Polysaccharides, Saponins, and Water Decoction of Astragalus membranaceus Significantly Enhance the Non-Specific Immune Response of Spotted Maigre (Nibea albiflora).

The effects of polysaccharides, saponins, and water decoction of the Chinese herb Astragalus membranaceus on the immune response of spotted maigre (Nibea albiflora) were investigated. Fish with an average initial weight of 49.6±5.5 g were fed a diet containing 2% extract for four weeks. The lysozyme and phagocytic activities of the fish were determined and compared with those of control fish fed an unsupplemented feed on days 0, 3, 7, 14, 21, and 28. Both activities were significantly higher in groups fed the Astragalus extract than in the control group (p<0.01) but there were no differences between the three Astragalus-fed groups (p>0.05). Most important, the Astragalus-fed groups were significantly protected against Vibrio vulnificus challenge compared to the control group (p<0.01). Our results indicatd that polysaccharides and saponins are main active components of Astragalus extracts and can enhance the non-specific immune response in spotted maigre. [ABSTRACT FROM AUTHOR]