Table 4: Redox potentials and antioxidant activity of hydroxycinnamic acids, ester and amide derivatives.

CompoundMW (gmol−1)DPPH (TE)*DPPH (IC50)*† (mV)Reference

p-Coumaric164.16>100+736[6]
Caffeic acid180.161.2916.6+183[7, 8]
Hydrocaffeic acid182.182.0515.4#+139[8]
5-Bromocaffeic acid259.051.01+182[7]
Methyl caffeate194.1814.0+165[9]
Ethyl caffeate208.2113.5+170[9]
Ethyl 5-bromocaffeate287.110.938+174[7]
Propyl caffeate222.2414.5+173[9]
Butyl caffeate236.2614.1+176[9]
Hexylcaffeate264.320.970+175[8]
Hexylhydrocaffeate266.340.990+125[8]
Caffeoylhexylamide263.341.11+162[8]
Hydrocaffeoylhexylamide265.351.00+125[8]
Ferulic acid194.190.781
44.6+335; +447[7]
Hydroferulic acid196.2084.0#+410[8]
5-Bromoferulic acid273.080.808+335; +442[7]
Methyl ferulate208.2174.7+375[9]
Ethyl ferulate222.2466.7+370[9]
Ethyl 5-bromoferulate301.130.558+365[7]
Propyl ferulate236.2664.1+364[9]
Butyl ferulate250.2956.3+343[9]
Hexylferulate278.35+328[8]
Hexylhydroferulate280.36+434[8]
Feruloylhexylamide277.36+322[8]
Hydroferuloylhexylamide279.38+388[8]
Sinapic acid224.210.86232.2+188; +295[10]
Methyl sinapate238.2448.7+219[10]
Ethyl sinapate252.2651.9+189[10]
Propyl sinapate266.2950.6+182[10]
Butyl sinapate280.3250.1+190[10]
3,4,5-Trihydroxycinnamic acid196.1611.8+11; +384[11]
Ethyl 3,4,5-trihydroxycinnamate224.2115.1+26; +133[11]

 *The results of DPPH assays are usually expressed as TEAC (trolox equivalent antioxidant capacity) or IC50 (concentration which is required to scavenge 50% of DPPH free radicals). These values are not convertible.
IC50 is presented in μmol L−1.
#Unpublished results.