Chemical composition, antioxidant and antimicrobial activity of Chinese tallow tree leaves

In the present study, the chemical compositions, antioxidant and antimicrobial activities of fractions of extracts of Chinese tallow tree (CTT, Sapium sebiferum L.) leaves were evaluated. The ethanol extract of CTT leaves was fractionated, then obtained ethyl acetate fraction (EAF), n-butyl alcohol fraction (nBF) and water residue fraction (WF). UPLC-PDA method was adopted for chemical composition analysis; Four chemical methods, including DPPH and ABTS radicals scavenging, reducing power and ORAC assays were adopted for the determination of antioxidant activities; MIC method was employed to test inhibitory effects on Staphylococcus aureus growth. Eight phenolic compounds were identified, including gallic acid, rutin, ellagic acid, hyperin, isoquercitrin, astragalin, quercetin and keampferol. EAF contained higher contents of all identified components except rutin. Meantime, WF contained more un-retained, high polar compounds. All fractions exhibited antioxidant activities. EAF exhibited strongest antioxidant activity, nBF taken second place, while antioxidant of WF was weakest. The anti-bacterial activity was also found in order of EAF > nBF > WF. Results of bioactivity tests were in accordance to the relative content of most identified phenolic compounds, which indicate that identified compounds may be responsible for the bioactivity of CTT leaves. This study provided evidence for the selection of EAF of CTT leaves as a bioactivity resource, which might improve the development and application of CTT leaves.