Anti- and Pro-Oxidant Activity of Polyphenols Extracts of Syrah and Chardonnay Grapevine Pomaces on Melanoma Cancer Cells

Abstract

The phenolic composition of Syrah and Chardonnay grape pomaces was studied to assess their antioxidant and prooxidant properties. Polyphenols were extracted by a "green" hydroalcoholic solvent (ethanol/water 1:1 v/v), and a detailed chemical and electrochemical characterization of the phenolic compounds was performed. The antioxidant and prooxidant capacity of the pomace was first studied by cyclic voltammetry (CV) and other reference analytical assays, then with biological tests on B16F10 metastatic melanoma cancer cells. Electrochemical data showed that, when a +0.5 V potential was applied, a low to moderate antioxidant capacity was observed. MTT test showed an increasing viability of melanoma cells, after treatments at low concentration (up to 100 µg/mL) and for a short time (6 h), but when cells were treated with higher doses of extract (≥ 250 µg/mL for 12/24 h), their viability decreased from 25 to 50% vs. control, depending on treatment time, dose, and extract origin. A stronger prooxidant activity resulted when 250 µg/mL of extract was combined with non-toxic doses of H2O2; this activity was correlated with the presence of copper in the extracts. This study shows the potential of winemaking by-products and suggests the opportunity to exploit them for the production of cosmeceuticals, or for combined therapies with approved anticancer drugs.

Phytochemical evaluation and exploration of some biological activities of aqueous and ethanolic extracts of two species of the genus Plantago L.

“…Indeed, compared to the control, at 0.1 μg/ml the viability was lower (38% and 31% for leaf and root, respectively) with respect to 250 μg/mL (24% and 21% for leaf and root, respectively). The higher inhibition efficacy observed at low concentrations suggests a hormesis-like behavior, aligning with previous research [ 44 , 46 ].…”

“…The electrochemical evaluation of antioxidant activity is based on the principle that the lower the ionization potential, the greater the antioxidant capacity of a molecule, or of a phytocomplex [ 33 , 34 , 36 , 43 , 44 ]. The electrochemical behavior of the extracts at different applied potential, was carried out by cyclic voltammetry, in accordance with previous studies [ 45 ].…”

The Bioactivity of a Hydroxytyrosol-Enriched Extract Originated after Direct Hydrolysis of Olive Leaves from Greek Cultivars

“…On the other hand, decreased TBARS levels were noticed at lower DHOLE concentrations at myoblasts, while no alteration was observed at endothelial cells. The increased ROS levels could be justified by the fact that polyphenols can exert pro-oxidant activity after reaching a crucial concentration, at which point they are converted into radicals [ 59 , 60 , 61 ]. However, this alteration did not affect TBARS levels ( Figure 2 ) or cellular DNA, as shown by the Comet assay experiments, at endothelial cells ( Figure 5 and Figure 6 ).…”

Possible Side Effects of Polyphenols and Their Interactions with Medicines

“…Moreover, it is not only pure polyphenols which can act as prooxidants. A prooxidant activity was observed for polyphenolic extracts prepared from Syrah and Chardonnay grape pomaces [ 389 ] or wines [ 390 ]. The extracts made from red raspberry ( Rubus idaeus L.) stem could exert prooxidant activity when adequate conditions of pH and temperature are provided [ 391 ].…”