Phenols, proanthocyanidins, flavones and flavonols in some plant materials and their antioxidant activities

• Published in: Food chemistry Vol. 89; no. 2; pp. 191 - 198
• Main Authors: Škerget, Mojca, Kotnik, Petra, Hadolin, Majda, Hraš, Andreja Rižner, Simonič, Marjana, Knez, Željko
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.02.2005; Elsevier
• Subjects: Antioxidant activity; antioxidants; apigenin; Biological and medical sciences; chemical composition; Contents in plant extracts; Crataegus laevigata; Emulsion; Flavones; Flavonols; food additives; Food industries; Fundamental and applied biological sciences. Psychology; hydrolysis; Hypericum perforatum; kaempferol; Laurus nobilis; leaves; lipid peroxidation; luteolin; methanol; myricetin; Oil; Olea europaea; optimization; oregano; Origanum vulgare; peroxide value; plant extracts; Proanthocyanidins; quercetin; Total phenols; Mediterranean region; Flavonols; Oil; Emulsion; Flavones; Antioxidant activity; Total phenols; Contents in plant extracts; Proanthocyanidins; Materials; Extract; Antioxidant; Flavonoid; Phenol; Phenols; Chemical composition; Proanthocyanidin
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2004.02.025

Methanol extracts prepared from five plant materials native to the Mediterranean area, namely olive tree ( Olea europaea) leaf, St. John's wort ( Hypericum perforatum), hawthorn ( Crataegus laevigata), oregano ( Origanum vulgare) and laurel leaf ( Lauris nobilis), were examined for their phenolic components. Total phenolic content was determined by the Folin–Ciocalteu method. The content of proanthocyanidins in acid-hydrolysed extracts was determined spectrophotometrically. The contents of free flavones (apigenin and luteolin) and flavonols (kaempferol, myricetin and quercetin) were determined by HPLC analysis. The time of hydrolysis of flavones, flavonols and proanthocyanidins was optimised. Antioxidant activities of apigenin, luteolin, kaempferol, myricetin, quercetin and of plant extracts were examined. Antioxidative activities were studied in sunflower oil at 98 °C, by measuring peroxide value, and in an aqueous emulsion system of β-carotene and linoleic acid by measuring the absorbance of the sample. Among flavones and flavonols investigated, only myricetin inhibited oxidation of sunflower oil. All other flavones and flavonols showed pro-oxidative activity. Oppositely, in the emulsion system, only apigenin showed pro-oxidative activity while other flavones and flavonols and plant extracts inhibited oxidation of β-carotene.