Phytochemical composition and cultivar-dependent variation in colored lettuce (Lactuca sativa) and their α-amylase inhibitory activity.

BACKGROUND

This study investigated cultivar-dependent variation in the phytochemical composition of lettuce (Lactuca sativa) using liquid chromatography-tandem mass spectrometry (LC-MS/MS) profiling and high-performance liquid chromatography (HPLC) quantification, with a focus on enzyme inhibitory activity.

RESULTS

Significant differences were observed among six colored cultivars, with red cultivars exhibiting higher levels of phenolic compounds, particularly miquelianin (2), chicoric acid (4), and quercetin 3-O-malonylglucoside (3). Quantitative analysis revealed that these metabolites were markedly enriched in red-pigmented cultivars. Multivariate analysis further confirmed a clear compositional separation between red and green cultivars. α-Amylase inhibitory activity was also evaluated, and the red leaf crude extract yielded the highest efficacy among the matrices (IC50 = 1.24 mg mL⁻¹). Among the pure constituents, quercetin 3-O-malonylglucoside (3) demonstrated the strongest enzymatic inhibition (IC50 = 18.57 μg mL⁻¹). Molecular docking analysis supported these findings, revealing that compound 3 possessed the highest binding affinity (-9.8 kcal mol⁻¹) toward the α-amylase catalytic site by interacting with key active residues.

CONCLUSION

These findings demonstrate that phytochemical composition and enzyme inhibitory activity in L. sativa are strongly influenced by cultivar type. Particularly, red-pigmented cultivars represent promising sources of bioactive compounds with potential applications in nutritional and functional food development. © 2026 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.