Effects of the antioxidant Pycnogenol^® on cellular redox systems in U1285 human lung carcinoma cells

Abstract

Pycnogenol®, which is extracted from the bark of French maritime pine, has been shown to have antioxidant and free radical scavenging activities. Thioredoxin reductase (TrxR), glutathione peroxidase (GPx) and glutathione reductase (GR) are three central redox enzymes that are active in endogenous defence against oxidative stress in the cell. Treatment of cells with Pycnogenol® decreased the activity of both TrxR and GPx in cells by more than 50%, but GR was not affected. As previously reported, both enzymes were induced after treatment with hydrogen peroxide and selenite. The presence of Pycnogenol® efficiently decreased selenite‐mediated reactive oxygen species (ROS) production. Addition of Pycnogenol® after selenite treatment reduced the mRNA expression and activity of TrxR to basal levels. In contrast, the GPx activity was completely unaffected. The discrepancy between TrxR and GPx regulation may indicate that transcription of TrxR is induced primarily by oxidative stress. As TrxR is induced in various pathological conditions, including tumours and inflammatory conditions, decreased activity mediated by a non‐toxic agent such as Pycnogenol® may be of great value.

Evaluation of cytotoxicity and oxidative DNA damaging effects of di(2-ethylhexyl)-phthalate (DEHP) and mono(2-ethylhexyl)-phthalate (MEHP) on MA-10 Leydig cells and protection by selenium

“…Like GPx1, it plays a role in reducing oxidative species either directly or by regeneration of cellular antioxidants (Xia et al, 2003), and maintain the redox balance in the cell (Mustacich and Powis, 2000). Available data also indicate that cytosolic TrxR is regulated by the redox state of the cell (Gandin et al, 2009), and its specific activity is highly sensitive to concentration of Se in cellular milieu. Our findings showing~2.4-fold decrease in cytosolic TrxR activity by both DEHP and MEHP exposures and significant restoration by Se supplementation, thus, provided more evidence for the alterations of cellular redox state induced by these two phthalates.…”

Oleic acid-induced ADRP expression requires both AP-1 and PPAR response elements, and is reduced by Pycnogenol through mRNA degradation in NMuLi liver cells

“…Instead, we found that PYC shortened the half-life of ADRP mRNA. Although dominant biological effects of PYC have been attributed to its antioxidant property (20,47), it seems that the effect on the ADRP expression could not be necessarily ascribed to it. In this study and our previous report (23), we demonstrated that DNA binding of AP-1 or NF-B, typical redox-sensitive transcription factors, was not inhibited by PYC.…”

Selenium compounds are substrates for glutaredoxins: a novel pathway for selenium metabolism and a potential mechanism for selenium-mediated cytotoxicity

“…Both protein level and protein activity increased equally over time, which suggests that selenite does not decrease the protein synthesis of Grx1, nor inhibit the activity. The induction of translation and transcription of Grx is most likely due to the oxidizing effects of selenite and the redox sensory role of the glutaredoxins [44]. The effect of selenium compounds after suppressing Grx1 with siRNA increased the cell viability with up to 20 % compared to control cells (scrambled).…”