Solarplast®-An Enzymatically Treated Spinach Extract

Abstract

In the modern world we are constantly bombarded by environmental and natural stimuli that can result in oxidative stress. Antioxidant molecules and enzymes help the human body scavenge reactive oxygen species and prevent oxidative damage. Most organisms possess intrinsic antioxidant activity, but also benefit from the consumption of antioxidants from their diet. Leafy green vegetables such as spinach are a well-researched rich source of dietary antioxidant molecules. However, plant cell walls are difficult to digest for many individuals and the bio-accessibility of nutrients and antioxidants from these sources can be limited by the degree of digestion and assimilation. Through a specific enzymatic process, Solarplast^® contains organic spinach protoplasts without the cell wall, which may facilitate higher yield and efficacy of beneficial antioxidant molecules. In this study, analytical techniques coupled to in vitro bioassays were used to determine the potential antioxidant activity of Solarplast^® and determine its antioxidant enzymatic capabilities. Solarplast^® demonstrated superior antioxidant activity when compared to frozen spinach leaves in TOC, FRAP and TEAC antioxidant assays. Several antioxidant enzymes were also increased in Solarplast^®, when compared to frozen spinach. As a functional readout, Solarplast^® attenuated hydrogen peroxide-, ethanol- and acetaminophen-induced increases in oxidative stress and cytotoxicity in both intestinal (HT-29) and liver (HepG2) cell lines. These findings suggest that Solarplast^® may represent a non-GMO, plant-based food supplement to help reduce oxidative stress in the human body.

Keywords: HT-29; HepG2; Solarplast®; antioxidant; oxidative stress; spinach.

Figure 1

Solarplast^® had significantly higher total antioxidant activity than frozen spinach extracts. Total antioxidant activity was measured using (A) Trolox (TOC), (B) ferric reducing (FRAP) and (C) total antioxidant capacity (TEAC). Bars indicate average concentration (n = 9) ± SEM. Significantly higher than frozen spinach, **** p < 0.0001.

Figure 2

Solarplast^® had significantly higher levels of antioxidant enzymes compared to frozen spinach except for catalase. (A) Superoxide dismutase, (B) peroxidase, (C) glutathione-S-transferase, (D) catalase, (E) glutathione peroxidase and (F) monodehydroascorbate reductase. Results show average (n = 6) ± SEM. ** p < 0.01, *** p < 0.001 and **** p < 0.0001 indicate significantly higher concentrations.

Figure 3

Solarplast^® extracts were not cytotoxic in intestinal HT-29 and liver HepG2 cell lines. (A) Solarplast^® was not cytotoxic in HT-29 cell line. Results show average survival (n = 6) ± SEM. (B) Solarplast^® was not cytotoxic in HepG2 cell line. Results show average survival (n = 9) ± SEM. ++++ p < 0.0001 significantly higher than untreated cells.

Figure 4

Solarplast^® extracts reduced ROS levels in intestinal HT-29 and liver HepG2 cell lines exposed to H₂O₂. (A) Solarplast^® reduced ROS concentration in HT-29 cells exposed to H₂O₂. Results show average ROS production (n = 6) ± SEM. (B) Solarplast^® reduced ROS concentration in HepG2 cells exposed to H₂O₂ (control). Results show average ROS production (n = 6) ± SEM. All cells were exposed to 2 mM H₂O₂ except for the untreated group. ** p < 0.01 and **** p < 0.0001 indicate significantly lower than control H₂O₂-exposed cells. ++++ p < 0.0001 significantly higher than untreated cells.

Figure 5

Solarplast^® extracts reduced ROS levels in intestinal HT-29 and liver HepG2 cell lines exposed to 6% ethanol. (A) Solarplast^® reduced ROS concentration in HT-29 cells exposed to ethanol. Results show average ROS production (n = 12) ± SEM. (B) Solarplast^® reduced ROS concentration in HepG2 cells exposed to ethanol. Results show average ROS production (n = 12) ± SEM. All cells were exposed to 6% ethanol except for the untreated group. * p < 0.05, ** p < 0.01 and **** p < 0.0001 indicate significantly lower than control ethanol-exposed cells. +++ p < 0.001 and ++++ p < 0.0001 significantly higher than untreated cells.

Figure 6

Solarplast^® extracts reduced ROS levels in intestinal HT-29 and liver HepG2 cell lines exposed to acetaminophen. (A) Solarplast^® reduced ROS concentration in HT-29 cells exposed to acetaminophen. Results show average ROS production (n = 9) ± SEM. (B) Solarplast^® reduced ROS concentration in HepG2 cells exposed to acetaminophen. Results show average ROS production (n = 9) ± SEM. All cells were exposed to 30 mM acetaminophen except for the untreated group. * p < 0.05, *** p < 0.0005 and **** p < 0.0001 indicate significantly lower than control acetaminophen-exposed cells. ++ p < 0.01 significantly higher than untreated cells.