Impact of extraction processes on phytochemicals content and biological activity of Citrus × clementina Hort. Ex Tan. leaves: New opportunity for under-utilized food by-products

Plants are a rich source of natural bioactive compounds with a wide range of applications in the food andpharmaceutical industries.Citrus × clementinaleaves extracts and essential oils may be a potential candidate forformulation of products characterized by hypoglycaemic, antioxidant and anti-browning properties.C. × clementinaleaves collected in three different areas in Calabria (South Italy) were extracted by Soxhletapparatus, maceration, Ultrasound assisted maceration, and hydrodistillation. Hesperidin, tangeritin, and si-nensetin were identified by HPLC-DAD analysis as dominant constituents of the extracts. The absence of cou-marins and furanocoumarins was demonstrated. GC–MS analyses of essential oils evidenced the presence ofsabinene, linalool, and (E)-β-ocimene as main compounds. Based on RACI and GAS values calculated by theintegration of data obtained by DPPH, ABTS, FRAP andβ-carotene bleaching methods, hydroalcoholic extractobtained by Ultrasound assisted maceration of the leaves collected in Corigliano Calabro showed the highestantioxidant activity. Ultrasound assisted hydroalcoholic extract of Cetraro leaves revealed the highestα-amylaseinhibitory activity (IC50of 64.37μg/ml). Promising results ofC. × clementinaextracts as tyrosinase inhibitorswere also obtained. To evaluate the relationship between identified compounds and bioactivity PCA was per-formed. Taking into account results obtained by this study,C. × clementinaleaves that were consideredCitrus-by-products could be utilized for formulation of food additives, nutraceuticals and functional foods.