Valine-curcumin complex improves bioavailability and disease resistance in juvenile largemouth bass

Curcumin (Cur) is a polyphenolic compound with pharmacological properties, including anti-inflammatory, antioxidant, and anticancer activities. However, its low solubility and poor stability limit its absorption in vivo. Our laboratory previously synthesized a highly water-soluble valine-curcumin (Val-Cur), increasing its solubility by approximately 9000 times. In this study, based on the evaluation of the antibacterial ability of Val-Cur against three common aquatic pathogens ( Aeromonas hydrophila , Edwardsiella tarda , and Aeromonas veronii ), Val-Cur was added to the feed of juvenile largemouth bass, and for the first time, HPLC was used for Val-Cur detection in vivo; additionally, its pharmacokinetics and effects on disease resistance in fish were investigated. Following a single oral dose (10 mg/kg) of Cur or Val-Cur to largemouth bass, the drug concentration in blood exceeded that in the liver and muscle within 48 h. Compared with Cur, Val-Cur exhibited a delayed peak time in blood, a higher peak concentration (C max = 4.404 μg/mL), a 149 % increase in retention time, and a total drug clearance of 0.005 L·(h·kg) −1 (a 20.4-fold decrease). In the liver and muscle, Val-Cur showed a peak concentration (C max ) 9–10 times higher than Cur, with a 74 %-103 % increase in retention duration and a 15- to 16-fold decrease in clearance. Fecal analysis revealed that Cur excretion was more than five times that of Val-Cur excretion. Compared to those that fed the basal diet (CK) or the diet supplemented with 60 mg/kg curcumin (Cur), the survival rate of largemouth bass infected with Aeromonas hydrophila was significantly higher in the group that fed a diet supplemented with 60 mg/kg Val-Cur. Additionally, the Val-Cur-supplemented diet better preserved the integrity of the intestinal tissue structure. This study provides a valuable theoretical foundation for elucidating the mechanisms of Val-Cur and supports the application of water-soluble curcumin in aquaculture.