The growth promoting and immunomodulatory effects of a medicinal plant leaf extract obtained from Salvia officinalis and Lippia citriodora in gilthead seabream (Sparus aurata)

Abstract In the present study, we evaluated the effects of a medicinal plant leaf extract (MPLE; 10%, ursolic acid, 3% other triterpenic compounds; 2% verbascoside and   0.05). In order to evaluate the cellular immune competence of fish, an ex vivo assay with splenocytes primary cell culture (SPCC) from both dietary groups was conducted. SPCC were incubated with lipopolysaccharide (LPS) for 24 h and the expression of genes associated to several immune processes was evaluated (humoral immune response, pro- and anti-inflammatory cytokines, cell surface markers, and antioxidant enzymes). Particularly at 4 h post-exposure, dietary supplementation with 0.1% MPLE enhanced SPCC immune response to LPS by the up-regulation of genes involved in humoral immunity (lys, IgM), pro- (tnf-α, il-1β) and anti-inflammatory (tgf-β1, il10) cytokines, the leucocyte cell surface marker cd4, and antioxidative stress enzymes (mn-sod, cat). Therefore, a medicinal plant leaf extract (MPLE) obtained from L. citriodora and S. officinalis may be considered as efficient additive to be used in aquafeed since it does not induce a significant immune reaction under basal conditions, but it provides immune protection after LPS treatment, together with increasing overall fish growth and improvement of feed efficiency values.