Flavonoids with lipase inhibitory activity from lemon squeezing waste: isolation, multispectroscopic and in silico studies

BACKGROUND: Obesity is recognized as a lifestyle-related disease and the main risk factor for a series of pathological conditions, including cardiovascular diseases, hypertension and type 2 diabetes. Citrus limon is an important medicinal plant, and its fruits are rich in flavonoids investigated for their potential in managing obesity. In the present work, a green extraction applied to lemon squeezing waste (LSW) was optimized to recover pancreatic lipase (PL) inhibitors. RESULTS: The microwave-assisted procedure yielded an extract with higher lipase inhibitory activity than those obtained by maceration and ultrasound. The main compounds present in the extract were identified by high-performance liquid chromatographic–mass spectrometric analysis, and hesperidin, eriocitrin and 4′-methyllucenin II were isolated. The three compounds were evaluated for in vitro PL inhibitory activity, and 4′-methyllucenin II resulted in the most promising inhibitor (IC50 = 12.1 μmol L−1; Ki = 62.2 μmol L−1). Multispectroscopic approaches suggested the three flavonoids act as competitive inhibitors and the binding studies indicated a greater interaction between PL and 4′-methyllucenin II. Docking analysis indicated the significant interactions of the three flavonoids with the PL catalytic site. CONCLUSION: The present work highlights flavonoid glycosides as promising PL inhibitors and proposes LSW as a safe ingredient for the preparation of food supplements for managing obesity. © 2024 Society of Chemical Industry.