Amber, red and blue LEDs modulate phenolic contents and antioxidant activities in eight Cruciferous microgreens

Abstract

Grass pea seeds of 30 varieties from Poland, Slovakia, Czech, Russia, Ukraine, Hungary, Bulgaria, India, Iran, Tunisia, Ethiopia, Canada, and Chile were investigated. Phenolic compounds were extracted from seeds into 80% (v/v) methanol. The total phenolics compounds content of the extracts was determined using Folin-Ciocalteu’s phenol reagent. The antioxidant activity was determined using ABTS and FRAP assays. Total phenolic contents ranged from 2.74 to 10.7 mg/g extract and from 35.9 to 144.7 mg/100 g seeds. The extracts and seeds were characterized using Trolox equivalent antioxidant capacity values of 0.014–0.060 mmol Trolox/g extract and 0.188–0.866 mmol Trolox/100 g seeds, and FRAP values of 0.188–0.866 mmol Fe2+/g extract and 0.541–1.398 Fe2+/100 g seeds. The total phenolics content of grass pea extract was correlated with the results of the ABTS (r = 0.854) and FRAP (r = 0.958) assays. A similar correlation existed between the results of both assays (r = 0.890). Phenolic acids were the dominant phenolic compounds of two cultivars of grass pea. Syringic and sinapic acids had the highest amounts while ferulic, p-hydroxybenzoic, protocatechuic, and p-coumaric acids were present in much lower quantitie. Phenolic acids were present in the form of free compounds, esters, and glycosides.

Microgreens: Functional Food with Antiproliferative Cancer Properties Influenced by Light

“…The overall polyphenol content of Red Rambo was higher than the two remaining Brassica species (radish and rocket) in the present study, corroborating previous results also showing higher contents, as well as FRAP, under conditions favoring a predominance in B LED light [11]. The total polyphenol content of Red Rambo in the present study, if expressed on a dry mass basis, was comparable with that reported under B light [11]. The polyphenol content of rocket was similarly comparable to that reported previously [8].…”

“…The results of the present study corroborate previous investigations which demonstrated an increased presence of polyphenols and anti-oxidant activity with B LED [11][12][13]. Of relevance is that different spectra in LED lighting have been shown to induce the expression of different individual polyphenol constituents within the total pool [7,12].…”

“…This shows that anti-tumor effects were attributable to polyphenol constituents sufficiently expressed under both light treatments, despite the significantly overall lower polyphenol content under florescent lighting. Total polyphenol content from all five microgreens was not shown to be related to cytotoxic effects in either the sarcoma lines or healthy fibroblast lines, corroborating a largely species-dependent effect [8,11]. Notwithstanding the higher overall polyphenol content of Red Rambo, followed by soybean under LED, neither species displayed antiproliferative effects on A673, and soybean was similarly ineffective on RD-ES.…”

“…The advent of LED lighting has provided research impetus to examine phytochemical expression in response to light spectra [7,[9][10][11][12][13]. Of interest to the present study was the use of combination LED (B:G:R) with a peak spectrum in B wavelength, known to induce increased expression of polyphenols [11,13], with the objective of investigating the functional efficacy of polyphenol constituents extracted from five microgreens (cultivated under fluorescent (control) and LED lighting) on two Ewing sarcoma cell lines.…”

“…The advent of LED lighting has provided research impetus to examine phytochemical expression in response to light spectra [7,[9][10][11][12][13]. Of interest to the present study was the use of combination LED (B:G:R) with a peak spectrum in B wavelength, known to induce increased expression of polyphenols [11,13], with the objective of investigating the functional efficacy of polyphenol constituents extracted from five microgreens (cultivated under fluorescent (control) and LED lighting) on two Ewing sarcoma cell lines. The present study shows, for the first time, the anti-proliferative and pro-apoptotic effects of Pisum sativum (LED-grown) microgreen extracts (2.1 µg polyphenols in 40 µL) on both RD-ES and A673 sarcoma in tumor form (3D spheroids), with no cytotoxic effects on healthy L929 fibroblast cells.…”