Antioxidant activity of polyphenols from solid olive residues of c.v. Coratina.

Abstract

The antioxidant profile of extracts from solid olive residue (SOR) of c.v. Coratina, a cultivar widely diffused in the south of Italy, using both cell-free and cell-based experimental models, was investigated. A total hydroalcoholic extract (polyphenols content 19.7%) and a purified extract (Oleaselecttrade mark) (polyphenols content 35.1%) were tested for their ability to quench the stable free radical DPPH, the peroxyl radicals (ORAC assay), by monitoring the loss in fluorescence of R-phycoerythrin induced by the peroxyl radical generator AAPH and their ability to inhibit the cumene hydroperoxide-induced lysis of rat red blood cells (RBC). The total hydroalcoholic extract showed IC(50) 26.96+/-1.53 microg/ml in the DPPH assay, that 10 microg/ml were equivalent to 2.11+/-0.12 microg/ml Trolox (ORAC assay) and IC(50) 1.7+/-0.20 microg/ml in the RBC hemolysis. The Oleaselect extract was 4 to 5 folds more active than the hydroalcoholic extract in all the experimental models, with IC(50) values of 7.36+/-0.38 microg/ml in the DPPH test and of 0.38+/-0.03 microg/ml in RBC; the antioxidant activity in the ORAC assay was slightly greater than that of Trolox (10 microg/ml equivalent to 11.45+/-0.40 microg/ml). The scavenging effect of the extract in the ORAC assay was compared to that of verbascoside (the main polyphenol component) and of caffeic acid (the basic constituent of verbascoside): the results indicate that caffeic acid (10 microg/ml equivalent to 35.70+/-2.95 microg/ml Trolox) is more potent than verbascoside (10 microg/ml equivalent to 15.42+/-1.21 microg/ml Trolox) in entrapping peroxyl radicals. Finally the antioxidant activity of the Oleaselect extract was confirmed in human umbilical endothelial cells (EC) exposed to the site-specific peroxyl radical inducer AAPH, where a massive lipid peroxidation process (marker the fluorescence probe BODIPY) takes place, paralleled by a marked loss of cell viability (calcein assay). The purified extract (1-20 microg/ml) pre-incubated with EC for 1 h dose-dependently inhibited both the lipid-peroxidation damage and cell death. Taking into account the total polyphenol content, these results clearly indicate a greater antioxidant activity for the purified extract, due to a cooperative antioxidant interaction among its polyphenol constituents.

• Authors: G Aldini, A Piccoli, G Beretta, P Morazzoni, A Riva, C Marinello, R Maffei Facino
• Journal: Fitoterapia (Fitoterapia) Vol. 77 Issue 2 Pg. 121-8 (Feb 2006) ISSN: 0367-326X [Print] Netherlands
• PMID: 16406361 (Publication Type: Journal Article)

Chemical References

• Amidines
• Antioxidants
• Biphenyl Compounds
• Flavonoids
• Free Radicals
• Hydrazines
• Phenols
• Picrates
• Plant Extracts
• Polyphenols
• 2,2'-azobis(2-amidinopropane)
• 1,1-diphenyl-2-picrylhydrazyl

Topics

• Amidines (chemistry)
• Animals
• Antioxidants (chemistry, isolation & purification, pharmacology)
• Biphenyl Compounds (antagonists & inhibitors)
• Cell Line
• Cells, Cultured
• Dose-Response Relationship, Drug
• Endothelial Cells (cytology, metabolism)
• Flavonoids (chemistry, pharmacology)
• Free Radicals
• Hemolysis (drug effects)
• Humans
• Hydrazines (antagonists & inhibitors)
• Male
• Olea (chemistry)
• Phenols (chemistry, pharmacology)
• Picrates
• Plant Extracts (chemistry, isolation & purification, pharmacology)
• Polyphenols
• Rats
• Rats, Wistar