Antioxidant Activities of Methanol Extracts from Selected Taiwanese Herbaceous Plants

Abstract

The purpose of this study was to evaluate the total phenolic and flavonoid contents in acid methanol extracts of 19 plant species grown and used in Taiwan. The antioxidant activity of leafy plant extracts was determined by measuring the trolox equivalent antioxidant capacity (TEAC), oxygen radical absorption capacity (ORAC), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity. Polyphenol, flavonol, and flavonoid levels were high in <i>Sonchus</i><i> </i><i>oleraceus</i> (SO), <i>Ohwia</i><i> </i><i>caudate</i><i> </i>Thunb. Ohashi (OC), <i>Foeniculum</i><i> </i><i>vulgare</i> Mill. (FV), and <i>Artemisia</i><i> </i><i>princeps</i><i> </i>Pamp. var. orientalis (Pamp.) Hars. (ArP, fresh) as compared to the rest of tested plants. In addition, quercetin, myricetin, and morin were abundant in <i>Dendranthe</i><i> </i><i>mamori</i><i> </i><i>folium</i> (Ramat.) Tzvelev. (DM, dry), FV, SO, <i>Alternanthera</i><i> </i><i>philoxeroides</i> (Moq.) Griseb. (AlP), ArP (fresh) and <i>Lonicera</i><i> </i><i>japonica </i>Thunb. (LJ). Higher levels of the TEAC, ORAC, and DPPH radical scavenger were generated from extracts of OC, SO, DM (dry), and ArP (fresh). Significant and positive correlations among antioxidant activity and polyphenols and anthocyanidins were observed. ORAC values were also correlated with quercitin and morin. Therefore, these phytochemicals were some of the main components responsible for the antioxidant efficacy of tested plants.