Pheophorbide Derivatives Isolated From A？aí Berries (Euterpea oleracea) Activate an Antioxidant Response Element In Vitro

Activity-guided fractionation was used to isolate and identify 2 components of the Brazilian a？aí berry (Euterpe oleracea Mart.) with the ability to induce antioxidant response element (ARE)-dependent gene transcription in human hepatoma (HepG2) cells. Using an ARE-luciferase reporter construct in cultured HepG2 cells, a suite of fractions from dried and powdered a？aí berries were evaluated for transcriptional upregulation of the luciferase gene. Active fractions were further refined until several pure compounds were isolated and identified. These compounds belong to the pheophorbide class of molecules, and are composed of the methyl and ethyl esters of the parent pheophorbide A, all of which are classified as photosensitizers. Using standard pheophorbides, dose-response studies were carried out, and ARE activation could be observed at concentrations as low as 8.2 and 16.9 μM for pheophorbide A methyl ester and pheophorbide A, respectively. These studies not only suggest a possible source of antioxidant properties for the a？aí berry, but may also explain the recently identified photosensitizing abilities of a？aí products as well