The Bright Side of Gelatinous Blooms: Nutraceutical Value and Antioxidant Properties of Three Mediterranean Jellyfish (Scyphozoa)

Abstract

Jellyfish are recorded with increasing frequency and magnitude in many coastal areas and several species display biological features comparable to the most popular Asiatic edible jellyfish. The biochemical and antioxidant properties of wild gelatinous biomasses, in terms of nutritional and nutraceutical values, are still largely unexplored. In this paper, three of the most abundant and commonly recorded jellyfish species (Aurelia sp.1, Cotylorhiza tuberculata and Rhizostoma pulmo) in the Mediterranean Sea were subject to investigation. A sequential enzymatic hydrolysis of jellyfish proteins was set up by pepsin and collagenase treatments of jellyfish samples after aqueous or hydroalcoholic protein extraction. The content and composition of proteins, amino acids, phenolics, and fatty acids of the three species were recorded and compared. Protein content (mainly represented by collagen) up to 40% of jellyfish dry weight were found in two of the three jellyfish species (C. tuberculata and R. pulmo), whereas the presence of ω-3 and ω-6 polyunsaturated fatty acids (PUFAs) was significantly higher in the zooxanthellate jellyfish C. tuberculata only. Remarkable antioxidant ability was also recorded from both proteinaceous and non proteinaceous extracts and the hydrolyzed protein fractions in all the three species. The abundance of collagen, peptides and other bioactive molecules make these Mediterranean gelatinous biomasses a largely untapped source of natural compounds of nutraceutical, cosmeceutical and pharmacological interest.

Keywords: antioxidants; collagen; macrozooplankton; marine jellyfish; novel foods; nutraceuticals.

Scheme 1

Protocol set up for the lyophilized jellyfish “sample extraction” by hydroalcoholic solvents or phosphate buffered saline (PBS), followed by sequential enzymatic hydrolysis of proteins.

Figure 1

Total phenolic compounds in jellyfish extracted with phosphate buffered saline (PBS), 80% methanol and 80% ethanol from freeze-dried tissues of Aurelia sp.1, C. tuberculata and R. pulmo. Data are expressed as μg of gallic acid equivalents (GAE) per gram of dry weight and are means of three independent experiments performed in triplicate, bars represent mean ± standard deviation (SD). A,B,C: the different capital letters indicate differences among species for the same extraction type; a,b,c: the different lower case letters indicate significant differences among extracts in the same jellyfish species, (p < 0.05).

Figure 2

Total antioxidant activity in jellyfish extracted with phosphate buffered saline (PBS), 80% methanol and 80% ethanol from freeze-dried tissues of Aurelia sp.1, C. tuberculata and R. pulmo. Antioxidant activity is expressed as nmol of Trolox eq. (TE) per gram of dry weight or as nmol TE per mg of proteins (inset). Data are the mean of three independent experiments performed in triplicate, bars represent mean ± standard deviation. A,B,C: different capital letters indicate differences among species for the same extraction type; a,b,c: the different lower case letters indicate significant differences among extracts in the same jellyfish species, (p < 0.05).

Figure 3

Total antioxidant activity in pepsin hydrolyzed proteins (A,B) and collagenase hydrolyzed peptides (C,D) from freeze-dried tissues of Aurelia sp.1, C. tuberculata and R. pulmo. Chicken collagen was hydrolyzed in parallel and used as a comparison. Antioxidant activity is expressed as nmol of Trolox eq. (TE) per gram of dry weight (DW) (A,C) or as nmol TE per mg of proteins (B,D). Data are the mean of three independent experiments performed in triplicate, bars represent mean ± standard deviation (SD). A,B,C: the different capital letters inside the figures indicate differences among species for the same treatment type; a,b,c: the different lower case letters inside the figures indicate significant differences among treatments in the same jellyfish species, (p < 0.05).

Figure 4

Polypeptide patterns of pepsin hyrolysates (a) or collagenase hyrolysates (b) separated by 12% reducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The molecular weight size marker (range of 250–15kDa), was run in parallel with samples for molecular weight estimation. Each line contained 30 μg of proteins and bands were visualized by staining gels with Coomassie Brillian Blue R-250 dye.