Antimicrobial and antioxidant activity in some Echinoderm species.

Echinoderms represent one interesting marine renewable resource and produce bioactive compounds related to their innate immune system. These invertebrates indeed are able to differentiate self from non-self through the production of soluble molecules and coelomocytes response playing an important role in the resistance to disease. Therefore, they appear as a promising alternative valuable source of new compounds for drug development. In particular, the application of new marine antioxidants in foods, food supplements, nutraceuticals and medicine is recently considered from the perspective of benefits to human health. In this study, the antimicrobial and antioxidant activity of several echinoderm species was investigated. We focused our attention on the two sea urchins Sphaerechinus granularis and Arbacia lixula and on the sea star Echinaster sepositus. Coelomic fluid and coelomocyte lysate of each species were utilized for antimicrobial activity assay using the Kirby Bauer method (1966). The antioxidant activity of the samples was measured by two in vitro assays: the TEAC (Trolox Equivalent Antioxidant Capacity) assay based on a single electron transfer (SET) reaction, using ABTS [2-2'-azino-bis (3- ethylbenz-thazoline-6-sulfonic acid)] as chromogen and the ORAC (oxygen radical absorbance capacity) based on a hydrogen transfer mechanism (HAT). Both the antioxidant assays showed a higher antioxidant activity in the coelomocyte lysate compared to coelomic fluid for all the Echinoderm species studied. Moreover A. lixula cell lysate had the highest antioxidand activity both with TEAC and ORAC assay. These antioxidant values are comparable with those reported in the literature for various high antioxidant fruit and spice extracts. Among the investigated species, the coelomocyte lysate of A. lixula showed a bacteriostatic activity against two emerging pathogenic bacteria Pseudomonas aerugionsa and Staphylococcus aureus and against the yeast Candida famata. These results are noteworthy considering the resistance against antibiotics developed by bacteria and the need to control human infections. The antioxidant activity was also of interest since it is the first record for the investigated species and represents a potential for applicative purposes.