In vitro and in vivo anti-angiogenesis effect of shallot (Allium ascalonicum): A heat-stable and flavonoid-rich fraction of shallot extract potently inhibits angiogenesis

This study has been undertaken to elucidate the anti-angiogenic properties of shallot extract in vitro and in vivo and also to define the responsible fraction and its stability. After preparation of the extract of shallot bulbs with 50% ethanol, the extract was successively fractionated into n-hexane, ethyl acetate, n-butanol and aqueous fractions. The ethyl acetate fraction was further fractionated to three subfractions using thin layer chromatography. Anti-angiogenic activity of fractions and subfractions were examined on human umbilical vein endothelial cells (HUVECs) in collagen matrix and chicken chorioallantoic membrane (CAM) models. Among the fractions, ethyl acetate fraction and one of its subfractions potently inhibited angiogenesis in vitro and in vivo. Furthermore, ethyl acetate fraction sustained its inhibitory effect significantly even after treatment in high thermal and low pH conditions. These findings provided a useful basis for further investigations on shallot as a useful herb with therapeutic or preventive activity against angiogenesis related disorders.