Betulin

Betulin (Fig. 1) (purity?≥?98%, determined by the normalization method using HPLC) was purchased from Sichuan Weikeqi Bio- technology Co., Ltd. (Sichuan, People's Republic of China). HPLC-grade methanol and formic acid used for UPLC analysis were purchased from J. T.

Betulin (purity≥98%, determined by the normalization method using HPLC) was purchased from Sichuan Weikeqi Bio-technology Co., Ltd. (Fig. 1). HPLC-grade DPPH and ABTS (purity≥98%, determined by the normalization method using HPLC) were purchased from Nanjing Bio-technology Co.

Reference compounds, comprising specnuezhenide, oleuropein, nuezhenidic acid, ligustroflavone, G13, oleoside 11-methyl ester, tyrosol, hydroxytyrosol, salidroside, acteoside, protocatechuic acid, galuteolin, apigenin, quercitrin, rutin, luteolin, quercetin, oleanolic acid, ursolic acid, betulin, emodinmonomethyl ether, 3β-O-acetylpomolic acid, oleonuezhenide, 6′-O-trans-cinnamoyl-8-epikingisidic acid, ligulucidumoside A, ligulucidumoside C, oleuropeinic acid, echinacoside, 3β-O-acetylpomolic acid, oleonuezhenide, 6′-O-trans-cinnamoyl-8-epikingisidic acid, ligulucidumoside A, ligulucidumoside C and geniposide (purity ≥98%), were provided by Yifang S&T Co. Ltd (Tianjin, China), the National Institutes for Food and Drug Control and Sichuan Weikeqi Pharmaceutical Technology Co. Ltd. Methanol and acetonitrile (chromatographic purity) were obtained from Fisher Scientific (Fair Lawn, NJ, USA). The Milli-Q water purification system (Millipore, Bedford, MA, USA) was used to produce Ultrapure-water. All reagents were analytical grade.