TENTATIVE EVIDENCE OF A ROSMARINIC ACID PEROXIDASE IN CELL-CULTURES FROM LAVANDIN (LAVANDULA X INTERMEDIA) FLOWERS

The oxidative stability of rosmarinic acid (alpha-O-caffeoyl-3,4-dihyd roxyphenyllactic acid) in lavandin (Lavandula x intermedia) cell cultu res was studied in an attempt to explain the decrease in the rosmarini c acid content of aging cell cultures, a process which is associated w ith the appearance of brown pigments. The oxidation of rosmarinic acid by a partially purified protein fraction was followed spectrophotomet rically and by HPLC. The results showed that rosmarinic acid oxidation was almost totally dependent on the presence of H2O2 and protein, and that brownish products were the result of this oxidation, resembling those shown by aging cell cultures. Since this protein fraction contai ns peroxidase activities and shows the total absence of tropolone-sens itive polyphenoloxidase (catecholase) and laccase activities, rosmarin ic acid oxidation is tentatively proposed to be caused by a peroxidase -like activity. These results support the existence of a rosmarinic ac id peroxidase in cell cultures of lavandin flowers, which may be invol ved in the oxidative destruction of rosmarinic acid, and which may als o be responsible for the formation of brown pigments during aging, low ering the yields of rosmarinic acid.