of the alga with
air. There was also a significant quantity of non-extractable or recalcitrant arsenic
present.
Key words: algae, arsenoribosides, degradation, HPLC-ICPMS