Polysaccharides from the green alga Caulerpa racemosa (Agardh, 1873) improve the immune response and antioxidant status in the white shrimp Litopenaeus vannamei (Boone, 1931) (Dendrobranchiata, Penaeidae)

Abstract

The objective of this study was to investigate the effects of Caulerpa racemosa (Agardh, 1873) polysaccharides (CRP) on non-specific immunity of the white shrimp, Litopenaeus vannamei (Boone, 1931). The extracted polysaccharide consists of galactose, glucose, and mannose. Total polyphenolic compound and total flavonoids content in CRP were determined. In vitro CRP treatment did not alter cell viability of haemocytes and significantly activated phenoloxidase (PO) activity, superoxide anion production capacity, phagocytic rate, and index in haemocytes. Immune parameters, such as total haemocyte count, PO activity, phagocytosis, and superoxide anion production, were significantly elevated in CRP-fed shrimp during the rearing period. Malondialdehyde levels in the hepatopancreas of CRP-fed shrimp were lower than in control shrimp from day 7 to day 28. These results show that CRP exhibits antioxidant activity and can activate immune responses of white shrimp in vitro and in vivo. Therefore, CRP can be considered a functional feed additive to improve white shrimp immunity.