Christelle Simon-Colin

Isethionic Acid and Floridoside Isolated from the Red Alga, Grateloupia turuturu, Inhibit Settlement of Balanus amphitrite Cyprid Larvae

Isethionic acid (2-hydroxyethane sulfonic acid) and floridoside (2-O-α-D-galactopyranosylglycerol) were extracted from the red alga, Grateloupia turuturu, and tested for anti-settlement activity against cyprid larvae of the tropical barnacle, Balanus amphitrite and for their toxicity to nauplius larvae. Isethionic acid was active for anti-settlement but had the disadvantage of being toxic to nauplius larvae. Floridoside was a potent inhibitor of cyprid settlement at non-toxic concentrations to nauplii (0.01 mg ml−1).

Complete 1H and 13C spectral assignment of floridoside.

Floridoside (2-O-alpha-D-galactopyranosylglycerol) was extracted from the red marine alga Rhodymenia palmata, and purified by ion-exchange chromatography: 1D and 2D NMR spectroscopy experiments were used to unambiguously assign the complete 1H and 13C spectra.

Crystal structure and chirality of natural floridoside.

The crystal structure and absolute configuration of natural floridoside (2-O-alpha-D-galactopyranosylglycerol) were determined by single-crystal X-ray diffraction analysis. The space group is orthorhombic P2(1)2(1)2(1) with Z=4, a=4.885(1), b=9.734(1), c=23.886(2) A at 296 +/- 2 K. The structure was solved by a direct method and refined to R=0.0351 from 1914 reflections of Cu Kalpha radiation.

Floridoside Extracted from the Red Alga Mastocarpus stellatus Is a Potent Activator of the Classical Complement Pathway

Many biological properties of algae have been found to have useful applications in human health, particularly in the fields of oncology and immunology. Floridoside, extracted from the red alga Mastocarpus stellatus, has a structure similar to the xenoantigen Gal alpha 1–3 Gal. This xenoantigen has been described to induce a high immune response in human xenografts and is mediated by natural anti-gal antibodies that activate the classical complement pathway. Based on this property, we analyzed the potential activities of floridoside on the immune system. We demonstrated that floridoside activates a complement cascade via the classical complement pathway, through the recruitment and activation of natural IgM. This algal molecule could represent an important step in the development of a potent new anticomplementary agent for use in therapeutic complement depletion.

Characterization of N‐methyl‐L‐methionine sulfoxide and isethionic acid from the red alga Grateloupia doryphora

Isethionic acid (2‐hydroxyethane sulfonic acid) and N‐methyl‐L‐methionine sulfoxide (4‐methane sulfinyl‐2‐methylamino butyric acid) were isolated from the red alga Grateloupia doryphora (Cryptonemiales) collected from Brittany (France); they were identified as major organic solutes together with floridoside (α‐D‐galacto‐pyranosyl‐(1–2)‐glycerol). The presence of isethionic acid has recently been reported in certain red algae, however, the occurrence of N‐methyl‐L‐methionine sulfoxide is still very rare. This report deals with the first isolation of isethionic acid and N‐methyl‐L‐methionine sulfoxide from G. doryphora and their subsequent NMR characterization.

An alternative HPLC method for the quantification of floridoside in salt-stressed cultures of the red alga Grateloupia doryphora

The floridoside content of the marine red alga Grateloupiadoryphora was measured using a new, alternative High PerformanceLiquid Chromatography method suitable for the analysis of a large number ofsamples. This assay was to study the quantitative changes in floridosideconcentration in G. doryphora cultivated in differentsalinities for 10 days. Marked changes in floridoside concentration occurredrapidly observed in reponse to osmotic stress, providing evidence of itsosmoregulatory function. Interestingly, after a rapid decrease at low salinityand a strong increase at high salinity, the floridoside content then slowlyreturned to its initial level over the last 3 days of culture. This observationconfirms the high physiological capacity of G. doryphoratowithstand environmental variations and probably contributes to its actualproliferation along French coasts.

Purification and characterization of 4-methanesulfinyl-2-methylamino butyric acid from the red alga Grateloupia doryphora Howe

An unsual sulfoxide amino acid (4-methanesulfinyl-2-methylamino butyric acid) was isolated from the red macroalgae Grateloupia doryphora. Its structure was elucidated on the basis of analyses by NMR and Mass sepctroscopies.