Hadeer Fathy Badran, Riad H. Khalil, Haiam Morsy Aboul Ela, Hala Saber Khalil
Capparis spinosa L. (caper) is a drought-resistant shrub valued for its therapeutic, pharmaceutical, and culinary properties. This study evaluated the biological activities of its aqueous (AQE) and methanolic (MEE) extracts on growth performance, innate immunity, antioxidant activity, immune-related gene expression, and resistance to Vibrio parahaemolyticus in Litopenaeus vannamei . Aqueous and methanolic extracts were prepared and analyzed, demonstrating that the methanolic extract of C. spinosa (MEE) exhibited significantly stronger antioxidant activity (P < 0.05) in terms of total phenolic content (TPC), ferric reducing antioxidant power (FRAP), and DPPH scavenging activity than the aqueous extract (AQE). According to HPLC analysis, RP-HPLC for phenolic component characterization in C. spinosa L. extractions identified 16 phenolic compounds; sinapic acid predominated in MEE, while only trace gentisic and benzoic acids were noticed in AQE, with all the other phenolics being absent from AQE. Overall, MEE exhibited substantially higher phenolic content than AQE. For feeding/challenge test: A three-month nourishment experiment was performed to investigate the impact of supplementing the diet with AQE and MEE of C. spinosa at concentrations of 1.0, 2.0, and 3.0% kg -1 feed. Juvenile shrimp 1.66 ± 0.55 g (N = 2100) were randomly distributed into 21 fiberglass tanks (250 L), with three replicates per treatment, and fed the experimental diets. Diets containing higher MEE levels (3.0% kg -1 ) significantly (P<0.05) improved growth performance, feed utilization, immune parameters, antioxidant activities, and expression of immune-related genes, particularly hemocyanin (Hc) and penaeidin-3a (Pen-3a) genes compared with other groups. Following the V. parahaemolyticus challenge, shrimp fed the 3.0% MEE diet showed the highest survival (75%; P< 0.05). These results indicate that adding 3.0% methanolic extract of C. spinosa to the diet enhances growth, immunological status, antioxidant response, and resistance to infection in juvenile L. vannamei .