A novel arsenic containing riboside (arsenosugar) in three species of gastropod

Arsenic compounds in three marine gastropods (Thais bitubercularis, Thais distinguenda, Morula musiva) from Phuket, Thailand were examined by HPLC using ICP-MS as an arsenic specific detector. Aqueous methanol treatment of the freeze-dried samples (initially 112–339 μg As g−1 dry mass) extracted >96% of the total arsenic. HPLC-ICP-MS of the extracts demonstrated the presence of arsenobetaine (93–95% of total extractable arsenic), arsenocholine (3.1–4.6%), tetramethylarsonium ion (0.21–2.2%), two unknown arsenic compounds (each approx. 0.1%), and an unresolved mixture of arsenic compounds (∼1%). One of the unknowns was identified as a new natural product, the arsenosugar 2′,3′-dihydroxypropyl 5-deoxy-5-trimethylarsonioriboside, by co-chromatography with synthetic material. The presence of these arsenic compounds in the gastropods is consistent with the hypothesis that trimethylated arsenosugars are transformed into arsenobetaine via arsenocholine within animals.