Antioxidant activity of polyphenols from solid olive residues of c.v. Coratina.
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.
Aldini
G
G
Istituto Chimico Farmaceutico Tossicologico, Facoltà di Farmacia, Università degli Studi di Milano, Abruzzi, Italy. giancarlo.aldin@unimi.it
Piccoli
A
A
Beretta
G
G
Morazzoni
P
P
Riva
A
A
Marinello
C
C
Maffei Facino
R
R
D000578:Amidines / Q000737:chemistry; D000818:Animals; D000975:Antioxidants / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D001713:Biphenyl Compounds / Q000037:antagonists & inhibitors; D002460:Cell Line; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism; D005419:Flavonoids / Q000737:chemistry* / Q000494:pharmacology*; D005609:Free Radicals; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D006834:Hydrazines / Q000037:antagonists & inhibitors; D008297:Male; D031658:Olea / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry* / Q000494:pharmacology*; D010851:Picrates; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D059808:Polyphenols; D051381:Rats; D017208:Rats, Wistar
D000578:Amidines; D000975:Antioxidants; D001713:Biphenyl Compounds; D005419:Flavonoids; D005609:Free Radicals; D006834:Hydrazines; D010636:Phenols; D010851:Picrates; D010936:Plant Extracts; D059808:Polyphenols; C046728:2,2'-azobis(2-amidinopropane); C004931:1,1-diphenyl-2-picrylhydrazyl