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Article Dans Une Revue Planta Medica Année : 2016

Isolation and characterisation of new compounds from Gambierdiscus belizeanus

Résumé

Ciguatera fish poisoning (CFP) is a human foodborne intoxication caused by ingestion of tropical fish contaminated with ciguatoxins (CTXs), potent polyether compounds. These toxins are produced by dinoflagellates from the genus Gambierdiscus. These microalgae are known to produce several toxins such as maitotoxin (MTX), gambieric acid and derivatives and CTX-like compounds. Since it was not described the isolation of these compounds from Gambierdiscus belizeanus growing under controlled conditions, the aim of this work was the purification and identification of compounds produced by a commercial strain of G. belizeanus ccmp401. This strain was incubated at 24 °C in K medium with 33 ‰ salinity, pH between 7 – 8 and 14/10 cycles of light/dark. After two months, the cells were harvested by filtration, broken by ultrasounds and extracted with methanol. The methanolic extracts were analysed by ULPC-MS/MS using scan in positive mode between 900 – 1200 m/z, seeking for the characteristic fragmentation pathway of MTXs and CTXs. MTXs scanning resulted in the identification of their characteristic mass fragmentation pattern: the loss of sulphate group and the loss of a sulphate group plus water. CTXs scanning resulted in the identification of their fragmentation pathway: the formation of two adducts with sodium and ammonium and the loss of several water molecules. Checking these conditions, four unknown compounds m/z 1025.4849, m/z 1039.4883, 1069.7305 and m/z 1053.7401 with the same fragmentation pattern were detected. The compounds produced in higher amount, m/z 1025.4849 and m/z 1053.7401, were purified using several solid phase extractions and preparative HPLC. Thereby two new compounds, 99% pure, were identified by NMR analysis: (1) m/z 1025.4849 and molecular formula C51H76O19S and (2) m/z 1053.7401 and molecular formula C59H104O15. These two new natural products presented biological activity similar to CTX over sodium currents tested by electrophysiological measurements.
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Dates et versions

hal-01854491 , version 1 (06-08-2018)

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L. Rodriguez, O Calabro, O. Thomas, L Botana, Claude Alfonso, et al.. Isolation and characterisation of new compounds from Gambierdiscus belizeanus. Planta Medica, 2016, 81 (S 01), pp.S1 - S381. ⟨10.1055/s-0036-1596421⟩. ⟨hal-01854491⟩
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