Characteristics of the leaf parts of some traditional Korean salad plants used for food

BACKGROUND: Total phenolics content, antioxidant activity and cytotoxicity of the methanol extracts from leaf parts of 13 Korean traditional salad plants were investigated in order to determine their properties. RESULTS: The highest phenolics content (mg ferulic acid equivalents kg^-1 dry weight (d.w.), omit one) was found in methanol extracts from Polygonum aviculare, at 293.7 ± 6.0, followed by Euonymus alatus, at 250.7 ± 3.3, Saxifraga stolonifera, at 125.0 ± 8.1 and Ligularia fischeri, at 122.5 ± 5.9. The methanol plant extracts dose-dependently increased free radical scavenging activity. Methanol extracts of Polygonum aviculare, Euonymus alatus and Saxifraga stolonifera, at 31 mg kg^-1, exhibited the highest 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (%) by 90.8 ± 4.2, 85.7 ± 3.9 and 64.1 ± 3.2, respectively. According to 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, the methanol extracts from Portulaca oleracea (IC₅₀ < 25.0 μg mL^-1) showed the highest cytotoxicity against Calu-6, followed by Plantago asiatica (49.2 μg mL^-1) and Osmunda japonica (89.6 μg mL^-1). CONCLUSION: Total phenolics content of the tested plant extracts was correlated with the DPPH radical scavenging activity, suggesting the phenolics compounds are contributing to the antioxidant properties of Korean salad plants. The leaf parts of the 13 Korean traditional salad plants described here that are currently used as foods may also provide some benefit to human health, and research into their potential benefits as preventative and/or therapeutic agents is warranted.