Screening for aromatase ligands in the extract of Broussonetia papyrifera using high performance liquid chromatography and ESI-mass spectrometry

Aromatase (CYP19), which can catalyze the conversion of androgens to estrogens, has been one of the main inducers of hormone-related cancers. As a result, it is very important and necessary to find an aromatase inhibitor quickly and effectively. In this article, we screened for compounds that can bind to aromatase in the extract of Broussonetia papyrifera. The screening method HPLC/ESI-MS was employed in this presentation. Structures of twelve compounds were studied on the basis of LC-MS data. Six compounds were characterized as aromatase ligands through HPLC. Three of the ligands were identified as the glucosides of scopoletin, kaempferol and apigenin, whilst the others were vitexin, luteolin-7-O-β-D-glucopyranosid and dihydrochalcone. The bioassay indicated these compounds had aromatase inhibitory activity. We concluded that HPLC/ESI-MS was an effective means to reveal aromatase ligands. Moreover, five of the ligands found in this study were flavonoids. The C2, C3 double bond and the 7-OH were essential for the binding activity, which may be the binding sites for flavonoids.