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

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.

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; K_i = 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.

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.