In Vitro Antibacterial, Antimutagenic and Anti-Influenza Virus Activity of Caffeic Acid Phenethyl Esters

We assayed in vitro the biological activities of caffeic acid phenethyl esters that had been enzymatically synthesized from 5-chlorogenic acid and phenethyl alcohol. Caffeic acid phenethyl esters showed antioxidant and hyaluronidase-inhibitory activities similar to those of chlorogenic acid and caffeic acid, and markedly higher antibacterial, antimutagenic, and antiviral activities than chlorogenic acid. The antimicrobial activities of caffeic acid phenylethyl esters against Staphylococcus aureus, Bacillus subtiiis, and Pseudomonas aeruginosa (MIC; 0.22-0.44, 0.44-0.88, and 0.44-0.88 mM, respectively) were higher than those of 5-chlorogenic acid and caffeic acid. 2-caffeic acid phenylethyl ester showed potent antimutagenic activity against quinoline compounds, aromatic amines, and heterocyclic compounds. In addition, 2-caffeic acid phenylethyl ester at concentrations of less than 35 μM promoted the proliferation of normal human pulmonary fibroblasts (WI-38 cells) in culture, but inhibited the proliferation of virus-transformed fibroblasts (WI-38 VA cells; IC50 of 60 μM). 1-and 2-Caffeic acid phenylethyl esters at a concentration of 8.8 μM inhibited the growth of type A influenza virus by 95% and 96%, respectively, and that of type B influenza virus by 92% and 94%, respectively. These results indicate that caffeic acid phenylethyl esters have higher antimutagenic and anti-influenza virus activities than chlorogenic acid and caffeic acid.