Synthesis and Antioxidant Activity of a Novel Water-Soluble Gallic Acid Derivative and Its Effect on Preserving Refrigerated Litopenaeus vannamei

To address the issue of the poor antioxidant and preservative effects of gallic acid (GA) on the quality of aquatic products due to its poor water solubility, a novel water-soluble GA derivative GA-CONH-SO₃H was successfully synthesized and confirmed by high resolution mass spectrometry (HRMS), nuclear magnetic resonance (NMR), and spectroscopy. Theoretical calculations of non-covalent interactions (NCI) revealed that GA-CONH-SO₃H exhibited abundant hydrogen bonding to water molecules, with binding energy stronger that than of GA. Moreover, the measured saturation solubility of GA-CONH-SO₃H in water at room temperature was 290.02 mg/mL, which was 26-fold higher than that of GA. Meanwhile, the 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxy, and superoxide anion radical scavenging capacities of GA-CONH-SO₃H were 92.80%, 98.09% and 99.74%, while those of GA at 58.78 μmol/L, 1.76 mmol/L and 23.51 mmol/L were only 89.77%, 49.56% and 29.89%, respectively. After 8 days of storage at 4 ℃, the pH of shrimp (Litopenaeus vannamei) soaked in GA-CONH-SO₃H solution was 7.44 compared to 7.71 with GA, and after 6 days, the total volatile basic nitrogen (TVB-N) content, thiobarbituric acid reactive substances (TBARS) value were total viable count (TVC) were 27.07 mg/100 g, 0.87 mg/kg and (5.09 ± 0.02) (lg(CFU/g)) as opposed to 35.47 mg/100 g, 0.94 mg/kg and (5.66 ± 0.03) (lg(CFU/g)) with GA, which indicated that the preservative effect of GA-CONH-SO₃H was significant. It extended the shelf life by 2 days. Additionally, GA-CONH-SO₃H was significantly superior to 4-hexylresorcinol (4-HR) as a commercial fresh shrimp preservative in inhibiting the increase of TVB-N, TBARS and TVC values. Furthermore, GA-CONH-SO₃H exhibited very low cytotoxicity. Therefore, GA-CONH-SO₃H has great potential as an antioxidant preservative for aquatic products.