Enhancement of Glucosinolate Formation in Broccoli Sprouts by Hydrogen Peroxide Treatment

Abstract

Broccoli sprouts are known as a rich source of health-beneficial phytonutrients: glucosinolates and phenolic compounds. The production of phytonutrients can be stimulated by elicitors that activate the plant stress response. The aim of this study was enhancing the nutritional value of broccoli sprouts using hydrogen peroxide (H2O2) as an elicitor. Daily spraying with H2O2 (500–1000 mM) enhanced the accumulation of glucosinolates, doubling their content in the cotyledons of 16/8 h photoperiod-grown 7-day sprouts compared to the water-treated controls. The application of H2O2 on dark-grown sprouts showed a smaller extent of glucosinolate stimulation than with light exposure. The treatment affected sprout morphology without reducing their yield. The H2O2-treated sprouts had shorter hypocotyls and roots, negative root tropism and enhanced root branching. The activated glucosinolate production became evident 24 h after the first H2O2 application and continued steadily until harvest. Applying the same treatment to greenhouse-grown wild rocket plants caused scattered leaf bleaching, a certain increase in glucosinolates but decline in phenolics content. The H2O2 treatment of broccoli sprouts caused a 3.5-fold upregulation of APK1, a gene related to sulfur mobilization for glucosinolate synthesis. Comparing the APK1 expression with the competing gene GSH1 using sulfur for antioxidant glutathione production indicated that glutathione synthesis prevailed in the sprouts over the formation of glucosinolates.

Elicitation as a Process of Enhancing Bioactive Compounds Concentration in Sprouts

“…The elicitation of radishes with saline changed the total phenolic contents of 3-and 5-day-old sprouts, and TPCs were significantly increased by 25-50% after treatment with 100 mM of NaCl [65]. In the case of elicitation treatment, more research was conducted with broccoli sprouts since broccoli is a great source of sulforaphane possessing potent anti-cancer activity, and [67][68][69] studied the influence of hydrogen peroxide on broccoli sprouts. Elicitation by 0-1000 mM H 2 O 2 solutions did not cause a significant change in total phenolic compounds concentration in the fresh matter of sprouts, and it was approximately 160 mg GAE/100 g FW.…”

Genotypes of Eruca vesicaria subsp. sativa grown in contrasting field environments differ on transcriptomic and metabolomic levels, significantly impacting nutritional quality

“…hypothesised that glutathione metabolism and GSL biosynthesis are competing pathways for sulfur (Vanegas Torres et al, 2022).…”

Effect of Sprouting on the Phenolic Compounds, Glucosinolates, and Antioxidant Activity of Five Camelina sativa (L.) Crantz Cultivars

“…Several scientific research works have reported that the content of bioactive compounds in Brassicaceae vegetables varies with the genotype, growth conditions, storage, and processing [ 20 , 21 , 22 , 23 ]. Biondi et al underlined how the phytochemical load of broccoli depends upon both genetics and environment, and there is a large possibility of improving the quality of Brassica products through appropriate agronomic practices; nevertheless, the effects of the treatments are strictly genotype dependent [ 21 ].…”