Urushiol oligomer preparation and evaluations of their antibacterial, antioxidant, and thermal stability

There have been studies published on the composition and coating uses of raw lacquers following enzymatic oxidative polymerization. The change of urushiol' thermal stability and biological activity following polymerization to create oligomer, however, has received little attention. This work using silica gel column chromatography to separate urushiol and urushiol oligomer from polymerized raw lacquer and assessed its antibacterial, antioxidant, and thermal stability in an effort to decrease the allergenicity of urushiol and increase its application. By using gel chromatography, the urushiol oligomer were discovered to be polymers with 2-5 degrees of polymerization. According to characterization results from techniques like UV, FT-IR, and ¹H NMR, urushiol was converted into urushiol oligomer by addition reactions, and C-C coupling. The findings demonstrated that the urushiol oligomer' IC₅₀ values for scavenging DPPH and ABTS free radicals were 40.8 and 27.4 μg/mL, respectively, and that their minimum inhibitory concentrations against <i>Staphylococcus aureus</i> and <i>Staphylococcus epidermidis</i> were 250 and 125 μg/mL. The urushiol oligomer's thermogravimetric differential curve peak temperature (461.8 °C) was higher than urushiol's (239.5 °C), indicating that urushiol undergoes polymerization with enhanced thermal stability. The study's findings establish a foundation for the use of polymerized urushiol and urushiol oligomer in applications including functional materials and additives.