Antioxidant activity of plant extracts containing phenolic compounds

The antioxidative activity of a total of 92 phenolic extracts from edible a nd nonedible plant materials (berries, fruits, vegetables, herbs, cereals, tree materials, plant sprouts, and seeds) was examined by autoxidation of m ethyl linoleate. The content of total phenolics in the extracts was determi ned spectrometrically according to the Folin-Ciocalteu procedure and calcul ated as gallic acid equivalents (GAE). Among edible plant materials, remark able high antioxidant activity and high total phenolic content (GAE > 20 mg /g) were found in berries, especially aronia and crowberry. Apple extracts (two varieties) showed also strong antioxidant activity even though the tot al phenolic contents were low (GAE < 12.1 mg/g). Among nonedible plant mate rials, high activities were found in tree materials, especially in willow b ark, spruce needles, pine bark and cork, and birch phloem, and in some medi cinal plants including heather, bog-rosemary, willow herb, and meadowsweet; In addition, potato peel and beetroot peel extracts showed strong antioxid ant effects. To utilize these significant sources of natural antioxidants, further characterization of the phenolic composition is needed.