Oxygen Availability during Growth Modulates the Phytochemical Profile and the Chemo-Protective Properties of Spinach Juice.

Francesco Milano,Silvia Fornaciari,Francesca Mussi,Laura Arru,Annamaria Buschini,Meltem Altunoz,Luca Forti

doi:10.3390/biom9020053

Francesco Milano, Silvia Fornaciari + Show 5 more

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https://doi.org/10.3390/biom9020053

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Abstract

Fruits and vegetables are a good source of potentially biologically active compounds. Their regular consumption in the human diet can help reduce the risk of developing chronic diseases such as cardiovascular diseases and cancer. Plants produce additional chemical substances when subject to abiotic stress or infected by microorganisms. The phytochemical profile of spinach leaves (Spinacia oleracea L.), which is a vegetable with widely recognized health-promoting activity, has been affected by applying root hypoxic and re-oxygenation stress during plant growth. Leaf juice at different sampling times has been subject to liquid chromatography mass spectrometry (LC-MSn) analysis and tested on the human colorectal adenocarcinoma cell line HT29 by using the Comet assay. The cells were previously treated with H2O2 to simulate the presence of an oxidative stress (as in colon cancer condition) and the leaf juice application resulted in a significant antioxidant and protective in vitro effect. The duration of the hypoxic/re-oxygenation stress imposed on the plant reflects the antioxidant leaf juice content. After hypoxic stress (24 h) and reoxygenation (2 h), we show a decrease (50%) of the relative abundance of the principal identified antioxidant molecules but a higher antioxidant activity of the spinach juice on HT29 cells (20%). Data shows a complex relation between plant growing conditions and the modulation of secondary metabolites content in leaf juice that results in different chemo-protective activities in colon cancer cells.

Highlights

A diet rich in fruits and vegetables has beneficial preventive effects on human health, which helps the free-radical scavenging and the metal ions chelating mechanisms of the human body due to the presence of natural occurring antioxidant compounds such as polyphenols
LC-MSn obtained data have been compared with spinach MS data provided in literature to help identify the most significant antioxidant secondary metabolites
LC-MSn analysis evidence in the spinach leaf juice, the presence of both common and more peculiar flavonoid compounds, flavonol derived molecules, and low molecular mass antioxidants appear to be modulated when plants are subject to hypoxic stress

Summary

Introduction

A diet rich in fruits and vegetables has beneficial preventive effects on human health, which helps the free-radical scavenging and the metal ions chelating mechanisms of the human body due to the presence of natural occurring antioxidant compounds such as polyphenols. The importance of these scavenging mechanisms lies in reducing the harmful effect of the oxidative species on DNA, proteins, and lipids at a cellular level [1,2]. The hypothesis is that the already unbalanced redox state (with a high amount of Reactive Oxygen Species (ROS) typical of cancer cells) makes the cells more susceptible to any additional oxidative stress [18]

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