“…Among eleven piperic acid ester derivatives, 2-(3,4-dihydroxyphenyl)ethyl ester [4] showed the highest cytotoxicity against OSCC cell lines (mean CC 50 =17 μM), followed by (4-methoxyphenyl)methyl ester (38 μM) [1], 2-(4-methoxyphenyl)ethyl ester [5] (42 μM), 2-(4-hydroxyphenyl)ethyl ester (46 μM) [3], 2-phenylethyl ester [7] (61 μM) and 2-(3,4-dimethoxyphenyl)ethyl ester [6] (102 μM). On the other hand, (4-hydroxy-3-methoxyphenyl)methyl ester [2] (>368 μM), 3-phenylpropyl ester [8], 4-phenyl-2-butyl ester [9], 4-phenylbutyl ester [10] and decyl ester [11] (>400 μM) were essentially inactive (Table I).…”