Effect of Elicitation and Precursor Feeding on Bioactive Properties and Polyphenol Metabolism of Lentil (Lens culinaris) Sprouts

This study investigated the effect of different elicitors, namely salicylic acid, ascorbic acid, sucrose, and folic acid applied alone or in combination with phenolic precursors (phenylalanine and tyrosine), on the phytochemical profile and biofunctional properties of lentil sprouts. Among all treatments, sucrose (200 mM) combined with phenylalanine proved most effective, markedly enhancing phenylpropanoid metabolism. This treatment resulted in substantial increases in total phenolics, flavonoids and condensed tannins (5.3, 3.4, and 6.5-fold, respectively), accompanied by significantly improved antioxidant capacity, as reflected by reduced IC₅₀ values for DPPH scavenging and reducing power (68.84% and 71.18%, respectively), and increased FRAP (2.9-fold) and metal ion chelation (3.0-fold) activities. Mechanistic analysis revealed pronounced upregulation of key enzymes involved in phenolic biosynthesis and oxidation, with 2.0, 5.1, 2.7, and 5.2-fold increases in PAL, TAL, POD, and PPO activities, respectively, compared to the control. In parallel, sucrose—phenylalanine elicitation significantly enhanced α-amylase, α-glucosidase and acetylcholinesterase inhibitory activities (1.9, 1.8, and 3.5-fold, respectively). Overall, these findings demonstrate that elicitation, particularly using sucrose in combination with phenylalanine, represents an effective and natural strategy to stimulate phenolic biosynthesis and enhance the nutraceutical potential of lentil sprouts.