Chromatographic, NMR and vibrational spectroscopic investigations of astaxanthin esters: application to "Astaxanthin-rich shrimp oil" obtained from processing of Nordic shrimps.

Astaxanthin (ASTX) is a keto carotenoid, which possesses a non-polar linear central conjugated chain and polar ß-ionone rings with ketone and hydroxyl groups at the extreme ends. It is well known as a super anti-oxidant, and recent clinical studies have established its nutritional benefits. Although it occurs in several forms, including free molecule, crystalline, aggregates and various geometrical isomers, in nature it exists primarily in the form of esters. Marine animals accumulate ASTX from primary sources such as algae. Nordic shrimps (P. borealis), which are harvested widely in the Atlantic Ocean, form a major source of astaxanthin esters. "Astaxanthin-rich shrimp oil" was developed as a novel product in a shrimp processing plant in Eastern Canada. A compositional analysis of the shrimp oil was performed, with a view to possibly use it as a nutraceutical product for humans and animals. Astaxanthin-rich shrimp oil contains 50% MUFAs and 22% PUFAs, of which 20% are omega-3. In addition, the shrimp oil contains interesting amounts of EPA and DHA, with 10%/w and 8%/w, respectively. Astaxanthin concentrations varied between 400 and 1000 ppm, depending on the harvesting season of the shrimp. Astaxanthin and its esters were isolated from the oil and analysed by NMR, FTIR and Micro-Raman spectroscopy. Astaxanthin mono- and diesters were synthesized and used as standards for the analysis of astaxanthin-rich shrimp oil. NMR and vibrational spectroscopy techniques were successfully used for the rapid characterization of monoesters and diesters of astaxanthin. Raman spectroscopy provided important intermolecular interactions present in the esterified forms of astaxanthin molecules. Also discussed in this paper is the use of NMR, FTIR and Micro-Raman spectroscopy for the detection of astaxanthin esters in shrimp oil.

Photocatalytic properties of nanocrystalline titanium dioxide films in the degradation of domoic acid in aqueous solution: potential for use in molluscan shellfish biotoxin depuration facilities.

Domoic acid (DA) is a water-soluble marine neurotoxin produced and released by certain species of the diatom genus Pseudo-nitzschia. Present in coastal waters, it can be a threat to public health and marine life, and can result in severe economic losses to the molluscan shellfish and crustacean harvesting industries. Here we report on the efficiency of nanocrystalline (NC) titania (TiO(2)) thin films used as a photocatalyst in the ultraviolet light photodegradation of DA. Titanium dioxide thin films produced by a sol-gel dip-coating method in the presence of polyethylene glycol of different molecular weights (200, 400 and 600) were deposited on glass substrates and crystallised at 90 degrees C. The films were characterised using spectroscopic ellipsometry, Fourier transform infrared spectrometer (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy. The photocatalytic activity measurements were carried out by immersing the NC TiO(2) films in a DA solution (2500 ng ml(-1)) and then exposing them for various times at room temperature to UVA irradiation (lambda = approximately 350 nm). The degradation of DA, quantified by HPLC analysis, was not significant when using daylight or ultraviolet light irradiation alone, whereas the NC TiO(2) films prepared at low temperature proved to be a very efficient photocatalyst when used in conjunction with UVA light. The effectiveness of the photodegradation was improved by increasing molecular weight of polyethylene glycol, which increased the thickness of the film. The presence, transformation and degradation of three DA isomers were observed. The approach may eventually be practical for destroying DA in seawater used by aquaculture industry depuration facilities.