Stability of Rosmarinic Acid in Aqueous Extracts from Different Lamiaceae Species after in vitro Digestion with Human Gastrointestinal Enzymes

The present study compares the gastrointestinal stability of rosmarinic acid in aqueous extracts of thyme, winter savory and lemon balm with the stability of pure rosmarinic acid. The stability of rosmarinic acid was detected aft er two-phase in vitro digestion process (gastric and duodenal) with human gastrointestinal enzymes. The concentration of rosmarinic acid in undigested and digested samples was detected using HPLC-DAD. Results showed that gastrointestinal stability of pure rosmarinic acid was signifi cantly higher than that of rosmarinic acid from plant extracts aft er both gastric and intestinal phases of digestion. Among plant extracts, rosmarinic acid was the most stable in lemon balm aft er gastric (14.10 %) and intestinal digestion phases (6.5 %). The temperature (37 C) and slightly alkaline medium (pH=7.5) did not aff ect the stability of rosmarinic acid, while acid medium (pH=2.5) signifi cantly decreased its stability (50 %). In addition, the stability rate of rosmarinic acid is infl uenced by the concentration of human gastrointestinal juices.