In vitro Antioxidative Activities and Phenolic Composition of Hot Water Extract from Different Parts of Cudrania tricuspidata

We evaluated total phenolics and antioxidative activities of water extracts from different parts of Cudrania tricuspidata (specifically, the leaves, stems, roots, and fruits). The antioxidative activities of these samples were determined using five methods, including 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid (ABTS) radical scavenging, reducing power, ferric reducing ability of plasma (FRAP), and $\beta$-carotene/linoleic acid system. The water extract of leaves exhibited the higher DPPH, ABTS radical scavenging activities, reducing power, and FRAP than water extract of stem, roots, and fruits. Inhibition values on linoleic oxidation of water extracts from leaves, stems, roots, and fruits were calculated as 45.98%, 33.03%, 39.73%, and 25.48% at 10 mg/mL, respectively. The water extract of C. tricuspidata leaves had the highest amount of toal phenolics (73.60$\pm$0.28 mg/g). High-performance liquid chromatography (HPLC) analysis showed that quercetin is the predominant phenolic compound in water extract of leaves. Thus, our study verified that the water extract of leaves has strong antioxidant activities which are correlated with its high level of phenolic compounds, particularly quercetin. This water extract of C. tricuspidata leaves can be used as an effective and safe source of antioxidants.