Effect of pre-soaking mustard green seeds prior to cold plasma treatment on bioactive aspects of microgreens

Abstract

Microgreens have been reported to contain higher phytochemicals than mature plants. Mustard green (MG) is rich in glucosinolates that produce isothiocyanates (ITCs) upon degradation. ITCs have well-known chemopreventive benefits. Previously, non-thermal plasma treatment on MG seeds could enhance bioactive content; However, seed pretreatment before non-thermal plasma treatment was yet to be studied. The aim of this work was to evaluate the impact of pre-soaking MG seeds overnight before non-thermal plasma treatment at 21 kV for 5 min on phytochemicals and activities of MG microgreens. Plasma-treated pre-soaked (PTPS) seeds and control seeds (no plasma treatment) received deionized water for 7 days. No difference in germination percentage, stem height or fresh/dried weight of MG between PTPS seeds and the control was observed. Total ITC content in MG microgreens from PTPS seeds (1.62 mmol/100 g DW) was significantly higher than control seeds (1.00 mmol/100 g DW). Antioxidant capacity and total phenolic/flavonoid compounds were similar in both MG microgreens. Lower IC50 values were recorded for MG microgreens from PTPS seeds at most time intervals, indicating higher cytotoxicity against MCF-7 and HepG2, and greater effectiveness in cancer proliferation inhibition than the control. No differences in Bax, Caspase-3 and Bcl-2 mRNA expressions were detected for all samples; however, MMP-9 mRNA expression was reduced in MG microgreens from PTPS seeds for HepG2. Pre-soaking MG seeds before plasma treatment at 21 kV for 5 min increased ITC levels and increased anticancer activities of MG microgreens without adverse effects compared to MG microgreens from control seeds. © 2021 Matra et al.