Sea cucumbers are echinoderms from the Holothuroidea class. They are seen as a source of molecules with a high biological value that can be used for pharmaceutical, nutraceutical, and cosmeceutical products. In this paper, aqueous extracts (AEs) of sea cucumbers from Moroccan littorals Holothuria tubulosa were obtained using two different extraction times by freeze-drying and spray-drying techniques. The impact of these drying techniques on morphological properties, chemical nature, phenolic composition, and antioxidant capacity was evaluated. It was found that the spray-dried particles were irregularly spherical and shrivelled particles, while the freeze-dried particles were plate-shaped particles with irregular morphology. The antioxidant activities of AEs were investigated by means of three methods: 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), 2,2-Diphenyl-1-picrylhydrazyl, and Ferrous ion chelating assays. Various concentrations of AEs exhibited a dose-dependent anti-radical activity. Phenolic compounds were identified using a high-performance liquid chromatograph with an ultraviolet detector. This analysis identified and quantified 12 phenolic compounds from different extracts, mainly flavonoids and phenolic acids, which explains the high concentration of total content of these bioactive molecules evaluated through analytical methods. The total phenolic and flavonoid contents of AEs were remarked to be correlating with their antioxidant activity values. These findings indicate the possibility of using this species of sea cucumber as a potential source of natural antioxidants.
Key words: Holothuria Tubulosa, Spray-drying, Freeze-drying, Polyphenols, Antioxidant activity