Biol. Pharm. Bull., 28(7),1211-1215, July 2005

Regular Articles

Evaluation of Polyphenolic Acid Esters as Potential Antioxidants

Ling-Yih HSU,^a Chi-Fu LIN,^a Wen-Chuan HSU,^a Wen-Lin HSU,^*,c and Tsu-Chung CHANG^*,b

^a School of Pharmacy, Pharmaceutical Research Institute, and ^b Department of Biochemistry, National Defense Medical Center; Taipei, Taiwan: and ^c Cancer Medical Center and Department of Radiation Oncology, Buddhist Tzu Chi Medical Center; Hualien, Taiwan, ROC. * To whom correspondence should be addressed. e-mail: tcchang@ndmctsgh.edu.tw

Six polyphenolic acid esters were synthesized and their antioxidative properties were evaluated in three model systems [2,2′-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay, 2,2′-azobis(2-amidinopropane)dihydrochloride (AAPH)-induced lipid peroxidation system, and the dye-bleaching assay of peroxynitrite radical]. Among these compounds, we found that compounds 4 [3,4-dihydroxy-benzoic acid-(2-phenoxyethyl ester)], and 5 [3,4-dihydroxy-cinnamic acid-(2-phenoxyethyl ester)] provided comparable activity to caffeic acid phenethyl ester (CAPE) in the DPPH model. Compound 3 [2,5-dihydroxy-benzoic acid-(2-phenoxyethyl ester)], was found to be more active than CAPE in the AAPH system, it also displayed about 2-fold greater activity than CAPE in the peroxynitrite radical model. These results suggest that these phenolic acid ester derivatives, with their potent anti-oxidant activities, may have useful applications as antioxidants.

Key words polyphenolic acid ester; caffeic acid analogue; antioxidant; free radical scavenging activity