Protective effect of a phenolic extract from Corema album berries against oxidative stress on HepG2 cells.

AJ León-González1, S Ramos2, MA Martín2, R Mateos2, B Sarriá2, M López-Lázaro1, L Bravo2, C Martín-Cordero1, L Goya2. 1University of Seville, Department of Pharmacology, School of Pharmacy, 41012, Spain, 2ICTAN-CSIC, Department of Metabolism and Nutrition, Spain

Corema album (L.) D. Don (Ericaceae) fruit is a wild edible berry traditionally consumed along the Atlantic littoral of the Iberian Peninsula. Because of the growing interest in other berries of the same family as functional foods, the aim of this study was to evaluate the protective effect of an acetone extract from this fruit against oxidative stress on HepG2 cells.

Characterization of the extract on phenolic compounds was achieved by liquid chromatography-mass spectrometry (LC-MS). Human hepatoma HepG2 cells were pretreated with 1-40 µg/mL of berry extract for 20 hours and then exposed to oxidative stress, induced by tert-butylhydroperoxide (t-BOOH). Several biomarkers of cellular redox status were evaluated: cell viability (lactate dehydrogenase leakage), generation of reactive oxygen species (ROS), concentration of reduced glutathione (GSH) and activity of glutathione reductase (GR) and glutathione peroxidase (GPx). Levels of malondialdehyde (MDA) and carbonyl groups were also analyzed to evaluate lipid peroxidation and protein oxidative damage, respectively. Data were expressed as mean ± SEM. Statistical analysis was performed with the SPSS program (version 19.0) by using the one-way ANOVA test, followed by a Bonferroni test when variances were homogeneous, or by Tamhane test when they were not.

Chemical characterization of the acetone extract of Corema album berries, showed a total phenolic compound concentration of 1472.83 ± 0.05 mg/ 100 g extract. Treatment with 400 µM t-BOOH for 3 hours evoked a great increase in lactate dehydrogenase (LDH) activity in the culture medium (39.3 ± 2.8 % extracellular LDH) and a significant increase in the cellular concentration of MDA (2.44 ± 0.08 nmol/ mg protein) and carbonyl groups (4.3 ± 0.3 nmol/ mg protein). Pretreatment of HepG2 cells with 10 µg/mL Corema album berry extract limited cell damage (7.7 ± 0.9 % extracellular LDH), and protected cells against oxidative damage to lipids (1.13 ± 0.06 nmol MDA/ mg protein) and to proteins (3.9 ± 0.4 nmol/ mg protein). The extract also partially reduced the ROS levels, prevented the decrease of GSH and modulated the changes in GR and GPx activities, induced by t-BOOH. Further experiments are required to determine the potential beneficial effect of Corema album berry consumption in the prevention of oxidative stress-related diseases.

Keywords. Corema album, berry, oxidative stress, HepG2 cells, antioxidant.