<em>In vitro</em> and <em>in vivo</em> effects of purslane (<em>Portulaca oleracea</em> L.) on gilthead seabream (<em>Sparus aurata</em> L.)

Due to the natural, innocuous and bioactive compounds that medicinal plants contain, their application in aquafeeds has great potential to ensure more sustainable aquaculture. The aim of the present study was to evaluate the <em>in vitro</em> biological activities of purslane (<em>Portulaca oleracea L.</em>) as well as its <em>in vivo</em> effects after dietary administration to gilthead seabream (<em>Sparus aurata</em> <em>L.</em>) specimens. To carry out this work we first analysed the <em>in vitro</em> effect purslane aqueous and ethanolic extracts on head-kidney (HK) leucocytes from gilthead seabream, as well as their cytotoxic, bactericidal and antioxidant activities. After that, we studied the effect on gilthead seabream growth performance and immune status after the addiction of purslane to its diet. Regarding the <em>in vitro</em> study, purslane aqueous and ethanolic extracts had immunostimulant properties on HK leucocyte phagocytosis, bactericidal activity against marine pathogenic bacteria (<em>Vibrio harveyi</em>, <em>V. anguillarum</em> and <em>Photobacteium damselae</em>) and cytotoxic (mainly against PLHC-1 tumor cells) and antioxidant activities. On the other hand, the dietary inclusion of 2% purslane for 15 or 30 days had no impact on growth performance while improving the fish&#39;s immune status. More specifically, skin mucus IgM levels and the phagocytic capacity of HK leucocytes of fish-fed purslane diets for 15 and 30 days, respectively, increased statistically significant with respect to the values recorded for the fish-fed control diet. Overall, the results suggest that purslane extracts, when used in adequate concentrations, have different beneficial properties, and that the dietary incorporation of purslane improves some immune parameters at local and systemic levels while having no negative effect on growth. These results make purslane an interesting candidate for incorporation as an additive in functional diets for farmed fish.