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.

In order to enhance the photodynamic inactivation (PDI) effect of curcumin, a novel class of halogenated curcumin derivatives X-cur (X = F, Cl or Br) was synthesized and screened for its potential for PDI by ultraviolet-visible (UV-Vis) absorption and fluorescence spectroscopy, singlet oxygen (¹O₂) generation capacity and theoretical calculations of excited states. The results demonstrated that as the relative molecular mass of the nonmetallic heavy atom halogen increased, the spin-spin coupling effect was gradually strengthened, so the smallest energy level difference (ΔE_st(S1-T3)) between singlet excited state (S₁) and triplet excited state (T₃) (0.140 eV) and the highest spin-orbit coupling value (0.642262 cm^-1) were observed in Br-cur. This finding suggested that Br-cur was most likely to undergo transition into triplet state through intersystem crossing. Furthermore, compared to curcumin and other halogenated curcumins, Br-cur exhibited the smallest energy level difference (3.260 eV) between its S₁ and ground state (S₀). Due to the aforementioned factors, Br-cur was highly prone to photooxidation and had the highest ¹O₂ generation capacity. Br-cur had a PDI effect on Vibrio parahaemolyticus, a prevalent foodborne pathogen in aquatic products, which depended on its concentration and light exposure duration and was significantly higher than that of curcumin. Thus, Br-cur has great potential for application as a novel PDI agent.