Impact of Simulated Gastrointestinal Digestion on Antiglycoxidant Activity of Lemon Verbena (Aloysia triphylla) Herbal Tea and Characterization of Key Polyphenols via DPPH/MGO Pre-Column HPLC.

Aloysia triphylla (lemon verbena, LV) herbal tea is a rich source of phenolic compounds with recognized antioxidant and antiglycoxidant properties, although their stability during digestion remains insufficiently understood. This study evaluated the impact of simulated gastrointestinal digestion on the phenolic composition and bioactivity of LV infusion using a standardized in vitro model. Total phenolic, flavonoid, and phenolic acid contents were determined spectrophotometrically, while individual compounds were analyzed by HPLC. Antioxidant activity was assessed using complementary assays (DPPH•, ABTS•, FRAP, ORAC, and nitric oxide scavenging), and antiglycation activity was evaluated using a BSA/D-ribose model. Digestion did not significantly affect total phenolic and phenolic acid contents, whereas flavonoids moderately decreased during the intestinal phase. Verbascoside underwent partial degradation, leading to increased levels of isoverbascoside and caffeic acid. Despite these transformations, antioxidant capacity was maintained or enhanced, particularly in ABTS and ORAC assays, suggesting a contribution of digestion-derived metabolites. Antiglycation activity remained stable after digestion. Pre-column HPLC analyses identified verbascoside and its derivatives as the main contributors to radical scavenging and methylglyoxal trapping activities. These findings indicate that LV infusion retains its bioactive potential after digestion and supports its relevance as a functional beverage.