Hardy kiwi leaves extracted by multi-frequency multimode modulated technology: A sustainable and promising by-product for industry

The aim of this study is to evaluate hardy kiwi (Actinidia arguta L.) leaves, a crop waste, as a source of bioactive compounds with potential application in different industries, such as food industry. For this study, a new, green and sustainable extraction technique was employed: Multi-Frequency Multimode Modulated Technology. The total phenolic and flavonoid contents (TPC and TFC, respectively) as well as the antioxidant activity (through DPPH and FRAP assays) and the scavenging capacity against reactive species (O-2(center dot-), H2O2, NO center dot, ROO center dot, HOCl and ONOO center dot) were evaluated. The cell viability effects were assessed on keratinocytes and fibroblasts and the phytochemical profile was stablished by HPLC-DAD-EIS-MS. The extract displayed a high antioxidant activity (IC50 = 270.17 +/- 69.94 mu g/mL through scavenging activity on DPPH radicals and 3219.55 +/- 34.29 mu mol Fe2+/g dm in the FRAP assay). The TPC was higher than the one reported for fruit. On the contrary, the TFC is lower. Concerning the scavenging capacity against reactive species, the extract was more effective against O-2(center dot-) and H2O2. Regarding the cell viability assays, the extract did not affect the cell viability on HaCaT and HFF cells, in concentrations below 500 mu g/mL and 125 mu g/mL, respectively. The HPLC-DAD-EIS-MS-based phytochemical profile reported the presence of chlorogenic acid and glycosylated quercetin as well as kaempferol derivatives. Overall, the present results suggest that A. arguta leaves are a promising by-product when extracted by this innovative technology, being a valuable source of bioactive compounds for different industries, particularly food industry.