“…Considering that the antioxidant potential of phenolic acids is closely correlated with various biological, pharmacological, and medicinal abilities, our efforts have focused on the development of phenolic acid derivatives with stronger antioxidant activities than their corresponding phenolic acids. We previously synthesized phenolic acid phenethyl ureas (PAPU) containing one aromatic hydroxyl group from phenolic acids by a Curtius rearrangement [Kim et al, ]. The PAPU compounds synthesized were: ( E )‐1‐(3,4‐dihydroxyphenethyl)‐3‐styrylurea (DPS‐U), ( E )‐1‐(3,4‐dihydroxystyryl)‐3‐phenethylurea (DSP‐U), ( E )‐1‐(3,4‐dihydroxystyryl)‐3‐(4‐hydroxyphenethyl) urea (DSHP‐U), ( E )‐1‐(3,4‐dihydrophenethyl)‐(3,4‐dihydroxystyryl) urea (DPDS‐U), ( E )‐1‐(4‐methoxyphenethyl)‐3‐(4‐methoxystyryl) urea (MPMS‐U), and ( E )‐1‐(3,4‐dihydroxyphenethyl)‐3‐(4‐hydroxystyryl) urea (DPHS‐U) (Fig.…”