Plasma-Activated Water Dipping of Fresh-Cut Eruca sativa: An Extended Investigation of the Glucosinolate-Myrosinase System and Cellular Responses.

Abstract

Plasma-Activated Water (PAW) is an emerging non-thermal technology with potential applications in fresh-cut vegetable preservation. The present study investigated the effect of PAW dipping on the glucosinolate-myrosinase system of rocket salad (Eruca sativa) and on selected cellular responses in human Caco-2 cells. Leaves were dipped in PAW for 20 min (PAW-20) or in untreated water (UT). Glucosinolates (GLSs) and their corresponding isothiocyanates (ITCs) were determined by UHPLC-ESI-MS/MS and GC-MS, while myrosinase activity was assessed in crude enzyme extracts. Caco-2 cells were exposed to extracts derived from PAW-20 or UT rocket leaf samples. Instrumental analyses revealed higher levels of the precursor GLSs, glucoerucin and glucoraphanin, in the PAW-20 sample compared with the UT one, whereas the corresponding ITCs, erucin and sulforaphane, were present at lower levels despite no detectable differences in myrosinase activity. In Caco-2 cells, PAW-20-derived leaf extracts induced the upregulation of the mRNA levels of specific UDP-glucuronosyltransferases (UGTs), while no significant modulation of glutathione S-transferases (GSTs) or the nuclear factor erythroid 2-related factor 2 (Nrf2) mRNA levels was observed. Moreover, only minor changes were detected in inflammation-related target genes. Overall, under the experimental conditions tested, PAW treatment was associated with changes in the glucosinolate-isothiocyanate balance in rocket leaf extracts and with selective modulation of phase II detoxification gene expression in Caco-2 cells.